Service Component Architecture Assembly Model Specification
Version 1.1
12 January 2010
Specification URIs:
This Version:
http://docs.oasis-open.org/opencsa/sca-assembly/sca-assembly-1.1-spec-cd05.html
http://docs.oasis-open.org/opencsa/sca-assembly/sca-assembly-1.1-spec-cd05.doc
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http://docs.oasis-open.org/opencsa/sca-assembly/sca-assembly-1.1-spec-cd03.pdf (Authoritative)
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http://docs.oasis-open.org/opencsa/sca-assembly/sca-assembly-1.1-spec.html
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Technical Committee:
OASIS Service Component Architecture / Assembly (SCA-Assembly) TC
Chair(s):
Martin Chapman, Oracle
Mike Edwards, IBM
Editor(s):
Michael Beisiegel, IBM
Khanderao Khand, Oracle
Anish Karmarkar, Oracle
Sanjay Patil, SAP
Michael Rowley, Active Endpoints
Related work:
This specification replaces or supercedes:
This specification is related to:
Declared XML Namespace(s):
http://docs.oasis-open.org/ns/opencsa/sca/200912
Abstract:
Service Component Architecture (SCA) provides a programming model for building applications and solutions based on a Service Oriented Architecture. It is based on the idea that business function is provided as a series of services, which are assembled together to create solutions that serve a particular business need. These composite applications can contain both new services created specifically for the application and also business function from existing systems and applications, reused as part of the composition. SCA provides a model both for the composition of services and for the creation of service components, including the reuse of existing application function within SCA composites.
SCA is a model that aims to encompass a wide range of technologies for service components and for the access methods which are used to connect them. For components, this includes not only different programming languages, but also frameworks and environments commonly used with those languages. For access methods, SCA compositions allow for the use of various communication and service access technologies that are in common use, including, for example, Web services, Messaging systems and Remote Procedure Call (RPC).
The SCA Assembly Model consists of a series of artifacts which define the configuration of an SCA Domain in terms of composites which contain assemblies of service components and the connections and related artifacts which describe how they are linked together.
This document describes the SCA Assembly Model, which covers
· A model for the assembly of services, both tightly coupled and loosely coupled
· A model for applying infrastructure capabilities to services and to service interactions, including Security and Transactions
Status:
This document was last revised or approved by the OASIS Service Component Architecture / Assembly (SCA-Assembly) TC on the above date. The level of approval is also listed above. Check the “Latest Version” or “Latest Approved Version” location noted above for possible later revisions of this document.
Technical Committee members should send comments on this specification to the Technical Committee’s email list. Others should send comments to the Technical Committee by using the “Send A Comment” button on the Technical Committee’s web page at http://www.oasis-open.org/committees/sca-assembly/.
For information on whether any patents have been disclosed that may be essential to implementing this specification, and any offers of patent licensing terms, please refer to the Intellectual Property Rights section of the Technical Committee web page (http://www.oasis-open.org/committees/sca-assembly/ipr.php.
The non-normative errata page for this
specification is located at
http://www.oasis-open.org/committees/sca-assembly/
Copyright © OASIS® 2005, 20092010.
All Rights Reserved.
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The names "OASIS", "SCA" and "Service Component Architecture" are trademarks of OASIS, the owner and developer of this specification, and should be used only to refer to the organization and its official outputs. OASIS welcomes reference to, and implementation and use of, specifications, while reserving the right to enforce its marks against misleading uses. Please see http://www.oasis-open.org/who/trademark.php for above guidance.
2.1 Diagram used to Represent SCA Artifacts
3 Implementation and ComponentType
4.3.1 Specifying the Target Service(s) for a Reference.
4.4.1 Property Type Compatibility
5.5 Using Composites as Component Implementations
5.5.1 Component Type of a Composite used as a Component Implementation
5.5.2 Example of Composite used as a Component Implementation
5.6 Using Composites through Inclusion
5.6.1 Included Composite Examples
5.7 Composites which Contain Component Implementations of Multiple Types
5.8 Structural URI of Components
6.1 Local and Remotable Interfaces
6.4 Long-running Request-Response Operations
6.4.2 Definition of "long-running"
6.4.3 The asyncInvocation Intent
6.4.4 Requirements on Bindings
6.4.5 Implementation Type Support
6.5 SCA-Specific Aspects for WSDL Interfaces
6.6.1 Example of interface.wsdl
7.1 Messages containing Data not defined in the Service Interface
7.4 Form of the URI of a Deployed Binding
7.4.2 Determining the URI scheme of a deployed binding
9.1 Defining an Interface Type
9.2 Defining an Implementation Type
10.2.1 SCA Artifact Resolution
10.2.2 SCA Contribution Metadata Document
10.2.3 Contribution Packaging using ZIP
10.3 States of Artifacts in the Domain
10.4.1 Installed Artifact URIs
10.5 Operations for Contributions
10.5.1 install Contribution & update Contribution
10.5.2 add Deployment Composite & update Deployment Composite
10.6 Use of Existing (non-SCA) Mechanisms for Resolving Artifacts
10.7.1 add To Domain-Level Composite
10.7.2 remove From Domain-Level Composite
10.7.3 get Domain-Level Composite
10.8 Dynamic Behaviour of Wires in the SCA Domain
10.9 Dynamic Behaviour of Component Property Values.
11.1.1 Errors which can be Detected at Deployment Time
11.1.2 Errors which are Detected at Runtime
A.6 sca-implementation-java.xsd
A.7 sca-implementation-composite.xsd
A.8 sca-binding-webservice.xsd
This document describes the SCA Assembly Model, which covers
· A model for the assembly of services, both tightly coupled and loosely coupled
· A model for applying infrastructure capabilities to services and to service interactions, including Security and Transactions
The document starts with a short overview of the SCA Assembly Model.
The next part of the document describes the core elements of SCA, SCA components and SCA composites.
The final part of the document defines how the SCA assembly model can be extended.
This specification is defined in terms of Infoset and not in terms of XML 1.0, even though the specification uses XML 1.0 terminology. A mapping from XML to infoset is trivial and it is suggested that this is used for any non-XML serializations.
The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in this document are to be interpreted as described in [RFC2119].
S. Bradner, Key words for use in RFCs to Indicate Requirement
Levels,
IETF RFC 2119, March 1997.
http://www.ietf.org/rfc/rfc2119.txt,
IETF RFC 2119, March 1997.
[SCA-Java]
OASIS Committee Draft
01, "SCA JavaPOJO
Component Implementation Specification Version 1.1", May
2009
OASIS Committee Draft 03, "SCA Java Common Annotations and APIs Specification Version 1.1", May 2009
[SCA BPEL]
OASIS Committee Draft 02, "SCA WS-BPEL Client and Implementation Specification Version 1.1", March 2009
http://docs.oasis-open.org/opencsa/sca-bpel/sca-bpel-1.1-spec-cd-0102.pdf
[SDO] SDO
OASIS Committee Draft 02, "Service Data Objects Specification Version 3.0", November 2009
[3] SCA Example Code document
JAX-WS Specification
[4] JAX-WS SpecificationWSI-BP]
http://jcp.org/en/jsr/detail?id=101
[5] WS-I
Basic Profile
http://www.ws-i.org/deliverables/workinggroup.aspx?wg=basicprofile
WS-I Basic Security Profile
http://www.ws-i.org/deliverables/workinggroup.aspx?wg=basicsecurity
OASIS Standard,
"Web Services Business Process Execution Language (BPEL)Version
2.0"
http://wwwdocs.oasis-open.org/committees/documents.php?wg_abbrev=wsbpel/2.0/OS/wsbpel-v2.0-OS.pdf
[8]
WSDL-11]
WSDL Specification version 1.1
WSDL 1.1: http://www.w3.org/TR/wsdl
WSDL 2.0:
OASIS Committee Draft 03, "SCA Web Services Binding Specification Version 1.1", July 2009
http://www.w3docs.oasis-open.org/TR/wsdl20/opencsa/sca-bindings/sca-wsbinding-1.1-spec-cd03.pdf
[9] SCA Web
Services Binding Specification
OASIS Committee Draft 02, "SCA Policy Framework Specification Version 1.1", February 2009
http://docs.oasis-open.org/opencsa/sca-bindingspolicy/sca-wsbindingpolicy-1.1-spec-cd01cd02.pdf
[10] SCA Policy
Framework-JMSBINDING ]
OASIS Committee Draft 03, "SCA JMS Binding Specification Version 1.1 Version 1.1", July 2009
http://docs.oasis-open.org/opencsa/sca-policybindings/sca-policyjmsbinding-1.1-spec-cd-0103.pdf
[11]
[SCA
JMS Binding-CPP-Client]
OASIS Committee Draft 04, "SCA Client and Implementation for C++ Specification Version 1.1", March 2009
http://docs.oasis-open.org/opencsa/sca-bindingsc-cpp/sca-jmsbindingcppcni-1.1-spec-cd01cd04.pdf
[SCA-CPP-Client]
OASIS Committee Draft 03, "SCA C++
Client and Implementation for C Specification
Version 1.1", March 2009
http://docs.oasis-open.org/opencsa/sca-c-cpp/sca-cppcniccni-1.1-spec-cd-0104.pdf
[SCA-C-Client] SCA C
Client and Implementation SpecificationZIP-FORMAT]
http://docs.oasis-open.org/opencsa/sca-c-cpp/sca-ccni-1.1-spec-cd-01.pdf
[12] ZIP Format Definition
http://www.pkware.com/documents/casestudies/APPNOTE.TXT
[13] XML-INFOSET]
Infoset Specification
http://www.w3.org/TR/xml-infoset/
[WSDL11_Identifiers]
WSDL 1.1 Element Identiifiers
http://www.w3.org/TR/wsdl11elementidentifiers/
This specification follows some naming conventions for artifacts defined by the specification,
as follows:
·
For the names of elements and the names of attributes within XSD
files, the names follow the CamelCase convention, with all names starting with
a lower case letter.
e.g. <element name="componentType"
type="sca:ComponentType"/>
·
For the names of types within XSD files, the names follow the
CamelCase convention with all names starting with an upper case letter.
eg. <complexType name="ComponentService">
·
For the names of intents, the names follow the CamelCase
convention, with all names starting with a lower case letter, EXCEPT for cases
where the intent represents an established acronym, in which case the entire
name is in upper case.
An example of an intent which is an acronym is the "SOAP" intent.
Service Component Architecture (SCA) provides a programming model for building applications and solutions based on a Service Oriented Architecture. It is based on the idea that business function is provided as a series of services, which are assembled together to create solutions that serve a particular business need. These composite applications can contain both new services created specifically for the application and also business function from existing systems and applications, reused as part of the composition. SCA provides a model both for the composition of services and for the creation of service components, including the reuse of existing application function within SCA composites.
SCA is a model that aims to encompass a wide range of technologies for service components and for the access methods which are used to connect them. For components, this includes not only different programming languages, but also frameworks and environments commonly used with those languages. For access methods, SCA compositions allow for the use of various communication and service access technologies that are in common use, including, for example, Web services, Messaging systems and Remote Procedure Call (RPC).
The SCA Assembly Model consists of a series of artifacts which define the configuration of an SCA Domain in terms of composites which contain assemblies of service components and the connections and related artifacts which describe how they are linked together.
One basic artifact of SCA is the component, which is the unit of construction for SCA. A component consists of a configured instance of an implementation, where an implementation is the piece of program code providing business functions. The business function is offered for use by other components as services. Implementations can depend on services provided by other components – these dependencies are called references. Implementations can have settable properties, which are data values which influence the operation of the business function. The component configures the implementation by providing values for the properties and by wiring the references to services provided by other components.
SCA allows for a wide variety of implementation technologies, including "traditional" programming languages such as Java, C++, and BPEL, but also scripting languages such as PHP and JavaScript and declarative languages such as XQuery and SQL.
SCA describes the content and linkage of an application in assemblies called composites. Composites can contain components, services, references, property declarations, plus the wiring that describes the connections between these elements. Composites can group and link components built from different implementation technologies, allowing appropriate technologies to be used for each business task. In turn, composites can be used as complete component implementations: providing services, depending on references and with settable property values. Such composite implementations can be used in components within other composites, allowing for a hierarchical construction of business solutions, where high-level services are implemented internally by sets of lower-level services. The content of composites can also be used as groupings of elements which are contributed by inclusion into higher-level compositions.
Composites are deployed within an SCA Domain. An SCA Domain typically represents a set of services providing an area of business functionality that is controlled by a single organization. As an example, for the accounts department in a business, the SCA Domain might cover all financial related function, and it might contain a series of composites dealing with specific areas of accounting, with one for customer accounts, another dealing with accounts payable. To help build and configure the SCA Domain, composites can be used to group and configure related artifacts.
SCA defines an XML file format for its artifacts. These XML files define the portable representation of the SCA artifacts. An SCA runtime might have other representations of the artifacts represented by these XML files. In particular, component implementations in some programming languages might have attributes or properties or annotations which can specify some of the elements of the SCA Assembly model. The XML files define a static format for the configuration of an SCA Domain. An SCA runtime might also allow for the configuration of the Domain to be modified dynamically.
This document introduces diagrams to represent the various SCA artifacts, as a way of visualizing the relationships between the artifacts in a particular assembly. These diagrams are used in this document to accompany and illuminate the examples of SCA artifacts and do not represent any formal graphical notation for SCA.
The following pictureFigure
2‑1Figure
2‑1
illustrates some of the features of an SCA component:
Figure 122‑1:
SCA Component Diagram
The following pictureFigure
2‑2Figure
2‑2
illustrates some of the features of a composite assembled using a set of
components:
Figure 222‑2:
SCA Composite Diagram
The following pictureFigure
2‑3Figure
2‑3
illustrates an SCA Domain assembled from a series of high-level composites,
some of which are in turn implemented by lower-level composites:
Figure 322‑3:
SCA Domain Diagram
Component implementations are concrete implementations of business function which provide services and/or which make references to services provided elsewhere. In addition, an implementation can have some settable property values.
SCA allows a choice of any one of a wide range of implementation types, such as Java, BPEL or C++, where each type represents a specific implementation technology. The technology might not simply define the implementation language, such as Java, but might also define the use of a specific framework or runtime environment. Examples include SCA Composite, Java implementations done using the Spring framework or the Java EE EJB technology.
Services, references and properties are the configurable aspects of an implementation. SCA refers to them collectively as the component type.
Depending on the implementation type, the implementation can declare the services, references and properties that it has and it also might be able to set values for all the characteristics of those services, references and properties.
So, for example:
· for a service, the implementation might define the interface, binding(s), a URI, intents, and policy sets, including details of the bindings
· for a reference, the implementation might define the interface, binding(s), target URI(s), intents, policy sets, including details of the bindings
· for a property the implementation might define its type and a default value
· the implementation itself might define policy intents or concrete policy sets
The means by which an implementation declares its services, references and properties depend on the type of the implementation. For example, some languages like Java, provide annotations which can be used to declare this information inline in the code.
Most of the characteristics of the services, references and properties can be overridden by a component that uses and configures the implementation, or the component can decide not to override those characteristics. Some characteristics cannot be overridden, such as intents. Other characteristics, such as interfaces, can only be overridden in particular controlled ways (see the Component section for details).
Component type represents the configurable aspects of an implementation. A component type consists of services that are offered, references to other services that can be wired and properties that can be set. The settable properties and the settable references to services are configured by a component that uses the implementation.
An implementation type specification (for example, the WS-BPEL Client and Implementation Specification Version 1.1 [SCA BPEL]) specifies the mechanism(s) by which the component type associated with an implementation of that type is derived.
Since SCA allows a broad range of implementation technologies, it is expected that some implementation technologies (for example, the Java Component Implementation Specification Version 1.1 [SCA-Java]) allow for introspecting the implementation artifact(s) (for example, a Java class) to derive the component type information. Other implementation technologies might not allow for introspection of the implementation artifact(s). In those cases where introspection is not allowed, SCA encourages the use of a SCA component type side file. A component type side file is an XML file whose document root element is sca:componentType.
The implementation type specification defines whether introspection is allowed, whether a side file is allowed, both are allowed or some other mechanism specifies the component type. The component type information derived through introspection is called the introspected component type. In any case, the implementation type specification specifies how multiple sources of information are combined to produce the effective component type. The effective component type is the component type metadata that is presented to the using component for configuration.
The extension of a componentType side file name MUST be .componentType. [ASM40001] The name and location of a componentType side file, if allowed, is defined by the implementation type specification.
If a component type side file is not allowed for a particular implementation type, the effective component type and introspected component type are one and the same for that implementation type.
For the rest of this document, when the term 'component type' is used it refers to the 'effective component type'.
The following snippetSnippet 3‑1Snippet 3‑1 shows the componentType pseudo-schema:
<?xml version="1.0" encoding="ASCII"?>
<!-- Component type schema snippet -->
<componentType
xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903"
constrainingType="xs:QName"? 200912">
<service … />*
<reference … />*
<property … />*
<implementation … />?
</componentType>
The componentType element has the
following attribute:
·constrainingType :
QName (0..1) – If present, the @constrainingType attribute of a
<componentType/> element MUST reference a <constrainingType/>
element in the Domain through its QName. [ASM40002]
When specified, the set of services, references and properties of the
implementation, plus related intents, is constrained to the set defined by the
constrainingType. See the
ConstrainingType Section for more details.
The componentType element has the
following child elements:
Snippet 33‑1: componentType Pseudo-Schema
The componentType element has the child elements:
· service : Service (0..n) – see component type service section.
· reference : Reference (0..n) – see component type reference section.
· property : Property (0..n) – see component type property section.
· implementation : Implementation (0..1) – see component type implementation section.
A Service represents an addressable
interface of the implementation. The service is represented by a service
element which is a child of the componentType element. There can be zero
or more service elements in a componentType. The following
snippetSnippet
3‑2Snippet
3‑2
shows the component type componentType pseudo-schema
with the pseudo-schema for a service child
element:
<?xml version="1.0" encoding="ASCII"?>
<!-- Component type service schema snippet -->
<componentType
xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912" … >
<service name="xs:NCName"
requires="list of xs:QName"? policySets="list of xs:QName"?>*
<interface … />
<binding … />*
<callback>?
<binding … />+
</callback>
<requires/>*
<policySetAttachment/>*
</service>
<reference … />*
<property … />*
<implementation … />?
</componentType>
Snippet 33‑2: componentType Pseudo-Schema with service Child Element
The service element has the following
attributes:
· name : NCName (1..1) - the name of the service. The @name attribute of a <service/> child element of a <componentType/> MUST be unique amongst the service elements of that <componentType/>. [ASM40003]
·
requires : QNamelistOfQNames (0..n1)
- a list of policy intents. See the Policy Framework specification
[10]SCA-POLICY] for a description of this attribute.
·
policySets : QNamelistOfQNames (0..n1)
- a list of policy sets. See
the Policy Framework specification [10]SCA-POLICY] for a description of this attribute.
The service element has the following
child elements:
· interface : Interface (1..1) - A service has one interface, which describes the operations provided by the service. For details on the interface element see the Interface section.
· binding : Binding (0..n) - A service element has zero or more binding elements as children. If the binding element is not present it defaults to <binding.sca>. Details of the binding element are described in the Bindings section.
· callback (0..1) / binding : Binding (1..n) - A callback element is used if the interface has a callback defined, and the callback element has one or more binding elements as subelements. The callback and its binding subelements are specified if there is a need to have binding details used to handle callbacks. If the callback element is not present, the behaviour is runtime implementation dependent. For details on callbacks, see the Bidirectional Interfaces section.
· requires : requires (0..n) - A service element has zero or more requires subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
· policySetAttachment : policySetAttachment (0..n) - A service element has zero or more policySetAttachment subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
A Reference represents a requirement that the implementation
has on a service provided by another component. The reference is represented by
a reference element which is a child of the componentType element.
There can be zero or more reference elements in a component type definition. The following snippetSnippet 3‑3Snippet 3‑3 shows the component
type componentType pseudo-schema
with the pseudo-schema for a reference child element:
<?xml version="1.0" encoding="ASCII"?>
<!-- Component type reference schema snippet -->
<componentType
xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912" … >
<service … />*
<reference name="xs:NCName"
autowire="xs:boolean"?
multiplicity="0..1 or 1..1 or 0..n or 1..n"?
wiredByImpl="xs:boolean"?
requires="list of xs:QName"?
policySets="list of xs:QName"?>*
<interface … />
<binding … />*
<callback>?
<binding … />+
</callback>
<requires/>*
<policySetAttachment/>*
</reference>
<property … />*
<implementation … />?
</componentType>
Snippet 33‑3: componentType Pseudo-Schema with reference Child Element
The reference element has the following
attributes:
· name : NCName (1..1) - the name of the reference. The @name attribute of a <reference/> child element of a <componentType/> MUST be unique amongst the reference elements of that <componentType/>. [ASM40004]
· multiplicity : 0..1|1..1|0..n|1..n (0..1) - defines the number of wires that can connect the reference to target services. The multiplicity can have the following values
– 0..1 – zero or one wire can have the reference as a source
– 1..1 – one wire can have the reference as a source
– 0..n - zero or more wires can have the reference as a source
– 1..n – one or more wires can have the reference as a source
If @multiplicity is not specified, the default value is "1..1".
· autowire : boolean (0..1) - whether the reference is autowired, as described in the Autowire section. Default is false.
· wiredByImpl : boolean (0..1) - a boolean value, "false" by default. If set to "false", the reference is wired to the target(s) configured on the reference. If set to "true" it indicates that the target of the reference is set at runtime by the implementation code (e.g. by the code obtaining an endpoint reference by some means and setting this as the target of the reference through the use of programming interfaces defined by the relevant Client and Implementation specification). If @wiredByImpl is set to "true", then any reference targets configured for this reference MUST be ignored by the runtime. [ASM40006]
·
requires : QNamelistOfQNames (0..n1)
- a list of policy intents. See the Policy Framework specification
[10]SCA-POLICY] for a description of this attribute.
·
policySets : QNamelistOfQNames (0..n1)
- a list of policy sets. See
the Policy Framework specification [10]SCA-POLICY] for a description of this attribute.
The reference element has the following
child elements:
· interface : Interface (1..1) - A reference has one interface, which describes the operations used by the reference. The interface is described by an interface element which is a child element of the reference element. For details on the interface element see the Interface section.
· binding : Binding (0..n) - A reference element has zero or more binding elements as children. Details of the binding element are described in the Bindings section.
When used with a reference element, a binding element specifies an endpoint which is the target of that binding. A reference cannot mix the use of endpoints specified via binding elements with target endpoints specified via the @target attribute. If the @target attribute is set, the reference cannot also have binding subelements. If binding elements with endpoints are specified, each endpoint uses the binding type of the binding element in which it is defined.
· callback (0..1) / binding : Binding (1..n) - al callback element is used if the interface has a callback defined and the callback element has one or more binding elements as subelements. The callback and its binding subelements are specified if there is a need to have binding details used to handle callbacks. If the callback element is not present, the behaviour is runtime implementation dependent. For details on callbacks, see the Bidirectional Interfaces section.
· requires : requires (0..n) - A service element has zero or more requires subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
· policySetAttachment : policySetAttachment (0..n) - A service element has zero or more policySetAttachment subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
For a full description of the setting of target service(s) for a reference, see the section "Specifying the Target Service(s) for a Reference".
Properties allow for the configuration of an implementation
with externally set values. Each Property is defined as a property element.
The componentType element can have zero
or more property elements as
its children. The following
snippetSnippet 3‑4Snippet 3‑4 shows the component type componentType pseudo-schema
with the pseudo-schema for a reference child element:
<?xml version="1.0" encoding="ASCII"?>
<!-- Component type property schema snippet -->
<componentType
xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912" … >
<service … />*
<reference … >*
<property name="xs:NCName" (type="xs:QName" | element="xs:QName")
many="xs:boolean"?
mustSupply="xs:boolean"?
requires="list of
xs:QName"?
policySets="list of
xs:QName"?>*
default-property-value?
</property>
<implementation … />?
</componentType>
Snippet 33‑4: componentType Pseudo-Schema with property Child Element
The property element has the following
attributes:
· name : NCName (1..1) - the name of the property. The @name attribute of a <property/> child element of a <componentType/> MUST be unique amongst the property elements of that <componentType/>. [ASM40005]
· one of (1..1):
– type : QName - the type of the property defined as the qualified name of an XML schema type. The value of the property @type attribute MUST be the QName of an XML schema type. [ASM40007]
– element : QName - the type of the property defined as the qualified name of an XML schema global element – the type is the type of the global element. The value of the property @element attribute MUST be the QName of an XSD global element. [ASM40008]
A single property element MUST NOT contain both a @type attribute and an @element attribute. [ASM40010]
· many : boolean (0..1) - whether the property is single-valued (false) or multi-valued (true). In the case of a multi-valued property, it is presented to the implementation as a collection of property values. If many is not specified, it takes a default value of false.
· mustSupply : boolean (0..1) - whether the property value needs to be supplied by the component that uses the implementation. Default value is "false". When the componentType has @mustSupply="true" for a property element, a component using the implementation MUST supply a value for the property since the implementation has no default value for the property. [ASM40011] If the implementation has a default-property-value then @mustSupply="false" is appropriate, since the implication of a default value is that it is used when a value is not supplied by the using component.
· file : anyURI (0..1) - a dereferencable URI to a file containing a value for the property.
§requires
: QName (0..n) - a list of policy
intents. See the Policy Framework specification [10] for a
description of this attribute.
§policySets
: QName (0..n) - a list of policy
sets. See the Policy Framework specification [10] for a
description of this attribute.
The property element can contain a default property value as its content. The form of the default property value is as described in the section on Component Property.
The value for a property is supplied to the implementation of a component at the time that the implementation is started. The implementation can use the supplied value in any way that it chooses. In particular, the implementation can alter the internal value of the property at any time. However, if the implementation queries the SCA system for the value of the property, the value as defined in the SCA composite is the value returned.
The componentType property element can contain an SCA default value for the property declared by the implementation. However, the implementation can have a property which has an implementation defined default value, where the default value is not represented in the componentType. An example of such a default value is where the default value is computed at runtime by some code contained in the implementation. If a using component needs to control the value of a property used by an implementation, the component sets the value explicitly. The SCA runtime MUST ensure that any implementation default property value is replaced by a value for that property explicitly set by a component using that implementation. [ASM40009]
Implementation represents characteristics inherent to the
implementation itself, in particular intents and policies. See the Policy
Framework specification [10]SCA-POLICY] for a description of intents and policies. The following snippetSnippet 3‑5Snippet 3‑5 shows the component
typecomponentType pseudo-schema with the pseudo-schema for a
implementation child element:
<?xml version="1.0" encoding="ASCII"?>
<!-- Component type implementation schema snippet -->
<componentType
xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912" … >
<service … />*
<reference … >*
<property … />*
<implementation requires="list of xs:QName"?
policySets="list of xs:QName"?/"?>
<requires/>*
<policySetAttachment/>*
</implementation>?
</componentType>
Snippet 33‑5: componentType Pseudo-Schema with implementation Child Element
The implementation element has the following
attributes:
·
requires : QNamelistOfQNames (0..n1)
- a list of policy intents. See the Policy Framework specification
[10]SCA-POLICY] for a description of this attribute.
·
policySets : QNamelistOfQNames (0..n1)
- a list of policy sets. See
the Policy Framework specification [10]SCA-POLICY] for a description of this attribute.
The implementation element has the subelements:
· requires : requires (0..n) - A service element has zero or more requires subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
· policySetAttachment : policySetAttachment (0..n) - A service element has zero or more policySetAttachment subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
The following snippetSnippet 3‑6Snippet 3‑6 shows the contents of the componentType file for
the MyValueServiceImpl implementation. The componentType file shows the
services, references, and properties of the MyValueServiceImpl implementation.
In this case, Java is used to define interfaces:
<?xml version="1.0" encoding="ASCII"?>
<componentType
xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903">
<componentType xmlns=http://docs.oasis-open.org/ns/opencsa/sca/200912
xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<service name="MyValueService">
<interface.java interface="services.myvalue.MyValueService"/>
</service>
<reference name="customerService">
<interface.java interface="services.customer.CustomerService"/>
</reference>
<reference name="stockQuoteService">
<interface.java
interface="services.stockquote.StockQuoteService"/>
</reference>
<property name="currency" type="xsd:string">USD</property>
</componentType>
Snippet 33‑6: Example componentType
The following is an example implementation, written
in Java. See the SCA Example Code document [3] for details.
Snippet 3‑7Snippet 3‑7 and Snippet 3‑8Snippet 3‑8 are an example implementation, written in Java.
AccountServiceImpl implements the AccountService interface, which is defined via a Java interface:
package services.account;
@Remotable
public interface AccountService {
AccountReport getAccountReport(String customerID);
}
The followingSnippet 33‑7:
Example Interface in Java
Snippet 3‑8Snippet 3‑8 is a full listing of the AccountServiceImpl class, showing the Service it implements, plus the service references it makes and the settable properties that it has. Notice the use of Java annotations to mark SCA aspects of the code, including the @Property, @Reference and @Service annotations:
package services.account;
import java.util.List;
import commonj.sdo.DataFactory;
import org.oasisopen.sca.annotation.Property;
import org.oasisopen.sca.annotation.Reference;
import org.oasisopen.sca.annotation.Service;
import services.accountdata.AccountDataService;
import services.accountdata.CheckingAccount;
import services.accountdata.SavingsAccount;
import services.accountdata.StockAccount;
import services.stockquote.StockQuoteService;
@Service(AccountService.class)
public class AccountServiceImpl implements AccountService {
@Property
private String currency = "USD";
@Reference
private AccountDataService accountDataService;
@Reference
private StockQuoteService stockQuoteService;
public AccountReport getAccountReport(String customerID) {
DataFactory dataFactory = DataFactory.INSTANCE;
AccountReport accountReport =
(AccountReport)dataFactory.create(AccountReport.class);
List accountSummaries = accountReport.getAccountSummaries();
CheckingAccount checkingAccount = accountDataService.getCheckingAccount(customerID);
AccountSummary checkingAccountSummary =
(AccountSummary)dataFactory.create(AccountSummary.class);
checkingAccountSummary.setAccountNumber(checkingAccount.getAccountNumber());
checkingAccountSummary.setAccountType("checking");
checkingAccountSummary.setBalance(fromUSDollarToCurrency(checkingAccount.getBalance()));
accountSummaries.add(checkingAccountSummary);
SavingsAccount savingsAccount = accountDataService.getSavingsAccount(customerID);
AccountSummary savingsAccountSummary =
(AccountSummary)dataFactory.create(AccountSummary.class);
savingsAccountSummary.setAccountNumber(savingsAccount.getAccountNumber());
savingsAccountSummary.setAccountType("savings");
savingsAccountSummary.setBalance(fromUSDollarToCurrency(savingsAccount.getBalance()));
accountSummaries.add(savingsAccountSummary);
StockAccount stockAccount = accountDataService.getStockAccount(customerID);
AccountSummary stockAccountSummary =
(AccountSummary)dataFactory.create(AccountSummary.class);
stockAccountSummary.setAccountNumber(stockAccount.getAccountNumber());
stockAccountSummary.setAccountType("stock");
float balance =
(stockQuoteService.getQuote(stockAccount.getSymbol()))*stockAccount.getQuantity();
stockAccountSummary.setBalance(fromUSDollarToCurrency(balance));
accountSummaries.add(stockAccountSummary);
return accountReport;
}
private float fromUSDollarToCurrency(float value){
if (currency.equals("USD")) return value; else
if (currency.equals("EURO")) return value * 0.8f; else
return 0.0f;
}
}
Snippet 33‑8: Example Component Implementation in Java
The following is the SCA componentType definition for the AccountServiceImpl, derived by introspection of the code above:
<?xml version="1.0" encoding="ASCII"?>
<componentType
xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<service name="AccountService">
<interface.java interface="services.account.AccountService"/>
</service>
<reference name="accountDataService">
<interface.java
interface="services.accountdata.AccountDataService"/>
</reference>
<reference name="stockQuoteService">
<interface.java
interface="services.stockquote.StockQuoteService"/>
</reference>
<property name="currency" type="xsd:string"/>
</componentType>
Snippet 33‑9: Example componentType for Implementation in Snippet 3‑8Snippet 3‑8
Note that the componentType property element for "currency" has no default value declared, despite the code containing an initializer for the property field setting it to "USD". This is because the initializer cannot be introspected at runtime and the value cannot be extracted.
For full details about Java implementations, see the Java Component Implementation Specification [SCA-Java]. Other implementation types have their own specification documents.
Components are the basic elements of business function in an SCA assembly, which are combined into complete business solutions by SCA composites.
Components are configured instances of implementations. Components provide and consume services. More than one component can use and configure the same implementation, where each component configures the implementation differently.
Components are declared as subelements of a
composite in a file with a .composite extension. A component is represented by a component element which is a child of the composite element. There
can be zero or more component elements within a composite. The following snippetSnippet 4‑1Snippet 4‑1 shows the composite pseudo-schema with the pseudo-schema for the component child element.:
<?xml version="1.0" encoding="UTF-8"?>
<!-- Component schema snippet -->
<composite
xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912" … >
…
<component name="xs:NCName" autowire="xs:boolean"?
requires="list
of xs:QName"? policySets="list
of xs:QName"? "?>*
constrainingType="xs:QName"?>*
<implementation … />?
<service … />*
<reference … />*
<property … />*
<requires/>*
<policySetAttachment/>*
</component>
…
</composite>
The component element has the
following attributes:
·name : NCName
(1..1) – the name of the component. The @name attribute of a <component/> child
element of a <composite/> MUST be unique amongst the component elements
of that <composite/> [ASM50001]
Snippet 44‑1: composite Pseudo-Schema with component Child Element
The component element has the attributes:
· name : NCName (1..1) – the name of the component. The @name attribute of a <component/> child element of a <composite/> MUST be unique amongst the component elements of that <composite/>The @name attribute of a <component/> child element of a <composite/> MUST be unique amongst the component elements of that <composite/> [ASM50001]
· autowire : boolean (0..1) – whether contained component references are autowired, as described in the Autowire section. Default is false.
·
requires : QNamelistOfQNames (0..n1)
– a list of policy intents. See the Policy Framework specification
[10]SCA-POLICY] for a description of this attribute.
·
policySets : QNamelistOfQNames (0..n1)
– a list of policy sets. See
the Policy Framework specification [10]SCA-POLICY] for a description of this attribute.
·constrainingType :
QName (0..1) – the name of a
constrainingType. When specified, the set of services, references and
properties of the component, plus related intents, is constrained to the set
defined by the constrainingType. See the ConstrainingType
Section for more details.
The component element has the following
child elements:
· implementation : ComponentImplementation (0..1) – see component implementation section.
· service : ComponentService (0..n) – see component service section.
· reference : ComponentReference (0..n) – see component reference section.
· property : ComponentProperty (0..n) – see component property section.
· requires : requires (0..n) - A service element has zero or more requires subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
· policySetAttachment : policySetAttachment (0..n) - A service element has zero or more policySetAttachment subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
A component element has zero or one implementation element as its child, which points to the implementation
used by the component. A
component with no implementation element is not runnable, but components of
this kind can be useful during a "top-down" development process as a
means of defining the necessary characteristics of the implementation before
the implementation is written.
<?xml version="1.0" encoding="UTF-8"?>
<!-- Component Implementation schema snippet -->
<composite xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912" … >
…
<component … >*
<implementation … />?requires="list
of xs:QName"?
policySets="list of xs:QName"?>
<requires/>*
<policySetAttachment/>*
</implementation>
<service … />*
<reference … />*
<property … />*
</component>
…
</composite>
Snippet 44‑2: component Psuedo-Schema with implementation Child Element
The component provides the extensibility point in the assembly model for different implementation types. The references to implementations of different types are expressed by implementation type specific implementation elements.
For example the elements implementation.java, implementation.bpel, implementation.cpp, and implementation.c point to Java, BPEL, C++, and C implementation types respectively. implementation.composite points to the use of an SCA composite as an implementation. implementation.spring and implementation.ejb are used for Java components written to the Spring framework and the Java EE EJB technology respectively.
The following snippetsSnippet 4‑3Snippet 4‑3 – Snippet 4‑5Snippet 4‑5 show implementation elements for the Java and BPEL
implementation types and for the use of a composite as an implementation:
<implementation.java class="services.myvalue.MyValueServiceImpl"/>
Snippet 44‑3: Example implementation.java Element
<implementation.bpel process="ans:MoneyTransferProcess"/>
Snippet 44‑4: Example implementation.bpel Element
<implementation.composite name="bns:MyValueComposite"/>
Snippet 44‑5: Example implementation.composite Element
New implementation types can be added to the model as described in the Extension Model section.
At runtime, an implementation instance is a specific runtime instantiation of the implementation – its runtime form depends on the implementation technology used. The implementation instance derives its business logic from the implementation on which it is based, but the values for its properties and references are derived from the component which configures the implementation.
Figure 444‑1:
Relationship of Component and Implementation
The component element can have zero or more service elements as children which are used to configure the services
of the component. The services that can be configured are defined by the
implementation. The following
snippetSnippet 4‑6Snippet 4‑6 shows the component pseudo-schema with the pseudo-schema for a service child element:
<?xml version="1.0" encoding="UTF-8"?>
<!-- Component Service schema snippet -->
<composite xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912" … >
…
<component … >*
<implementation … />?
<service
name="xs:NCName" requires="list
of xs:QName"?
policySets="list
of xs:QName"?>*
<interface
… />?
<binding
… />*
<callback>?
<binding
… />+
</callback>
<requires/>*
<policySetAttachment/>*
</service>
<reference … />*
<property … />*
</component>
…
</composite>
Snippet 44‑6: component Psuedo-Schema with service Child Element
The component service element has the following
attributes:
·
name : NCName (1..1) - the name of the service. The @name attribute of
a service element of a <component/> MUST be unique amongst the service
elements of that <component/>The @name attribute of
a service element of a <component/> MUST be unique amongst the service
elements of that <component/> [ASM50002] The @name attribute of
a service element of a <component/> MUST match the @name attribute of a
service element of the componentType of the <implementation/> child
element of the component.The @name attribute of a service element of a
<component/> MUST match the @name attribute of a service element of the
componentType of the <implementation/> child element of the component. [ASM50003]
·
requires : QNamelistOfQNames (0..n1)
– a list of policy intents. See the Policy Framework specification
[10]SCA-POLICY] for a description of this attribute.
Note: The effective set of policy intents for the service consists of any
intents explicitly stated in this @requires attribute, combined with any
intents specified for the service by the implementation.
·
policySets : QNamelistOfQNames (0..n1)
– a list of policy sets. See
the Policy Framework specification [10]SCA-POLICY] for a description of this attribute.
The component
service element has the following child elements:
·
interface : Interface
(0..1) - A service has zero or one interface, which describes the operations provided by the
service. The interface is described by an interface
element which is a child
element of the service element. If no interface is specified, then the
interface specified for the service in the componentType of the implementation
is in effect. If a <service/>
element has an interface subelement
specifiedis declared for a component service, the interface MUST provide a compatible subset of
the interface declared onfor the equivalent
service in the componentType of the implementationIf an interface is
declared for a component service, the interface MUST provide a compatible
subset of the interface declared for the equivalent service in the
componentType of the implementation [ASM50004] For details on the interface element see the
Interface section.
·
binding : Binding (0..n) - A service element has zero or more binding
elements as children. If no binding elements
are specified for the service, then the bindings specified for the equivalent
service in the componentType of the implementation MUST be used, but if the
componentType also has no bindings specified, then <binding.sca/> MUST be
used as the binding. If binding elements are specified for the service, then
those bindings MUST be used and they override any bindings specified for the
equivalent service in the componentType of the implementation.If no binding elements
are specified for the service, then the bindings specified for the equivalent
service in the componentType of the implementation MUST be used, but if the
componentType also has no bindings specified, then <binding.sca/> MUST be
used as the binding. If binding elements are specified for the service, then
those bindings MUST be used and they override any bindings specified for the
equivalent service in the componentType of the implementation. [ASM50005] Details
of the binding element are described in the Bindings section. The binding, combined with any PolicySets in
effect for the binding, needs to satisfy the set of policy intents for the
service, as described in the Policy Framework
specification [10]SCA-POLICY].
·
callback (0..1) / binding
: Binding (1..n) - A callback element is used if the interface has a callback defined and the
callback element has one or more binding elements as subelements. The callback and its binding subelements are specified if there is a need to
have binding details used to handle callbacks. If the callback
element is present and contains one or more binding child elements, then those
bindings MUST be used for the callback.If the callback
element is present and contains one or more binding child elements, then those
bindings MUST be used for the callback. [ASM50006] If the callback element is not present, the
behaviour is runtime implementation dependent.
· requires : requires (0..n) - A service element has zero or more requires subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
· policySetAttachment : policySetAttachment (0..n) - A service element has zero or more policySetAttachment subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
The component element can have zero or more reference elements
as children which are used to configure the references of the component. The
references that can be configured are defined by the implementation. The following snippetSnippet 4‑7Snippet 4‑7 shows the component pseudo-schema with the pseudo-schema for a reference child element:
<?xml version="1.0" encoding="UTF-8"?>
<!-- Component Reference schema snippet -->
<composite
xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912" … >
…
<component … >*
<implementation … />?
<service … />*
<reference name="xs:NCName"
target="list of xs:anyURI"? autowire="xs:boolean"?
multiplicity="0..1 or 1..1 or 0..n or 1..n"?
nonOverridable="xs:boolean"
wiredByImpl="xs:boolean"? requires="list
of xs:QName"?
policySets="list of xs:QName"?>*
<interface … />?
<binding uri="xs:anyURI"? requires="list
of xs:QName"?
policySets="list
of xs:QName"?/>*
<callback>?
<binding … />+
</callback>
<requires/>*
<policySetAttachment/>*
</reference>
<property … />*
</component>
…
</composite>
Snippet 44‑7: component Psuedo-Schema with reference Child Element
The component
reference element has the following attributes:
·
name : NCName (1..1) – the name of the reference. The @name attribute of
a service element of a <component/> MUST be unique amongst the service
elements of that <component/>The @name attribute of
a service element of a <component/> MUST be unique amongst the service
elements of that <component/> [ASM50007] The @name attribute of
a reference element of a <component/> MUST match the @name attribute of a
reference element of the componentType of the <implementation/> child
element of the component.The @name attribute of a reference element of a
<component/> MUST match the @name attribute of a reference element of the
componentType of the <implementation/> child element of the component. [ASM50008]
·autowire : boolean
(0..1) – whether the reference is autowired, as described in the Autowire section. Default is false.
· The default value of the @autowire attribute MUST be the value of the @autowire attribute on the component containing the reference, if present, or else the value of the @autowire attribute of the composite containing the component, if present, and if neither is present, then it is "false".The default value of the @autowire attribute MUST be the value of the @autowire attribute on the component containing the reference, if present, or else the value of the @autowire attribute of the composite containing the component, if present, and if neither is present, then it is "false". [ASM50043]
·
requires : QNamelistOfQNames (0..n1)
– a list of policy intents. See the Policy Framework specification
[10]SCA-POLICY] for a description of this attribute.
Note: The effective set of policy intents for the reference consists of any
intents explicitly stated in this @requires attribute, combined with any
intents specified for the reference by the implementation.
·
policySets : QNamelistOfQNames (0..n1)
– a list of policy sets. See
the Policy Framework specification [10]SCA-POLICY] for a description of this attribute.
· multiplicity : 0..1|1..1|0..n|1..n (0..1) - defines the number of wires that can connect the reference to target services. Overrides the multiplicity specified for this reference in the componentType of the implementation. The multiplicity can have the following values
– 0..1 – zero or one wire can have the reference as a source
– 1..1 – one wire can have the reference as a source
– 0..n - zero or more wires can have the reference as a source
– 1..n – one or more wires can have the reference as a source
The value of multiplicity for a component reference
MUST only be equal or further restrict any value for the multiplicity of the
reference with the same name in the componentType of the implementation, where
further restriction means 0..n to 0..1 or 1..n to 1..1.The value of multiplicity for a component reference
MUST only be equal or further restrict any value for the multiplicity of the
reference with the same name in the componentType of the implementation, where
further restriction means 0..n to 0..1 or 1..n to 1..1. [ASM50009]
If not present, the value of multiplicity is equal to the multiplicity specificed for this reference in the componentType of the implementation - if not present in the componentType, the value defaults to 1..1.
· target : anyURI (0..n) – a list of one or more of target service URI’s, depending on multiplicity setting. Each value wires the reference to a component service that resolves the reference. For more details on wiring see the section on Wires. Overrides any target specified for this reference on the implementation.
·
wiredByImpl : boolean
(0..1) – a boolean value,
"false" by default, which indicates that the implementation wires
this reference dynamically. If set to "true" it indicates that the
target of the reference is set at runtime by the implementation code (e.g. by
the code obtaining an endpoint reference by some means and setting this as the
target of the reference through the use of programming interfaces defined by
the relevant Client and Implementation specification). If
@wiredByImpl="true" is set for a reference, then the reference MUST
NOT be wired statically within a composite, but left unwired.If
@wiredByImpl="true" is set for a reference, then the reference MUST
NOT be wired statically within a composite, but left unwired. [ASM50010]
·
nonOverridable : boolean
(0..1) - a boolean value,
"false" by default, which indicates whether this component reference
can have its targets overridden by a composite reference which promotes the
component reference.
If @nonOverridable==false, the
if any target(s) ofare configured onto the promoting composite references which promote the component reference,
then those targets replace all the targets explicitly declared on the
component reference for any value of @multiplicity on the component reference. If the
component reference has @nonOverridable==false and @multiplicity 1..1 and no targets are defined on any of the reference
has a target, then any composite
referencereferences which promotes the component reference has @multiplicity 0..1.by default and MAY have an
explicit @multiplicity of either 0..1 or 1..1.,
then any targets explicitly declared on the component reference are used. This
means in effect that any targets declared on the component reference
If @nonOverridable==true, and the has
@multiplicity 0..1 or 1..1 and the componentact as default targets for that reference
also declares a target, promotion implies that the promoting composite
reference has @wiredbyImpl==true and the composite reference cannot supply a
target, but can influence the policy attached to the component reference. .
If a component
reference has @multiplicity 0..1 or 1..1 and @nonOverridable==true, then the
component reference MUST NOT be promoted by any composite reference.If a component
reference has @multiplicity 0..1 or 1..1 and @nonOverridable==true, then the
component reference MUST NOT be promoted by any composite reference. [ASM50042]
If @nonOverridable==true, and the component reference @multiplicity is 0..n or
1..n, promotion targeting
isany targets configured
onto the composite references which promote the component reference are added
to any references declared on the component reference - that is, the targets
are additive.
The component reference element has the following
child elements:
·
interface : Interface
(0..1) - A reference has zero or one interface, which describes the operations of the reference.
The interface is described by an interface
element which is a child
element of the reference element. If no interface is specified, then the
interface specified for the reference in the componentType of the
implementation is in effect. If an interface is declared for a component
reference, the interface MUST provide a compatible superset of the interface
declared for the equivalent reference in the componentType of the
implementation, i.e. provide the same operations or a .If an interface is
declared for a component reference, the interface MUST provide a compatible
superset of the operations defined byinterface declared for
the equivalent reference in the componentType of the implementation for the reference. [ASM50011] For
details on the interface element see the Interface section.
·
binding : Binding (0..n) - A reference element has zero
or more binding elements as children.If no binding elements are specified for the
reference, then the bindings specified for the equivalent reference in the
componentType of the implementation MUST be used. If binding elements are
specified for the reference, then those bindings MUST be used and they override
any bindings specified for the equivalent reference in the componentType of the
implementation.If
no binding elements are specified for the reference, then the bindings
specified for the equivalent reference in the componentType of the
implementation MUST be used. If binding elements are specified for the
reference, then those bindings MUST be used and they override any bindings
specified for the equivalent reference in the componentType of the
implementation. [ASM50012] It is valid for there to be no binding
elements on the component reference and none on the reference in the
componentType - the binding used for such a reference is determined by the
target service. See the section on the bindings of
component services for a description of how the binding(s) applying to a
service are determined.
Details of the binding element are described in the Bindings
section. The binding,
combined with any PolicySets in effect for the binding, needs to satisfy the
set of policy intents for the reference, as described in the
Policy Framework specification [10]SCA-POLICY].
A reference identifies zero or more target services that satisfy the reference. This can be done in a number of ways, which are fully described in section "Specifying the Target Service(s) for a Reference"
·
callback (0..1) / binding : Binding (1..n) - A callback element used if the interface has a callback
defined and the callback element has one or more binding
elements as subelements. The callback and its binding subelements are specified if there
is a need to have binding details used to handle callbacks. If the callback
element is present and contains one or more binding child elements, then those
bindings MUST be used for the callback.If the callback
element is present and contains one or more binding child elements, then those
bindings MUST be used for the callback. [ASM50006] If the callback element is not present, the
behaviour is runtime implementation dependent.
· requires : requires (0..n) - A service element has zero or more requires subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
· policySetAttachment : policySetAttachment (0..n) - A service element has zero or more policySetAttachment subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
A reference defines zero or more target services that satisfy the reference. The target service(s) can be defined in the following ways:
1. Through a value specified in the @target attribute of the reference element
2. Through a target URI specified in the @uri attribute of a binding element which is a child of the reference element
3. Through the setting of one or more values for binding-specific attributes and/or child elements of a binding element that is a child of the reference element
4. Through the specification of @autowire="true" for the reference (or through inheritance of that value from the component or composite containing the reference)
5. Through the specification of @wiredByImpl="true" for the reference
6. Through the promotion of a component reference by a composite reference of the composite containing the component (the target service is then identified by the configuration of the composite reference)
7. Through the presence of a <wire/> element which has the reference specified in its @source attribute.
Combinations of these different methods are allowed, and the following rules MUST be observed:
·
If @wiredByImpl="true", other methods of
specifying the target service MUST NOT be used.If @wiredByImpl="true", other methods of
specifying the target service MUST NOT be used. [ASM50013]
·
If @autowire="true", the autowire
procedure MUST only be used if no target is identified by any of the other ways
listed above. It is not an error if @autowire="true" and a target is
also defined through some other means, however in this case the autowire
procedure MUST NOT be used.If @autowire="true", the autowire
procedure MUST only be used if no target is identified by any of the other ways
listed above. It is not an error if @autowire="true" and a target is
also defined through some other means, however in this case the autowire
procedure MUST NOT be used.
[ASM50014]
·
If a reference has a value specified for one or
more target services in its @target attribute, there MUST NOT be any child
<binding/> elements declared for that reference.If a reference has a value specified for one or
more target services in its @target attribute, there MUST NOT be any child
<binding/> elements declared for that reference. [ASM50026]
·
If a binding element has a value specified for a
target service using its @uri attribute, the binding element MUST NOT identify
target services using binding specific attributes or elements.If a binding element has a value specified for a
target service using its @uri attribute, the binding element MUST NOT identify
target services using binding specific attributes or elements. [ASM50015]
·
It is possible that a particular binding type MAY require that uses
more than a simple URI for the address of a target service uses more than a simple URI. . In
cases where a reference element has a binding subelement of such a typethat
uses more than simple URI, the @uri attribute of the binding element MUST NOT
be used to identify the target service - instead,in this case binding
specific attributes and/or child elements MUST be used.It is possible that a particular binding type uses
more than a simple URI for the address of a target service. In cases where a
reference element has a binding subelement that uses more than simple URI, the
@uri attribute of the binding element MUST NOT be used to identify the target
service - in this case binding specific attributes and/or child elements MUST
be used. [ASM50016]
·
If any <wire/> element with its @replace
attribute set to "true" has a particular reference specified in its
@source attribute, the value of the @target attribute for that reference MUST
be ignored and MUST NOT be used to define target services for that reference.If any <wire/> element with its @replace
attribute set to "true" has a particular reference specified in its
@source attribute, the value of the @target attribute for that reference MUST
be ignored and MUST NOT be used to define target services for that reference. [ASM50034]
The number of target services configured for a reference are constrained by the following rules.
·A reference with multiplicity 0..1 or 0..n MAYMUST have no more than one target service defined.A
reference with multiplicity 0..1 MUST have no more than one target service
defined. [ASM50018]
·
A reference with multiplicity 0..1 or 1..1 MUST NOT have more thatexactly
one target service defined.A reference with multiplicity 1..1 MUST have
exactly one target service defined. [ASM50019ASM50040]
·A reference with multiplicity 1..1 orn
MUST have at least one target service defined.A
reference with multiplicity 1..n MUST have at least one target service defined. [ASM50020]
· A reference with multiplicity 0..n can have any number of target services defined.
·A
reference with multiplicity 0..n or 1..n MAY have one or more target services
defined.Where
it is detected that the rules for the number of target services for a reference
have been violated, either at deployment or at execution time, an SCA Runtime
MUST raise an error no later than when the reference is invoked by the
component implementation.Where it is detected
that the rules for the number of target services for a reference have been
violated, either at deployment or at execution time, an SCA Runtime MUST raise
an error no later than when the reference is invoked by the component
implementation. [ASM50021]
Where it is detected
that the rules for the number of target services for a reference have been violated,
either at deployment or at execution time, an SCA Runtime MUST raise an error
no later than when the reference is invoked by the component implementation. [ASM50022]
For example, where a composite is used as a component implementation, wires and target services cannot be added to the composite after deployment. As a result, for components which are part of the composite, both missing wires and wires with a non-existent target can be detected at deployment time through a scan of the contents of the composite.
A contrasting example is a component deployed to the SCA Domain. At the Domain level, the target of a wire, or even the wire itself, can form part of a separate deployed contribution and as a result these can be deployed after the original component is deployed. For the cases where it is valid for the reference to have no target service specified, the component implementation language specification needs to define the programming model for interacting with an untargetted reference.
Where a component reference is promoted by a
composite reference, the promotion MUST be treated from a multiplicity
perspective as providing 0 or more target services for the component reference,
depending upon the further configuration of the composite reference. These
target services are in addition to any target services identified on the
component reference itself, subject to the rules relating to multiplicity.Where a component reference is promoted by a
composite reference, the promotion MUST be treated from a multiplicity
perspective as providing 0 or more target services for the component reference,
depending upon the further configuration of the composite reference. These
target services are in addition to any target services identified on the
component reference itself, subject to the rules relating to multiplicity. [ASM50025]
The component element has zero or more property elements as its children, which are used to configure data values of properties of the implementation. Each property element provides a value for the named property, which is passed to the implementation. The properties that can be configured and their types are defined by the component type of the implementation. An implementation can declare a property as multi-valued, in which case, multiple property values can be present for a given property.
The property value can be specified in one of five ways:
·
As a value, supplied in the @value attribute of the
property element.
If the @value attribute of a component property
element is declared, the type of the property MUST be an XML Schema simple type
and the @value attribute MUST contain a single value of that type.If the @value attribute of a component property element
is declared, the type of the property MUST be an XML Schema simple type and the
@value attribute MUST contain a single value of that type. [ASM50027]
For example,
<property name="pi" value="3.14159265" />
·As a value,
supplied as the content of the value subelement(s) of the
property element.
If the value subelement of a component property is
specified, the type of the property MUST be an XML Schema simple type or an XML
schema complex type. [ASM50028]
Snippet 44‑8: Example property using @value attribute
· As a value, supplied as the content of the value subelement(s) of the property element.
If the value subelement of a component property is specified, the type of the property MUST be an XML Schema simple type or an XML schema complex type.If the value subelement of a component property is specified, the type of the property MUST be an XML Schema simple type or an XML schema complex type. [ASM50028]
For example,
– property defined using a XML Schema simple type and which contains a single value
<property name="pi">
<value>3.14159265</value>
</property>
Snippet 44‑9: Example property with a Simple Type Containing a Single Value
– property defined using a XML Schema simple type and which contains multiple values
<property name="currency">
<value>EURO</value>
<value>USDollar</value>
</property>
Snippet 44‑10: Example property with a Simple Type Containing Multiple Values
– property defined using a XML Schema complex type and which contains a single value
<property name="complexFoo">
<value attr="bar">
<foo:a>TheValue</foo:a>
<foo:b>InterestingURI</foo:b>
</value>
</property>
Snippet 44‑11: Example property with a Complex Type Containing a Single Value
– property defined using a XML Schema complex type and which contains multiple values
<property name="complexBar">
<value anotherAttr="foo">
<bar:a>AValue</bar:a>
<bar:b>InterestingURI</bar:b>
</value>
<value attr="zing">
<bar:a>BValue</bar:a>
<bar:b>BoringURI</bar:b>
</value>
</property>
·As a value,
supplied as the content of the property element.
If a component property value is declared using a
child element of the <property/> element, the type of the property MUST
be an XML Schema global element and the declared child element MUST be an
instance of that global element. [ASM50029]
Snippet 44‑12: Example property with a Complex Type Containing Multiple Values
· As a value, supplied as the content of the property element.
If a component property value is declared using a child element of the <property/> element, the type of the property MUST be an XML Schema global element and the declared child element MUST be an instance of that global element.If a component property value is declared using a child element of the <property/> element, the type of the property MUST be an XML Schema global element and the declared child element MUST be an instance of that global element. [ASM50029]
For example,
– property defined using a XML Schema global element declartion and which contains a single value
<property name="foo">
<foo:SomeGED ...>...</foo:SomeGED>
</property>
Snippet 44‑13: Example property with a Global Element Declaration Containing a Single Value
– property defined using a XML Schema global element declaration and which contains multiple values
<property name="bar">
<bar:SomeOtherGED ...>...</bar:SomeOtherGED>
<bar:SomeOtherGED ...>...</bar:SomeOtherGED>
</property>
Snippet 44‑14 Example property with a Global Element Declaration Containing Multiple Values
·
By referencing a Property value of the composite which contains
the component. The reference is made using the @source attribute of the property element.
The form of the value of the @source attribute follows
the form of an XPath expression. This form allows a specific property of the
composite to be addressed by name. Where the composite property is of a
complex type, the XPath expression can be extended to refer to a sub-part of
the complex property value.
So, for example, source="$currency" is used to reference a property of the composite called "currency", while source="$currency/a" references the sub-part "a" of the complex composite property with the name "currency".
· By specifying a dereferencable URI to a file containing the property value through the @file attribute. The contents of the referenced file are used as the value of the property.
If more than one property value specification is present, the @source attribute takes precedence, then the @file attribute.
For a property defined using a XML Schema simple type and for which a single value is desired, can be set either using the @value attribute or the <value> child element. The two forms in such a case are equivalent.
When
a property has multiple values set, they MUST all be contained within the same
property element. A <component/> element MUST NOT contain two
<property/> subelements with the same value of the @name attribute.When a property has multiple values set, all the
values MUST be contained within a single property element.When a property has multiple values set, all the
values MUST be contained within a single property element. [ASM50030ASM50044]
The type of the property can be specified in one of two ways:
· by the qualified name of a type defined in an XML schema, using the @type attribute
· by the qualified name of a global element in an XML schema, using the @element attribute
The
property type specified for the property element of a component MUST be
compatible with the type of the property with the same @name declared in the
component type of the implementation used by the component. If no type is
declared in the component property element, the type of the property declared
in the componentType of the implementation MUST be used.The property type specified for the property
element of a component MUST be compatible with the type of the property with
the same @name declared in the component type of the implementation used by the
component. If no type is declared in the component property element, the type
of the property declared in the componentType of the implementation MUST be
used. [ASM50036]
The following snippetmeaning of
"compatible" for property types is defined in the section Property Type Compatibility.
Snippet 4‑15Snippet 4‑15 shows the component pseudo-schema with the pseudo-schema for a property child element:
<?xml version="1.0" encoding="UTF-8"?>
<!-- Component Property schema snippet -->
<composite xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912" … >
…
<component … >*
<implementation … />?
<service … />*
<reference … />*
<property name="xs:NCName"
(type="xs:QName" | element="xs:QName")?
many="xs:boolean"?
source="xs:string"? file="xs:anyURI"?
requires="list
of xs:QName"?
policySets="list
of xs:QName"?
value="xs:string"?>*
[<value>+ | xs:any+ ]?
</property>
</component>
…
</composite>
The component property element has
the following attributes:
§name
: NCName (1..1) – the name of the
property. The @name attribute of a property element of a
<component/> MUST be unique amongst the property elements of that
<component/>. [ASM50031] The @name attribute of a property element of a
<component/> MUST match the @name attribute of a property element of the
componentType of the <implementation/> child element of the component. [ASM50037]
Snippet 44‑15: component Psuedo-Schema with property Child Element
The component property element has the attributes:
· name : NCName (1..1) – the name of the property. The @name attribute of a property element of a <component/> MUST be unique amongst the property elements of that <component/>.The @name attribute of a property element of a <component/> MUST be unique amongst the property elements of that <component/>. [ASM50031] The @name attribute of a property element of a <component/> MUST match the @name attribute of a property element of the componentType of the <implementation/> child element of the component.The @name attribute of a property element of a <component/> MUST match the @name attribute of a property element of the componentType of the <implementation/> child element of the component. [ASM50037]
· zero or one of (0..1):
– type : QName – the type of the property defined as the qualified name of an XML schema type
– element : QName – the type of the property defined as the qualified name of an XML schema global element – the type is the type of the global element
A single property element MUST NOT contain both a
@type attribute and an @element attribute.A single property element MUST NOT contain both a
@type attribute and an @element attribute. [ASM50035]
· source : string (0..1) – an XPath expression pointing to a property of the containing composite from which the value of this component property is obtained.
· file : anyURI (0..1) – a dereferencable URI to a file containing a value for the property
· many : boolean (0..1) – whether the property is single-valued (false) or multi-valued (true). Overrides the many specified for this property in the componentType of the implementation. The value can only be equal or further restrict, i.e. if the implementation specifies many true, then the component can say false. In the case of a multi-valued property, it is presented to the implementation as a Collection of property values. If many is not specified, it takes the value defined by the component type of the implementation used by the component.
· value : string (0..1) - the value of the property if the property is defined using a simple type.
§requires
: QName (0..n) - a list of policy
intents. See the Policy Framework specification [10] for a
description of this attribute.
§policySets
: QName (0..n) - a list of policy
sets. See the Policy Framework specification [10] for a
description of this attribute.
The component property element has
the following child element:
value :any (0..n) -
A property has zero or more, value elements that specify the
value(s) of a property that is defined using a XML Schema type. The component
property element has the child element:
· value :any (0..n) - A property has zero or more, value elements that specify the value(s) of a property that is defined using a XML Schema type. If a property is single-valued, the <value/> subelement MUST NOT occur more than once.If a property is single-valued, the <value/> subelement MUST NOT occur more than once. [ASM50032] A property <value/> subelement MUST NOT be used when the @value attribute is used to specify the value for that property.A property <value/> subelement MUST NOT be used when the @value attribute is used to specify the value for that property. [ASM50033]
There are a number of situations where the declared type of a property element is matched with the declared type of another property element. These situations include:
· Where a component <property/> sets a value for a property of an implementation, as declared in the componentType of the implementation
· Where a component <property/> gets its value from the value of a composite <property/> by means of its @source attribute. This situation can also involve the @source attribute referencing a subelement of the composite <property/> value, in which case it is the type of the subelement which must be matched with the type of the component <property/>
· Where the componentType of a composite used as an implementation is calculated and componentType <property/> elements are created for each composite <property/>
If a property is single-valued, the <value/>
subelement MUST NOT occur more than once.In these cases where the types of two property
elements are matched, the types declared for the two <property/> elements
MUST be compatibleIn
these cases where the types of two property elements are matched, the types
declared for the two <property/> elements MUST be compatible [ASM50032] A property <value/> subelement MUST NOT be used
when the @value attribute is used to specify the value for that property.
[ASM50033]
Two property types are compatible if they have the same XSD type (where declared as XSD types) or the same XSD global element (where declared as XSD global elements). For cases where the type of a property is declared using a different type system (eg Java), then the type of the property is mapped to XSD using the mapping rules defined by the appropriate implementation type specification
The following figureFigure 4‑2Figure 4‑2 shows the component
symbol that is used to
represent a component in an assembly diagram.
Figure 544‑2:
Component symbol
The following figureFigure
4‑3Figure
4‑3
shows the assembly diagram for the MyValueComposite containing the
MyValueServiceComponent.
Figure 644‑3:
Assembly diagram for MyValueComposite
The following snippetSnippet
4‑16: Example
compositeSnippet 4‑16:
Example composite shows the MyValueComposite.composite file for
the MyValueComposite containing the component element for the
MyValueServiceComponent. A value is set for the property named currency, and
the customerService and stockQuoteService references are promoted:
<?xml version="1.0" encoding="ASCII"?>
<!-- MyValueComposite_1 example -->
<composite
xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
targetNamespace="http://foo.com"
name="MyValueComposite" >
<service name="MyValueService" promote="MyValueServiceComponent"/>
<component name="MyValueServiceComponent">
<implementation.java
class="services.myvalue.MyValueServiceImpl"/>
<property name="currency">EURO</property>
<reference name="customerService"/>
<reference name="stockQuoteService"/>
</component>
<reference name="CustomerService"
promote="MyValueServiceComponent/customerService"/>
<reference name="StockQuoteService"
promote="MyValueServiceComponent/stockQuoteService"/>
</composite>
Snippet 44‑16: Example composite
Note that the references of MyValueServiceComponent are explicitly declared only for purposes of clarity – the references are defined by the MyValueServiceImpl implementation and there is no need to redeclare them on the component unless the intention is to wire them or to override some aspect of them.
The following snippet gives an example of the layout of a composite file if both the currency property and the customerService reference of the MyValueServiceComponent are declared to be multi-valued (many=true for the property and multiplicity=0..n or 1..n for the reference):
<?xml version="1.0" encoding="ASCII"?>
<!-- MyValueComposite_2 example -->
<composite
xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
targetNamespace="http://foo.com"
name="MyValueComposite" >
<service name="MyValueService" promote="MyValueServiceComponent"/>
<component name="MyValueServiceComponent">
<implementation.java
class="services.myvalue.MyValueServiceImpl"/>
<property name="currency">
<value>EURO</value>
<value>Yen</value>
<value>USDollar</value>
</property>
<reference name="customerService"
target="InternalCustomer/customerService"/>
<reference name="stockQuoteService"/>
</component>
...
<reference name="CustomerService"
promote="MyValueServiceComponent/customerService"/>
<reference name="StockQuoteService"
promote="MyValueServiceComponent/stockQuoteService"/>
</composite>
Snippet 44‑17: Example composite with Multi-Valued property and reference
….this assumes that the composite has another component called InternalCustomer (not shown) which has a service to which the customerService reference of the MyValueServiceComponent is wired as well as being promoted externally through the composite reference CustomerService.
An SCA composite is used to assemble SCA elements in logical groupings. It is the basic unit of composition within an SCA Domain. An SCA composite contains a set of components, services, references and the wires that interconnect them, plus a set of properties which can be used to configure components.
Composites can be used as component implementations in higher-level composites – in other words the higher-level composites can have components that are implemented by composites. For more detail on the use of composites as component implementations see the section Using Composites as Component Implementations.
The content of a composite can be used within another composite through inclusion. When a composite is included by another composite, all of its contents are made available for use within the including composite – the contents are fully visible and can be referenced by other elements within the including composite. For more detail on the inclusion of one composite into another see the section Using Composites through Inclusion.
A composite can be used as a unit of deployment.
When used in this way, composites contribute components and wires to an SCA
Domain. A composite can be deployed to the SCA Domain either by inclusion, or a composite can be deployed to the Domain as an
implementation. For more detail on the deployment of composites, see the
section dealing with the SCA Domain.
A composite is defined in an xxx.composite file. A composite is represented by a composite element. The
following snippetSnippet 5‑1Snippet 5‑1 shows the pseudo-schema for the composite element. :
<?xml version="1.0" encoding="ASCII"?>
<!-- Composite schema snippet -->
<composite xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
targetNamespace="xs:anyURI"
name="xs:NCName" local="xs:boolean"?
autowire="xs:boolean"? constrainingType="xs:QName"?
requires="list of xs:QName"? policySets="list of xs:QName"?>
<include … />*
<requires/>*
<policySetAttachment/>*
<service … />*
<reference … />*
<property … />*
<component … />*
<wire … />*
</composite>
Snippet 55‑1: composite Pseduo-Schema
The composite element has the following
attributes:
·
name : NCName (1..1) – the name of the composite. The form of a
composite name is an XML QName, in the namespace identified by the @targetNamespace
attribute. A composite @name attribute value MUST be unique
within the namespace of the composite.A composite @name
attribute value MUST be unique within the namespace of the composite. [ASM60001]
· targetNamespace : anyURI (0..1) – an identifier for a target namespace into which the composite is declared
·
local : boolean (0..1) – whether all the components within the composite
all run in the same operating system process. @local="true" for a composite means that
all the components within the composite MUST run in the same operating system
process.@local="true"
for a composite means that all the components within the composite MUST run in
the same operating system process. [ASM60002]
local="false", which is the default, means that different components
within the composite can run in different operating system processes and they
can even run on different nodes on a network.
· autowire : boolean (0..1) – whether contained component references are autowired, as described in the Autowire section. Default is false.
·constrainingType :
QName (0..1) – the name of a
constrainingType. When specified, the set of services, references and
properties of the composite, plus related intents, is constrained to the set
defined by the constrainingType. See the ConstrainingType
Section for more details.
·
requires : QNamelistOfQNames (0..n1)
– a list of policy intents.
See the Policy Framework specification [10]SCA-POLICY] for a description of this attribute.
·
policySets : QNamelistOfQNames (0..n1)
– a list of policy sets. See
the Policy Framework specification [10]SCA-POLICY] for a description of this attribute.
The composite element has the following
child elements:
· service : CompositeService (0..n) – see composite service section.
· reference : CompositeReference (0..n) – see composite reference section.
· property : CompositeProperty (0..n) – see composite property section.
· component : Component (0..n) – see component section.
· wire : Wire (0..n) – see composite wire section.
· include : Include (0..n) – see composite include section
· requires : requires (0..n) - A service element has zero or more requires subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
· policySetAttachment : policySetAttachment (0..n) - A service element has zero or more policySetAttachment subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
Components contain configured implementations which hold the business logic of the composite. The components offer services and use references to other services. Composite services define the public services provided by the composite, which can be accessed from outside the composite. Composite references represent dependencies which the composite has on services provided elsewhere, outside the composite. Wires describe the connections between component services and component references within the composite. Included composites contribute the elements they contain to the using composite.
Composite services involve the promotion of one service of one of the components within the
composite, which means that the composite service is actually provided by one
of the components within the composite. Composite references involve the promotion of one or more references of one or more
components. Multiple component references can be promoted to the same
composite reference, as long as alleach of
the component references arehas
an interface that is a compatible with
one anothersubset
of the interface on the composite reference. Where multiple component references are promoted
to the same composite reference, then they all share the same configuration,
including the same target service(s).
Composite services and composite references can use the configuration of their promoted services and references respectively (such as Bindings and Policy Sets). Alternatively composite services and composite references can override some or all of the configuration of the promoted services and references, through the configuration of bindings and other aspects of the composite service or reference.
Component services and component references can be promoted to composite services and references and also be wired internally within the composite at the same time. For a reference, this only makes sense if the reference supports a multiplicity greater than 1.
The services of a composite are defined by promoting services defined by components contained in the composite. A component service is promoted by means of a composite service element.
A composite service is represented by a service element
which is a child of the composite element. There can be zero or more service elements in a composite. The following snippetSnippet 5‑2Snippet 5‑2 shows the composite
pseudo-schema with the pseudo-schema
for a service child element:
<?xml version="1.0" encoding="ASCII"?>
<!-- Composite Service schema snippet -->
<composite xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912" … >
…
<service name="xs:NCName" promote="xs:anyURI"
requires="list of xs:QName"? policySets="list
of xs:QName"?>*
<interface … />?
<binding … />*
<callback>?
<binding … />+
</callback>
<requires/>*
<policySetAttachment/>*
</service>
…
</composite>
Snippet 55‑2: composite Psuedo-Schema with service Child Element
The composite
service element has the following attributes:
·
name : NCName (1..1) – the name of the service.The name of a
composite <service/> element MUST be unique across all the composite
services in the composite.The name of a composite <service/> element
MUST be unique across all the composite services in the composite. [ASM60003] The name of the
composite service can be different from the name of the promoted component
service.
·
promote : anyURI (1..1) – identifies the promoted service, the value is of
the form <component-name>/<service-name>. The service name can be
omitted if the target component only has one service. The same component service
can be promoted by more then one composite service. A composite
<service/> element's @promote attribute MUST identify one of the
component services within that composite.A composite
<service/> element's @promote attribute MUST identify one of the
component services within that composite. [ASM60004] <include/>
processing MUST take place before the processing of the @promote attribute of a
composite service is performed.<include/>
processing MUST take place before the processing of the @promote attribute of a
composite service is performed. [ASM60038]
·
requires : QNamelistOfQNames (0..n1)
– a list of policy intents. See the Policy Framework specification
[10]SCA-POLICY] for a description of this attribute. Specified intents add
to or further qualify the required intents defined by the promoted component
service.
·
policySets : QNamelistOfQNames (0..n1)
– a list of policy sets. See
the Policy Framework specification [10]SCA-POLICY] for a description of this attribute.
The composite
service element has the following child elements, whatever is not specified is defaulted from the
promoted component service.
·
interface : Interface
(0..1) - an interface which
decribes the operations provided by the composite service. If a composite service interface is specified it MUST be the same or a compatible
subset of the interface provided by the promoted component service, i.e. provide a
subset of the operations defined by the component service.If a composite service
interface is specified it MUST
be the same or a compatible subset of the interface provided by the promoted
component service, i.e. provide a
subset of the operations defined by the component service.If a composite
service interface is specified it
MUST be the same or a compatible subset of the interface provided by the
promoted component service, i.e. provide a subset of the operations defined by
the component service [ASM60005] The interface is described by zero or one interface element which is a child element of the service element.
For details on the interface element see the Interface section. .
· binding : Binding (0..n) - If bindings are specified they override the bindings defined for the promoted component service from the composite service perspective. The bindings defined on the component service are still in effect for local wires within the composite that target the component service. A service element has zero or more binding elements as children. Details of the binding element are described in the Bindings section. For more details on wiring see the Wiring section.
· callback (0..1) / binding : Binding (1..n) - A callback element is used if the interface has a callback defined and the callback has one or more binding elements as subelements. The callback and its binding subelements are specified if there is a need to have binding details used to handle callbacks. Callback binding elements attached to the composite service override any callback binding elements defined on the promoted component service. If the callback element is not present on the composite service, any callback binding elements on the promoted service are used. If the callback element is not present at all, the behaviour is runtime implementation dependent.
· requires : requires (0..n) - A service element has zero or more requires subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
· policySetAttachment : policySetAttachment (0..n) - A service element has zero or more policySetAttachment subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
The following figureFigure 5‑1Figure 5‑1 shows the service symbol that used to represent a
service in an assembly diagram:
Figure 755‑1:
Service symbol
The following figureFigure 5‑2Figure 5‑2 shows the assembly diagram for the MyValueComposite
containing the service MyValueService.
Figure 855‑2:
MyValueComposite showing Service
The following snippetSnippet 5‑3Snippet 5‑3 shows the MyValueComposite.composite file for the
MyValueComposite containing the service element for the MyValueService, which
is a promote of the service offered by the MyValueServiceComponent. The name of
the promoted service is omitted since MyValueServiceComponent offers only one
service. The composite service MyValueService is bound using a Web service
binding.
<?xml version="1.0" encoding="ASCII"?>
<!-- MyValueComposite_4 example -->
<composite
xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
targetNamespace="http://foo.com"
name="MyValueComposite" >
...
<service name="MyValueService" promote="MyValueServiceComponent">
<interface.java interface="services.myvalue.MyValueService"/>
<binding.ws
portwsdlElement="http://www.myvalue.org/MyValueService#
wsdl.endpointport(MyValueService/MyValueServiceSOAP)"/>
</service>
<component name="MyValueServiceComponent">
<implementation.java
class="services.myvalue.MyValueServiceImpl"/>
<property name="currency">EURO</property>
<service name="MyValueService"/>
<reference name="customerService"/>
<reference name="stockQuoteService"/>
</component>
...
</composite>
Snippet 55‑3: Example composite with a service
The references of a composite are defined by promoting references defined by components contained in the composite. Each promoted reference indicates that the component reference needs to be resolved by services outside the composite. A component reference is promoted using a composite reference element.
A composite reference is represented by a reference element which is a child of a composite element. There can
be zero or more
reference elements in a composite. The following snippetSnippet 5‑4Snippet 5‑4 shows the composite pseudo-schema with the pseudo-schema for a reference element.:
<?xml version="1.0" encoding="ASCII"?>
<!-- Composite Reference schema snippet -->
<composite
xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912" … >
…
<reference name="xs:NCName" target="list of xs:anyURI"?
promote="list
of xs:anyURI"
wiredByImpl="xs:boolean"?
multiplicity="0..1
or 1..1 or 0..n or 1..n"?
requires="list
of xs:QName"? policySets="list
of xs:QName"?>*
<interface … />?
<binding … />*
<callback>?
<binding … />+
</callback>
<requires/>*
<policySetAttachment/>*
</reference>
…
</composite>
Snippet 55‑4: composite Psuedo-Schema with reference Child Element
The composite
reference element has the following attributes:
·
name : NCName (1..1) – the name of the reference. The name of a
composite <reference/> element MUST be unique across all the composite
references in the composite.The name of a composite <reference/> element
MUST be unique across all the composite references in the composite. [ASM60006] The name of the
composite reference can be different than the name of the promoted component
reference.
·
promote : anyURI (1..n) – identifies one or more promoted component
references. The value is a list of values of the form
<component-name>/<reference-name> separated by spaces. The
reference name can be omitted if the component has only one reference. Each of the URIs
declared by a composite reference's @promote attribute MUST identify a
component reference within the composite.Each of the URIs
declared by a composite reference's @promote attribute MUST identify a
component reference within the composite. [ASM60007] <include/>
processing MUST take place before the processing of the @promote attribute of a composite reference is
performed.<include/>
processing MUST take place before the processing of the @promote attribute of a composite
reference is
performed. [ASM60037]
The same component reference can be promoted more than once, using different composite references, but only if the multiplicity defined on the component reference is 0..n or 1..n. The multiplicity on the composite reference can restrict accordingly.
Where a composite reference promotes two or more component references:
– the interfaces of the component references promoted
by a composite reference MUST be the same, or if the composite reference itself
declares an interface then alleach of the component
reference interfaces MUST be a compatible withsubset of the
composite reference interface. Compatible means that..the interfaces of the component references promoted
by a composite reference interface
isMUST be the same, or is a strictif the composite reference itself declares an
interface then each of the component reference interfaces MUST be a compatible
subset of the composite reference interface.. [ASM60008]
– the intents declared
on a composite reference and on the component references which it promoites
MUST NOT be mutually exclusive.the intents declared
on a composite reference and on the component references which it promoites
MUST NOT be mutually exclusive. [ASM60009] The intents which
apply to the composite reference in this case are the union of the intents
specified for each of the promoted component references plus any intents declared
on the composite reference itself. If any intents in the
set which apply to a composite reference are mutually exclusive then the SCA
runtime MUST raise an error.If any intents in the set which apply to a
composite reference are mutually exclusive then the SCA runtime MUST raise an
error. [ASM60010]
·
requires : QNamelistOfQNames (0..n1)
– a list of policy intents. See the Policy Framework specification
[10]SCA-POLICY] for a description of this attribute. Specified intents add
to or further qualify the intents defined for the promoted component reference.
·
policySets : QNamelistOfQNames (0..n1)
– a list of policy sets. See
the Policy Framework specification [10]SCA-POLICY] for a description of this attribute.
·
multiplicity : (01..1) -
Defines the number of wires that can connect the reference to target services.
When present, theThe
multiplicity of a composite
reference is always specified explicitly and can
have one of the following values
– 0..1 – zero or one wire can have the reference as a source
– 1..1 – one wire can have the reference as a source
– 0..n - zero or more wires can have the reference as a source
– 1..n – one or more wires can have the reference as a source
The default value for the @multiplicity attribute
is 1..1.The value specified for the @multiplicity attribute of a
composite reference MUST be compatible with the multiplicity specified on each
of the promoted component references, i.e. the multiplicity has to be equal or
further restrict. So multiplicity 0..1 can be used where the promoted component
reference has multiplicity 0..n, multiplicity 1..1 can be used where the
promoted component reference has multiplicity 0..n or 1..n and multiplicity 1..n
can be used where the promoted component reference has multiplicity 0..n.,
However, a composite reference of multiplicity 0..n or 1..n cannot be used to
promote a component reference of multiplicity 0..1 or 1..1 respectively.
The value specified
for the @multiplicity attribute of a
composite reference MUST be compatible with the multiplicity specified on each
of the promoted component references, i.e. the multiplicity has to be equal or
further restrict. So multiplicity 0..1 can be used where the promoted component
reference has multiplicity 0..n, multiplicity 1..1 can be used where the
promoted component reference has multiplicity 0..n or 1..n and multiplicity
1..n can be used where the promoted component reference has multiplicity 0..n.,
However, a composite reference of multiplicity 0..n or 1..n cannot be used to
promote a component reference of multiplicity 0..1 or 1..1 respectively.The value specified
for the @multiplicityThe multiplicity of a
composite reference MUST be equal to or further restrict the multiplicity of
each of the component references that it promotes, with the exception that the
multiplicity of the composite reference does not have to require a target if
there is already a target on the component reference. This means that a
component reference with multiplicity 1..1 and a target can be promoted by a
composite reference with multiplicity 0..1, and a component reference with
multiplicity 1..n and one or more targets can be promoted by a composite
reference with multiplicity 0..n or 0..1. attribute of a
composite reference MUST be compatible with the multiplicity specified on each
of the promoted component references, i.e. the multiplicity has to be equal or
further restrict. So multiplicity 0..1 can be used where the promoted component
reference has multiplicity 0..n, multiplicity 1..1 can be used where the
promoted component reference has multiplicity 0..n or 1..n and multiplicity
1..n can be used where the promoted component reference has multiplicity 0..n.,
However, a composite reference of multiplicity 0..n or 1..n cannot be used to
promote a component reference of multiplicity 0..1 or 1..1 respectively.The multiplicity of a
composite reference MUST be equal to or further restrict the multiplicity of
each of the component references that it promotes, with the exception that the
multiplicity of the composite reference does not have to require a target if
there is already a target on the component reference. This means that a
component reference with multiplicity 1..1 and a target can be promoted by a
composite reference with multiplicity 0..1, and a component reference with
multiplicity 1..n and one or more targets can be promoted by a composite
reference with multiplicity 0..n or 0..1. [ASM60011]
The valid values for
composite reference multiplicity are shown in the following tables:
Composite Reference multiplicity |
Component Reference multiplicity (where there are no targets declared) |
|||
0..1 |
1..1 |
0..n |
1..n |
|
0..1 |
YES |
NO |
YES |
NO |
1..1 |
YES |
YES |
YES |
YES |
0..n |
NO |
NO |
YES |
NO |
1..n |
NO |
NO |
YES |
YES |
Composite Reference multiplicity |
Component Reference multiplicity (where there are targets declared) |
|||
0..1 |
1..1 |
0..n |
1..n |
|
0..1 |
YES |
YES |
YES |
YES |
1..1 |
YES |
YES |
YES |
YES |
0..n |
NO |
NO |
YES |
YES |
1..n |
NO |
NO |
YES |
YES |
· target : anyURI (0..n) – a list of one or more of target service URI’s, depending on multiplicity setting. Each value wires the reference to a service in a composite that uses the composite containg the reference as an implementation for one of its components. For more details on wiring see the section on Wires.
·
wiredByImpl : boolean
(0..1) – a boolean value. If
set to "true" it indicates that the target of the reference is set at
runtime by the implementation code (for example by the code obtaining an
endpoint reference by some means and setting this as the target of the
reference through the use of programming interfaces defined by the relevant
Client and Implementation specification). If "true" is set, then the
reference is not intended to be wired statically within a using composite, but
left unwired.
All
the component references promoted by a single composite reference MUST have the
same value for @wiredByImpl.All the component references promoted by a single
composite reference MUST have the same value for @wiredByImpl. [ASM60035] If the @wiredByImpl
attribute is not specified on the composite reference, the default value is
"true" if all of the promoted component references have a wiredByImpl
value of "true", and the default value is "false" if all
the promoted component references have a wiredByImpl value of
"false". If the @wiredByImpl attribute is specified, its value MUST
be "true" if all of the promoted component references have a
wiredByImpl value of "true", and its value MUST be "false"
if all the promoted component references have a wiredByImpl value of
"false".If the @wiredByImpl attribute is not specified on
the composite reference, the default value is "true" if all of the
promoted component references have a wiredByImpl value of "true", and
the default value is "false" if all the promoted component references
have a wiredByImpl value of "false". If the @wiredByImpl attribute is
specified, its value MUST be "true" if all of the promoted component
references have a wiredByImpl value of "true", and its value MUST be
"false" if all the promoted component references have a wiredByImpl
value of "false".
[ASM60036]
The composite reference element has the following
child elements, whatever is not specified is
defaulted from the promoted component reference(s).
·
interface : Interface
(0..1) - zero or one interface element which declares an interface for the composite
reference. If a composite reference has an interface specified, it MUST provide an interface which is
the same or which is a compatible superset of the interface(s) declared by the
promoted component reference(s), i.e. provide a
superset of the operations in the interface defined by the component for the
reference.If a composite
reference has an interface specified, it MUST
provide an interface which is the same or which is a compatible superset of the
interface(s) declared by the promoted component reference(s), i.e. provide a
superset of the operations in the interface defined by the component for the
reference.If a composite reference has an interface specified, it MUST
provide an interface which is the same or which is a compatible superset of the
interface(s) declared by the promoted component reference(s), i.e. provide a
superset of the operations in the interface defined by the component for the
reference.). [ASM60012] If no interface is declared on a composite
reference, the interface from one of its promoted component references is used, which MUST be used for the same as or a
compatible superset of component type associated with the composite.If no interface(s) is declared byon a composite
reference, the interface from one of its promoted component reference(s). MUST be used for the
component type associated with the composite. [ASM60013] For
details on the interface element see the Interface section.
· binding : Binding (0..n) - A reference element has zero or more binding elements as children. If one or more bindings are specified they override any and all of the bindings defined for the promoted component reference from the composite reference perspective. The bindings defined on the component reference are still in effect for local wires within the composite that have the component reference as their source. Details of the binding element are described in the Bindings section. For more details on wiring see the section on Wires.
A reference identifies zero or more target services which satisfy the reference. This can be done in a number of ways, which are fully described in section "Specifying the Target Service(s) for a Reference".
· callback (0..1) / binding : Binding (1..n) - A callback element is used if the interface has a callback defined and the callback element has one or more binding elements as subelements. The callback and its binding subelements are specified if there is a need to have binding details used to handle callbacks. Callback binding elements attached to the composite reference override any callback binding elements defined on any of the promoted component references. If the callback element is not present on the composite service, any callback binding elements that are declared on all the promoted references are used. If the callback element is not present at all, the behaviour is runtime implementation dependent.
· requires : requires (0..n) - A service element has zero or more requires subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
· policySetAttachment : policySetAttachment (0..n) - A service element has zero or more policySetAttachment subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
The following figureFigure 5‑3Figure 5‑3 shows the reference symbol that is used to
represent a reference in an assembly diagram.
Figure 955‑3:
Reference symbol
The following figureFigure 5‑4Figure 5‑4 shows the assembly diagram for the MyValueComposite
containing the reference CustomerService and the reference StockQuoteService.
Figure 1055‑4:
MyValueComposite showing References
The following snippetSnippet 5‑5Snippet 5‑5 shows the MyValueComposite.composite file for the
MyValueComposite containing the reference elements for the CustomerService and
the StockQuoteService. The reference CustomerService is bound using the SCA
binding. The reference StockQuoteService is bound using the Web service
binding. The endpoint addresses of the bindings can be specified, for example
using the binding @uri attribute (for details see the Bindings
section), or overridden in
an enclosing composite. Although in this case the reference StockQuoteService
is bound to a Web service, its interface is defined by a Java interface, which
was created from the WSDL portType of the target web service.
<?xml version="1.0" encoding="ASCII"?>
<!-- MyValueComposite_3 example -->
<composite
xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
targetNamespace="http://foo.com"
name="MyValueComposite" >
...
<component name="MyValueServiceComponent">
<implementation.java
class="services.myvalue.MyValueServiceImpl"/>
<property name="currency">EURO</property>
<reference name="customerService"/>
<reference name="stockQuoteService"/>
</component>
<reference name="CustomerService"
promote="MyValueServiceComponent/customerService">
<interface.java interface="services.customer.CustomerService"/>
<!-- The following forces the binding to be binding.sca -->
<!-- whatever is specified by the component reference or -->
<!-- by the underlying implementation -->
<binding.sca/>
</reference>
<reference name="StockQuoteService"
promote="MyValueServiceComponent/stockQuoteService">
<interface.java
interface="services.stockquote.StockQuoteService"/>
<binding.ws
portwsdlElement="http://www.stockquote.org/StockQuoteService#
wsdl.endpointport(StockQuoteService/StockQuoteServiceSOAP)"/>
</reference>
...
</composite>
Snippet 55‑5: Example composite with a reference
Properties allow for the configuration of an implementation with externally set data values. A composite can declare zero or more properties. Each property has a type, which is either simple or complex. An implementation can also define a default value for a property. Properties can be configured with values in the components that use the implementation.
The declaration of a property in a composite
follows the form described in the following schema snippet:
Snippet 5‑6Snippet 5‑6 shows the composite pseudo-schema with the pseudo-schema for a reference element:
<?xml version="1.0" encoding="ASCII"?>
<!-- Composite Property schema snippet -->
<composite
xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912" … >
…
<property name="xs:NCName" (type="xs:QName" | element="xs:QName")
requires="list
of xs:QName"?
policySets="list
of xs:QName"?
many="xs:boolean"? mustSupply="xs:boolean"?>*
default-property-value?
</property>
…
</composite>
Snippet 55‑6: composite Psuedo-Schema with property Child Element
The composite
property element has the following attributes:
·
name : NCName (1..1) - the name of the property. The @name attribute of
a composite property MUST be unique amongst the properties of the same
composite.The @name attribute of a composite property MUST be
unique amongst the properties of the same composite. [ASM60014]
· one of (1..1):
– type : QName – the type of the property - the qualified name of an XML schema type
– element : QName – the type of the property defined as the qualified name of an XML schema global element – the type is the type of the global element
A
single property element MUST NOT contain both a @type attribute and an @element
attribute.A
single property element MUST NOT contain both a @type attribute and an @element
attribute. [ASM60040]
· many : boolean (0..1) - whether the property is single-valued (false) or multi-valued (true). The default is false. In the case of a multi-valued property, it is presented to the implementation as a collection of property values.
· mustSupply : boolean (0..1) – whether the property value has to be supplied by the component that uses the composite – when mustSupply="true" the component has to supply a value since the composite has no default value for the property. A default-property-value is only worth declaring when mustSupply="false" (the default setting for the @mustSupply attribute), since the implication of a default value is that it is used only when a value is not supplied by the using component.
§requires
: QName (0..n) - a list of policy
intents. See the Policy Framework specification [10] for a
description of this attribute.
§policySets
: QName (0..n) - a list of policy
sets. See the Policy Framework specification [10] for a
description of this attribute.
The property element can contain a default-property-value, which provides default value for the property. The form of the default property value is as described in the section on Component Property.
Implementation types other than composite can declare properties in an implementation-dependent form (e.g. annotations within a Java class), or through a property declaration of exactly the form described above in a componentType file.
Property values can be configured when an implementation is used by a component. The form of the property configuration is shown in the section on Components.
For the following
example of Property
declaration and value setting in Snippet 5‑8Snippet 5‑8, the following
complex type in Snippet 5‑7Snippet 5‑7 is
used as an example:
<xsd:schema xmlns="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://foo.com/"
xmlns:tns="http://foo.com/">
<!-- ComplexProperty schema -->
<xsd:element name="fooElement" type="tns:MyComplexType"/>
<xsd:complexType name="MyComplexType">
<xsd:sequence>
<xsd:element name="a" type="xsd:string"/>
<xsd:element name="b" type="xsd:anyURI"/>
</xsd:sequence>
<attribute name="attr" type="xsd:string" use="optional"/>
</xsd:complexType>
</xsd:schema>
Snippet 55‑7: Complex Type for Snippet 5‑8Snippet 5‑8
The following composite demostrates the declaration of a property of a complex type, with a default value, plus it demonstrates the setting of a property value of a complex type within a component:
<?xml version="1.0" encoding="ASCII"?>
<composite xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
xmlns:foo="http://foo.com"
targetNamespace="http://foo.com"
name="AccountServices">
<!-- AccountServices Example1 -->
...
<property name="complexFoo" type="foo:MyComplexType">
<value>
<foo:a>AValue</foo:a>
<foo:b>InterestingURI</foo:b>
</value>
</property>
<component name="AccountServiceComponent">
<implementation.java class="foo.AccountServiceImpl"/>
<property name="complexBar" source="$complexFoo"/>
<reference name="accountDataService"
target="AccountDataServiceComponent"/>
<reference name="stockQuoteService" target="StockQuoteService"/>
</component>
...
</composite>
Snippet 55‑8: Example property with a Complext Type
In the declaration of the property named complexFoo in the composite AccountServices, the property is defined to be of type foo:MyComplexType. The namespace foo is declared in the composite and it references the example XSD, where MyComplexType is defined. The declaration of complexFoo contains a default value. This is declared as the content of the property element. In this example, the default value consists of the element value which is of type foo:MyComplexType and it has two child elements <foo:a> and <foo:b>, following the definition of MyComplexType.
In the component AccountServiceComponent, the component sets the value of the property complexBar, declared by the implementation configured by the component. In this case, the type of complexBar is foo:MyComplexType. The example shows that the value of the complexBar property is set from the value of the complexFoo property – the @source attribute of the property element for complexBar declares that the value of the property is set from the value of a property of the containing composite. The value of the @source attribute is $complexFoo, where complexFoo is the name of a property of the composite. This value implies that the whole of the value of the source property is used to set the value of the component property.
The following exampleSnippet 5‑9Snippet 5‑9 illustrates the setting of the value of a property
of a simple type (a string) from part
of the value of a property of the containing composite which has a complex
type:
<?xml version="1.0" encoding="ASCII"?>
<composite xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
xmlns:foo="http://foo.com"
targetNamespace="http://foo.com"
name="AccountServices">
<!-- AccountServices Example2 -->
...
<property name="complexFoo" type="foo:MyComplexType">
<value>
<foo:a>AValue</foo:a>
<foo:b>InterestingURI</foo:b>
</value>
</property>
<component name="AccountServiceComponent">
<implementation.java class="foo.AccountServiceImpl"/>
<property name="currency" source="$complexFoo/a"/>
<reference name="accountDataService"
target="AccountDataServiceComponent"/>
<reference name="stockQuoteService" target="StockQuoteService"/>
</component>
...
</composite>
Snippet 55‑9: Example property with a Simple Type
In this
the example in Snippet 5‑9Snippet 5‑9, the component AccountServiceComponent sets the value of a property called currency, which is of type string. The value is set from a property of
the composite AccountServices using the @source attribute set to $complexFoo/a. This is an XPath expression that selects the
property name complexFoo and then selects the value of the a
subelement of the value of complexFoo. The "a" subelement is a
string, matching the type of the currency property.
Further examples of declaring properties and setting
property values in a component
follow:
– Declaration of a property with a simple type and a default value:
<property name="SimpleTypeProperty" type="xsd:string">
<value>MyValue</value>
</property>
Snippet 55‑10: Example property with a Simple Type and Default Value
– Declaration of a property with a complex type and a default value:
<property name="complexFoo" type="foo:MyComplexType">
<value>
<foo:a>AValue</foo:a>
<foo:b>InterestingURI</foo:b>
</value>
</property>
Snippet 55‑11: Example property with a Complex Type and Default Value
– Declaration of a property with a global element type:
<property name="elementFoo" element="foo:fooElement">
<foo:fooElement>
<foo:a>AValue</foo:a>
<foo:b>InterestingURI</foo:b>
</foo:fooElement>
</property>
Snippet 55‑12: Example property with a Global Element Type
SCA wires within a composite connect source component references to target component services.
One way of defining a wire is by configuring a reference of a component using its @target attribute. The reference element is configured with the wire-target-URI of the service(s) that resolve the reference. Multiple target services are valid when the reference has a multiplicity of 0..n or 1..n.
An alternative way of defining a Wire is by means of a wire element which is a child of the composite element. There can be zero or more wire elements in a composite. This alternative method for defining wires is useful in circumstances where separation of the wiring from the elements the wires connect helps simplify development or operational activities. An example is where the components used to build a Domain are relatively static but where new or changed applications are created regularly from those components, through the creation of new assemblies with different wiring. Deploying the wiring separately from the components allows the wiring to be created or modified with minimum effort.
Note that a Wire specified via a wire element is equivalent to a wire specified via the @target attribute of a reference. The rule which forbids mixing of wires specified with the @target attribute with the specification of endpoints in binding subelements of the reference also applies to wires specified via separate wire elements.
The following snippetSnippet 5‑13Snippet 5‑13 shows the composite pseudo-schema with the pseudo-schema for the reference
elements of components and composite services and the wire child element:
<?xml
version="1.0"
encoding="ASCII"?>
<!-- Wires schema snippet -->
<composite ...>
...
<wire source="xs:anyURI" target="xs:anyURI" replace="xs:boolean"?/>*
...
</composite>
Snippet 55‑13: composite Psuedo-Schema with wire Child Element
The reference element of a component has a list of one or more of the following wire-target-URI values for the target, with multiple values separated by a space:
·<component-name>/<service-name>
owhere
the target is a service of a component. The service name can be omitted if the
target component only has one service with a compatible interface
The wire element has the following
attributes:
·source (1..1)
– names the source component reference. Valid URI schemes are:
o<component-name>/<reference-name>
· <component-name>[ /<service-name> [/<binding-name>]? ]?
o <component-name> is the name of the target component.
o <service-name> is the name of the target service within the component.
If <service-name> is present, the component service with @name corresponding to <service-name> MUST be used for the wire.If <service-name> is present, the component service with @name corresponding to <service-name> MUST be used for the wire. [ASM60046]
If there is no component service with @name corresponding to <service-name>, the SCA runtime MUST raise an error.If there is no component service with @name corresponding to <service-name>, the SCA runtime MUST raise an error. [ASM60047]
If <service-name> is not present, the target component MUST have one and only one service with an interface that is a compatible superset of the wire source’s interface and satisifies the policy requirements of the wire source, and the SCA runtime MUST use this service for the wire.If <service-name> is not present, the target component MUST have one and only one service with an interface that is a compatible superset of the wire source’s interface and satisifies the policy requirements of the wire source, and the SCA runtime MUST use this service for the wire. [ASM60048]
o
<binding-name> is the name of the service’s
binding to use. The <binding-name> can be the default name of a binding
element (see section 8 “Binding”).
If <binding-name> is present, the
<binding/> subelement of the target service with @name corresponding to
<binding-name> MUST be used for the wire.If <binding-name> is present, the
<binding/> subelement of the target service with @name corresponding to
<binding-name> MUST be used for the wire. [ASM60049] If there is no <binding/> subelement of the
target service with @name corresponding to <binding-name>, the SCA
runtime MUST raise an error.If
there is no <binding/> subelement of the target service with @name
corresponding to <binding-name>, the SCA runtime MUST raise an error. [ASM60050] If <binding-name> is not present and the
target service has multiple <binding/> subelements, the SCA runtime MUST
choose one and only one of the <binding/> elements which satisfies the
mutual policy requirements of the reference and the service, and the SCA
runtime MUST use this binding for the wire.If <binding-name> is not present and the target
service has multiple <binding/> subelements, the SCA runtime MUST choose
one and only one of the <binding/> elements which satisfies the mutual
policy requirements of the reference and the service, and the SCA runtime MUST
use this binding for the wire. [ASM60051]
The wire element has the attributes:
· source (1..1) – names the source component reference. The valid URI scheme is:
– <component-name>[/<reference-name>]?
· where the source is a component reference. The reference name can be omitted if the source component only has one reference
·target (1..1) –
names the target component service. ValidThe
valid URI schemes are
o<component-name>/<service-name>
§where
scheme is the target is a service
of a component. The service name can be omitted ifsame
as the target component only has one service
with a compatible interface
· defined for component references above.
·
replace (0..1) - a boolean value, with the default
of "false". When a wire element has @replace="false", the
wire is added to the set of wires which apply to the reference identified by
the @source attribute. When a wire element has @replace="true", the
wire is added to the set of wires which apply to the reference identified by
the @source attribute - but any wires for that reference specified by means of
the @target attribute of the reference are removed from the set of wires which
apply to the reference.
In other words, if any <wire/> element with @replace="true" is used for a particular reference, the value of the @target attribute on the reference is ignored - and this permits existing wires on the reference to be overridden by separate configuration, where the reference is on a component at the Domain level.
<include/> processing MUST take place before
the @source and @target attributes of a wire are resolved.<include/> processing MUST take place before
the @source and @target attributes of a wire are resolved. [ASM60039]
For a composite used as a component implementation, wires can only link sources and targets that are contained in the same composite (irrespective of which file or files are used to describe the composite). Wiring to entities outside the composite is done through services and references of the composite with wiring defined by the next higher composite.
A wire can only connect a source to a target if the
target implements an interface that is compatible with the interface declared
by the source. The source and the target are compatible if the
target interface is a compatible superset of the source
interface, defined as follows:
1.the source The interface
anddeclared by
the target interface
of a wire MUST either both be remotable or else botha compatible superset of the interface declared by
the source of the wire.The
interface declared by the target of a wire MUST be locala
compatible superset of the interface declared by the source of the wire. [ASM60015]
2.1.the operations on the target interface of a wire MUST
be the same as or be a superset of the operations in the interface specified on
the source [ASM60016]
3.1.compatibility between the source interface and the
target interface for a wire for the individual operations is defined as
compatibility of the signature, that is operation name, input types, and output
types MUST be the same. [ASM60017]
4.1.the order of the input and output types for
operations in the source interface and the target interface of a wire also MUST
be the same. [ASM60018]
5.1.the set of Faults and Exceptions expected by each
operation in the source interface MUST be the same or be a superset of those
specified by the target interface. [ASM60019]
If either the source interface of a wire or the
target interface of a wire declares a callback interface then both the source
interface and the target interface MUST declare a callback interface and the
callback interface declared on the target MUST be a compatible superset of the
callback interface declared on the source. [ASM60020]
[ASM60043] See the section on Interface Compatibility for a definition of "compatible superset".
A Wire can connect between different interface languages (e.g. Java interfaces and WSDL portTypes) in either direction, as long as the operations defined by the two interface types are equivalent. They are equivalent if the operation(s), parameter(s), return value(s) and faults/exceptions map to each other.
Service clients cannot (portably) ask questions at runtime about additional interfaces that are provided by the implementation of the service (e.g. the result of “instance of” in Java is non portable). It is valid for an SCA implementation to have proxies for all wires, so that, for example, a reference object passed to an implementation might only have the business interface of the reference and might not be an instance of the (Java) class which is used to implement the target service, even where the interface is local and the target service is running in the same process.
Note: It is permitted to deploy a composite that has references that are not wired. For the case of an un-wired reference with multiplicity 1..1 or 1..n the deployment process provided by an SCA runtime SHOULD issue a warning. [ASM60021]
The following figureFigure 5‑5: MyValueComposite2 showing WiresFigure 5‑5: MyValueComposite2 showing Wires shows the assembly diagram for the
MyValueComposite2 containing wires between service, components and references.
Figure 1155‑5:
MyValueComposite2 showing Wires
The following snippet
Snippet 5‑14: Example composite with a wireSnippet 5‑14: Example composite with a wire shows the MyValueComposite2.composite file for the
MyValueComposite2 containing the configured component and service references.
The service MyValueService is wired to the MyValueServiceComponent, using an
explicit <wire/> element. The MyValueServiceComponent’s customerService
reference is wired to the composite's CustomerService reference. The
MyValueServiceComponent’s stockQuoteService reference is wired to the StockQuoteMediatorComponent,
which in turn has its reference wired to the StockQuoteService reference of the
composite.
<?xml version="1.0" encoding="ASCII"?>
<!-- MyValueComposite Wires examples -->
<composite
xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
targetNamespace="http://foo.com"
name="MyValueComposite2" >
<service name="MyValueService" promote="MyValueServiceComponent">
<interface.java interface="services.myvalue.MyValueService"/>
<binding.ws
portwsdlElement="http://www.myvalue.org/MyValueService#
wsdl.endpointport(MyValueService/MyValueServiceSOAP)"/>
</service>
<component name="MyValueServiceComponent">
<implementation.java
class="services.myvalue.MyValueServiceImpl"/>
<property name="currency">EURO</property>
<service name="MyValueService"/>
<reference name="customerService"/>
<reference name="stockQuoteService"/>
</component>
<wire source="MyValueServiceComponent/stockQuoteService"
target="StockQuoteMediatorComponent"/>
<component name="StockQuoteMediatorComponent">
<implementation.java class="services.myvalue.SQMediatorImpl"/>
<property name="currency">EURO</property>
<reference name="stockQuoteService"/>
</component>
<reference name="CustomerService"
promote="MyValueServiceComponent/customerService">
<interface.java interface="services.customer.CustomerService"/>
<binding.sca/>
</reference>
<reference name="StockQuoteService"
promote="StockQuoteMediatorComponent">
<interface.java
interface="services.stockquote.StockQuoteService"/>
<binding.ws portwsdlElement="http://www.stockquote.org/StockQuoteService#
wsdl.endpointport(StockQuoteService/StockQuoteServiceSOAP)"/>
</reference>
</composite>
Snippet 55‑14: Example composite with a wire
SCA provides a feature named Autowire, which can help to simplify the assembly of composites. Autowire enables component references to be automatically wired to component services which will satisfy those references, without the need to create explicit wires between the references and the services. When the autowire feature is used, a component reference which is not promoted and which is not explicitly wired to a service within a composite is automatically wired to a target service within the same composite. Autowire works by searching within the composite for a service interface which matches the interface of the references.
The autowire feature is not used by default. Autowire is enabled by the setting of an @autowire attribute to "true". Autowire is disabled by setting of the @autowire attribute to "false" The @autowire attribute can be applied to any of the following elements within a composite:
· reference
· component
· composite
Where an element does not have an explicit setting for the @autowire attribute, it inherits the setting from its parent element. Thus a reference element inherits the setting from its containing component. A component element inherits the setting from its containing composite. Where there is no setting on any level, autowire="false" is the default.
As an example, if a composite element has autowire="true" set, this means that autowiring is enabled for all component references within that composite. In this example, autowiring can be turned off for specific components and specific references through setting autowire="false" on the components and references concerned.
For each component reference for which autowire is
enabled, the SCA runtime MUST search within the composite for target services
which arehave
an interface that is a compatible withsuperset of the
interface of the reference.For each component reference for which autowire is
enabled, the SCA runtime MUST search within the composite for target services
which have an interface that is a compatible superset of the interface of the
reference. [ASM60022] "Compatible"
here means:
·the target service interface MUST be a compatible
superset of the reference interface when using autowire to wire a reference (as
defined in the section on Wires)the target service
interface MUST be a compatible superset of the reference interface when using
autowire to wire a reference (as defined in the section on Wires)The intents, and
policies applied to the service MUST be compatible with those on the reference
when using autowire to wire a reference – so that wiring the reference to the
service will not cause an error due to policy mismatchThe
intents, and policies applied to the service MUST be compatible with those on
the reference when using autowire to wire a reference – so that wiring the
reference to the service will not cause an error due to policy mismatch [ASM60023]
·the intents, and policies applied to the service MUST
be compatible with those on the reference when using autowire to wire a
reference – so that wiring the reference to the service will not cause an error
due to policy mismatch [ASM60024] (see the Policy Framework specification [10] for details)
[ASM60024] (see the Policy Framework specification [SCA-POLICY] for details)
If the search finds 1 or more valid target service for a particular reference, the action taken depends on the multiplicity of the reference:
·
for an autowire reference with multiplicity 0..1 or
1..1, the SCA runtime MUST wire the reference to one of the set of valid target
services chosen from the set in a runtime-dependent fashionfor an autowire reference with multiplicity 0..1 or
1..1, the SCA runtime MUST wire the reference to one of the set of valid target
services chosen from the set in a runtime-dependent fashion [ASM60025]
·
for an autowire reference with multiplicity 0..n or
1..n, the reference MUST be wired to all of the set of valid target servicesfor an autowire reference with multiplicity 0..n or
1..n, the reference MUST be wired to all of the set of valid target services [ASM60026]
If the search finds no valid target services for a particular reference, the action taken depends on the multiplicy of the reference:
·
for an autowire reference with multiplicity 0..1 or
0..n, if the SCA runtime finds no valid target service, there is no problem –
no services are wired and the SCA runtime MUST NOT raise an errorfor an autowire reference with multiplicity 0..1 or
0..n, if the SCA runtime finds no valid target service, there is no problem –
no services are wired and the SCA runtime MUST NOT raise an error [ASM60027]
·
for an autowire reference with multiplicity 1..1 or
1..n, if the SCA runtime finds no valid target services an error MUST be raised
by the SCA runtime since the reference is intended to be wiredfor an autowire reference with multiplicity 1..1 or
1..n, if the SCA runtime finds no valid target services an error MUST be raised
by the SCA runtime since the reference is intended to be wired [ASM60028]
This example demonstratesSnippet 5‑15Snippet 5‑15 and Snippet 5‑16Snippet 5‑16 demonstrate two versions of the same composite – the first
version is done using explicit wires, with no autowiring used, the second
version is done using autowire. In both cases the end result is the same – the
same wires connect the references to the services.
First, hereFigure 5‑6Figure 5‑6 is a diagram for the composite:
Figure 12
Figure 55‑6: Example Composite for Autowire
First,
Snippet 5‑15Snippet 5‑15 is the composite using explicit wires:
<?xml version="1.0" encoding="UTF-8"?>
<!-- Autowire Example - No autowire -->
<composite xmlns:xsd="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
xmlns:foo="http://foo.com"
targetNamespace="http://foo.com"
name="AccountComposite">
<service name="PaymentService" promote="PaymentsComponent"/>
<component name="PaymentsComponent">
<implementation.java class="com.foo.accounts.Payments"/>
<service name="PaymentService"/>
<reference name="CustomerAccountService"
target="CustomerAccountComponent"/>
<reference name="ProductPricingService"
target="ProductPricingComponent"/>
<reference name="AccountsLedgerService"
target="AccountsLedgerComponent"/>
<reference name="ExternalBankingService"/>
</component>
<component name="CustomerAccountComponent">
<implementation.java class="com.foo.accounts.CustomerAccount"/>
</component>
<component name="ProductPricingComponent">
<implementation.java class="com.foo.accounts.ProductPricing"/>
</component>
<component name="AccountsLedgerComponent">
<implementation.composite name="foo:AccountsLedgerComposite"/>
</component>
<reference name="ExternalBankingService"
promote="PaymentsComponent/ExternalBankingService"/>
</composite>
Secondly,Snippet 55‑15:
Example composite with Explicit wires
Snippet 5‑16Snippet 5‑16 is the composite using autowire:
<?xml version="1.0" encoding="UTF-8"?>
<!-- Autowire Example - With autowire -->
<composite xmlns:xsd="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
xmlns:foo="http://foo.com"
targetNamespace="http://foo.com"
name="AccountComposite">
<service name="PaymentService" promote="PaymentsComponent">
<interface.java class="com.foo.PaymentServiceInterface"/>
</service>
<component name="PaymentsComponent" autowire="true">
<implementation.java class="com.foo.accounts.Payments"/>
<service name="PaymentService"/>
<reference name="CustomerAccountService"/>
<reference name="ProductPricingService"/>
<reference name="AccountsLedgerService"/>
<reference name="ExternalBankingService"/>
</component>
<component name="CustomerAccountComponent">
<implementation.java class="com.foo.accounts.CustomerAccount"/>
</component>
<component name="ProductPricingComponent">
<implementation.java class="com.foo.accounts.ProductPricing"/>
</component>
<component name="AccountsLedgerComponent">
<implementation.composite name="foo:AccountsLedgerComposite"/>
</component>
<reference name="ExternalBankingService"
promote="PaymentsComponent/ExternalBankingService"/>
</composite>
Snippet 55‑16: composite of Snippet 5‑15Snippet 5‑15 Using autowire
In this second case, autowire is set on for the PaymentsComponent and there are no explicit wires for any of its references – the wires are created automatically through autowire.
Note: In the second example, it would be possible to omit all of the service and reference elements from the PaymentsComponent. They are left in for clarity, but if they are omitted, the component service and references still exist, since they are provided by the implementation used by the component.
Composites can be used as component implementations in higher-level composites – in other words the higher-level composites can have components which are implemented by composites.
When a composite is used as a component implementation, it defines a boundary of visibility. Components within the composite cannot be referenced directly by the using component. The using component can only connect wires to the services and references of the used composite and set values for any properties of the composite. The internal construction of the composite is invisible to the using component. The boundary of visibility, sometimes called encapsulation, can be enforced when assembling components and composites, but such encapsulation structures might not be enforceable in a particular implementation language.
A composite used as a component implementation also needs to honor a completeness contract. The services, references and properties of the composite form a contract (represented by the component type of the composite) which is relied upon by the using component. The concept of completeness of the composite implies that, once all <include/> element processing is performed on the composite:
1. For
a composite used as a component implementation, each composite service offered
by the composite MUST promote a component service of a component that is within
the composite. For
a composite used as a component implementation, each composite service offered
by the composite MUST promote a component service of a component that is within
the composite. [ASM60032]
2. For
a composite used as a component implementation, every component reference of
components within the composite with a multiplicity of 1..1 or 1..n MUST be
wired or promoted.For
a composite used as a component implementation, every component reference of
components within the composite with a multiplicity of 1..1 or 1..n MUST be
wired or promoted. [ASM60033] (according to the various rules for specifying target
services for a component reference described in the section " Specifying
the Target Service(s) for a Reference").
3. For
a composite used as a component implementation, all properties of components
within the composite, where the underlying component implementation specifies "mustSupply=true"
for the property, MUST either specify a value for the property or source the
value from a composite property. For a composite used as a component implementation,
all properties of components within the composite, where the underlying component
implementation specifies "mustSupply=true" for the property, MUST
either specify a value for the property or source the value from a composite
property. [ASM60034]
The component type of a composite is defined by the set of composite service elements, composite reference elements and composite property elements that are the children of the composite element.
Composites are used as component implementations
through the use of the implementation.composite element as a child element of the component. The Snippet 5‑17Snippet 5‑17 shows the pseudo-schema snippet
for the
implementation.composite element
is:
<!-- implementation.composite pseudo-schema -->
<implementation.composite name="xs:QName" requires="list of xs:QName"? policySets="list of xs:QName"?>
Snippet 55‑17: implementation.composite Pseudo-Schema
The implementation.composite element has the following
attributes:
·
name (1..1) – the name of the composite used as an implementation.
The
@name attribute of an <implementation.composite/> element MUST contain
the QName of a composite in the SCA Domain.The @name attribute of
an <implementation.composite/> element MUST contain the QName of a
composite in the SCA Domain.
[ASM60030]
·
requires : QNamelistOfQNames (0..n1)
– a list of policy intents. See the Policy Framework specification
[10]SCA-POLICY] for a description of this attribute. Specified intents add
to or further qualify the required intents defined for the promoted component
reference.
·
policySets : QNamelistOfQNames (0..n1)
– a list of policy sets. See
the Policy Framework specification [10]SCA-POLICY] for a description of this attribute.
An SCA runtime MUST introspect the componentType of a Composite used as a Component Implementation following the rules defined in the section "Component Type of a Composite used as a Component Implementation"An SCA runtime MUST introspect the componentType of a Composite used as a Component Implementation following the rules defined in the section "Component Type of a Composite used as a Component Implementation" [ASM60045]
The componentType of a Composite used as a Component Implementation is introspected from the Composite document as follows:
A <service/> element exists for each direct <service/> subelement of the <composite/> element
A <reference/> element exists for each direct <reference/> subelement of the <composite/> element.
A <property/> element exists for each direct <property/> subelement of the <composite/> element.
A <implementation/> element exists if the <composite/> element has either of the @requires or @policySets attributes declared, with:
The following isSnippet 5‑18Snippet 5‑18 shows an example
of a composite which contains two components, each of which is implemented by a
composite:
<?xml version="1.0" encoding="UTF-8"?>
<!-- CompositeComponent example -->
<composite xmlns:xsd="http://www.w3.org/2001/XMLSchema-instance"
xsd:schemaLocation="http://docs.oasis-open.org/ns/opencsa/sca/200903200912
file:/C:/Strategy/SCA/v09_osoaschemas/schemas/sca.xsd"
xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
targetNamespace="http://foo.com"
xmlns:foo="http://foo.com"
name="AccountComposite">
<service name="AccountService" promote="AccountServiceComponent">
<interface.java interface="services.account.AccountService"/>
<binding.ws
portwsdlElement="AccountService#
wsdl.endpointport(AccountService/AccountServiceSOAP)"/>
</service>
<reference name="stockQuoteService"
promote="AccountServiceComponent/StockQuoteService">
<interface.java
interface="services.stockquote.StockQuoteService"/>
<binding.ws
portwsdlElement="http://www.quickstockquote.com/StockQuoteService#
wsdl.endpointport(StockQuoteService/StockQuoteServiceSOAP)"/>
</reference>
<property name="currency" type="xsd:string">EURO</property>
<component name="AccountServiceComponent">
<implementation.composite name="foo:AccountServiceComposite1"/>
<reference name="AccountDataService" target="AccountDataService"/>
<reference name="StockQuoteService"/>
<property name="currency" source="$currency"/>
</component>
<component name="AccountDataService">
<implementation.composite name="foo:AccountDataServiceComposite"/>
<property name="currency" source="$currency"/>
</component>
</composite>
Snippet 55‑18: Example of a composite Using implementation.composite
In order to assist team development, composites can be developed in the form of multiple physical artifacts that are merged into a single logical unit.
A composite can include another composite by using the include element. This provides a recursive inclusion capability. The semantics of included composites are that the element content children of the included composite are inlined, with certain modification, into the using composite. This is done recursively till the resulting composite does not contain an include element. The outer included composite element itself is discarded in this process – only its contents are included as described below:
1. All the element content children of the included composite are inlined in the including composite.
2. The
attributes @targetNamespace, @name,
@constrainingType, and @local of the
included composites are discarded.
3. All the namespace declaration on the included composite element are added to the inlined element content children unless the namespace binding is overridden by the element content children.
4. The attribute @autowire, if specified on the included composite, is included on all inlined component element children unless the component child already specifies that attribute.
5. The attribute values of @requires and @policySet, if specified on the included composite, are merged with corresponding attribute on the inlined component, service and reference children elements. Merge in this context means a set union.
6. Extension attributes ,if present on the included composite, follow the rules defined for that extension. Authors of attribute extensions on the composite element define the rules applying to those attributes for inclusion.
If the included
composite has the value true for the attribute @local then the including composite MUST have the same
value for the @local attribute, else it is an error.If the included
composite has the value true for the attribute @local then the including
composite MUST have the same value for the @local attribute, else it is
an error.If the included composite has the value true for the attribute @local then the including composite MUST have the same
value for the @local [ASM60041] attribute, else it is an error.
The composite file used for inclusion can have any
contents .
The composite element can contain any
of the elements which are valid as child elements of a composite element,
namely components, services, references, wires and includes. There is no need
for the content of an included composite to be complete, so that artifacts
defined within the using composite or in another associated included composite
file can be referenced. For example, it is permissible to have two components
in one composite file while a wire specifying one component as the source and
the other as the target can be defined in a second included composite file.
The SCA runtime MUST raise an error if the
composite resulting from the inclusion of one composite into another is
invalid.The
SCA runtime MUST raise an error if the composite resulting from the inclusion
of one composite into another is invalid. [ASM60031] For
example, it is an error if there are duplicated elements in the using composite
(e.g. two services with the same uri contributed by different included
composites). It is not considered an erorr if the (using) composite resulting
from the inclusion is incomplete (eg. wires with non-existent source or
target). Such incomplete resulting composites are permitted to allow recursive
composition.
The followingSnippet 5‑19Snippet 5‑19 snippet shows the pseudo-schema for the include
element.:
<?xml version="1.0" encoding="UTF-8"?>
<!-- Include snippet -->
<composite ...>
...
<include name="xs:QName"/>*
...
</composite>
Snippet 55‑19: include Pseudo-Schema
The include element has the following attribute:
·
name: QName (1..1) – the name of the composite that
is included. The @name attribute of
an include element MUST be the QName of a composite in the SCA Domain.The @name attribute of an include element MUST be
the QName of a composite in the SCA Domain. [ASM60042]
The following figureFigure 5‑7Figure 5‑7 shows the assembly diagram for the
MyValueComposite2 containing four included composites. The MyValueServices composite contains the MyValueService service. The MyValueComponents composite contains the MyValueServiceComponent and the StockQuoteMediatorComponent
as well as the wire between them. The MyValueReferences
composite contains the
CustomerService and StockQuoteService references. The MyValueWires composite contains the wires that connect the MyValueService
service to the MyValueServiceComponent, that connect the customerService
reference of the MyValueServiceComponent to the CustomerService reference, and
that connect the stockQuoteService reference of the StockQuoteMediatorComponent
to the StockQuoteService reference. Note that this is just one possible way of
building the MyValueComposite2 from a set of included composites.
Figure 13
Figure 55‑7 MyValueComposite2 built from 4 included composites
The following snippetSnippet 5‑20Snippet 5‑20 shows the contents of the
MyValueComposite2.composite file for the MyValueComposite2 built using included
composites. In this sample it only provides the name of the composite. The
composite file itself could be used in a scenario using included composites to
define components, services, references and wires.
<?xml version="1.0" encoding="ASCII"?>
<composite xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
targetNamespace="http://foo.com"
xmlns:foo="http://foo.com"
name="MyValueComposite2" >
<include name="foo:MyValueServices"/>
<include name="foo:MyValueComponents"/>
<include name="foo:MyValueReferences"/>
<include name="foo:MyValueWires"/>
</composite>
The following snippetSnippet
55‑20:
Example composite with includes
Snippet 5‑21Snippet 5‑21 shows the content of the MyValueServices.composite file.
<?xml version="1.0" encoding="ASCII"?>
<composite xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
targetNamespace="http://foo.com"
xmlns:foo="http://foo.com"
name="MyValueServices" >
<service name="MyValueService" promote="MyValueServiceComponent">
<interface.java interface="services.myvalue.MyValueService"/>
<binding.ws
portwsdlElement="http://www.myvalue.org/MyValueService#
wsdl.endpointport(MyValueService/MyValueServiceSOAP)"/>
</service>
</composite>
The following snippetSnippet
55‑21:
Example Partial composite with Only a service
Snippet 5‑22Snippet 5‑22 shows the content of the MyValueComponents.composite file.
<?xml version="1.0" encoding="ASCII"?>
<composite xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
targetNamespace="http://foo.com"
xmlns:foo="http://foo.com"
name="MyValueComponents" >
<component name="MyValueServiceComponent">
<implementation.java
class="services.myvalue.MyValueServiceImpl"/>
<property name="currency">EURO</property>
</component>
<component name="StockQuoteMediatorComponent">
<implementation.java class="services.myvalue.SQMediatorImpl"/>
<property name="currency">EURO</property>
</component>
<composite>
The following snippetSnippet
55‑22:
Example Partial composite with Only components
Snippet 5‑23Snippet 5‑23 shows the content of the MyValueReferences.composite file.
<?xml version="1.0" encoding="ASCII"?>
<composite xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
targetNamespace="http://foo.com"
xmlns:foo="http://foo.com"
name="MyValueReferences" >
<reference name="CustomerService"
promote="MyValueServiceComponent/CustomerService">
<interface.java interface="services.customer.CustomerService"/>
<binding.sca/>
</reference>
<reference name="StockQuoteService"
promote="StockQuoteMediatorComponent">
<interface.java
interface="services.stockquote.StockQuoteService"/>
<binding.ws
portwsdlElement="http://www.stockquote.org/StockQuoteService#
wsdl.endpointport(StockQuoteService/StockQuoteServiceSOAP)"/>
</reference>
</composite>
The following snippetSnippet
55‑23:
Example Partial composite with Only references
Snippet 5‑24Snippet 5‑24 shows the content of the MyValueWires.composite file.
<?xml version="1.0" encoding="ASCII"?>
<composite xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
targetNamespace="http://foo.com"
xmlns:foo="http://foo.com"
name="MyValueWires" >
<wire source="MyValueServiceComponent/stockQuoteService"
target="StockQuoteMediatorComponent"/>
</composite>
Snippet 55‑24: Example Partial composite with Only a wire
A Composite containing multiple components can have multiple component implementation types. For example, a Composite can contain one component with a Java POJO as its implementation and another component with a BPEL process as its implementation.
The structural URI is a relative URI that describes each use of a given component in the Domain, relative to the URI of the Domain itself. It is never specified explicitly, but it calculated from the configuration of the components configured into the Domain.
A component in a composite can be used more than once in the Domain, if its containing composite is used as the implementation of more than one higher-level component. The structural URI is used to separately identify each use of a component - for example, the structural URI can be used to attach different policies to each separate use of a component.
For components directly deployed into the Domain, the structural URI is simply the name of the component.
Where components are nested within a composite which is used as the implementation of a higher level component, the structural URI consists of the name of the nested component prepended with each of the names of the components upto and including the Domain level component.
For example, consider a component named Component1 at the Domain level, where its implementation is Composite1 which in turn contains a component named Component2, which is implemented by Composite2 which contains a component named Component3. The three components in this example have the following structural URIs:
1. Component1: Component1
2. Component2: Component1/Component2
3. Component3: Component1/Component2/Component3
The structural URI can also be extended to refer to specific parts of a component, such as a service or a reference, by appending an appropriate fragment identifier to the component's structural URI, as follows:
·
Service:
#service(servicename)
·
Reference:
#reference(referencename)
·
Service binding:
#service-binding(servicename/bindingname)
·
Reference binding:
#reference-binding(referencename/bindingname)
So, for example, the structural URI of the service named "testservice" of component "Component1" is Component1#service(testservice).
SCA allows a component, and its associated
implementation, to be constrained by a constrainingType. The
constrainingType element provides assistance in developing top-down usecases in
SCA, where an architect or assembler can define the structure of a composite,
including the necessary form of component implementations, before any of the
implementations are developed.
A constrainingType is expressed as an element which
has services, reference and properties as child elements and which can have
intents applied to it. The constrainingType is independent of any
implementation. Since it is independent of an implementation it cannot contain
any implementation-specific configuration information or defaults.
Specifically, constrainingType does not contain bindings, policySets, property
values or default wiring information. The constrainingType is applied to a
component through a @constrainingType attribute on the component.
A constrainingType provides the "shape"
for a component and its implementation. Any component configuration that points
to a constrainingType is constrained by this shape. The constrainingType specifies the services,
references and properties that MUST be provided by the implementation of the
component to which the constrainingType is attached. [ASM70001]
This provides the ability for the implementer to program to a specific set of
services, references and properties as defined by the constrainingType.
Components are therefore configured instances of implementations and are
constrained by an associated constrainingType.
If the configuration of the component or its
implementation does not conform to the constrainingType specified on the
component element, the SCA runtime MUST raise an error. [ASM70002]
A constrainingType is represented by a constrainingType
element. The following snippet shows the pseudo-schema for the composite
element.
<?xml
version="1.0"
encoding="ASCII"?>
<!--
ConstrainingType schema snippet -->
<constrainingType
xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903"
multiplicity="0..1
or 1..1 or 0..n or 1..n"?>*
<property
name="xs:NCName"
(type="xs:QName"
| element="xs:QName")
many="xs:boolean"?
mustSupply="xs:boolean"?/>*
The constrainingType element has the following attributes:
·name (1..1)
– the name of the constrainingType. The form of a constraingType name is an XML
QName, in the namespace identified by the @targetNamespace attribute. The @name attribute of the constraining type MUST be
unique in the SCA Domain. [ASM70003]
·targetNamespace
(0..1) – an identifier for a
target namespace into which the constrainingType is declared
ConstrainingType contains zero or more
properties, services, references.
When an implementation is constrained by a
constrainingType its component type MUST contain all the services, references
and properties specified in the constrainingType. [ASM70004]
The constraining type’s references and services will have interfaces specified
and can have intents specified. An implementation MAY contain additional services,
additional references with @multiplicity=0..1 or @multiplicity=0..n and
additional properties with @mustSupply=false beyond those declared in the
constraining type, but MUST NOT contain additional references with
@multiplicity=1..1 or @multiplicity=1..n or additional properties with
@mustSupply=true [ASM70005]
When a component is constrained by a
constrainingType via the @constrainingType attribute, the entire componentType
associated with the component and its implementation is not visible to the
containing composite. The containing composite can only see a projection of the
componentType associated with the component and implementation as scoped by the
constrainingType of the component. Additional services, references and properties
provided by the implementation which are not declared in the constrainingType
associated with a component MUST NOT be configured in any way by the containing
composite. [ASM70006] This
requirement ensures that the constrainingType contract cannot be violated by
the composite.
A constrainingType can be applied to an
implementation. In this case, the implementation's componentType has a
@constrainingType attribute set to the QName of the constrainingType.
The following snippet shows the contents of the
component called "MyValueServiceComponent" which is constrained by
the constrainingType myns:CT. The componentType associated with the
implementation is also shown.
<component name="MyValueServiceComponent"
constrainingType="myns:CT>
<implementation.java
class="services.myvalue.MyValueServiceImpl"/>
<property name="currency">EURO</property>
<reference name="customerService"
target="CustomerService">
<reference name="stockQuoteService"
target="StockQuoteMediatorComponent"/>
targetNamespace="http://myns.com">
<service name="MyValueService">
<interface.java interface="services.myvalue.MyValueService"/>
<reference name="customerService">
<interface.java interface="services.customer.CustomerService"/>
<reference name="stockQuoteService">
<interface.java interface="services.stockquote.StockQuoteService"/>
<property name="currency"
type="xsd:string"/>
The component MyValueServiceComponent is
constrained by the constrainingType CT which means that it needs to provide:
·service MyValueService
with the interface services.myvalue.MyValueService
·reference customerService
with the interface services.stockquote.StockQuoteService
·reference stockQuoteService
with the interface services.stockquote.StockQuoteService
·property currency
of type xsd:string.
Interfaces define one or more business functions. These business functions are provided by Services and are used by References. A Service offers the business functionality of exactly one interface for use by other components. Each interface defines one or more service operations and each operation has zero or one request (input) message and zero or one response (output) message. The request and response messages can be simple types such as a string value or they can be complex types.
SCA currently supports the following interface type systems:
· Java interfaces
·
WSDL 1.1 portTypes (Web
Services Definition Language [8]WSDL-11])
· C++ classes
· Collections of 'C' functions
SCA is also extensible in terms of interface types. Support for other interface type systems can be added through the extensibility mechanisms of SCA, as described in the Extension Model section.
The following snippetSnippet 6‑1 shows the definitionpseudo-schema for the interface base element.:
<interface remotable="boolean"? requires="list of xs:QName"?
policySets="list of xs:QName"?/>"?>
<requires/>*
<policySetAttachment/>*
</interface>
Snippet 6‑1: interface Pseudo-Schema
The interface base element has the following attributes:
·
remotable : boolean (0..1)
– indicates whether an
interface is remotable or not (see Error! Reference source not found.the section on Local and Remotable interfaces). A value of “true” means the interface is
remotable, and a value of “false” means it is not. The @remotable attribute
has no default value. This attribute is used as an alternative to interface
type specific mechanisms such as the @Remotable annotation on a Java
interface. The remotable nature of an interface in the absence of this attribute
is interface type specific. The rules governing how this attribute relates to
interface type specific mechanisms are defined by each interface type. When
specified on an interface definition which includes a callback, this attribute
also applies to the callback interface (see
Error! Reference source not found.the section on Bidirectional Interfaces).
·
requires : QNamelistOfQNames (0..n1)
– a list of policy intents. See the Policy Framework specification
[10]SCA-POLICY] for a description of this attribute
·
policySets : QNamelistOfQNames (0..n1)
– a list of policy sets. See
the Policy Framework specification [10]SCA-POLICY] for a description of this attribute.
The interface element has the following subelements:
· requires : requires (0..n) - A service element has zero or more requires subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
· policySetAttachment : policySetAttachment (0..n) - A service element has zero or more policySetAttachment subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
For information about Java interfaces, including details of SCA-specific annotations, see the SCA Java Common Annotations and APIs specification [SCA-Common-Java].
For information about WSDL interfaces, including details of SCA-specific extensions, see SCA-Specific Aspects for WSDL Interfaces and WSDL Interface Type.
For information about C++ interfaces, see the SCA C++ Client and Implementation Model specification [SCA-CPP-Client].
For information about C interfaces, see the SCA C Client and Implementation Model specification [SCA-C-Client].
A remotable service is one which can be called by a client which is running in an operating system process different from that of the service itself (this also applies to clients running on different machines from the service). Whether a service of a component implementation is remotable is defined by the interface of the service. WSDL defined interfaces are always remotable. See the relevant specifications for details of interfaces defined using other languages.
The style of remotable interfaces is typically coarse grained and intended for loosely
coupled interactions. Remotable service
Interfaces MUST NOT make use of method or operation overloading.Remotable service Interfaces MUST NOT make use of method or operation
overloading.Remotable service Interfaces MUST NOT make use of method or operation overloading [ASM80002] This restriction on operation overloading for
remotable services aligns with the WSDL 2.0 specification, which disallows
operation overloading, and also with the WS-I Basic Profile 1.1 (section 4.5.3
- R2304) which has a constraint which disallows operation overloading when
using WSDL 1.1..
Independent of whether the remotable service is called remotely from outside
the process where the service runs or from another component running in the
same process, the data exchange semantics are by-value.
Implementations of remotable services can modify
input messages (parameters) during or after an invocation and can modify return
messages (results) after the invocation. If a
remotable service is called locally or remotely, the SCA container MUST ensure
sure that no modification of input messages by the service or post-invocation
modifications to return messages are seen by the caller.If a remotable service is called locally or
remotely, the SCA container MUST ensure sure that no modification of input
messages by the service or post-invocation modifications to return messages are
seen by the caller.
[ASM80003]
Here is a snippet whichSnippet 6‑2 shows an example of a remotable java interface:
package services.hello;
@Remotable
public interface HelloService {
String hello(String message);
}
Snippet 6‑2: Example remotable interface
It is possible for the implementation of a remotable service to indicate that it can be called using by-reference data exchange semantics when it is called from a component in the same process. This can be used to improve performance for service invocations between components that run in the same process. This can be done using the @AllowsPassByReference annotation (see the Java Client and Implementation Specification).
A service typed by a local interface can only be called by clients that are running in the same process as the component that implements the local service. Local services cannot be published via remotable services of a containing composite. In the case of Java a local service is defined by a Java interface definition without a @Remotable annotation.
The style of local interfaces is typically fine grained and intended for tightly coupled interactions. Local service interfaces can make use of method or operation overloading.
The data exchange semantic for calls to services typed by local interfaces is by-reference.
The compatibility of two interfaces is defined in this section and these definitions are used throughout this specification. Three forms of compatibility are defined:
· Compatible interfaces
· Compatible subset
· Compatible superset
Note that WSDL 1.1 message parts can point to an XML Schema element declaration or to an XML Schema types. When determining compatibility between two WSDL operations, a message part that points to an XML Schema element declaration is considered to be incompatible with a message part that points to an XML Schema type.
An interface A is Compatible with a second interface B if and only if all of points 1 through 7 in the following list apply:
1. interfaces A and B are either both remotable or else both local
2. the set of operations in interface A is the same as the set of operations in interface B
3. compatibility for individual operations of the interfaces A and B is defined as compatibility of the signature, i.e., the operation name, the input types, and the output types are the same
4. the order of the input and output types for each operation in interface A is the same as the order of the input and output types for the corresponding operation in interface B
5. the set of Faults and Exceptions expected by each operation in interface A is the same as the set of Faults and Exceptions specified by the corresponding operation in interface B
6.
for checking the compatibility of 2 remotable
interfaces which are in different interface languages, both are mapped to WSDL
1.1 (if not already WSDL 1.1) and compatibility checking is done between the
WSDL 1.1 mapped interfaces.
For checking the compatibility of 2 local interfaces which are in different
interface languages, the method of checking compatibility is defined by the
specifications which define those interface types, which must define mapping
rules for the 2 interface types concerned.
7. if either interface A or interface B declares a callback interface then both interface A and interface B declare callback interfaces and the callback interface declared on interface A is compatible with the callback interface declared on interface B, according to points 1 through 6 above
An interface A is a Compatible Subset of a second interface B if and only if all of points 1 through 7 in the following list apply:
1. interfaces A and B are either both remotable or else both local
2. the set of operations in interface A is the same as or is a subset of the set of operations in interface B
3. compatibility for individual operations of the interfaces A and B is defined as compatibility of the signature, i.e., the operation name, the input types, and the output types are the same
4. the order of the input and output types for each operation in interface A is the same as the order of the input and output types for the corresponding operation in interface B
5. the set of Faults and Exceptions expected by each operation in interface A is the same as or is a superset of the set of Faults and Exceptions specified by the corresponding operation in interface B
6.
for checking the compatibility of 2 remotable
interfaces which are in different interface languages, both are mapped to WSDL
1.1 (if not already WSDL 1.1) and compatibility checking is done between the
WSDL 1.1 mapped interfaces.
For checking the compatibility of 2 local interfaces which are in different
interface languages, the method of checking compatibility is defined by the
specifications which define those interface types, which must define mapping
rules for the 2 interface types concerned.
7. if either interface A or interface B declares a callback interface then both interface A and interface B declare callback interfaces and the callback interface declared on interface B is a compatible subset of the callback interface declared on interface A, according to points 1 through 6 above
An interface A is a Compatible Superset of a second interface B if and only if all of points 1 through 7 in the following list apply:
1. interfaces A and B are either both remotable or else both local
2. the set of operations in interface A is the same as or is a superset of the set of operations in interface B
3. compatibility for individual operations of the interfaces A and B is defined as compatibility of the signature, i.e., the operation name, the input types, and the output types are the same
4. the order of the input and output types for each operation in interface B is the same as the order of the input and output types for the corresponding operation in interface A
5. the set of Faults and Exceptions expected by each operation in interface A is the same as or is a subset of the set of Faults and Exceptions specified by the corresponding operation in interface B
6.
for checking the compatibility of 2 remotable
interfaces which are in different interface languages, both are mapped to WSDL
1.1 (if not already WSDL 1.1) and compatibility checking is done between the
WSDL 1.1 mapped interfaces.
For checking the compatibility of 2 local interfaces which are in different
interface languages, the method of checking compatibility is defined by the
specifications which define those interface types, which must define mapping
rules for the 2 interface types concerned.
7. if either interface A or interface B declares a callback interface then both interface A and interface B declare callback interfaces and the callback interface declared on interface B is a compatible superset of the callback interface declared on interface A, according to points 1 through 6 above
The relationship of a business service to another business service is often peer-to-peer, requiring a two-way dependency at the service level. In other words, a business service represents both a consumer of a service provided by a partner business service and a provider of a service to the partner business service. This is especially the case when the interactions are based on asynchronous messaging rather than on remote procedure calls. The notion of bidirectional interfaces is used in SCA to directly model peer-to-peer bidirectional business service relationships.
An interface element for a particular interface type system needs to allow the specification of a callback interface. If a callback interface is specified, SCA refers to the interface as a whole as a bidirectional interface.
The following snippetSnippet 6‑3 shows the interface element defined using Java
interfaces with a @callbackInterface attribute.
<interface.java interface="services.invoicing.ComputePrice"
callbackInterface="services.invoicing.InvoiceCallback"/>
Snippet 6‑3: Example interface with a callback
If a service is defined using a bidirectional interface element then its implementation implements the interface, and its implementation uses the callback interface to converse with the client that called the service interface.
If a reference is defined using a bidirectional
interface element, the client component implementation using the reference
calls the referenced service using the interface. The client MUST provide an
implementation of the callback interface.If a reference is defined using a bidirectional
interface element, the client component implementation using the reference
calls the referenced service using the interface. The client MUST provide an
implementation of the callback interface. [ASM80004]
Callbacks can be used for both remotable and local
services. Either both interfaces of a bidirectional service
MUST be remotable, or both MUST be local. A bidirectional service MUST NOT mix
local and remote services.Either both interfaces of a bidirectional service
MUST be remotable, or both MUST be local. A bidirectional service MUST NOT mix
local and remote services.
[ASM80005]
Note that an interface document such as a WSDL file
or a Java interface can contain annotations that declare a callback interface
for a particular interface (see the section on
WSDL Interface type and the
Java Common Annotations and APIs specification [SCA-Common-Java]). Whenever an interface document declaring a callback
interface is used in the declaration of an <interface/> element in SCA,
it MUST be treated as being bidirectional with the declared callback interface.Whenever an interface document declaring a callback
interface is used in the declaration of an <interface/> element in SCA,
it MUST be treated as being bidirectional with the declared callback interface. [ASM80010] In
such cases, there is no requirement for the <interface/> element to
declare the callback interface explicitly.
If an <interface/> element references an
interface document which declares a callback interface and also itself contains
a declaration of a callback interface, the two callback interfaces MUST be
compatible.If
an <interface/> element references an interface document which declares a
callback interface and also itself contains a declaration of a callback interface,
the two callback interfaces MUST be compatible. [ASM80011]
Where a component uses an implementation and the
component configuration explicitly declares an interface for a service or a
reference, if the matching service or reference declaration in the component
type declares an interface which has a callback interface, then the component
interface declaration MUST also declare a compatible interface with a
compatible callback interface. [ASM80012] [ASM80011]
See the section on Interface Compatibility for a definition of "compatible interfaces".
If the service or reference declaration in the
component type declares an interface without a callback interface, then the
component configuration for the corresponding service or reference MUST NOT
declare an interface with a callback interface.In a bidirectional interface, the service interface
can have more than one operation defined, and the callback interface can also
have more than one operation defined. SCA runtimes MUST allow an invocation of
any operation on the service interface to be followed by zero, one or many
invocations of any of the operations on the callback interface.In a bidirectional interface, the service interface
can have more than one operation defined, and the callback interface can also
have more than one operation defined. SCA runtimes MUST allow an invocation of
any operation on the service interface to be followed by zero, one or many invocations
of any of the operations on the callback interface.
[ASM80013]
Where a composite declares an interface for a
composite service or a composite reference, if the promoted service or promoted
reference has an interface which has a callback interface, then the interface
declaration for the composite service or the composite reference MUST also
declare a compatible interface with a compatible callback interface. [ASM80014]
If the promoted service or promoted reference has an
interface without a callback interface, then the interface declaration for the
composite service or composite reference MUST NOT declare a callback interface.
[ASM80015]
See Section 6.4 Wires for a definition of
"compatible interfaces".
In a bidirectional
interface, the service interface can have more than one operation defined, and
the callback interface can also have more than one operation defined. SCA
runtimes MUST allow an invocation of any operation on the service interface to
be followed by zero, one or many invocations of any of the operations on the
callback interface.
[ASM80009] These callback operations can be invoked either
before or after the operation on the service interface has returned a response
message, if there is one.
For a given invocation of a service operation, which operations are invoked on the callback interface, when these are invoked, the number of operations invoked, and their sequence are not described by SCA. It is possible that this metadata about the bidirectional interface can be supplied through mechanisms outside SCA. For example, it might be provided as a written description attached to the callback interface.
A service offering one or more operations which map to a WSDL request-response pattern might be implemented in a long-running, potentially interruptible, way. Consider a BPEL process with receive and reply activities referencing the WSDL request-response operation. Between the two activities, the business process logic could be a long-running sequence of steps, including activities causing the process to be interrupted. Typical examples are steps where the process waits for another message to arrive or a specified time interval to expire, or the process performs asynchronous interactions such as service invocations bound to asynchronous protocols or user interactions. This is a common situation in business processes, and it causes the implementation of the WSDL request-response operation to run for a very long time, e.g., several months (!). In this case, it is not meaningful for any caller to remain in a synchronous wait for the response while blocking system resources or holding database locks.
Note that it is possible to model long-running interactions as a pair of two independent operations as described in the section on bidirectional interfaces. However, it is a common practice (and in fact much more convenient) to model a request-response operation and let the infrastructure deal with the asynchronous message delivery and correlation aspects instead of putting this burden on the application developer.
A request-response operation is considered long-running if the implementation does not guarantee the delivery of the response within any specified time interval. Clients invoking such request-response operations are strongly discouraged from making assumptions about when the response can be expected.
This specification permits a long-running request-response operation or a complete interface containing such operations to be marked using a policy intent with the name asyncInvocation. It is also possible for a service to set the asyncInvocation. intent when using an interface which is not marked with the asyncInvocation. intent. This can be useful when reusing an existing interface definition that does not contain SCA information.
In order to support a service operation which is marked with the asyncInvocation intent, it is necessary for the binding (and its associated policies) to support separate handling of the request message and the response message. Bindings which only support a synchronous style of message handling, such as a conventional HTTP binding, cannot be used to support long-running operations.
The requirements on a binding to support the asyncInvocation intent are the same as those to support services with bidirectional interfaces - namely that the binding needs to be able to treat the transmission of the request message separately from the transmission of the response message, with an arbitrarily large time interval between the two transmissions.
An example of a binding/policy combination that supports long-running request-response operations is a Web service binding used in conjunction with the WS-Addressing "wsam:NonAnonymousResponses" assertion.
SCA implementation types can provide special asynchronous client-side and asynchronous server-side mappings to assist in the development of services and clients for long-running request-response operations.
There are a number of aspects that SCA applies to interfaces in general, such as marking them as having a callback interface. These aspects apply to the interfaces themselves, rather than their use in a specific place within SCA. There is thus a need to provide appropriate ways of marking the interface definitions themselves, which go beyond the basic facilities provided by the interface definition language.
For WSDL interfaces, there is an extension mechanism
that permits additional information to be included within the WSDL document.
SCA takes advantage of this extension mechanism. In order to use the SCA
extension mechanism, the SCA namespace (http://docs.oasis-open.org/ns/opencsa/sca/200903200912) needs to be declared within the WSDL document.
First, SCA defines a global attribute element in the SCA namespace which provides a mechanism to attach policy
intents - @requires. The Snippet 6‑4 shows the definition of this
attribute is as followsthe
requires element:
<attribute
<element name="requires">
<complexType>
<sequence minOccurs="0" maxOccurs="unbounded">
<any namespace="##other" processContents="lax"/>
</sequence>
<attribute name="intents" type="sca:listOfQNames" use="required"/>
<anyAttribute namespace="##other" processContents="lax"/>
</complexType>
</element>
<simpleType name="listOfQNames">
<list
itemType="QName"/>
</simpleType>
The @Snippet
6‑4: requires
attributeWSDL extension
definition
The requires element
can be applied
to WSDL Port Type elements (used
as a subelement of the WSDL
1.1). The
attributeportType
and operation elements.
The element contains
one or more intent names, as defined by the Policy Framework
specification [10]SCA-POLICY]. Any
service or reference that uses an interface marked with intents MUST implicitly
add those intents to its own @requires list.Any service or reference that uses an interface
marked with intents MUST implicitly add those intents to its own @requires
list. [ASM80008]
SCA defines an attribute which is used to indicate that a
given WSDL Port portType
element (WSDL 1.1) has an associated callback interface. This is the @callback
attribute, which applies to a WSDL <portType/>
element.
Snippet
6‑5 shows the definition of the @callback
attribute
The is defined as a global attribute in the SCA
namespace, as follows::
<attribute name="callback" type="QName"/>
Snippet 6‑5: callback WSDL extension definition
The value of the
@callback attribute is the QName of a Port portType.
The port typeportType
declared by the @callback attribute is the callback interface to use for the
portType which is annotated by the @callback attribute.
Snippet
6‑6 is an example of a portType element with a @callback attribute:
Here
<portType name="LoanService" sca:callback="foo:LoanServiceCallback">
<operation name="apply">
<input message="tns:ApplicationInput"/>
<output message="tns:ApplicationOutput"/>
</operation>
...
</portType>
Snippet 6‑6: Example use of @callback
The WSDL interface type is used to declare interfaces for
services and for references, where the interface is defined in terms of
a WSDL document. An interface is defined in terms of a WSDL 1.1 Port
portType with the arguments and return
of the service operations described using XML schema.
A WSDL interface is declared by an interface.wsdl
element. The following Snippet
6‑7 shows the pseudo-schema for the
interface.wsdl element:
<!-- WSDL Interface schema snippet -->
<interface.wsdl
interface="xs:anyURI" callbackInterface="xs:anyURI"?
remotable="xs:boolean"? >
requires="listOfQNames"?
policySets="listOfQNames">
<requires/>*
<policySetAttachment/>*
</interface.wsdl>
Snippet 6‑7: interface.wsdl Pseudo-Schema
The interface.wsdl
element has the following attributes:
·
interface : uri (1..1) - the URI of a WSDL Port
portType
The interface.wsdl @interface attribute MUST
reference a portType of a WSDL 1.1 document.The interface.wsdl @interface
attribute MUST reference a portType of a WSDL 1.1 document.The interface.wsdl
@interface attribute MUST reference a portType of a WSDL 1.1 document [ASM80001].
·
callbackInterface : uri (0..1) - a callback
interface, which is the URI of a WSDL Port portType
The interface.wsdl
@callbackInterface attribute, if present, MUST reference a portType of a WSDL
1.1 document.The interface.wsdl
@callbackInterface attribute, if present, MUST reference a portType of a WSDL 1.1
document. [ASM80016]
·
remotable : boolean (0..1) – indicates whether the
interface is remotable or not. @remotable has a default value of true. WSDL interfaces are always remotable and therefore
an <interface.wsdl/> element MUST NOT contain remotable=”false”.WSDL interfaces are always remotable and therefore
an <interface.wsdl/> element MUST NOT contain remotable=”false”.
[ASM80017]
· requires : listOfQNames (0..1) – a list of policy intents. See the Policy Framework specification [SCA-POLICY] for a description of this attribute.
· policySets : listOfQNames (0..1) – a list of policy sets. See the Policy Framework specification [SCA-POLICY] for a description of this attribute.
The form of the URI for WSDL port typesportTypes
follows the syntax described in the WSDL 1.1 Element Identifiers specification
[WSDL11_Identifiers]
The interface.wsdl element has the following subelements:
· requires : requires (0..n) - A service element has zero or more requires subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
· policySetAttachment : policySetAttachment (0..n) - A service element has zero or more policySetAttachment subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
<interface.wsdl interface=”http://www.stockquote.org/StockQuoteService#
wsdl.porttype(StockQuote)”
callbackInterface=”http://www.stockquote.org/StockQuoteService#
wsdl.porttype(StockQuoteCallback)”/>
This declares an interface in terms of the WSDL
port type "StockQuote" with a callback interface defined by the
"StockQuoteCallback" port type.
Snippet 6‑8 shows an interface defined by the WSDL portType "StockQuote" with a callback interface defined by the "StockQuoteCallback" portType.
<interface.wsdl interface=”http://www.stockquote.org/StockQuoteService#
wsdl.porttype(StockQuote)”
callbackInterface=”http://www.stockquote.org/StockQuoteService#
wsdl.porttype(StockQuoteCallback)”/>
Snippet 6‑8: Example interface.wsdl
Bindings are used by services and references. References use bindings to describe the access mechanism used to call a service (which can be a service provided by another SCA composite). Services use bindings to describe the access mechanism that clients (which can be a client from another SCA composite) have to use to call the service.
SCA supports the use of multiple different types of bindings. Examples include SCA service, Web service, stateless session EJB, database stored procedure, EIS service. SCA provides an extensibility mechanism by which an SCA runtime can add support for additional binding types. For details on how additional binding types are defined, see the section on the Extension Model.
A binding is defined by a binding element which is a child element of a service or of a
reference element in a composite. The
following snippetSnippet 7‑1 shows the composite pseudo-schema with the pseudo-schema for the binding element.
<?xml version="1.0" encoding="ASCII"?>
<!-- Bindings schema snippet -->
<composite ... >
...
<service ... >*
<interface … />?
<binding uri="xs:anyURI"? name="xs:NCName"?
requires="list of xs:QName"?
policySets="list of xs:QName"?>*
<wireFormat/>?
<operationSelector/>?
<requires/>*
<policySetAttachment/>*
</binding>
<callback>?
<binding uri="xs:anyURI"? name="xs:NCName"?
requires="list of xs:QName"?
policySets="list of xs:QName"?>+
<wireFormat/>?
<operationSelector/>?
<requires/>*
<policySetAttachment/>*
</binding>
</callback>
</service>
...
<reference ... >*
<interface … />?
<binding uri="xs:anyURI"? name="xs:NCName"?
requires="list of xs:QName"?
policySets="list of xs:QName"?>*
<wireFormat/>?
<operationSelector/>?
<requires/>*
<policySetAttachment/>*
</binding>
<callback>?
<binding uri="xs:anyURI"? name="xs:NCName"?
requires="list of xs:QName"?
policySets="list of xs:QName"?>+
<wireFormat/>?
<operationSelector/>?
<requires/>*
<policySetAttachment/>*
</binding>
</callback>
</reference>
...
</composite>
Snippet 7‑1: composite Pseudo-Schema with binding Child element
The element name of the binding element is architected; it is in itself a qualified name. The first qualifier is always named “binding”, and the second qualifier names the respective binding-type (e.g. binding.sca, binding.ws, binding.ejb, binding.eis).
A binding element has the following
attributes:
·
uri (0..1) - has the following
semantic.:
– The @uri attribute can be omitted.
– For a binding of a reference the @uri attribute defines the target URI of the
reference. This MUST be either the componentName/serviceName/bindingName for a wire to an endpoint within the SCA Domain,
or the accessible address of some service endpoint either inside or outside the
SCA Domain (where the addressing scheme is defined by the type of the binding).For a binding of a reference the @uri attribute
defines the target URI of the reference. This MUST be either the componentName/serviceName/bindingName for a wire to an
endpoint within the SCA Domain, or the accessible address of some service
endpoint either inside or outside the SCA Domain (where the addressing scheme
is defined by the type of the binding).For a binding of a reference [ASM90001] the @uri attribute
defines the target URI of the reference. This MUST be either the
componentName/serviceName for a wire to an endpoint within the SCA Domain, or
the accessible address of some service endpoint either inside or outside the
SCA Domain (where the addressing scheme is defined by the type of the binding).
– The circumstances under which the @uri attribute can be used are defined in section "Specifying the Target Service(s) for a Reference."
– For a binding of a service the @uri attribute defines the bindingURI. If present, the bindingURI can be used by the binding as described in the section "Form of the URI of a Deployed Binding".
·
name (0..1)
– a name for the binding instance (an NCName). The @name attribute
allows distinction between multiple binding elements on a single service or
reference. The default value of the @name attribute is the service or
reference name. When a service or reference has multiple bindings, only one binding
can have the default @name value; all othersnon-callback bindings
of the service or reference MUST have a @name value
specified that is unique withinnames, and all
callback bindings of the service or
reference MUST have unique names.When a service or
reference has multiple bindings, all non-callback bindings of the service or
reference MUST have unique names, and all callback bindings of the service or
reference MUST have unique names. [ASM90002] This uniqueness requirement implies that only one
non-callback binding of a service or reference can have the default @name
value, and only one callback binding of a service or reference can have the
default @name value.
The @name also permits the
binding instance to be referenced from elsewhere – particularly useful for some
types of binding, which can be declared in a definitions document as a template
and referenced from other binding instances, simplifying the definition of more
complex binding instances (see the JMS Binding specification [11]SCA-JMSBINDING] for examples of this referencing).
·
requires (0..1) - a list of policy intents. See the Policy
Framework specification [10]SCA-POLICY] for a description of this attribute.
·
policySets (0..1) – a list of policy sets. See the Policy
Framework specification [10]SCA-POLICY] for a description of this attribute.
A binding element has the following
child elements:
· wireFormat (0..1) - a wireFormat to apply to the data flowing using the binding. See the wireFormat section for details.
· operationSelector(0..1) - an operationSelector element that is used to match a particular message to a particular operation in the interface. See the operationSelector section for details
· requires : requires (0..n) - A service element has zero or more requires subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
· policySetAttachment : policySetAttachment (0..n) - A service element has zero or more policySetAttachment subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
When multiple bindings exist for a service, it means that the service is available through any of the specified bindings. The technique that the SCA runtime uses to choose among available bindings is left to the implementation and it might include additional (nonstandard) configuration. Whatever technique is used needs to be documented by the runtime.
Services and References can always have their bindings overridden at the SCA Domain level, unless restricted by Intents applied to them.
If a reference has any bindings, they MUST be
resolved, which means that each binding MUST include a value for the @uri
attribute or MUST otherwise specify an endpoint. The reference MUST NOT be
wired using other SCA mechanisms.If a reference has any bindings, they MUST be
resolved, which means that each binding MUST include a value for the @uri
attribute or MUST otherwise specify an endpoint. The reference MUST NOT be
wired using other SCA mechanisms. [ASM90003] To specify
constraints on the kinds of bindings that are acceptable for use with a
reference, the user specifies either policy intents or policy sets.
Users can also specifically wire, not just to a component service, but to a
specific binding offered by that target service. To do so, a To wire to a specific binding
of a target MAY be specified
with a service the syntax of "componentName/serviceName/bindingName"." MUST be used.To wire to a specific
binding of a target service the syntax
"componentName/serviceName/bindingName" MUST be used. [ASM90004]
The following sections describe the SCA and Web service binding type in detail.
It is possible for a message to include information that is not defined in the interface used to define the service, for instance information can be contained in SOAP headers or as MIME attachments.
Implementation types can make this information available to component implementations in their execution context. The specifications for these implementation types describe how this information is accessed and in what form it is presented.
A wireFormat is the form that a data structure takes when it is transmitted using some communication binding. Another way to describe this is "the form that the data takes on the wire". A wireFormat can be specific to a given communication method, or it can be general, applying to many different communication methods. An example of a general wireFormat is XML text format.
Where a particular SCA binding can accommodate transmitting data in more than one format, the configuration of the binding can include a definition of the wireFormat to use. This is done using an <sca:wireFormat/> subelement of the <binding/> element.
Where a binding supports more than one wireFormat, the binding defines one of the wireFormats to be the default wireFormat which applies if no <wireFormat/> subelement is present.
The base sca:wireFormat element is abstract and it has no attributes and no child elements. For a particular wireFormat, an extension subtype is defined, using substitution groups, for example:
·
<sca:wireFormat.xml/>
A wireFormat that transmits the data as an XML text datastructure
·
<sca:wireFormat.jms/>
The "default JMS wireFormat" as described in the JMS Binding
specification
Specific wireFormats can have elements that include either attributes or subelements or both.
For details about specific wireFormats, see the related SCA Binding specifications.
An operationSelector is necessary for some types of transport binding where messages are transmitted across the transport without any explicit relationship between the message and the interface operation to which it relates. SOAP is an example of a protocol where the messages do contain explicit information that relates each message to the operation it targets. However, other transport bindings have messages where this relationship is not expressed in the message or in any related headers (pure JMS messages, for example). In cases where the messages arrive at a service without any explicit information that maps them to specific operations, it is necessary for the metadata attached to the service binding to contain the mapping information. The information is held in an operationSelector element which is a child element of the binding element.
The base sca:operationSelector element is abstract and it has no attributes and no child elements. For a particular operationSelector, an extension subtype is defined, using substitution groups, for example:
·
<sca:operationSelector.XPath/>
An operation selector that uses XPath to filter out specific messages and
target them to particular named operations.
Specific operationSelectors can have elements that include either attributes or subelements or both.
For details about specific operationSelectors, see the related SCA Binding specifications.
SCA Bindings specifications can choose to use the structural URI defined in the section "Structural URI of Components" above to derive a binding specific URI according to some Binding-related scheme. The relevant binding specification describes this.
Alternatively, <binding/> elements have a @uri attribute, which is termed a bindingURI.
If the bindingURI is specified on a given <binding/> element, the binding can use it to derive an endpoint URI relevant to the binding. The derivation is binding specific and is described by the relevant binding specification.
For binding.sca, which is described in the SCA Assembly specification, this is as follows:
· If the binding @uri attribute is specified on a reference, it identifies the target service in the SCA Domain by specifying the service's structural URI.
· If the binding @uri attribute is specified on a service, it is ignored.
Bindings that use non-hierarchical URI schemes (such as jms: or mailto:) can make use of the @uri attritibute, which is the complete representation of the URI for that service binding. Where the binding does not use the @uri attribute, the binding needs to offer a different mechanism for specifying the service address.
One of the things that needs to be determined when building the effective URI of a deployed binding (i.e. endpoint) is the URI scheme. The process of determining the endpoint URI scheme is binding type specific.
If the binding type supports a single protocol then there is only one URI scheme associated with it. In this case, that URI scheme is used.
If the binding type supports multiple protocols, the binding type implementation determines the URI scheme by introspecting the binding configuration, which can include the policy sets associated with the binding.
A good example of a binding type that supports
multiple protocols is binding.ws, which can be configured by referencing either
an “abstract” WSDL element (i.e. portType or interface) or a “concrete” WSDL
element (i.e. binding,
or port
or endpoint). When the
binding references a PortTypeportType or Interface, the protocol and therefore the URI
scheme is derived from the intents/policy sets attached to the binding. When
the binding references a “concrete” WSDL element, there are two cases:
1) The referenced WSDL binding element uniquely identifies a URI scheme. This is the most common case. In this case, the URI scheme is given by the protocol/transport specified in the WSDL binding element.
2) The referenced WSDL binding element doesn’t uniquely identify a URI scheme. For example, when HTTP is specified in the @transport attribute of the SOAP binding element, both “http” and “https” could be used as valid URI schemes. In this case, the URI scheme is determined by looking at the policy sets attached to the binding.
It is worth noting that an intent supported by a binding type can completely change the behavior of the binding. For example, when the intent "confidentiality/transport” is attached to an HTTP binding, SSL is turned on. This basically changes the URI scheme of the binding from “http” to “https”.
The SCA binding element is defined by the following pseudo-schema.
<binding.sca />uri="xs:anyURI"?
name="xs:NCName"?
requires="list of xs:QName"?
policySets="list of xs:QName"?>
<wireFormat/>?
<operationSelector/>?
<requires/>*
<policySetAttachment/>*
</binding.sca>
Snippet 7‑2: binding.sca pseudo-schema
A binding.sca element has the attributes:
· uri (0..1) - has the semantic:
– The @uri attribute can be omitted.
–
If a <binding.sca/> element of a component
reference specifies a URI via its @uri attribute, then this provides a wire to
a target service provided by another component. The form of the URI which
points to the service of a component that is in the same composite as the
source component is as follows:
<component-name>/<service-name>
or
<component-name>/<service-name>/<binding-name>
in cases where the service has multiple bindings present.
– The circumstances under which the @uri attribute can be used are defined in the section "Specifying the Target Service(s) for a Reference."
– For a binding.sca of a component service, the @uri attribute MUST NOT be present.For a binding.sca of a component service, the @uri attribute MUST NOT be present. [ASM90005]
· name (0..1) – a name for the binding instance (an NCName), as defined for the base <binding/> element type.
· requires (0..1) - a list of policy intents. See the Policy Framework specification [SCA-POLICY] for a description of this attribute.
· policySets (0..1) – a list of policy sets. See the Policy Framework specification [SCA-POLICY] for a description of this attribute.
A binding.sca element has the child elements:
· wireFormat (0..1) - a wireFormat to apply to the data flowing using the binding. binding.sca does not define any specific wireFormat elements.
· operationSelector(0..1) - an operationSelector element that is used to match a particular message to a particular operation in the interface. binding.sca does not define any specific operationSelector elements.
· requires : requires (0..n) - A service element has zero or more requires subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
· policySetAttachment : policySetAttachment (0..n) - A service element has zero or more policySetAttachment subelements. See the Policy Framework specification [SCA-POLICY] for a description of this element.
The SCA binding can be used for service interactions between
references and services contained within the SCA Domain. The way in which this
binding type is implemented is not defined by the SCA specification and it can
be implemented in different ways by different SCA runtimes. The only
requirement is that any specified qualities of service are implemented for the
SCA binding type. Qualities of service
for <binding.sca/> are expressed using intents and/or policy sets
following the rules defined in the SCA Policy
specification [SCA-POLICY].
The SCA binding type is not intended to be an interoperable binding type. For
interoperability, an interoperable binding type such as the Web service binding
is used.
An SCA runtime has to support the binding.sca binding type. See the section on SCA Runtime conformance.
A service definition with no
binding element specified uses the SCA binding. (see ASM50005 in
section 4.2 on Component Service). <binding.sca/> would only have has to be specified explicitly in override cases, or when you specify a set of bindings is specified on a service definition and
the SCA binding needs to be one of them.
If a reference does not have
a binding subelement specified, then the
binding used can be any is one of
the bindings specified by the service provider, as long as the intents attached
to the reference and the service are all honoured.
, as described in the section on Component References.
If the interface of the service or reference is local, then the local variant of the SCA binding will be used. If the interface of the service or reference is remotable, then either the local or remote variant of the SCA binding will be used depending on whether source and target are co-located or not.
If a <binding.sca/> element of a
<component/> <reference/>
specifies a URI via its @uri attribute, then this provides the defaulta
wire to a target service provided by another Domain
level component.
The valueform
of the URI haswhich points to bethe service of a component that is in the same
composite as the source component is as follows:
· <domain-component-name>/<service-name>
The following snippetSnippet 7‑3 shows the MyValueComposite.composite file for the
MyValueComposite containing the service element for the MyValueService and a
reference element for the StockQuoteService. Both the service and the reference
use an SCA binding. The target for the reference is left undefined in this
binding and would have to be supplied by the composite in which this composite
is used.
<?xml version="1.0" encoding="ASCII"?>
<!-- Binding SCA example -->
<composite
xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
targetNamespace="http://foo.com"
name="MyValueComposite" >
<service name="MyValueService" promote="MyValueComponent">
<interface.java interface="services.myvalue.MyValueService"/>
<binding.sca/>
…
</service>
…
<reference name="StockQuoteService"
promote="MyValueComponent/StockQuoteReference">
<interface.java interface="services.stockquote.StockQuoteService"/>
<binding.sca/>
</reference>
</composite>
Snippet 7‑3: Example binding.sca
SCA defines a Web services binding. This is
described in a separate specification document [9]SCA-WSBINDING].
SCA defines a JMS binding. This is described in a
separate specification document [11]SCA-JMSBINDING].
There are a variety of SCA artifacts which are generally useful and which are not specific to a particular composite or a particular component. These shared artifacts include intents, policy sets, bindings, binding type definitions and implementation type definitions.
All of these artifacts within an SCA Domain are
defined in SCA contributions in files called META-INF/definitions.xml (relative
to the contribution base URI). An
SCA runtime MUST make available to the Domain all the artifacts contained
within the definitions.xml files in the Domain.An SCA runtime MUST make available to the Domain
all the artifacts contained within the definitions.xml files in the Domain. [ASM10002] An SCA runtime MUST reject a definitions.xml file
that does not conform to the sca-definitions.xsd schema.An SCA runtime MUST reject a definitions.xml file that
does not conform to the sca-definitions.xsd schema. [ASM10003]
Although the definitions are specified within a
single SCA contribution, the definitions are visible throughout the Domain.
Because of this, all of the QNames for the definitions contained in
definitions.xml files MUST be unique within the Domain.all of the QNames for
the definitions contained in definitions.xml files MUST be unique within the
Domain.. [ASM10001] The definitions.xml file contains a definitions
element that conforms to the following
pseudo-schema snippetshown
in Snippet 8‑1:
<?xml version="1.0" encoding="ASCII"?>
<!-- Composite schema snippet -->
<definitions
xmlns="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
targetNamespace="xs:anyURI">
<sca:intent/>*
<sca:policySet/>*
<sca:binding/>*
<sca:bindingType/>*
<sca:implementationType/>*
</definitions>
Snippet 8‑1: definitions Pseudo-Schema
The definitions element has the following attribute:
· targetNamespace (1..1) – the namespace into which the child elements of this definitions element are placed (used for artifact resolution)
The definitions element contains child elements –
intent, policySet, binding,
bindingType and
implementationType. These elements are described elsewhere in this
specification or in the SCA Policy Framework specification [10]SCA-POLICY]. The use of the elements declared within a
definitions element is described in the SCA Policy Framework
specification [10]SCA-POLICY] and in the
JMS Binding specification [11].
The assembly model can be extended with support for new interface types, implementation types and binding types. The extension model is based on XML schema substitution groups. There are three XML Schema substitution group heads defined in the SCA namespace: interface, implementation and binding, for interface types, implementation types and binding types, respectively.
The SCA Client and Implementation specifications and
the SCA Bindings specifications (see [1], [9]SCA-WSBINDING], [11]) use these XML Schema substitution groups to define
some basic types of interfaces, implementations and bindings, but additional
types can be defined as needed, where support for these extra ones is available
from the runtime. The inteface type elements, implementation type elements, and
binding type elements defined by the SCA specifications are all part of the SCA
namespace ("http://docs.oasis-open.org/ns/opencsa/sca/200903200912"), as indicated in their respective schemas.
New interface types, implementation types and binding types that are defined
using this extensibility model, which are not part of these SCA specifications
are defined in namespaces other than the SCA namespace.
The "." notation is used in naming elements defined by the SCA specifications ( e.g. <implementation.java … />, <interface.wsdl … />, <binding.ws … />), not as a parallel extensibility approach but as a naming convention that improves usability of the SCA assembly language.
Note: How to contribute SCA model extensions and their runtime function to an SCA runtime will be defined by a future version of the specification.
The following snippetSnippet 9-1 shows the base definition for the interface element and Interface type contained in sca-core.xsd;
see appendixsca-core.xsd for the complete
schema.
<?xml version="1.0" encoding="UTF-8"?>
<!-- (c) Copyright SCA Collaboration 2006 -->
<schema xmlns="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
elementFormDefault="qualified">
...
<element name="interface" type="sca:Interface" abstract="true"/>
<complexType name="Interface"/>
<complexType
name="Interface" abstract="true">
<choice
minOccurs="0" maxOccurs="unbounded">
<element ref="sca:requires"/>
<element ref="sca:policySetAttachment"/>
</choice>
<attribute name="remotable" type="boolean" use="optional"/>
<attribute name="requires" type="sca:listOfQNames" use="optional"/>
<attribute name="policySets" type="sca:listOfQNames" use="optional"/>
</complexType>
...
</schema>
In the following
snippetSnippet 9-1:
interface and Interface Schema
Snippet 9‑2 is an example of how the base definition is extended to support Java interfaces. The snippet shows the definition of the interface.java element and the JavaInterface type contained in sca-interface-java.xsd.
<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200903200912">
<element name="interface.java" type="sca:JavaInterface"
substitutionGroup="sca:interface"/>
<complexType name="JavaInterface">
<complexContent>
<extension base="sca:Interface">
<attribute name="interface" type="NCName"
use="required"/>
</extension>
</complexContent>
</complexType>
</schema>
In the following
snippetSnippet 9‑2:
Extending interface to interface.java
Snippet 9‑3 is an example of how the base definition can be extended by other specifications to support a new interface not defined in the SCA specifications. The snippet shows the definition of the my-interface-extension element and the my-interface-extension-type type.
<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://www.example.org/myextension"
xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
xmlns:tns="http://www.example.org/myextension">
<element name="my-interface-extension"
type="tns:my-interface-extension-type"
substitutionGroup="sca:interface"/>
<complexType name="my-interface-extension-type">
<complexContent>
<extension base="sca:Interface">
...
</extension>
</complexContent>
</complexType>
</schema>
Snippet 9‑3: Example interface extension
The following snippetSnippet 9‑4 shows the base definition for the implementation element and Implementation type contained in sca-core.xsd; see appendix
sca-core.xsdfor complete schema.
<?xml version="1.0" encoding="UTF-8"?>
<!-- (c) Copyright SCA Collaboration 2006 -->
<schema xmlns="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
elementFormDefault="qualified">
...
<element
name="implementation" type="sca:Implementation"
abstract="true"/>
<complexType name="Implementation"/"
abstract="true">
<complexContent>
<extension base="sca:CommonExtensionBase">
<choice minOccurs="0" maxOccurs="unbounded">
<element ref="sca:requires"/>
<element ref="sca:policySetAttachment"/>
</choice>
<attribute name="requires" type="sca:listOfQNames"
use="optional"/>
<attribute name="policySets" type="sca:listOfQNames"
use="optional"/>
</extension>
</complexContent>
</complexType>
...
</schema>
In the following snippet we show Snippet
9‑4: implementation
and Implementation Schema
Snippet 9‑5 shows how the base definition is extended to support Java implementation. The snippet shows the definition of the implementation.java element and the JavaImplementation type contained in sca-implementation-java.xsd.
<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200903200912">
<element name="implementation.java" type="sca:JavaImplementation"
substitutionGroup="sca:implementation"/>
<complexType name="JavaImplementation">
<complexContent>
<extension base="sca:Implementation">
<attribute name="class" type="NCName"
use="required"/>
</extension>
</complexContent>
</complexType>
</schema>
In the following
snippetSnippet 9‑5:
Extending implementation to implementation.java
Snippet 9‑6 is an example of how the base definition can be extended by other specifications to support a new implementation type not defined in the SCA specifications. The snippet shows the definition of the my-impl-extension element and the my-impl-extension-type type.
<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://www.example.org/myextension"
xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
xmlns:tns="http://www.example.org/myextension">
<element name="my-impl-extension" type="tns:my-impl-extension-type"
substitutionGroup="sca:implementation"/>
<complexType name="my-impl-extension-type">
<complexContent>
<extension base="sca:Implementation">
...
</extension>
</complexContent>
</complexType>
</schema>
Snippet 9‑6: Example implementation extension
In addition to the definition for the new
implementation instance element, there needs to be an associated
implementationType element which provides metadata about the new implementation
type. The pseudo schema for the implementationType element is shown in the following snippetSnippet 9‑7:
<implementationType type="xs:QName"
alwaysProvides="list of intent xs:QName"
mayProvide="list of intent xs:QName"/>
Snippet 9‑7: implementationType Pseudo-Schema
The implementation type has the following attributes:
· type (1..1) – the type of the implementation to which this implementationType element applies. This is intended to be the QName of the implementation element for the implementation type, such as "sca:implementation.java"
·
alwaysProvides (0..1) – a set of intents which the implementation type
always provides. See the Policy Framework specification [10]SCA-POLICY] for details.
·
mayProvide (0..1) – a set of intents which the implementation type
provides only when the intent is attached to the implementation element. See the
Policy Framework specification [10]SCA-POLICY] for details.
The following snippetSnippet 9‑8 shows the base definition for the binding
element and Binding type contained in sca-core.xsd; see appendix
sca-core.xsdfor complete schema.
<?xml version="1.0" encoding="UTF-8"?>
<!-- binding type schema snippet -->
<!-- (c) Copyright SCA Collaboration 2006, 2009 -->
<schema xmlns="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
elementFormDefault="qualified">
...
<element name="binding" type="sca:Binding" abstract="true"/>
<complexType name="Binding">
<attribute name="uri" type="anyURI" use="optional"/>
<attribute name="name" type="NCName" use="optional"/>
<attribute name="requires" type="sca:listOfQNames"
use="optional"/>
<attribute name="policySets" type="sca:listOfQNames"
use="optional"/>
</complexType>
...
</schema>
In the following snippetSnippet
9‑8: binding
and Binding Schema
Snippet 9‑9 is an example of how the base definition is extended to support Web service binding. The snippet shows the definition of the binding.ws element and the WebServiceBinding type contained in sca-binding-webservice.xsd.
<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200903200912">
<element name="binding.ws" type="sca:WebServiceBinding"
substitutionGroup="sca:binding"/>
<complexType name="WebServiceBinding">
<complexContent>
<extension base="sca:Binding">
<attribute name="port" type="anyURI" use="required"/>
</extension>
</complexContent>
</complexType>
</schema>
In the following
snippetSnippet 9‑9:
Extending binding to binding.ws
Snippet 9‑10 is an example of how the base definition can be extended by other specifications to support a new binding not defined in the SCA specifications. The snippet shows the definition of the my-binding-extension element and the my-binding-extension-type type.
<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://www.example.org/myextension"
xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
xmlns:tns="http://www.example.org/myextension">
<element name="my-binding-extension"
type="tns:my-binding-extension-type"
substitutionGroup="sca:binding"/>
<complexType name="my-binding-extension-type">
<complexContent>
<extension base="sca:Binding">
...
</extension>
</complexContent>
</complexType>
</schema>
Snippet 9‑10: Example binding extension
In addition to the definition for the new binding
instance element, there needs to be an associated bindingType element which
provides metadata about the new binding type. The pseudo schema for the
bindingType element is shown in the
following snippetSnippet 9‑11:
<bindingType type="xs:QName"
alwaysProvides="list of intent QNames"?
mayProvide = "list of intent QNames"?/>
Snippet 9‑11: bindingType Pseudo-Schema
The binding type has the following attributes:
· type (1..1) – the type of the binding to which this bindingType element applies. This is intended to be the QName of the binding element for the binding type, such as "sca:binding.ws"
·
alwaysProvides (0..1) – a set of intents which the binding type always
provides. See the Policy Framework specification [10]SCA-POLICY] for details.
·
mayProvide (0..1) – a set of intents which the binding type provides
only when the intent is attached to the binding element. See the
Policy Framework specification [10]SCA-POLICY] for details.
The following snippetSnippet
9‑12 shows the base definition for the import
element and Import type contained in sca-core.xsd;
see appendix sca-core.xsdfor
complete schema.
<?xml version="1.0" encoding="UTF-8"?>
<!-- Copyright(C) OASIS(R) 2005,2009. All Rights Reserved. OASIS trademark, IPR and other policies apply. -->
<schema xmlns="http://www.w3.org/2001/XMLSchema"
xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
targetNamespace="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
elementFormDefault="qualified">
...
<!-- Import -->
<element name="importBase" type="sca:Import" abstract="true" />
<complexType name="Import" abstract="true">
<complexContent>
<extension base="sca:CommonExtensionBase">
<sequence>
<any namespace="##other" processContents="lax" minOccurs="0"
maxOccurs="unbounded"/>
</sequence>
</extension>
</complexContent>
</complexType>
<element name="import" type="sca:ImportType"
substitutionGroup="sca:importBase"/>
<complexType name="ImportType">
<complexContent>
<extension base="sca:Import">
<attribute name="namespace" type="string" use="required"/>
<attribute name="location" type="anyURI" use="required"/>
</extension>
</complexContent>
</complexType>
...
</schema>
In the following snippet we show Snippet
9‑12: import
and Import Schema
Snippet 9‑13 shows how the base import definition is extended to support Java imports. In the import element, the namespace is expected to be an XML namespace, an import.java element uses a Java package name instead. The snippet shows the definition of the import.java element and the JavaImportType type contained in sca-import-java.xsd.
<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200903200912">
<element name="import.java" type="sca:JavaImportType"
substitutionGroup="sca:importBase"/>
<complexType name="JavaImportType">
<complexContent>
<extension base="sca:Import">
<attribute name="package" type="xs:String" use="required"/>
<attribute name="location" type="xs:AnyURI" use="optional"/>
</extension>
</complexContent>
</complexType>
</schema>
In the following snippet we show Snippet
9‑13:
Extending import to import.java
Snippet 9‑14 shows an example of how the base definition can be extended by other specifications to support a new interface not defined in the SCA specifications. The snippet shows the definition of the my-import-extension element and the my-import-extension-type type.
<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://www.example.org/myextension"
xmlns:sca=" http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
xmlns:tns="http://www.example.org/myextension">
<element name="my-import-extension"
type="tns:my-import-extension-type"
substitutionGroup="sca:importBase"/>
<complexType name="my-import-extension-type">
<complexContent>
<extension base="sca:Import">
...
</extension>
</complexContent>
</complexType>
</schema>
Snippet 9‑14: Example import extension
For a complete example using this extension point, see the definition of import.java in the SCA Java Common Annotations and APIs Specification [SCA-Java].
The following snippetSnippet
9‑15 shows the base definition for the export
element and ExportType type contained in sca-core.xsd;
see appendix for complete schema.
<?xml version="1.0" encoding="UTF-8"?>
<!-- Copyright(C) OASIS(R) 2005,2009. All Rights Reserved. OASIS trademark, IPR and other policies apply. -->
<schema xmlns="http://www.w3.org/2001/XMLSchema"
xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
targetNamespace="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
elementFormDefault="qualified">
...
<!-- Export -->
<element name="exportBase" type="sca:Export" abstract="true" />
<complexType name="Export" abstract="true">
<complexContent>
<extension base="sca:CommonExtensionBase">
<sequence>
<any namespace="##other" processContents="lax" minOccurs="0"
maxOccurs="unbounded"/>
</sequence>
</extension>
</complexContent>
</complexType>
<element name="export" type="sca:ExportType"
substitutionGroup="sca:exportBase"/>
<complexType name="ExportType">
<complexContent>
<extension base="sca:Export">
<attribute name="namespace" type="string" use="required"/>
</extension>
</complexContent>
</complexType>
...
</schema>
The following snippetSnippet
9‑15: export
and Export Schema
Snippet 9‑16 shows how the base definition is extended to support Java exports. In a base export element, the @namespace attribute specifies XML namespace being exported. An export.java element uses a @package attribute to specify the Java package to be exported. The snippet shows the definition of the export.java element and the JavaExport type contained in sca-export-java.xsd.
<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200903200912">
<element name="export.java" type="sca:JavaExportType"
substitutionGroup="sca:exportBase"/>
<complexType name="JavaExportType">
<complexContent>
<extension base="sca:Export">
<attribute name="package" type="xs:String" use="required"/>
</extension>
</complexContent>
</complexType>
</schema>
In the following snippetSnippet
9‑16:
Extending export to export.java
Snippet
9‑17 we show shows an
example of how the base definition can be extended by other specifications to
support a new interface not defined in the SCA specifications. The snippet
shows the definition of the my-export-extension element and the my-export-extension-type
type.
<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://www.example.org/myextension"
xmlns:sca="http:// docs.oasis-open.org/ns/opencsa/sca/200903"
xmlns:tns="http://www.example.org/myextension">
<element name="my-export-extension"
type="tns:my-export-extension-type"
substitutionGroup="sca:exportBase"/>
<complexType name="my-export-extension-type">
<complexContent>
<extension base="sca:Export">
...
</extension>
</complexContent>
</complexType>
</schema>
Snippet 9‑17: Example export extension
For a complete example using this extension point, see the definition of export.java in the SCA Java Common Annotations and APIs Specification [SCA-Java].
This section describes the SCA Domain and the packaging and deployment of artifacts contributed to the Domain.
An SCA Domain represents a complete runtime configuration, potentially distributed over a series of interconnected runtime nodes.
A single SCA Domain defines the boundary of visibility for all SCA mechanisms. For example, SCA wires can only be used to connect components within a single SCA Domain. Connections to services outside the Domain use binding specific mechanisms for addressing services (such as WSDL endpoint URIs). Also, SCA mechanisms such as intents and policySets can only be used in the context of a single Domain. In general, external clients of a service that is developed and deployed using SCA are not able to tell that SCA is used to implement the service – it is an implementation detail.
The size and configuration of an SCA Domain is not constrained by the SCA Assembly specification and is expected to be highly variable. An SCA Domain typically represents an area of business functionality controlled by a single organization. For example, an SCA Domain might be the whole of a business, or it might be a department within a business.
As an example, for the accounts department in a business, the SCA Domain might cover all finance-related functions, and it might contain a series of composites dealing with specific areas of accounting, with one for Customer accounts and another dealing with Accounts Payable.
An SCA Domain has the following:
· A virtual domain-level composite whose components are deployed and running
· A set of installed contributions that contain implementations, interfaces and other artifacts necessary to execute components
· A set of logical services for manipulating the set of contributions and the virtual domain-level composite.
The information associated with an SCA Domain can be stored in many ways, including but not limited to a specific filesystem structure or a repository.
An SCA Domain might need a large number of different
artifacts in order to work. These artifacts include artifacts defined by SCA
and other artifacts such as object code files and interface definition files.
The SCA-defined artifact types are all XML documents. The root elements of the
different SCA definition documents are: composite, componentType, constrainingType and definitions. XML artifacts that are not
defined by SCA but which are needed by an SCA Domain include XML Schema
documents, WSDL documents, and BPEL documents. SCA constructs, like other
XML-defined constructs, use XML qualified names for their identity (i.e.
namespace + local name).
Non-XML artifacts are also needed within an SCA Domain. The most obvious examples of such non-XML artifacts are Java, C++ and other programming language files necessary for component implementations. Since SCA is extensible, other XML and non-XML artifacts might also be needed.
SCA defines an interoperable packaging format for contributions (ZIP), as specified below. This format is not the only packaging format that an SCA runtime can use. SCA allows many different packaging formats, but it is necessary for an SCA runtime to support the ZIP contribution format. When using the ZIP format for deploying a contribution, this specification does not specify whether that format is retained after deployment. For example, a Java EE based SCA runtime could convert the ZIP package to an EAR package. SCA expects certain characteristics of any packaging:
·
For any contribution packaging it MUST be possible
to present the artifacts of the packaging to SCA as a hierarchy of resources
based off of a single rootFor any contribution packaging it MUST be possible
to present the artifacts of the packaging to SCA as a hierarchy of resources
based off of a single root
[ASM12001]
· Within any contribution packaging A directory resource SHOULD exist at the root of the hierarchy named META-INF [ASM12002]
·
Within any
contribution packaging a document SHOULD exist directly under the META-INF
directory named sca-contribution.xml which lists the SCA Composites within the
contribution that are runnable. [ASM12003]
The same document can also list namespaces of
constructs that are defined within the contribution and which are available for
use by other contributions, through export elements.
Error!
Reference source not found.
These additional elements might not be physically
present in the packaging, but might be generated based on the definitions and
references that are present, or they might not exist at all if there are no
unresolved references.
See the section "SCA Contribution Metadata Document" for details of the format of this file.
To illustrate that a variety of packaging formats can be used with SCA, the following are examples of formats that might be used to package SCA artifacts and metadata (as well as other artifacts) as a contribution:
· A filesystem directory
· An OSGi bundle
· A compressed directory (zip, gzip, etc)
· A JAR file (or its variants – WAR, EAR, etc)
Contributions do not contain other contributions. If the packaging format is a JAR file that contains other JAR files (or any similar nesting of other technologies), the internal files are not treated as separate SCA contributions. It is up to the implementation to determine whether the internal JAR file is represented as a single artifact in the contribution hierarchy or whether all of the contents are represented as separate artifacts.
A goal of SCA’s approach to deployment is that the contents of a contribution do not need to be modified in order to install and use the contents of the contribution in a Domain.
Contributions can be self-contained, in that all of the artifacts necessary to run the contents of the contribution are found within the contribution itself. However, it can also be the case that the contents of the contribution make one or many references to artifacts that are not contained within the contribution. These references can be to SCA artifacts such as composites or they can be to other artifacts such as WSDL files, XSD files or to code artifacts such as Java class files and BPEL process files. Note: This form of artifact resolution does not apply to imports of composite files, as described in Section 6.6.
A contribution can use some artifact-related or packaging-related means to resolve artifact references. Examples of such mechanisms include:
· @wsdlLocation and @schemaLocation attributes in references to WSDL and XSD schema artifacts respectively
· OSGi bundle mechanisms for resolving Java class and related resource dependencies
Where present,
artifact-related or packaging-related artifact resolution mechanisms MUST be
used by the SCA runtime to resolve artifact dependencies.Where present,
artifact-related or packaging-related artifact resolution mechanisms MUST be
used by the SCA runtime to resolve artifact dependencies. [ASM12005] The SCA runtime MUST raise an error if an artifact
cannot be resolved using these mechanisms, if present.The SCA runtime MUST raise an error if an artifact
cannot be resolved using these mechanisms, if present. [ASM12021]
SCA also provides an artifact resolution mechanism. The SCA artifact resolution mechanism is can be used where no other mechanisms are available, for example in cases where the mechanisms used by the various contributions in the same SCA Domain are different. An example of this is where an OSGi Bundle is used for one contribution but where a second contribution used by the first one is not implemented using OSGi - e.g. the second contribution relates to a mainframe COBOL service whose interfaces are declared using a WSDL which is accessed by the first contribution.
The SCA artifact resolution is likely to be most useful for SCA Domains containing heterogeneous mixtures of contribution, where artifact-related or packaging-related mechanisms are unlikely to work across different kinds of contribution.
SCA artifact resolution works on the principle that a contribution which needs to use artifacts defined elsewhere expresses these dependencies using import statements in metadata belonging to the contribution. A contribution controls which artifacts it makes available to other contributions through export statements in metadata attached to the contribution. SCA artifact resolution is a general mechanism that can be extended for the handling of specific types of artifact. The general mechanism that is described in the following paragraphs is mainly intended for the handling of XML artifacts. Other types of artifacts, for example Java classes, use an extended version of artifact resolution that is specialized to their nature (eg. instead of "namespaces", Java uses "packages"). Descriptions of these more specialized forms of artifact resolution are contained in the SCA specifications that deal with those artifact types.
Import and export statements for XML artifacts work at the level of namespaces - so that an import statement declares that artifacts from a specified namespace are found in other contributions, while an export statement makes all the artifacts from a specified namespace available to other contributions.
An import declaration can simply specify the
namespace to import. In this case, the locations which are searched for
artifacts in that namespace are the contribution(s) in the Domain which have
export declarations for the same namespace, if any. Alternatively an import
declaration can specify a location from which artifacts for the namespace are
obtained, in which case, that specific location is searched. There can be multiple import declarations for a
given namespace. Where multiple import declarations are made for the same
namespace, all the locations specified MUST be searched in lexical order.There can be multiple import declarations for a
given namespace. Where multiple import declarations are made for the same
namespace, all the locations specified MUST be searched in lexical order. [ASM12022]
For an XML namespace, artifacts can be declared in multiple locations - for example a given namespace can have a WSDL declared in one contribution and have an XSD defining XML data types in a second contribution.
If the same artifact is declared in multiple locations, this is not an error. The first location as defined by lexical order is chosen. If no locations are specified no order exists and the one chosen is implementation dependent.
When a contribution contains a reference to an artifact from a namespace that is declared in an import statement of the contribution, if the SCA artifact resolution mechanism is used to resolve the artifact, the SCA runtime MUST resolve artifacts in the following order:
1. 1. from the locations identified by the import statement(s) for the namespace. Locations MUST NOT be searched recursively in order to locate artifacts (i.e. only a one-level search is performed).
1.
2. from the contents of
the contribution itself.When
a contribution contains a reference to an artifact from a namespace that is
declared in an import statement of the contribution, if the SCA artifact
resolution mechanism is used to resolve the artifact, the SCA runtime MUST
resolve artifacts in the following order:
1.1. from the locations identified by the import
statement(s) for the namespace. Locations MUST NOT be searched recursively in
order to locate artifacts (i.e. only a one-level search is performed).
2. from
the contents of the contribution itself.When a contribution
contains a reference to an artifact from a namespace that is declared in an
import statement of the contribution, if the SCA artifact resolution mechanism
is used to resolve the artifact, the SCA runtime MUST resolve artifacts in the
following order:
1. from the
locations identified by the import statement(s) for the namespace. Locations
MUST NOT be searched recursively in order to locate artifacts (i.e. only a
one-level search is performed).
2. 2. [ASM12023]from the contents of the contribution itself.
When a contribution
uses an artifact contained in another contribution through SCA artifact
resolution, if that artifact itself has dependencies on other artifacts, the
SCA runtime MUST resolve these dependencies in the context of the contribution
containing the artifact, not in the context of the original contribution.Checking
for errors in artifacts MUST NOT be done for artifacts in the Installed state
(ie where the artifacts are simply part of installed contributions)Checking for errors in artifacts MUST NOT be done
for artifacts in the Installed state (ie where the artifacts are simply part of
installed contributions)
[ASM12031]
For example:
· a first contribution "C1" references an artifact "A1" in the namespace "n1" and imports the "n1" namespace from a second contribution "C2".
· in contribution "C2" the artifact "A1" in the "n1" namespace references an artifact "A2" also in the "n1" namespace", which is resolved through an import of the "n1" namespace in "C2" which specifies the location "C3".
Figure 10‑14: Example of SCA Artifact Resolution between Contributions
The "A2" artifact is contained within the third contribution "C3" from which it is resolved by the contribution "C2". The "C3" contribution is never used to resolve artifacts directly for the "C1" contribution, since "C3" is not declared as an import location for "C1".
For example, if for a contribution "C1",an import is used to resolve a composite "X1" contained in contribution "C2", and composite "X1" contains references to other artifacts such as WSDL files or XSDs, those references in "X1" are resolved in the context of contribution "C2" and not in the context of contribution "C1".
The SCA runtime MUST ignore local definitions of an
artifact if the artifact is found through resolving an import statement.The SCA runtime MUST ignore local definitions of an
artifact if the artifact is found through resolving an import statement. [ASM12024]
The SCA runtime MUST raise an error if an artifact
cannot be resolved by using artifact-related or packaging-related artifact
resolution mechanisms, if present, by searching locations identified by the
import statements of the contribution, if present, and by searching the
contents of the contribution.The SCA runtime MUST raise an error if an artifact
cannot be resolved by using artifact-related or packaging-related artifact
resolution mechanisms, if present, by searching locations identified by the
import statements of the contribution, if present, and by searching the
contents of the contribution. [ASM12025]
The contribution can contain a document that declares runnable composites, exported definitions and imported definitions. The document is found at the path of META-INF/sca-contribution.xml relative to the root of the contribution. Frequently some SCA metadata needs to be specified by hand while other metadata is generated by tools (such as the <import> elements described below). To accommodate this, it is also possible to have an identically structured document at META-INF/sca-contribution-generated.xml. If this document exists (or is generated on an as-needed basis), it will be merged into the contents of sca-contribution.xml, with the entries in sca-contribution.xml taking priority if there are any conflicting declarations.
An SCA runtime MUST make the <import/> and
<export/> elements found in the META-INF/sca-contribution.xml and
META-INF/sca-contribution-generated.xml files available for the SCA artifact
resolution process.An
SCA runtime MUST make the <import/> and <export/> elements found in
the META-INF/sca-contribution.xml and META-INF/sca-contribution-generated.xml
files available for the SCA artifact resolution process. [ASM12026] An SCA runtime MUST
reject files that do not conform to the schema declared in
sca-contribution.xsd.An SCA runtime MUST reject files that do not
conform to the schema declared in sca-contribution.xsd. [ASM12027] An SCA runtime MUST
merge the contents of sca-contribution-generated.xml into the contents of
sca-contribution.xml, with the entries in sca-contribution.xml taking priority
if there are any conflicting declarations.An SCA runtime MUST
merge the contents of sca-contribution-generated.xml into the contents of
sca-contribution.xml, with the entries in sca-contribution.xml taking priority
if there are any conflicting declarations. [ASM12028]
The format of the document is:
<?xml version="1.0" encoding="ASCII"?>
<!-- sca-contribution pseudo-schema -->
<contribution xmlns=http://docs.oasis-open.org/ns/opencsa/sca/200903200912>
<deployable composite="xs:QName"/>*
<import namespace="xs:String" location=”xs:AnyURI”?/>*
<export namespace="xs:String"/>*
</contribution>
Snippet 10‑1: contribution Pseudo-Schema
deployable element: Identifies a composite which is a composite within
the contribution that is a composite intended for potential inclusion into the
virtual domain-level composite. Other composites in the contribution are not
intended for inclusion but only for use by other composites. New composites can
be created for a contribution after it is installed, by using the add Deployment Composite capability and the add To Domain Level Composite
capability. An SCA runtime MAY
deploy the composites in <deployable/> elements found in the
META-INF/sca-contribution.xml and META-INF/sca-contribution-generated.xml
files.An SCA runtime MAY deploy the composites in
<deployable/> elements found in the META-INF/sca-contribution.xml and
META-INF/sca-contribution-generated.xml files. [ASM12029]
Attributes of the deployable element:
· composite (1..1) – The QName of a composite within the contribution.
Export element: A declaration that artifacts belonging to a particular namespace are exported and are available for use within other contributions. An export declaration in a contribution specifies a namespace, all of whose definitions are considered to be exported. By default, definitions are not exported.
The SCA artifact export is useful for SCA Domains containing heterogeneous mixtures of contribution packagings and technologies, where artifact-related or packaging-related mechanisms are unlikely to work across different kinds of contribution.
Attributes of the export element:
·
namespace (1..1) – For XML definitions, which are identified by
QNames, the @namespace attribute of the export element SHOULD be the namespace
URI for the exported definitions.For XML definitions, which are identified by
QNames, the @namespace attribute of the export element SHOULD be the namespace
URI for the exported definitions. [ASM12030]
For XML technologies that define multiple symbol spaces that can be used
within one namespace (e.g. WSDL port typesportTypes
are a different symbol space from WSDL bindings), all definitions from all
symbol spaces are exported.
Technologies that use naming schemes other than QNames use a different export element from the same substitution group as the the SCA <export> element. The element used identifies the technology, and can use any value for the namespace that is appropriate for that technology. For example, <export.java> can be used to export java definitions, in which case the namespace is a fully qualified package name.
Import element: Import declarations specify namespaces of
definitions that are needed by the definitions and implementations within the
contribution, but which are not present in the contribution. It is expected
that in most cases import declarations will be generated based on introspection
of the contents of the contribution. In this case, the import declarations
would be found in the META-INF/ sca-contribution-generated.xml document.
Attributes of the import element:
·
namespace (1..1) – For XML definitions, which are
identified by QNames, the namespace is the namespace URI for the imported
definitions. For XML technologies that define multiple symbol spaces
that can be used within one namespace (e.g. WSDL port typesportTypes
are a different symbol space from WSDL bindings), all definitions from all
symbol spaces are imported.
Technologies that use naming schemes other than QNames use a different import element from the same substitution group as the the SCA <import> element. The element used identifies the technology, and can use any value for the namespace that is appropriate for that technology. For example, <import.java> can be used to import java definitions, in which case the namespace is a fully qualified package name.
·location (0..1) –
a URI to resolve the definitions for this import. SCA makes no specific
requirements for the form of this URI, nor the means by which it is resolved.
It can point to another contribution (through its URI) or it can point to some
location entirely outside the SCA Domain.
· It is expected that SCA runtimes can define implementation specific ways of resolving location information for artifact resolution between contributions. These mechanisms will however usually be limited to sets of contributions of one runtime technology and one hosting environment.
In order to accommodate imports of artifacts between contributions of disparate runtime technologies, it is strongly suggested that SCA runtimes honor SCA contribution URIs as location specification.
SCA runtimes that support contribution URIs for cross-contribution resolution of SCA artifacts are expected to do so similarly when used as @schemaLocation and @wsdlLocation and other artifact location specifications.
The order in which the import statements are specified can play a role in this mechanism. Since definitions of one namespace can be distributed across several artifacts, multiple import declarations can be made for one namespace.
The location value is only a default, and dependent contributions listed in the call to installContribution can override the value if there is a conflict. However, the specific mechanism for resolving conflicts between contributions that define conflicting definitions is implementation specific.
If the value of the @location attribute is an SCA contribution URI, then the contribution packaging can become dependent on the deployment environment. In order to avoid such a dependency, it is recommended that dependent contributions are specified only when deploying or updating contributions as specified in the section 'Operations for Contributions' below.
SCA allows many different packaging formats that SCA
runtimes can support, but SCA requires that all
runtimes MUST support the ZIP packaging format for contributions.SCA requires that all
runtimes MUST support the ZIP packaging format for contributions. [ASM12006] This format allows that metadata specified by the
section 'SCA Contribution Metadata Document' be present. Specifically, it can
contain a top-level "META-INF" directory and a
"META-INF/sca-contribution.xml" file and there can also be a
"META-INF/sca-contribution-generated.xml" file in the package. SCA
defined artifacts as well as non-SCA defined artifacts such as object files,
WSDL definition, Java classes can be present anywhere in the ZIP archive,
A definition of the ZIP file format is published by
PKWARE in an Application Note on the .ZIP file format [12ZIP-FORMAT].
Artifacts in the SCA domain are in one of 3 states:
Installed artifacts are artifacts that are part of a Contribution that is installed into the Domain. Installed artifacts are available for use by other artifacts that are deployed, See "install Contribution" and "remove Contribution" to understand how artifacts are installed and uninstalled.
Deployed artifacts are artifacts that are available to the SCA runtime to be run.. Artifacts are deployed either through explicit deployment actions or through the presence of <deployable/> elements in sca-contribution.xml files within a Contribution. If an artifact is deployed which has dependencies on other artifacts, then those dependent artifacts are also deployed.
When the SCA runtime has one or more deployable artifacts, the runtime attempts to put those artifacts and any artifacts they depend on into the Running state. This can fail due to errors in one or more of the artifacts or the process can be delayed until all dependencies are available.
Checking for errors in artifacts MUST NOT be done for artifacts in the Installed state (ie where the artifacts are simply part of installed contributions)Checking for errors in artifacts MUST NOT be done for artifacts in the Installed state (ie where the artifacts are simply part of installed contributions) [ASM12032]
Errors in artifacts MUST be detected either during the Deployment of the artifacts, or during the process of putting the artifacts into the Running state,Errors in artifacts MUST be detected either during the Deployment of the artifacts, or during the process of putting the artifacts into the Running state, [ASM12033]
As noted in the section above, the contents of a contribution do not need to be modified in order to install and use it within a Domain. An installed contribution is a contribution with all of the associated information necessary in order to execute deployable composites within the contribution.
An installed contribution is made up of the following things:
· Contribution Packaging – the contribution that will be used as the starting point for resolving all references
· Contribution base URI
· Dependent contributions: a set of snapshots of other contributions that are used to resolve the import statements from the root composite and from other dependent contributions
– Dependent contributions might or might not be shared with other installed contributions.
– When the snapshot of any contribution is taken is implementation defined, ranging from the time the contribution is installed to the time of execution
·
Deployment-time composites.
These are composites that are added into an installed contribution after it has
been deployed. This makes it possible to provide final configuration and
access to implementations within a contribution without having to modify the
contribution. These do not have to be provided as composites that already
exist within the contribution can also be used for deployment.
Installed contributions provide a context in which to resolve qualified names (e.g. QNames in XML, fully qualified class names in Java).
If multiple dependent contributions have exported definitions with conflicting qualified names, the algorithm used to determine the qualified name to use is implementation dependent. Implementations of SCA MAY also raise an error if there are conflicting names exported from multiple contributions. [ASM12007]
When a contribution is installed, all artifacts within the contribution are assigned URIs, which are constructed by starting with the base URI of the contribution and adding the relative URI of each artifact (recalling that SCA demands that any packaging format be able to offer up its artifacts in a single hierarchy).
SCA Runtimes provide the following conceptual functionality associated with contributions to the Domain (meaning the function might not be represented as addressable services and also meaning that equivalent functionality might be provided in other ways). An SCA runtime MAY provide the contribution operation functions (install Contribution, update Contribution, add Deployment Composite, update Deployment Composite, remove Contribution). [ASM12008]
Creates or updates an installed contribution with a supplied root contribution, and installed at a supplied base URI. A supplied dependent contribution list (<export/> elements) specifies the contributions that are used to resolve the dependencies of the root contribution and other dependent contributions. These override any dependent contributions explicitly listed via the @location attribute in the import statements of the contribution.
SCA follows the simplifying assumption that the use of a contribution for resolving anything also means that all other exported artifacts can be used from that contribution. Because of this, the dependent contribution list is just a list of installed contribution URIs. There is no need to specify what is being used from each one.
Each dependent contribution is also an installed
contribution, with its own dependent contributions. By default these dependent
contributions of the dependent contributions (which we will call indirect dependent contributions) are included as dependent contributions of the
installed contribution. However, if a contribution in the dependent
contribution list exports any conflicting definitions with an indirect
dependent contribution, then the indirect dependent contribution is not
included (i.e. the explicit list overrides the default inclusion of indirect
dependent contributions). Also, if
there is ever a conflict between two indirect dependent contributions, then the
conflict MUST be resolved by an explicit entry in the dependent contribution
list.if
there is ever a conflict between two indirect dependent contributions, then the
conflict MUST be resolved by an explicit entry in the dependent contribution
list. [ASM12009]
Note that in many cases, the dependent contribution list can be generated. In particular, if the creator of a Domain is careful to avoid creating duplicate definitions for the same qualified name, then it is easy for this list to be generated by tooling.
Adds or updates a deployment composite using a supplied composite ("composite by value" – a data structure, not an existing resource in the Domain) to the contribution identified by a supplied contribution URI. The added or updated deployment composite is given a relative URI that matches the @name attribute of the composite, with a “.composite” suffix. Since all composites run within the context of a installed contribution (any component implementations or other definitions are resolved within that contribution), this functionality makes it possible for the deployer to create a composite with final configuration and wiring decisions and add it to an installed contribution without having to modify the contents of the root contribution.
Also, in some use cases, a contribution might include only implementation code (e.g. PHP scripts). It is then possible for those to be given component names by a (possibly generated) composite that is added into the installed contribution, without having to modify the packaging.
Removes the deployed contribution identified by a supplied contribution URI.
For certain types of artifact, there are existing and commonly used mechanisms for referencing a specific concrete location where the artifact can be resolved.
Examples of these mechanisms include:
· For WSDL files, the @wsdlLocation attribute is a hint that has a URI value pointing to the place holding the WSDL itself.
· For XSDs, the @schemaLocation attribute is a hint which matches the namespace to a URI where the XSD is found.
Note: In neither of these cases is the runtime obliged to use the location hint and the URI does not have to be dereferenced.
SCA permits the use of these mechanisms Where present, non-SCA artifact resolution
mechanisms MUST be used by the SCA runtime in precendence to the SCA
mechanisms.Where
present, non-SCA artifact resolution mechanisms MUST be used by the SCA runtime
in precendence to the SCA mechanisms. [ASM12010] However, use of these mechanisms is discouraged
because tying assemblies to addresses in this way makes the assemblies less
flexible and prone to errors when changes are made to the overall SCA Domain.
Note:
If one of the non-SCA artifact resolution
mechanisms is present, but there is a failure to find the resource indicated
when using the mechanism (e.g. the URI is incorrect or invalid, say) the SCA
runtime MUST raise an error and MUST NOT attempt to use SCA resolution
mechanisms as an alternative.If one of the non-SCA artifact resolution
mechanisms is present, but there is a failure to find the resource indicated
when using the mechanism (e.g. the URI is incorrect or invalid, say) the SCA
runtime MUST raise an error and MUST NOT attempt to use SCA resolution
mechanisms as an alternative. [ASM12011]
The domain-level composite is a virtual composite, in that it is not defined by a composite definition document. Rather, it is built up and modified through operations on the Domain. However, in other respects it is very much like a composite, since it contains components, wires, services and references.
The value of @autowire for the logical Domain
composite MUST be autowire="false".The value of @autowire for the logical Domain
composite MUST be autowire="false". [ASM12012]
For components at the Domain level, with Referencesreferences for which @autowire="true" applies, the behaviour of the SCA runtime for a given Domain MUST take ONE of the 3 following forms:
1) The SCA runtime MAY disallowdisallows deployment of any components with autowire Referencesreferences. In this case, the SCA runtime MUST raise an exception at the point where the component is deployed.
2) The SCA runtime MAY evaluateevaluates the target(s) for the reference at the time that the component is deployed and does not update those targets when later deployment actions occur.
3) The SCA runtime MAY re-evaluateevaluates the target(s) for the reference
dynamically as later deployment actions occur resulting in updated reference
targets which match the new Domain configuration. How the new reconfiguration of the reference takes place is
described by the relevant client and implementation specifications.For components at the
Domain level, with Referencesreferences for which
@autowire="true" applies, the behaviour of the SCA runtime for a
given Domain MUST take ONE of the 3 following forms:
1) The SCA runtime MAY disallowdisallows deployment of any
components with autowire Referencesreferences. In this case, the
SCA runtime MUST raise an exception at the point where the component is
deployed.
2) The SCA runtime MAY evaluateevaluates the target(s) for the
reference at the time that the component is deployed and does not update those
targets when later deployment actions occur.
3) The SCA runtime MAY re-evaluateevaluates
the target(s) for the reference dynamically as later deployment actions occur
resulting in updated reference targets which match the new Domain
configuration. How the new configuration of
the reference takes place is described by the relevant client and
implementation specifications.For components at
the Domain level, with References for which @autowire="true" applies,
the behaviour of the SCA runtime for a given Domain MUST take ONE of the 3
following forms:
1) The SCA runtime
MAY disallow deployment of any components with autowire References. In this
case, the SCA runtime MUST raise an exception at the point where the component
is deployed.
2) The SCA runtime
MAY evaluate the target(s) for the reference at the time that the component is
deployed and not update those targets when later deployment actions occur.
3) The SCA runtime
MAY re-evaluate the
target(s) for the reference dynamically as later deployment actions occur
resulting in updated reference targets which match the new Domain
configuration. How the new configuration of the
reference takes place is described by the relevant client and implementation
specifications.
The abstract domain-level functionality for modifying the domain-level composite is as follows, although a runtime can supply equivalent functionality in a different form:
This functionality adds the composite identified by a supplied URI to the Domain Level Composite. The supplied composite URI refers to a composite within an installed contribution. The composite's installed contribution determines how the composite’s artifacts are resolved (directly and indirectly). The supplied composite is added to the domain composite with semantics that correspond to the domain-level composite having an <include> statement that references the supplied composite. All of the composites components become top-level components and the component services become externally visible services (eg. they would be present in a WSDL description of the Domain). The meaning of any promoted services and references in the supplied composite is not defined; since there is no composite scope outside the domain composite, the usual idea of promotion has no utility.
Removes from the Domain Level composite the elements corresponding to the composite identified by a supplied composite URI. This means that the removal of the components, wires, services and references originally added to the domain level composite by the identified composite.
Returns a <composite> definition that has an <include> line for each composite that had been added to the domain level composite. It is important to note that, in dereferencing the included composites, any referenced artifacts are resolved in terms of that installed composite.
In order to make sense of the domain-level composite
(as returned by get Domain-Level Composite), it needs to be possible to get the
definitions for named artifacts in the included composites. This functionality
takes the supplied URI of an installed contribution (which provides the
context), a supplied qualified name of a definition to look up, and a supplied
symbol space (as a QName, e.g. wsdl:PortTypeportType). The result is a single definition, in whatever
form is appropriate for that definition type.
Note that this, like all the other domain-level operations, is a conceptual operation. Its capabilities need to exist in some form, but not necessarily as a service operation with exactly this signature.
For components with references which are at the Domain level, there is the potential for dynamic behaviour when the wires for a component reference change (this can only apply to component references at the Domain level and not to components within composites used as implementations):
The configuration of the wires for a component reference of a component at the Domain level can change by means of deployment actions:
1. <wire/> elements can be added, removed or replaced by deployment actions
2. Components can be updated by deployment actions (i.e. this can change the component reference configuration)
3. Components which are the targets of reference wires can be updated or removed
4. Components can be added that are potential targets for references which are marked with @autowire=true
Where
<wire/> elements are added, removed or replaced by deployment actions,
the components whose references are affected by those deployment actions MAY
have their references updated by the SCA runtime dynamically without the need
to stop and start those components.. [ASM12014]
Where components are
updated by deployment actions (their configuration is changed in some way,
which includes changing the wires of component references), the new
configuration MUST apply to all new instances of those components once the
update is complete.Where
components are updated by deployment actions (their configuration is changed in
some way, which includes changing the wires of component references), the new
configuration MUST apply to all new instances of those components once the
update is complete. [ASM12015] An SCA
runtime MAY choose to maintain existing instances with the old configuration of
components updated by deployment actions, but an SCA runtime MAY choose to stop
and discard existing instances of those components. [ASM12016]
Where a component that is the target of a wire is removed, without the wire being changed, then future invocations of the reference that use that wire SHOULD fail with a ServiceUnavailable fault. If the wire is the result of the autowire process, the SCA runtime MUST:
· either cause future invocation of the target component's services to fail with a ServiceUnavailable fault
·
or alternatively, if an alternative target
component is available that satisfies the autowire process, update the
reference of the source component Where a component that is the target of a wire is
removed, without the wire being changed, then future invocations of the
reference that use that wire SHOULD fail with a ServiceUnavailable fault. If
the wire is the result of the autowire process, the SCA runtime MUST:
·either cause future invocation of the target
component's services to fail with a ServiceUnavailable fault
or alternatively, if
an alternative target component is available that satisfies the autowire process,
update the reference of the source component Where a component
that is the target of a wire is removed, without the wire being changed, then
future invocations of the reference that use that wire SHOULD fail with a
ServiceUnavailable fault. If the wire is the result of the autowire process,
the SCA runtime MUST:
·either cause future invocation of the target
component's services to fail with a ServiceUnavailable fault
·
[ASM12017]or alternatively, if
an alternative target component is available that satisfies the autowire
process, update the reference of the source component
Where a component that is the target of a wire is updated, future invocations of that reference SHOULD use the updated component. [ASM12018]
Where a component is added to the Domain that is a potential target for a domain level component reference where that reference is marked as @autowire=true, the SCA runtime MUST:
· either update the references for the source component once the new component is running.
·
or alternatively, defer the updating of the
references of the source component until the source component is stopped and
restarted.Where
a component is added to the Domain that is a potential target for a domain
level component reference where that reference is marked as @autowire=true, the
SCA runtime MUST:
·either update the references for the source
component once the new component is running.
or alternatively,
defer the updating of the references of the source component until the source
component is stopped and restarted.Where a component
is added to the Domain that is a potential target for a domain level component
reference where that reference is marked as @autowire=true, the SCA runtime
MUST:
-·either update the references for the source
component once the new component is running.
·
[ASM12020]or alternatively,
defer the updating of the references of the source component until the source
component is stopped and restarted.
For a domain level component with a Property whose
value is obtained from a Domain-level Property through the use of the @source
attribute, if the domain level property is updated by means of deployment
actions, the SCA runtime MUST
-either
update the property value of the domain level component once the update of the
domain property is complete
-or
defer the updating of the component property value until the component is
stopped and restarted
For a domain level component with a Property whose value is obtained from a Domain-level Property through the use of the @source attribute, if the domain level property is updated by means of deployment actions, the SCA runtime MUST
• either update the property value of the domain level component once the update of the domain property is complete
• or defer the updating of the component property value until the component is stopped and restartedFor a domain level component with a Property whose value is obtained from a Domain-level Property through the use of the @source attribute, if the domain level property is updated by means of deployment actions, the SCA runtime MUST
• either update the property value of the domain level component once the update of the domain property is complete
• or defer the updating of the component property value until the component is stopped and restarted
This section describes aspects of an SCA Runtime that are defined by this specification.
The SCA Assembly specification identifies situations where the configuration of the SCA Domain and its contents are in error. When one of these situations occurs, the specification requires that the SCA Runtime that is interacting with the SCA Domain and the artifacts it contains recognises that there is an error, raise the error in a suitable manner and also refuse to run components and services that are in error.
The SCA Assembly specification is not prescriptive about the functionality of an SCA Runtime and the specification recognizes that there can be a range of design points for an SCA runtime. As a result, the SCA Assembly specification describes a range of error handling approaches which can be adopted by an SCA runtime.
An SCA Runtime MUST raise an error for every situation where the configuration of the SCA Domain or its contents are in error. The error is either raised at deployment time or at runtime, depending on the nature of the error and the design of the SCA Runtime.An SCA Runtime MUST raise an error for every situation where the configuration of the SCA Domain or its contents are in error. The error is either raised at deployment time or at runtime, depending on the nature of the error and the design of the SCA Runtime. [ASM14005]
Some error situations can be detected at the point that artifacts are deployed to the Domain. An example is a composite document that is invalid in a way that can be detected by static analysis, such as containing a component with two services with the same @name attribute.
An SCA runtime SHOULD detect errors at deployment
time where those errors can be found through static analysis. An SCA runtime SHOULD
detect errors at deployment time where those errors can be found through static
analysis. [ASM14001]
The SCA runtime SHOULD
prevent deployment of contributions that are in error, and raise the error to
the process performing the deployment (e.g. write a message to an interactive
console or write a message to a log file).The SCA runtime SHOULD prevent deployment of
contributions that are in error, and raise the error to the process performing
the deployment (e.g. write a message to an interactive console or write a
message to a log file). [ASM14002]
The SCA Assembly specification recognizes that there are reasons why a particular SCA runtime finds it desirable to deploy contributions that contain errors (e.g. to assist in the process of development and debugging) - and as a result also supports an error handling strategy that is based on detecting problems at runtime. However, it is wise to consider reporting problems at an early stage in the deployment proocess.
An SCA runtime can detect problems at runtime. These errors can include some which can be found from static analysis (e.g. the inability to wire a reference because the target service does not exist in the Domain) and others that can only be discovered dynamically (e.g. the inability to invoke some remote Web service because the remote endpoint is unavailable).
Where errors can be detected through static analysis, the principle is that components that are known to be in error are not run. So, for example, if there is a component with a required reference (multiplicity 1..1 or 1..n) which is not wired, best practice is that the component is not run. If an attempt is made to invoke a service operation of that component, a "ServiceUnavailable" fault is raised to the invoker. It is also regarded as best practice that errors of this kind are also raised through appropriate management interfaces, for example to the deployer or to the operator of the system.
Where errors are only
detected at runtime, when the error is detected an error MUST be raised to the
component that is attempting the activity concerned with the error.Where errors are only detected at runtime, when the
error is detected an error MUST be raised to the component that is attempting
the activity concerned with the error. [ASM14003] For example, if a component invokes an
operation on a reference, but the target service is unavailable, a
"ServiceUnavailable" fault is raised to the component. When an error that could have been detected through
static analysis is detected and raised at runtime for a component, the
component SHOULD NOT be run until the error is fixed.When an error that could have been detected through
static analysis is detected and raised at runtime for a component, the component
SHOULD NOT be run until the error is fixed. [ASM14004] Such errors can
be fixed by redeployment or deployment of other components in the domain.
The XML schema pointed to by the RDDL document at the namespace URI, defined by this specification, are considered to be authoritative and take precedence over the XML schema defined in the appendix of this
document.
An SCA runtime MUST
reject a composite file that does not conform to the sca-core.xsd,
sca-interface-wsdl.xsd, sca-implementation-composite.xsd and
sca-binding-sca.xsd schema.An
SCA runtime MUST reject a composite file that does not conform to the
sca-core.xsd, sca-interface-wsdl.xsd, sca-implementation-composite.xsd and
sca-binding-sca.xsd schema.. [ASM13001]
An SCA runtime MUST
reject a contribution file that does not conform to the sca-contribution.xsd
schema.An SCA runtime MUST
reject a contribution file that does not conform to the sca-contribution.xsd
schema. [ASM13002]
An SCA runtime MUST
reject a definitions file that does not conform to the sca-definitions.xsd
schema.An SCA runtime MUST
reject a definitions file that does not conform to the sca-definitions.xsd
schema. [ASM13003]
There are two categories of artifacts that this specification defines conformance for: SCA Documents and SCA Runtimes.
For a document to be a valid SCA Document, it MUST comply with one of the SCA document types below:
SCA Composite Document:
An SCA Composite Document is a file that MUST have an SCA <composite/> element as its root element and MUST conform to the sca-core-1.1.xsd schema and MUST comply with the additional constraints on the document contents as defined in Appendix C.
SCA ComponentType Document:
An SCA ComponentType Document is a
file that MUST have an SCA <componentType/> element as its root element
and MUST conform to the sca-core-1.1.xsd schema and MUST comply with the
additional constraints on the document contents as defined in
Appendix C.
SCA ConstrainingType Document:
An SCA
ConstrainingType Document is a file that MUST have an SCA
<constrainingType/> element as its root element and MUST conform to the
sca-core-1.1.xsd schema and MUST comply with the additional constraints on the
document contents as defined in Appendix C.
SCA Definitions Document:
An SCA Definitions Document is a file that MUST have an SCA <definitions/> element as its root and MUST conform to the sca-definition-1.1.xsd schema and MUST comply with the additional constraints on the document contents as defined in Appendix C.
SCA Contribution Document:
An SCA Contribution Document is a file that MUST have an SCA <contributution/> element as its root element and MUST conform to the sca-contribution-1.1.xsd schema and MUST comply with the additional constraints on the document contents as defined in Appendix C.
SCA Interoperable Packaging Document:
A ZIP file containing SCA Documents and other related artifacts. The ZIP file SHOULD contain a top-level "META-INF" directory, and SHOULD contain a "META-INF/sca-contribution.xml" file, and MAY contain a "META-INF/sca-contribution-generated.xml" file.
An implementation that claims to conform to the requirements of an SCA Runtime defined in this specification MUST meet the following conditions:
1.
The implementation
MUST comply with all mandatory statements listed in table Appendix
CMandatory Items in Appendix
C:
Conformance Items,
related to an SCA
Runtime,
notably all MUST statements have to be implemented. .
2. The implementation MUST conform to the SCA Policy Framework v 1.1 Specification [Policy].
3. The implementation MUST support and comply with at least one of the OpenCSA Member Section adopted implementation types.
4. The implementation MUST support binding.sca and MUST support and conform to the SCA Web Service Binding Specification v 1.1.
In addition to mandatory items, Appendix C: Conformance Items lists a number of non-mandatory items that can be implemented SCA Runtimes. These items are categorized into functionally related classes as follows:
· Development – items to improve the development of SCA contributions, debugging, etc.
· Enhancement – items that add functionality and features to the SCA Runtime.
· Interoperation – items that improve interoperability of SCA contributions and Runtimes
These classifications are not rigid and some may overlap; items are classified according to their primary intent.
<?xml version="1.0" encoding="UTF-8"?>
<!-- Copyright(C) OASIS(R) 2005,2010. All Rights Reserved.
OASIS trademark, IPR and other policies apply. -->
<schema xmlns="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://docs.oasis-open.org/ns/opencsa/sca/200912"
xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200912">
<include schemaLocation="sca-core-1.1-cd05.xsd"/>
<include schemaLocation="sca-interface-java-1.1-cd04.xsd"/>
<include schemaLocation="sca-interface-wsdl-1.1-cd05.xsd"/>
<include schemaLocation="sca-interface-cpp-1.1-cd04.xsd"/>
<include schemaLocation="sca-interface-c-1.1-cd04.xsd"/>
<include schemaLocation="sca-implementation-java-1.1-cd02.xsd"/>
<include schemaLocation="sca-implementation-composite-1.1-cd05.xsd"/>
<include schemaLocation="sca-implementation-cpp-1.1-cd04.xsd"/>
<include schemaLocation="sca-implementation-c-1.1-cd04.xsd"/>
<include schemaLocation="sca-implementation-bpel-1.1-cd03.xsd"/>
<include schemaLocation="sca-implementation-spring-1.1-cd01.xsd"/>
<include schemaLocation="sca-binding-ws-1.1-cd04.xsd"/>
<include schemaLocation="sca-binding-ws-callback-1.1-cd04.xsd"/
<include schemaLocation="sca-binding-jms-1.1-cd04.xsd"/>
<include schemaLocation="sca-binding-jca-1.1-cd04.xsd"/>
<include schemaLocation="sca-binding-sca-1.1-cd05.xsd"/>
<include schemaLocation="sca-binding-ejb-1.1-cd01.xsd"/>
<include schemaLocation="sca-definitions-1.1-cd05.xsd"/>
<include schemaLocation="sca-policy-1.1-cd03.xsd"/>
<include schemaLocation="sca-contribution-1.1-cd05.xsd"/>
<include schemaLocation="sca-contribution-cpp-1.1-cd04.xsd"/>
<include schemaLocation="sca-contribution-c-1.1-cd04.xsd"/>
<include schemaLocation="sca-contribution-java-1.1-cd02.xsd"/>
</schema>
<?xml version="1.0" encoding="UTF-8"?>
<!-- Copyright(C) OASIS(R) 2005,2009. All Rights Reserved.
OASIS trademark, IPR and other policies apply. -->
<schema xmlns="http://www.w3.org/2001/XMLSchema"
xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200912"
targetNamespace="http://docs.oasis-open.org/ns/opencsa/sca/200903"
xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200903">
<include schemaLocation="sca-core-1.1-cd03.xsd"/>
<include schemaLocation="sca-interface-java-1.1-cd03.xsd"/>
<include schemaLocation="sca-interface-wsdl-1.1-cd03.xsd"/>
<include schemaLocation="sca-interface-cpp-1.1-cd02.xsd"/>
<include schemaLocation="sca-interface-c-1.1-cd02.xsd"/>
<include schemaLocation="sca-implementation-java-1.1-cd01.xsd"/>
<include schemaLocation="sca-implementation-composite-1.1-cd03.xsd"/>
<include schemaLocation="sca-implementation-cpp-1.1-cd02.xsd"/>
<include schemaLocation="sca-implementation-c-1.1-cd02.xsd"/>
<include schemaLocation="sca-implementation-bpel-1.1-cd02.xsd"/>
<include schemaLocation="sca-binding-ws-1.1-cd02.xsd"/>
<include schemaLocation="sca-binding-jms-1.1-cd02.xsd"/>
<include schemaLocation="sca-binding-jca-1.1-cd02.xsd"/>
<include schemaLocation="sca-binding-sca-1.1-cd03.xsd"/>
<include schemaLocation="sca-definitions-1.1-cd03.xsd"/>
<include schemaLocation="sca-policy-1.1-cd02.xsd"/>
<include schemaLocation="sca-contribution-1.1-cd03.xsd"/>
<include schemaLocation="sca-contribution-cpp-1.1-cd02.xsd"/>
<include schemaLocation="sca-contribution-c-1.1-cd02.xsd"/>
</schema>
<?xml version="1.0" encoding="UTF-8"?>
<!--
Copyright(C) OASIS(R) 2005,2009. All Rights Reserved.
OASIS
trademark, IPR and other policies apply. -->
<schema xmlns="http://www.w3.org/2001/XMLSchema"
xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200903"
targetNamespace="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
elementFormDefault="qualified">
<include schemaLocation="sca-policy-1.1-cd03.xsd"/>
<import namespace="http://www.w3.org/XML/1998/namespace"
schemaLocation="http://www.w3.org/2001/xml.xsd"/>
<!-- Common extension base for SCA definitions -->
<complexType name="CommonExtensionBase">
<sequence>
<element ref="sca:documentation" minOccurs="0"
maxOccurs="unbounded"/>
</sequence>
<anyAttribute namespace="##other" processContents="lax"/>
</complexType>
<element name="documentation" type="sca:Documentation"/>
<complexType name="Documentation" mixed="true">
<sequence>
<any namespace="##other" processContents="lax" minOccurs="0"
maxOccurs="unbounded"/>
</sequence>
<attribute ref="xml:lang"/>
</complexType>
<!-- Component Type -->
<element name="componentType" type="sca:ComponentType"/>
<complexType name="ComponentType">
<complexContent>
<extension base="sca:CommonExtensionBase">
<sequence>
<element ref="sca:implementation" minOccurs="0"/>
<choice minOccurs="0" maxOccurs="unbounded">
<element name="service" type="sca:ComponentService"/>
<element name="reference"
type="sca:ComponentTypeReference"/>
<element name="property" type="sca:Property"/>
</choice>
<any namespace="##other" processContents="lax" minOccurs="0"
maxOccurs="unbounded"/>
</sequence>
<attribute name="constrainingType"
type="QName" use="optional"/>
</extension>
</complexContent>
</complexType>
<!-- Composite -->
<element name="composite" type="sca:Composite"/>
<complexType name="Composite">
<complexContent>
<extension base="sca:CommonExtensionBase">
<sequence>
<element name="ref="sca:include" type="anyURI" minOccurs="0"
maxOccurs="unbounded"/>
<choice minOccurs="0" maxOccurs="unbounded">
<element ref="sca:requires"/>
<element ref="sca:policySetAttachment"/>
<element name="service" type="sca:Service"/>
<element name="property" type="sca:Property"/>
<element name="component" type="sca:Component"/>
<element name="reference" type="sca:Reference"/>
<element name="wire" type="sca:Wire"/>
</choice>
<any namespace="##other" processContents="lax" minOccurs="0"
maxOccurs="unbounded"/>
</sequence>
<attribute name="name" type="NCName" use="required"/>
<attribute name="targetNamespace" type="anyURI" use="required"/>
<attribute name="local" type="boolean" use="optional"
default="false"/>
<attribute name="autowire" type="boolean" use="optional"
default="false"/>
<attribute name="constrainingType"
type="QName" use="optional"/>
<attribute name="requires" type="sca:listOfQNames"
use="optional"/>
<attribute name="policySets" type="sca:listOfQNames"
use="optional"/>
</extension>
</complexContent>
</complexType>
<!-- Contract base type for Service, Reference -->
<complexType name="Contract" abstract="true">
<complexContent>
<extension base="sca:CommonExtensionBase">
<sequence>
<element ref="sca:interface" minOccurs="0" maxOccurs="1" />
<element ref="sca:binding" minOccurs="0"
maxOccurs="unbounded" />
<element ref="sca:callback" minOccurs="0" maxOccurs="1" />
<any namespace="##other"
processContents="laxelement
ref="sca:requires" minOccurs="0"
maxOccurs="unbounded"/>
<element ref="sca:policySetAttachment" minOccurs="0"
maxOccurs="unbounded"/>
<element ref="sca:extensions" minOccurs="0" maxOccurs="1" />
</sequence>
<attribute name="name" type="NCName" use="required" />
<attribute name="requires" type="sca:listOfQNames"
use="optional" />
<attribute name="policySets" type="sca:listOfQNames"
use="optional"/>
</extension>
</complexContent>
</complexType>
<!-- Service -->
<complexType name="Service">
<complexContent>
<extension base="sca:Contract">
<attribute name="promote" type="anyURI" use="required"/>
</extension>
</complexContent>
</complexType>
<!-- Interface -->
<element name="interface" type="sca:Interface" abstract="true"/>
<complexType name="Interface" abstract="true">
<complexContent>
<extension base="sca:CommonExtensionBase">
<choice minOccurs="0" maxOccurs="unbounded">
<element ref="sca:requires"/>
<element ref="sca:policySetAttachment"/>
</choice>
<attribute name="remotable" type="boolean" use="optional"/>
<attribute name="requires" type="sca:listOfQNames"
use="optional"/>
<attribute name="policySets" type="sca:listOfQNames"
use="optional"/>
</extension>
</complexContent>
</complexType>
<!-- Reference -->
<complexType name="Reference">
<complexContent>
<extension base="sca:Contract">
<attribute name="autowire"
type="boolean"
use="optional"/>
<attribute name="target" type="sca:listOfAnyURIs"
use="optional"/>
<attribute name="wiredByImpl" type="boolean" use="optional"
default="false"/>
<attribute name="multiplicity" type="sca:Multiplicity"
use="optional" default="1..1required"/>
<attribute name="promote" type="sca:listOfAnyURIs"
use="required"/>
</extension>
</complexContent>
</complexType>
<!-- Property -->
<complexType name="SCAPropertyBase" mixed="true">
<sequence>
<any namespace="##any" processContents="lax" minOccurs="0"
maxOccurs="unbounded"/>
<!-- NOT an extension point; This any exists to accept
the element-based or complex type property
i.e. no element-based extension point under "sca:property" -->
</sequence>
<!-- mixed="true" to handle simple type -->
<attribute name="requiresname" type="sca:listOfQNamesNCName"
use="required"/>
<attribute name="type" type="QName" use="optional"/>
<attribute name="policySetselement" type="sca:listOfQNamesQName" use="optional"/>
<attribute name="many" type="boolean" use="optional" default="false"/>
<attribute name="value" type="anySimpleType" use="optional"/>
<anyAttribute namespace="##other" processContents="lax"/>
</complexType>
<complexType name="Property" mixed="true">
<complexContent mixed="true">
<extension base="sca:SCAPropertyBase">
<attribute name="name" type="NCName" use="required"/>
<attribute name="type" type="QName" use="optional"/>
<attribute name="element"
type="QName" use="optional"/>
<attribute name="many" type="boolean"
use="optional"
default="false"/>
<attribute name="mustSupply" type="boolean" use="optional"
default="false"/>
<anyAttribute namespace="##any" processContents="lax"/>
</extension>
<!-- extension
defines the place to hold default value -->
<!-- an
extension point ; attribute-based only -->
</complexContent>
</complexType>
<!--
ConstrainingProperty is equivalent to the Property type but removes
the
capability to contain a value -->
<complexType name="ConstrainingProperty"
mixed="true">
<complexContent mixed="true">
<restriction base="sca:Property">
<attribute name="name" type="NCName" use="required"/>
<attribute name="type" type="QName" use="optional"/>
<attribute name="element"
type="QName" use="optional"/>
<attribute name="many" type="boolean"
use="optional"
default="false"/>
<attribute name="mustSupply"
type="boolean"
use="optional"
default="false"/>
<anyAttribute namespace="##any" processContents="lax"/>
</restriction>
</complexContent>
</complexType>
<complexType name="PropertyValue" mixed="true">
<complexContent mixed="true">
<extension base="sca:SCAPropertyBase">
<attribute name="name" type="NCName" use="required"/>
<attribute name="type" type="QName" use="optional"/>
<attribute name="element"
type="QName" use="optional"/>
<attribute name="many" type="boolean"
use="optional"
default="false"/>
<attribute name="source" type="string" use="optional"/>
<attribute name="file" type="anyURI" use="optional"/>
<anyAttribute namespace="##any" processContents="lax"/>
</extension>
<!-- an
extension point ; attribute-based only -->
</complexContent>
</complexType>
<!-- Binding -->
<element name="binding" type="sca:Binding" abstract="true"/>
<complexType name="Binding" abstract="true">
<complexContent>
<extension base="sca:CommonExtensionBase">
<sequence>
<element ref="sca:wireFormat" minOccurs="0" maxOccurs="1" />
<element ref="sca:operationSelector" minOccurs="0"
maxOccurs="1" />
<element ref="sca:requires" minOccurs="0"
maxOccurs="unbounded"/>
<element ref="sca:policySetAttachment" minOccurs="0"
maxOccurs="unbounded"/>
</sequence>
<attribute name="uri" type="anyURI" use="optional"/>
<attribute name="name" type="NCName" use="optional"/>
<attribute name="requires" type="sca:listOfQNames"
use="optional"/>
<attribute name="policySets" type="sca:listOfQNames"
use="optional"/>
</extension>
</complexContent>
</complexType>
<!-- Binding Type -->
<element name="bindingType" type="sca:BindingType"/>
<complexType name="BindingType">
<complexContent>
<extension base="sca:CommonExtensionBase">
<sequence>
<any namespace="##other" processContents="lax" minOccurs="0"
maxOccurs="unbounded"/>
</sequence>
<attribute name="type" type="QName" use="required"/>
<attribute name="alwaysProvides" type="sca:listOfQNames"
use="optional"/>
<attribute name="mayProvide" type="sca:listOfQNames"
use="optional"/>
</extension>
</complexContent>
</complexType>
<!-- WireFormat Type -->
<element name="wireFormat" type="sca:WireFormatType" abstract="true"/>
<complexType name="WireFormatType" abstract="true">
<sequence>
<any namespace="##other" processContents="lax" minOccurs="0"
maxOccurs="unbounded" />
</sequence>
<anyAttribute namespace="##other" processContents="lax"/>
</complexType>
<!-- OperationSelector Type -->
<element name="operationSelector" type="sca:OperationSelectorType"
abstract="true"/>
<complexType name="OperationSelectorType" abstract="true">
<sequence>
<any namespace="##other" processContents="lax" minOccurs="0"
maxOccurs="unbounded" />
</sequence>
<anyAttribute namespace="##other" processContents="lax"/>
</complexType>
<!-- Callback -->
<element name="callback" type="sca:Callback"/>
<complexType name="Callback">
<complexContent>
<extension base="sca:CommonExtensionBase">
<choice minOccurs="0" maxOccurs="unbounded">
<element ref="sca:binding"/>
<element ref="sca:requires"/>
<element ref="sca:policySetAttachment"/>
<any namespace="##other" processContents="lax"/>
</choice>
<attribute name="requires" type="sca:listOfQNames"
use="optional"/>
<attribute name="policySets" type="sca:listOfQNames"
use="optional"/>
</extension>
</complexContent>
</complexType>
<!-- Component -->
<complexType name="Component">
<complexContent>
<extension base="sca:CommonExtensionBase">
<sequence>
<element ref="sca:implementation" minOccurs="01"
maxOccurs="1"/>
<choice minOccurs="0" maxOccurs="unbounded">
<element name="service" type="sca:ComponentService"/>
<element name="reference" type="sca:ComponentReference"/>
<element name="property" type="sca:PropertyValue"/>
<element ref="sca:requires"/>
<element ref="sca:policySetAttachment"/>
</choice>
<any namespace="##other" processContents="lax" minOccurs="0"
maxOccurs="unbounded"/>
</sequence>
<attribute name="name" type="NCName" use="required"/>
<attribute name="autowire" type="boolean" use="optional"/>
<attribute name="constrainingType"
type="QName" use="optional"/>
<attribute name="requires" type="sca:listOfQNames"
use="optional"/>
<attribute name="policySets" type="sca:listOfQNames"
use="optional"/>
</extension>
</complexContent>
</complexType>
<!-- Component Service -->
<complexType name="ComponentService">
<complexContent>
<extension base="sca:Contract">
</extension>
</complexContent>
</complexType>
<!--
Constraining Service -->
<complexType name="ConstrainingService">
<complexContent>
<restriction base="sca:ComponentService">
<sequence>
<element ref="sca:interface"
minOccurs="0" maxOccurs="1" />
<element ref="sca:callback"
minOccurs="0" maxOccurs="1" />
<any namespace="##other"
processContents="lax" minOccurs="0"
maxOccurs="unbounded"
/>
</sequence>
<attribute name="name" type="NCName" use="required"
/>
</restriction>
</complexContent>
</complexType>
<!-- Component Reference -->
<complexType name="ComponentReference">
<complexContent>
<extension base="sca:Contract">
<attribute name="autowire" type="boolean" use="optional"/>
<attribute name="target" type="sca:listOfAnyURIs"
use="optional"/>
<attribute name="wiredByImpl" type="boolean" use="optional"
default="false"/>
<attribute name="multiplicity" type="sca:Multiplicity"
use="optional" default="1..1"/>
<attribute name="nonOverridable" type="boolean" use="optional"
default="false"/>
</extension>
</complexContent>
</complexType>
<!--
Constraining Reference -->
<complexType name="ConstrainingReference">
<complexContent>
<restriction base="sca:ComponentReference">
<sequence>
<element ref="sca:interface"
minOccurs="0" maxOccurs="1" />
<element ref="sca:callback"
minOccurs="0" maxOccurs="1" />
<any namespace="##other"
processContents="lax" minOccurs="0"
maxOccurs="unbounded"
/>
</sequence>
<attribute name="name" type="NCName" use="required"
/>
<attribute name="autowire"
type="boolean"
use="optional"/>
<attribute name="wiredByImpl"
type="boolean"
use="optional"
default="false"/>
<attribute name="multiplicity"
type="sca:Multiplicity"
use="optional"
default="1..1"/>
</restriction>
</complexContent>
</complexType>
<!-- Component Type Reference -->
<complexType name="ComponentTypeReference">
<complexContent>
<restriction base="sca:ComponentReference">
<sequence>
<element ref="sca:documentation" minOccurs="0"
maxOccurs="unbounded"/>
<element ref="sca:interface" minOccurs="0"/>
<element ref="sca:binding" minOccurs="0"
maxOccurs="unbounded"/>
<element ref="sca:callback" minOccurs="0"/>
<any namespace="##other"
processContents="laxelement
ref="sca:requires" minOccurs="0"
maxOccurs="unbounded"/>
<element ref="sca:policySetAttachment" minOccurs="0"
maxOccurs="unbounded"/>
<element ref="sca:extensions" minOccurs="0" maxOccurs="1" />
</sequence>
<attribute name="name" type="NCName" use="required"/>
<attribute name="autowire" type="boolean" use="optional"/>
<attribute name="wiredByImpl" type="boolean" use="optional"
default="false"/>
<attribute name="multiplicity" type="sca:Multiplicity"
use="optional" default="1..1"/>
<attribute name="requires" type="sca:listOfQNames"
use="optional"/>
<attribute name="policySets" type="sca:listOfQNames"
use="optional"/>
<anyAttribute namespace="##other" processContents="lax"/>
</restriction>
</complexContent>
</complexType>
<!-- Implementation -->
<element name="implementation" type="sca:Implementation" abstract="true"/>
<complexType name="Implementation" abstract="true">
<complexContent>
<extension base="sca:CommonExtensionBase">
<choice minOccurs="0" maxOccurs="unbounded">
<element ref="sca:requires"/>
<element ref="sca:policySetAttachment"/>
</choice>
<attribute name="requires" type="sca:listOfQNames"
use="optional"/>
<attribute name="policySets" type="sca:listOfQNames"
use="optional"/>
</extension>
</complexContent>
</complexType>
<!-- Implementation Type -->
<element name="implementationType" type="sca:ImplementationType"/>
<complexType name="ImplementationType">
<complexContent>
<extension base="sca:CommonExtensionBase">
<sequence>
<any namespace="##other" processContents="lax" minOccurs="0"
maxOccurs="unbounded"/>
</sequence>
<attribute name="type" type="QName" use="required"/>
<attribute name="alwaysProvides" type="sca:listOfQNames"
use="optional"/>
<attribute name="mayProvide" type="sca:listOfQNames"
use="optional"/>
</extension>
</complexContent>
</complexType>
<!-- Wire -->
<complexType name="Wire">
<complexContent>
<extension base="sca:CommonExtensionBase">
<sequence>
<any namespace="##other" processContents="lax" minOccurs="0"
maxOccurs="unbounded"/>
</sequence>
<attribute name="source" type="anyURI" use="required"/>
<attribute name="target" type="anyURI" use="required"/>
<attribute name="replace" type="boolean" use="optional"
default="false"/>
</extension>
</complexContent>
</complexType>
<!-- Include -->
<element name="include" type="sca:Include"/>
<complexType name="Include">
<complexContent>
<extension base="sca:CommonExtensionBase">
<attribute name="name" type="QName"/>
</extension>
</complexContent>
</complexType>
<!--
Constraining Type
<!-- Extensions element -->
<element name="constrainingType"
type="sca:ConstrainingType"/>
extensions">
<complexType name="ConstrainingType">
<complexContent>
<extension base="sca:CommonExtensionBase">
<sequence>
<choice minOccurs="0" maxOccurs="unbounded">
<element name="service"
type="sca:ConstrainingService"/>
<element name="reference"
type="sca:ConstrainingReference"/>
<element name="property"
type="sca:ConstrainingProperty"/>
</choice>
<any namespace="##other" processContents="lax"
minOccurs="0"
minOccurs="1" maxOccurs="unbounded"/>
</sequence>
<attribute name="name" type="NCName" use="required"/>
<attribute name="targetNamespace"
type="anyURI"/>
</extension>
</complexContent>
</complexType>
</element>
<!-- Intents within WSDL documents -->
<attribute name="requires" type="sca:listOfQNames"/>
<!-- Global attribute definition for @callback to mark a WSDL port type
as having a callback interface defined in terms of a second port
type. -->
<attribute name="callback" type="anyURI"/>
<!-- Value type definition for property values -->
<element name="value" type="sca:ValueType"/>
<complexType name="ValueType" mixed="true">
<sequence>
<any namespace="##any" processContents="lax" minOccurs="0"
maxOccurs='unbounded'/>
</sequence>
<!-- mixed="true" to handle simple type -->
<anyAttribute namespace="##any" processContents="lax"/>
</complexType>
<!-- Miscellaneous simple type definitions -->
<simpleType name="Multiplicity">
<restriction base="string">
<enumeration value="0..1"/>
<enumeration value="1..1"/>
<enumeration value="0..n"/>
<enumeration value="1..n"/>
</restriction>
</simpleType>
<simpleType name="OverrideOptions">
<restriction base="string">
<enumeration value="no"/>
<enumeration value="may"/>
<enumeration value="must"/>
</restriction>
</simpleType>
<simpleType name="listOfQNames">
<list itemType="QName"/>
</simpleType>
<simpleType name="listOfAnyURIs">
<list itemType="anyURI"/>
</simpleType>
<simpleType name="CreateResource">
<restriction base="string">
<enumeration value="always" />
<enumeration value="never" />
<enumeration value="ifnotexist" />
</restriction>
</simpleType>
</schema>
<?xml version="1.0" encoding="UTF-8"?>
<!-- Copyright(C) OASIS(R) 2005,2009. All Rights Reserved.
OASIS trademark, IPR and other policies apply. -->
<schema xmlns="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
elementFormDefault="qualified">
<include schemaLocation="sca-core-1.1-cd03cd05.xsd"/>
<!-- SCA Binding -->
<element name="binding.sca" type="sca:SCABinding"
substitutionGroup="sca:binding"/>
<complexType name="SCABinding">
<complexContent>
<extension base="sca:Binding"/>
</complexContent>
</complexType>
</schema>
Is described in the SCA Java Common Annotations and APIs specification [SCA-Common-Java].
<?xml version="1.0" encoding="UTF-8"?>
<!-- Copyright(C) OASIS(R) 2005,2009. All Rights Reserved.
OASIS trademark, IPR and other policies apply. -->
<schema xmlns="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
elementFormDefault="qualified">
<include schemaLocation="sca-core-1.1-cd03cd05.xsd"/>
<!-- WSDL Interface -->
<element name="interface.wsdl" type="sca:WSDLPortType"
substitutionGroup="sca:interface"/>
<complexType name="WSDLPortType">
<complexContent>
<extension base="sca:Interface">
<sequence>
<any namespace="##other" processContents="lax" minOccurs="0"
maxOccurs="unbounded"/>
</sequence>
<attribute name="interface" type="anyURI" use="required"/>
<attribute name="callbackInterface" type="anyURI"
use="optional"/>
<anyAttribute namespace="##any" processContents="lax"/>
</extension>
</complexContent>
</complexType>
</schema>
A.6 sca-implementation-java.xsd
Is described in the Java Component Implementation specification [SCA-Java]
A.7 sca-implementation-composite.xsd
<?xml version="1.0" encoding="UTF-8"?>
<!-- Copyright(C) OASIS(R) 2005,2009. All Rights Reserved.
OASIS trademark, IPR and other policies apply. -->
<schema xmlns="http://www.w3.org/2001/XMLSchema"
xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
targetNamespace="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
elementFormDefault="qualified">
<include schemaLocation="sca-core-1.1-cd03cd05.xsd"/>
<!-- Composite Implementation -->
<element name="implementation.composite" type="sca:SCAImplementation"
substitutionGroup="sca:implementation"/>
<complexType name="SCAImplementation">
<complexContent>
<extension base="sca:Implementation">
<sequence>
<any namespace="##other" processContents="lax" minOccurs="0"
maxOccurs="unbounded"/>
</sequence>
<attribute name="name" type="QName" use="required"/>
</extension>
</complexContent>
</complexType>
</schema>
A.8 sca-binding-webservice.xsd
Is described in the SCA Web
Services Binding specification [9]SCA-WSBINDING]
Is described in the SCA JMS
Binding specification [11]SCA-JMSBINDING]
Is described in the SCA Policy Framework
specification [10]SCA-POLICY]
<?xml version="1.0" encoding="UTF-8"?>
<!-- Copyright(C) OASIS(R) 2005,2009. All Rights Reserved.
OASIS trademark, IPR and other policies apply. -->
<schema xmlns="http://www.w3.org/2001/XMLSchema"
xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
targetNamespace="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
elementFormDefault="qualified">
<include schemaLocation="sca-core-1.1-cd03cd05.xsd"/>
<!-- Contribution -->
<element name="contribution" type="sca:ContributionType"/>
<complexType name="ContributionType">
<complexContent>
<extension base="sca:CommonExtensionBase">
<sequence>
<element name="deployable" type="sca:DeployableType"
minOccurs="0" maxOccurs="unbounded"/>
<element ref="sca:importBase" minOccurs="0"
maxOccurs="unbounded"/>
<element ref="sca:exportBase" minOccurs="0"
maxOccurs="unbounded"/>
<any namespace="##other" processContents="lax" minOccurs="0"
maxOccurs="unbounded"/>
</sequence>
</extension>
</complexContent>
</complexType>
<!-- Deployable -->
<complexType name="DeployableType">
<complexContent>
<extension base="sca:CommonExtensionBase">
<sequence>
<any namespace="##other" processContents="lax" minOccurs="0"
maxOccurs="unbounded"/>
</sequence>
<attribute name="composite" type="QName" use="required"/>
</extension>
</complexContent>
</complexType>
<!-- Import -->
<element name="importBase" type="sca:Import" abstract="true" />
<complexType name="Import" abstract="true">
<complexContent>
<extension base="sca:CommonExtensionBase">
<sequence>
<any namespace="##other" processContents="lax" minOccurs="0"
maxOccurs="unbounded"/>
</sequence>
</extension>
</complexContent>
</complexType>
<element name="import" type="sca:ImportType"
substitutionGroup="sca:importBase"/>
<complexType name="ImportType">
<complexContent>
<extension base="sca:Import">
<attribute name="namespace" type="string" use="required"/>
<attribute name="location" type="anyURI" use="optional"/>
</extension>
</complexContent>
</complexType>
<!-- Export -->
<element name="exportBase" type="sca:Export" abstract="true" />
<complexType name="Export" abstract="true">
<complexContent>
<extension base="sca:CommonExtensionBase">
<sequence>
<any namespace="##other" processContents="lax" minOccurs="0"
maxOccurs="unbounded"/>
</sequence>
</extension>
</complexContent>
</complexType>
<element name="export" type="sca:ExportType"
substitutionGroup="sca:exportBase"/>
<complexType name="ExportType">
<complexContent>
<extension base="sca:Export">
<attribute name="namespace" type="string" use="required"/>
</extension>
</complexContent>
</complexType>
</schema>
<?xml version="1.0" encoding="UTF-8"?>
<!-- Copyright(C) OASIS(R) 2005,2009. All Rights Reserved.
OASIS trademark, IPR and other policies apply. -->
<schema xmlns="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
xmlns:sca="http://docs.oasis-open.org/ns/opencsa/sca/200903200912"
elementFormDefault="qualified">
<include schemaLocation="sca-core-1.1-cd03cd05.xsd"/>
<include schemaLocation="sca-policy-1.1-cd02cd03.xsd"/>
<!-- Definitions -->
<element name="definitions" type="sca:tDefinitions"/>
<complexType name="tDefinitions">
<complexContent>
<extension base="sca:CommonExtensionBase">
<choice minOccurs="0" maxOccurs="unbounded">
<element ref="sca:intent"/>
<element ref="sca:policySet"/>
<element ref="sca:binding"/>
<element ref="sca:bindingType"/>
<element ref="sca:implementationType"/>
<any namespace="##other" processContents="lax"
minOccurs="0" maxOccurs="unbounded"/>
</choice>
<attribute name="targetNamespace" type="anyURI" use="required"/>
</extension>
</complexContent>
</complexType>
</schema>
Bindings are used by services and references. References use bindings to describe the access mechanism used to call the service to which they are wired. Services use bindings to describe the access mechanism(s) that clients use to call the service.
SCA supports multiple different types of bindings. Examples include SCA service, Web service, stateless session EJB, database stored procedure, EIS service. SCA provides an extensibility mechanism by which an SCA runtime can add support for additional binding types.
SCA components are configured instances of SCA implementations, which provide and consume services. SCA allows many different implementation technologies such as Java, BPEL, C++. SCA defines an extensibility mechanism that allows you to introduce new implementation types. The current specification does not mandate the implementation technologies to be supported by an SCA runtime, vendors can choose to support the ones that are important for them. A single SCA implementation can be used by multiple Components, each with a different configuration.
The Component has a reference to an implementation of which it is an instance, a set of property values, and a set of service reference values. Property values define the values of the properties of the component as defined by the component’s implementation. Reference values define the services that resolve the references of the component as defined by its implementation. These values can either be a particular service of a particular component, or a reference of the containing composite.
SCA services are used to declare the externally accessible services of an implementation. For a composite, a service is typically provided by a service of a component within the composite, or by a reference defined by the composite. The latter case allows the republication of a service with a new address and/or new bindings. The service can be thought of as a point at which messages from external clients enter a composite or implementation.
A service represents an addressable set of operations of an implementation that are designed to be exposed for use by other implementations or exposed publicly for use elsewhere (e.g. public Web services for use by other organizations). The operations provided by a service are specified by an Interface, as are the operations needed by the service client (if there is one). An implementation can contain multiple services, when it is possible to address the services of the implementation separately.
A service can be provided as SCA remote services, as Web services, as stateless session EJB’s, as EIS services, and so on. Services use bindings to describe the way in which they are published. SCA provides an extensibility mechanism that makes it possible to introduce new binding types for new types of services.
A Remotable Service is a service that is designed to be published remotely in a loosely-coupled SOA architecture. For example, SCA services of SCA implementations can define implementations of industry-standard web services. Remotable services use pass-by-value semantics for parameters and returned results.
Interfaces can be identified as remotable through the <interface /> XML, but are typically specified as remotable using a component implementation technology specific mechanism, such as Java annotations. See the relevant SCA Implementation Specification for more information. As an example, to define a Remotable Service, a Component implemented in Java would have a Java Interface with the @Remotable annotation
Local services are services that are designed to be only used “locally” by other implementations that are deployed concurrently in a tightly-coupled architecture within the same operating system process.
Local services can rely on by-reference calling conventions, or can assume a very fine-grained interaction style that is incompatible with remote distribution. They can also use technology-specific data-types.
How a Service is identified as local is dependant on the Component implementation technology used. See the relevant SCA Implementation Specification for more information. As an example, to define a Local Service, a Component implemented in Java would define a Java Interface that does not have the @Remotable annotation.
SCA references represent a dependency that an implementation has on a service that is provided by some other implementation, where the service to be used is specified through configuration. In other words, a reference is a service that an implementation can call during the execution of its business function. References are typed by an interface.
For composites, composite references can be accessed by components within the composite like any service provided by a component within the composite. Composite references can be used as the targets of wires from component references when configuring Components.
A composite reference can be used to access a service such as: an SCA service provided by another SCA composite, a Web service, a stateless session EJB, a database stored procedure or an EIS service, and so on. References use bindings to describe the access method used to their services. SCA provides an extensibility mechanism that allows the introduction of new binding types to references.
An implementation is concept that is used to describe a piece of software technology such as a Java class, BPEL process, XSLT transform, or C++ class that is used to implement one or more services in a service-oriented application. An SCA composite is also an implementation.
Implementations define points of variability including properties that can be set and settable references to other services. The points of variability are configured by a component that uses the implementation. The specification refers to the configurable aspects of an implementation as its componentType.
Interfaces define one or more business functions. These business functions are provided by Services and are used by components through References. Services are defined by the Interface they implement. SCA currently supports a number of interface type systems, for example:
SCA also provides an extensibility mechanism by which an SCA runtime can add support for additional interface type systems.
Interfaces can be bi-directional. A bi-directional service has service operations which are provided by each end of a service communication – this could be the case where a particular service demands a “callback” interface on the client, which it calls during the process of handing service requests from the client.
An SCA composite is the basic unit of composition within an SCA Domain. An SCA Composite is an assembly of Components, Services, References, and the Wires that interconnect them. Composites can be used to contribute elements to an SCA Domain.
A composite has the following characteristics:
One composite can be used to provide part of the definition of another composite, through the process of inclusion. This is intended to make team development of large composites easier. Included composites are merged together into the using composite at deployment time to form a single logical composite.
Composites are included into other composites through <include…/> elements in the using composite. The SCA Domain uses composites in a similar way, through the deployment of composite files to a specific location.
Properties allow for the configuration of an implementation with externally set data values. The data value is provided through a Component, possibly sourced from the property of a containing composite.
Each Property is defined by the implementation. Properties can be defined directly through the implementation language or through annotations of implementations, where the implementation language permits, or through a componentType file. A Property can be either a simple data type or a complex data type. For complex data types, XML schema is the preferred technology for defining the data types.
B.10 Domain
An SCA Domain represents a set of Services providing an area of Business functionality that is controlled by a single organization. As an example, for the accounts department in a business, the SCA Domain might cover all finance-related functions, and it might contain a series of composites dealing with specific areas of accounting, with one for Customer accounts, another dealing with Accounts Payable.
A Domain specifies the instantiation, configuration and connection of a set of components, provided via one or more composite files. A Domain also contains Wires that connect together the Components. A Domain does not contain promoted Services or promoted References, since promotion has no meaning at the Domain level.
SCA wires connect service references to services.
Valid wire sources are component references. Valid wire targets are component services.
When using included composites, the sources and targets of the wires don’t have to be declared in the same composite as the composite that contains the wire. The sources and targets can be defined by other included composites. Targets can also be external to the SCA Domain.
This section contains a list of conformance items for the SCA Assembly specification.
Conformance ID |
Description |
[ASM13001] |
|
[ASM13002] |
|
[ASM13003] |
|
[ASM40001] |
The extension of a componentType side file name MUST be .componentType. |
|
|
[ASM40003] |
|
[ASM40004] |
|
[ASM40005] |
|
[ASM40006] |
|
[ASM40007] |
The value of the property @type attribute MUST be the QName of an XML schema type. |
[ASM40008] |
The value of the property @element attribute MUST be the QName of an XSD global element. |
[ASM40009] |
|
[ASM40010] |
A single property element MUST NOT contain both a @type attribute and an @element attribute. |
[ASM40011] |
|
[ASM50001] |
|
[ASM50002] |
|
[ASM50003] |
|
[ASM50004] |
|
[ASM50005] |
|
[ASM50006] |
|
[ASM50007] |
The @name attribute of a service element of a <component/> MUST be unique amongst the service elements of that <component/> |
[ASM50008] |
|
[ASM50009] |
|
[ASM50010] |
|
[ASM50011] |
|
[ASM50012] |
|
[ASM50013] |
If @wiredByImpl="true", other methods of specifying the target service MUST NOT be used. |
[ASM50014] |
|
[ASM50015] |
|
[ASM50016] |
|
|
|
|
|
|
|
|
|
[ASM50022] |
|
|
|
|
|
[ASM50025] |
|
[ASM50026] |
|
[ASM50027] |
|
[ASM50028] |
|
[ASM50029] |
|
|
|
[ASM50031] |
|
[ASM50032] |
If a property is single-valued, the <value/> subelement MUST NOT occur more than once. |
[ASM50033] |
|
[ASM50034] |
|
[ASM50035] |
A single property element MUST NOT contain both a @type attribute and an @element attribute. |
[ASM50036] |
|
[ASM50037] |
|
[ASM50038] |
|
[ASM50039] |
A reference with multiplicity 0..1 MUST have no more than one target service defined. |
[ASM50040] |
A reference with multiplicity 1..1 MUST have exactly one target service defined. |
[ASM50041] |
A reference with multiplicity 1..n MUST have at least one target service defined. |
[ASM50042] |
|
[ASM50043][ASM50043] |
|
[ASM50044] |
|
[ASM60001] |
A composite @name attribute value MUST be unique within the namespace of the composite. |
[ASM60002] |
|
[ASM60003] |
|
[ASM60004] |
|
[ASM60005] |
|
[ASM60006] |
|
[ASM60007] |
|
[ASM60008] |
|
[ASM60009] |
|
[ASM60010] |
|
[ASM60011] |
|
[ASM60012] |
|
[ASM60013] |
|
[ASM60014] |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
[ASM60025] |
|
[ASM60026] |
|
[ASM60027] |
|
[ASM60028] |
|
[ASM60030] |
|
[ASM60031] |
|
[ASM60032] |
|
[ASM60033] |
|
[ASM60034] |
|
[ASM60035] |
|
[ASM60036] |
|
[ASM60037] |
|
[ASM60038] |
|
[ASM60039] |
|
[ASM60040] |
A single property element MUST NOT contain both a @type attribute and an @element attribute. |
[ASM60041] |
|
[ASM60042] |
The @name attribute of an include element MUST be the QName of a composite in the SCA Domain. |
|
|
|
|
|
|
|
|
|
|
[ASM70006] |
|
[ASM60050] |
|
[ASM60051] |
|
[ASM80001] |
The interface.wsdl @interface attribute MUST reference a portType of a WSDL 1.1 document. |
[ASM80002] |
Remotable service Interfaces MUST NOT make use of method or operation overloading. |
[ASM80003] |
|
[ASM80004] |
|
[ASM80005] |
|
[ASM80008] |
|
[ASM80009] |
|
[ASM80010] |
|
[ASM80011] |
|
|
|
|
|
|
|
|
|
|
|
[ASM80017] |
|
[ASM90001] |
|
[ASM90002] |
|
[ASM90003] |
|
[ASM90004] |
|
[ASM90005] |
For a binding.sca of a component service, the @uri attribute MUST NOT be present. |
[ASM10001] |
|
[ASM10002] |
|
[ASM10003] |
|
[ASM12001] |
|
|
|
|
|
|
|
[ASM12005] |
|
[ASM12006] |
SCA requires that all runtimes MUST support the ZIP packaging format for contributions. |
|
|
|
|
[ASM12009] |
|
[ASM12010] |
|
[ASM12011] |
|
[ASM12012] |
The value of @autowire for the logical Domain composite MUST be autowire="false". |
[ASM12013] |
1) The SCA runtime 2) The SCA runtime 3) The SCA runtime |
|
|
[ASM12015] |
|
|
|
[ASM12017] |
· either cause future invocation of the target component's services to fail with a ServiceUnavailable fault · or alternatively, if an alternative target component is available that satisfies the autowire process, update the reference of the source component |
|
|
[ASM12020] |
· either update the references for the source component once the new component is running. · or alternatively, defer the updating of the references of the source component until the source component is stopped and restarted. |
[ASM12021] |
|
[ASM12022] |
|
[ASM12023] |
1.
2.
|
[ASM12024] |
|
[ASM12025] |
|
[ASM12026] |
|
[ASM12027] |
An SCA runtime MUST reject files that do not conform to the schema declared in sca-contribution.xsd. |
[ASM12028] |
|
|
|
|
|
[ASM12031] |
When a contribution uses an artifact contained in another contribution through SCA artifact resolution, if that artifact itself has dependencies on other artifacts, the SCA runtime MUST resolve these dependencies in the context of the contribution containing the artifact, not in the context of the original contribution. |
|
|
|
|
[ASM12034] [ASM12034]
|
• either update the property value of the domain level component once the update of the domain property is complete • or defer the updating of the component property value until the component is stopped and restarted |
[ASM14003] |
|
|
Conformance ID |
Description |
Classification |
[ASM60021] |
Development |
|
[ASM12002] |
Interoperation |
|
[ASM12003] |
Interoperation |
|
[ASM12007] |
Development |
|
An SCA runtime MAY provide the contribution operation functions (install Contribution, update Contribution, add Deployment Composite, update Deployment Composite, remove Contribution). [ASM12008][ASM12008] |
Enhancement |
|
[ASM12014] |
Enhancement |
|
[ASM12016] |
Enhancement |
|
[ASM12018] |
Enhancement |
|
[ASM12029] |
Interoperation |
|
[ASM12030] |
Interoperation |
|
[ASM14001] |
Development |
|
[ASM14002] |
Development |
|
[ASM14004] |
Development |
The following individuals have participated in the creation of this specification and are gratefully acknowledged:
Participants:
Participant Name |
Affiliation |
Bryan Aupperle |
IBM |
Ron Barack |
SAP AG* |
Michael Beisiegel |
IBM |
Megan Beynon |
IBM |
Vladislav Bezrukov |
SAP AG* |
Henning Blohm |
SAP AG* |
Fraser Bohm |
IBM |
David Booz |
IBM |
Fred Carter |
AmberPoint |
Martin Chapman |
Oracle Corporation |
Graham Charters |
IBM |
Shih-Chang Chen |
Oracle Corporation |
Chris Cheng |
Primeton Technologies, Inc. |
Vamsavardhana Reddy Chillakuru |
IBM |
Mark Combellack |
Avaya, Inc. |
Jean-Sebastien Delfino |
IBM |
David DiFranco |
Oracle Corporation |
Mike Edwards |
IBM |
Jeff Estefan |
Jet Propulsion Laboratory:* |
Raymond Feng |
IBM |
Billy Feng |
Primeton Technologies, Inc. |
Paul Fremantle |
WSO2* |
Robert Freund |
Hitachi, Ltd. |
Peter Furniss |
Iris Financial Solutions Ltd. |
Genadi Genov |
SAP AG* |
Mark Hapner |
Sun Microsystems |
Zahir HEZOUAT |
IBM |
Simon Holdsworth |
IBM |
Sabin Ielceanu |
TIBCO Software Inc. |
Bo Ji |
Primeton Technologies, Inc. |
Uday Joshi |
Oracle Corporation |
Mike Kaiser |
IBM |
Khanderao Kand |
Oracle Corporation |
Anish Karmarkar |
Oracle Corporation |
Nickolaos Kavantzas |
Oracle Corporation |
Rainer Kerth |
SAP AG* |
Dieter Koenig |
IBM |
Meeraj Kunnumpurath |
Individual |
Jean Baptiste Laviron |
Axway Software* |
Simon Laws |
IBM |
Rich Levinson |
Oracle Corporation |
Mark Little |
Red Hat |
Ashok Malhotra |
Oracle Corporation |
Jim Marino |
Individual |
Carl Mattocks |
CheckMi* |
Jeff Mischkinsky |
Oracle Corporation |
Ian Mitchell |
IBM |
Dale Moberg |
Axway Software* |
Simon Moser |
IBM |
Simon Nash |
Individual |
Peter Niblett |
IBM |
Duane Nickull |
Adobe Systems |
Eisaku Nishiyama |
Hitachi, Ltd. |
Sanjay Patil |
SAP AG* |
Plamen Pavlov |
SAP AG* |
Peter Peshev |
SAP AG* |
Gilbert Pilz |
Oracle Corporation |
Nilesh Rade |
Deloitte Consulting LLP |
Martin Raepple |
SAP AG* |
Luciano Resende |
IBM |
Michael Rowley |
Active Endpoints, Inc. |
Vicki Shipkowitz |
SAP AG* |
Ivana Trickovic |
SAP AG* |
Clemens Utschig - Utschig |
Oracle Corporation |
Scott Vorthmann |
TIBCO Software Inc. |
Feng Wang |
Primeton Technologies, Inc. |
Tim Watson |
Oracle Corporation |
Eric Wells |
Hitachi, Ltd. |
Robin Yang |
Primeton Technologies, Inc. |
Prasad Yendluri |
Software AG, Inc.* |
Revision |
Date |
Editor |
Changes Made |
1 |
2007-09-24 |
Anish Karmarkar |
Applied the OASIS template + related changes to the Submission |
2 |
2008-01-04 |
Michael Beisiegel |
composite section - changed order of subsections from property, reference, service to service, reference, property - progressive disclosure of pseudo schemas, each section only shows what is described - attributes description now starts with name : type (cardinality) - child element description as list, each item starting with name : type (cardinality) - added section in appendix to contain complete pseudo schema of composite
- moved component section after implementation section - made the ConstrainingType section a top level section - moved interface section to after constraining type section
component section - added subheadings for Implementation, Service, Reference, Property - progressive disclosure of pseudo schemas, each section only shows what is described - attributes description now starts with name : type (cardinality) - child element description as list, each item starting with name : type (cardinality)
implementation section - changed title to “Implementation and ComponentType” - moved implementation instance related stuff from implementation section to component implementation section - added subheadings for Service, Reference, Property, Implementation - progressive disclosure of pseudo schemas, each section only shows what is described - attributes description now starts with name : type (cardinality) - child element description as list, each item starting with name : type (cardinality) - attribute and element description still needs to be completed, all implementation statements on services, references, and properties should go here - added complete pseudo schema of componentType in appendix
- added “Quick Tour by Sample” section, no content yet - added comment to introduction section that the following text needs to be added "This specification is efined in terms of infoset and not XML 1.0, even though the spec uses XML 1.0/1.1 terminology. A mapping from XML to infoset (... link to infoset specification ...) is trivial and should be used for non-XML serializations."
|
3 |
2008-02-15 |
Anish Karmarkar Michael Beisiegel |
Incorporated resolutions from 2008 Jan f2f. - issue 9 - issue 19 - issue 21 - issue 4 - issue 1A - issue 27
- in Implementation and ComponentType section added attribute and element description for service, reference, and property - removed comments that helped understand the initial restructuring for WD02 - added changes for issue 43 - added changes for issue 45, except the changes for policySet and requires attribute on property elements - used the NS http://docs.oasis-open.org/ns/opencsa/sca/200712 - updated copyright stmt - added wordings to make PDF normative and xml schema at the NS uri autoritative |
4 |
2008-04-22 |
Mike Edwards |
Editorial tweaks for CD01 publication: - updated URL for spec documents - removed comments from published CD01 version - removed blank pages from body of spec |
5 |
2008-06-30 |
Anish Karmarkar Michael Beisiegel |
Incorporated resolutions of issues: 3, 6, 14 (only as it applies to the component property element), 23, 25, 28, 25, 38, 39, 40, 42, 45 (except for adding @requires and @policySets to property elements), 57, 67, 68, 69 |
6 |
2008-09-23 |
Mike Edwards |
Editorial fixes in response to Mark Combellack's review contained in email: http://lists.oasis-open.org/archives/sca-assembly/200804/msg00089.html |
7 CD01 - Rev3 |
2008-11-18 |
Mike Edwards |
· Specification marked for conformance statements. New Appendix (D) added containing a table of all conformance statements. Mass of related minor editorial changes to remove the use of RFC2119 words where not appropriate. |
8 CD01 - Rev4 |
2008-12-11 |
Mike Edwards |
- Fix problems of misplaced statements in Appendix D - Fixed problems in the application of Issue 57 - section 5.3.1 & Appendix D as defined in email: http://lists.oasis-open.org/archives/sca-assembly/200811/msg00045.html - Added Conventions section, 1.3, as required by resolution of Issue 96. - Issue 32 applied - section B2 - Editorial addition to section 8.1 relating to no operation overloading for remotable interfaces, as agreed at TC meeting of 16/09/2008. |
9 CD01 - Rev5 |
2008-12-22 |
Mike Edwards |
- Schemas in Appendix B updated with resolutions of Issues 32 and 60 - Schema for contributions - Appendix B12 - updated with resolutions of Issues 53 and 74. - Issues 53 and 74 incorporated - Sections 11.4, 11.5 |
10 CD01-Rev6 |
2008-12-23 |
Mike Edwards |
- Issues 5, 71, 92 - Issue 14 - remaining updates applied to ComponentType (section 4.1.3) and to Composite Property (section 6.3) |
11 CD01-Rev7 |
2008-12-23 |
Mike Edwards |
All changes accepted before revision from Rev6 started - due to changes being applied to previously changed sections in the Schemas Issues 12 & 18 - Section B2 Issue 63 - Section C3 Issue 75 - Section C12 Issue 65 - Section 7.0 Issue 77 - Section 8 + Appendix D Issue 69 - Sections 5.1, 8 Issue 45 - Sections 4.1.3, 5.4, 6.3, B2. Issue 56 - Section 8.2, Appendix D Issue 41 - Sections 5.3.1, 6.4, 12.7, 12.8, Appendix D |
12 CD01-Rev8 |
2008-12-30 |
Mike Edwards |
Issue 72 - Removed Appendix A Issue 79 - Sections 9.0, 9.2, 9.3, Appendix A.2 Issue 62 - Sections 4.1.3, 5.4 Issue 26 - Section 6.5 Issue 51 - Section 6.5 Issue 36 - Section 4.1 Issue 44 - Section 10, Appendix C Issue 89 - Section 8.2, 8.5, Appendix A, Appendix C Issue 16 - Section 6.8, 9.4 Issue 8 - Section 11.2.1 Issue 17 - Section 6.6 Issue 30 - Sections 4.1.1, 4.1.2, 5.2, 5.3, 6.1, 6.2, 9 Issue 33 - insert new Section 8.4 |
12 CD01-Rev8a |
2009-01-13 |
Bryan Aupperle Mike Edwards |
Issue 99 - Section 8 |
13 CD02 |
2009-01-14 |
Mike Edwards |
All changes accepted All comments removed |
14 CD02-Rev2 |
2009-01-30 |
Mike Edwards |
Issue 94 applied (removal of conversations) |
15 CD02-Rev3 |
2009-01-30 |
Mike Edwards |
Issue 98 - Section 5.3 Minor editorial cleanup (various locations) Removal of <operation/> element as decided at Jan 2009 F2F - various sections Issue 95 - Section 6.2 Issue 37 - Sections 2.1, 6, 12.6.1, B10 Issue 48 - Sections 5.3, A2 Issue 90 - Sections 6.1, 6.2, 6.4 Issue 64 - Sections 7, A2 Issue 100 - Section 6.2 Issue 103 - Sections 10, 12.2.2, A.13 Issue 104 - Sections 4.1.3, 5.4, 6.3 Section 3 (Quick Tour By Sample) removed by decision of Jan 2009 Assembly F2F meeting |
16 CD02-Rev4 |
2009-02-06 |
Mike Edwards |
All changes accepted Major Editorial work to clean out all RFC2119 wording and to ensure that no normative statements have been missed. |
16 CD02-Rev6 |
2009-02-24 |
Mike Edwards |
Issue 107 - sections 4, 5, 11, Appendix C Editorial updates resulting from Review Issue 34 - new section 12 inserted, + minor editorial changes in sections 4, 11 Issue 110 - Section 8.0 Issue 111 - Section 4.4, Appendix C Issue 112 - Section 4.5 Issue 113 - Section 3.3 Issue 108 - Section 13, Appendix C Minor editorial changes to the example in section 3.3 |
17 CD02-Rev7 |
2009-03-02 |
Mike Edwards |
Editorial changes resulting from Vamsi's review of CD02 Rev6 Issue 109 - Section 8, Appendix A.2, Appendix B.3.1, Appendix C Added back @requires and @policySets to <interface/> as editorial correction since they were lost by accident in earlier revision Issue 101 - Section 13 Issue 120 - Section |
18 CD02-Rev 8 |
2009-03-05 |
Mike Edwards |
XSDs corrected and given new namespace. Namespace updated throughout document. |
19 CD03 |
2009-03-05 |
Mike Edwards |
All Changes Accepted |
20 CD03 |
2009-03-17 |
Anish Karmarkar |
Changed CD03 per TC’s CD03/PR01 resolution. Fixed the footer, front page. |
21 CD03 Rev1 |
2009-06-16 |
Mike Edwards |
Issue 115 - Sections 3.1.3, 4.4, 5.3, A.2 Editorial: Use the form "portType" in all cases when referring to WSDL portType Issue 117 - Sections 4.2, 4.3, 5.0, 5.1, 5.2, 5.4, 5.4.2, 6.0, add new 7.2, old 7.2 Note: REMOVED assertions: ASM60015 ASM60015 ASM60016 ASM60017 ASM60018 ASM60019 ASM60020 ASM60023 ASM60024 ASM80012 ASM80013 ASM80014 ASM80015 ADDED ASM70007 Issue 122 - Sections 4.3, 4.3.1, 4.3.1.1, 6.0, 8.0, 11.6 Issue 123 - Section A.2 Issue 124 - Sections A2, A5 Issue 125 - Section 7.6 Editorial - fixed broken reference links in Sections 7.0, 11.2 Issue 126 - Section 7.6 Issue 127 - Section 4.4, added Section 4.4.1 Issue 128 - Section A2 Issue 129 - Section A2 Issue 130 - multiple sections Issue 131 - Section A.11 Issue 135 - Section 8.4.2 Issue 141 - Section 4.3 |
22 CD03 Rev2 |
2009-07-28 |
Mike Edwards |
Issue 151 - Section A.2 Issue 133 - Sections 7, 11.2 Issue 121 - Section 13.1, 13.2, C.1, C.2 Issue 134 - Section 5.2 Issue 153 - Section 3.2, 5.3.1 |
23 CD03 Rev3 |
2009-09-23 |
Mike Edwards |
Major formatting update - all snippets and examples given a caption and consistent formatting. All references to snippets and examples updated to use the caption numbering. Issue 147 - Section 5.5.1 added Issue 136 - Section 4.3, 5.2 Issue 144 - Section 4.4 Issue 156 - Section 8 Issue 160 - Section 12.1 Issue 176 - Section A.5 Issue 180 - Section A.1 Issue 181 - Section 5.1, 5.2 |
24 CD03 Rev4 |
2009-09-23 |
Mike Edwards |
All changes accepted Issue 157 - Section 6 removed, other changes scattered through many other sections, including the XSDs and normative statements. Issue 182 - Appendix A |
25 CD03 Rev5 |
2009-11-20 |
Mike Edwards |
All changes accepted Issue 138 - Section 10.3 added Issue 142 - Section 4.3 updated Issue 143 - Section 7.5 updated Issue 145 - Section 4.4 updated Issue 158 - Section 5.3.1 updated Issue 183 - Section 7.5 updated Issue 185 - Section 10.9 updated |
26 CD03 Rev6 |
2009-12-03 |
Mike Edwards |
All changes accepted Issue 175 - Section A2 updated Issue 177 - Section A2 updated Issue 188 - Sections 3.1.1, 3.1.2, 3.1.4, 4, 4.1, 4.2, 4.3, 5, 5.1, 5.2, 6, 6.6, 7, 7.5, 9, A2 updated Issue 192 - editorial fixes in Sections 5.1, 5.2, 5.4.1, 5.5, 5.6.1 SCA namespace updated to http://docs.oasis-open.org/ns/opencsa/sca/200912 as decided at Dec 1st F2F meeting - changes scattered through the document Issue 137 - Sections 5.4, 7 updated Issue 189 - Section 6.5 updated |
27 CD04 |
2009-12-09 |
Mike Edwards |
All changes accepted |