oasis

TOSCA Simple Profile in YAML Version 1.0

Committee Specification Draft 05 /
Public Review Draft 02

04 February 2016

Specification URIs

This version:

http://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.0/csprd02/TOSCA-Simple-Profile-YAML-v1.0-csprd02.pdf (Authoritative)

http://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.0/csprd02/TOSCA-Simple-Profile-YAML-v1.0-csprd02.html

http://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.0/csprd02/TOSCA-Simple-Profile-YAML-v1.0-csprd02.docx

Previous version:

http://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.0/csprd01/TOSCA-Simple-Profile-YAML-v1.0-csprd01.pdf (Authoritative)

http://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.0/csprd01/TOSCA-Simple-Profile-YAML-v1.0-csprd01.html

http://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.0/csprd01/TOSCA-Simple-Profile-YAML-v1.0-csprd01.docx

Latest version:

http://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.0/TOSCA-Simple-Profile-YAML-v1.0.pdf (Authoritative)

http://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.0/TOSCA-Simple-Profile-YAML-v1.0.html

http://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.0/TOSCA-Simple-Profile-YAML-v1.0.docx

Technical Committee:

OASIS Topology and Orchestration Specification for Cloud Applications (TOSCA) TC

Chairs:

Paul Lipton (paul.lipton@ca.com), CA Technologies

Simon Moser (smoser@de.ibm.com), IBM

Editors:

Derek Palma (dpalma@vnomic.com), Vnomic

Matt Rutkowski (mrutkows@us.ibm.com), IBM

Thomas Spatzier (thomas.spatzier@de.ibm.com), IBM

Related work:

This specification is related to:

·         Topology and Orchestration Specification for Cloud Applications Version 1.0. Edited by Derek Palma and Thomas Spatzier. 25 November 2013. OASIS Standard. http://docs.oasis-open.org/tosca/TOSCA/v1.0/os/TOSCA-v1.0-os.html.

Declared XML namespaces:

·         http://docs.oasis-open.org/tosca/ns/simple/yaml/1.0

Abstract:

This document defines a simplified profile of the TOSCA version 1.0 specification in a YAML rendering which is intended to simplify the authoring of TOSCA service templates.  This profile defines a less verbose and more human-readable YAML rendering, reduced level of indirection between different modeling artifacts as well as the assumption of a base type system.

Status:

This document was last revised or approved by the OASIS Topology and Orchestration Specification for Cloud Applications (TOSCA) TC on the above date. The level of approval is also listed above. Check the “Latest version” location noted above for possible later revisions of this document. Any other numbered Versions and other technical work produced by the Technical Committee (TC) are listed at https://www.oasis-open.org/committees/tc_home.php?wg_abbrev=tosca#technical.

TC members should send comments on this specification to the TC’s email list. Others should send comments to the TC’s public comment list, after subscribing to it by following the instructions at the “Send A Comment” button on the TC’s web page at https://www.oasis-open.org/committees/tosca/.

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 TC’s web page (https://www.oasis-open.org/committees/tosca/ipr.php).

Citation format:

When referencing this specification the following citation format should be used:

[TOSCA-Simple-Profile-YAML-v1.0]

TOSCA Simple Profile in YAML Version 1.0. Edited by Derek Palma, Matt Rutkowski, and Thomas Spatzier. 04 February 2016. OASIS Committee Specification Draft 05 / Public Review Draft 02. http://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.0/csprd02/TOSCA-Simple-Profile-YAML-v1.0-csprd02.html. Latest version: http://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.0/TOSCA-Simple-Profile-YAML-v1.0.html.

 

Notices

Copyright © OASIS Open 2016. All Rights Reserved.

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Table of Contents

Table of Examples. 7

Table of Figures. 8

1        Introduction. 9

1.1 Objective. 9

1.2 Summary of key TOSCA concepts. 9

1.3 Implementations. 9

1.4 Terminology. 10

1.5 Notational Conventions. 10

1.6 Normative References. 10

1.7 Non-Normative References. 10

1.8 Glossary. 11

2        TOSCA by example. 12

2.1 A “hello world” template for TOSCA Simple Profile in YAML. 12

2.2 TOSCA template for a simple software installation. 14

2.3 Overriding behavior of predefined node types. 16

2.4 TOSCA template for database content deployment 17

2.5 TOSCA template for a two-tier application. 19

2.6 Using a custom script to establish a relationship in a template. 22

2.7 Using custom relationship types in a TOSCA template. 23

2.8 Defining generic dependencies between nodes in a template. 25

2.9 Describing abstract requirements for nodes and capabilities in a TOSCA template. 25

2.10 Using node template substitution for model composition. 30

2.11 Using node template substitution for chaining subsystems. 34

2.12 Grouping node templates. 39

2.13 Using YAML Macros to simplify templates. 42

2.14 Passing information as inputs to Nodes and Relationships. 43

2.15 Topology Template Model versus Instance Model 44

2.16 Using attributes implicitly reflected from properties. 45

3        TOSCA Simple Profile definitions in YAML. 47

3.1 TOSCA Namespace URI and alias. 47

3.2 Parameter and property types. 48

3.3 Normative values. 57

3.4 TOSCA Metamodel 59

3.5 Reusable modeling definitions. 59

3.6 Type-specific definitions. 78

3.7 Template-specific definitions. 95

3.8 Topology Template definition. 105

3.9 Service Template definition. 111

4        TOSCA functions. 123

4.1 Reserved Function Keywords. 123

4.2 Environment Variable Conventions. 123

4.3 Intrinsic functions. 125

4.4 Property functions. 127

4.5 Attribute functions. 129

4.6 Operation functions. 130

4.7 Navigation functions. 131

4.8 Artifact functions. 131

4.9 Context-based Entity names (global) 134

5        TOSCA normative type definitions. 135

5.1 Assumptions. 135

5.2 Data Types. 135

5.3 Artifact Types. 142

5.4 Capabilities Types. 145

5.5 Requirement Types. 153

5.6 Relationship Types. 153

5.7 Interface Types. 157

5.8 Node Types. 162

5.9 Group Types. 173

5.10 Policy Types. 174

6        TOSCA Cloud Service Archive (CSAR) format 176

6.1 Overall Structure of a CSAR. 176

6.2 TOSCA Meta File. 176

7        TOSCA networking. 177

7.1 Networking and Service Template Portability. 177

7.2 Connectivity Semantics. 177

7.3 Expressing connectivity semantics. 178

7.4 Network provisioning. 180

7.5 Network Types. 184

7.6 Network modeling approaches. 189

8        Non-normative type definitions. 195

8.1 Artifact Types. 195

8.2 Capability Types. 195

8.3 Node Types. 197

9        Component Modeling Use Cases. 200

10      Application Modeling Use Cases. 207

10.1 Use cases. 207

11      TOSCA Policies. 253

11.1 A declarative approach. 253

11.2 Consideration of Event, Condition and Action. 253

11.3 Types of policies. 253

11.4 Policy relationship considerations. 254

11.5 Use Cases. 255

12      Conformance. 258

12.1 Conformance Targets. 258

12.2 Conformance Clause 1: TOSCA YAML service template. 258

12.3 Conformance Clause 2: TOSCA processor 258

12.4 Conformance Clause 3: TOSCA orchestrator 258

12.5 Conformance Clause 4: TOSCA generator 259

12.6 Conformance Clause 5: TOSCA archive. 259

Appendix A. Known Extensions to TOSCA v1.0. 260

A.1 Model Changes. 260

A.2 Normative Types. 260

Appendix B. Acknowledgments. 262

Appendix C. Revision History. 263

Table of Examples

Example 1 - TOSCA Simple "Hello World". 12

Example 2 - Template with input and output parameter sections. 13

Example 3 - Simple (MySQL) software installation on a TOSCA Compute node. 14

Example 4 - Node Template overriding its Node Type's "configure" interface. 16

Example 5 - Template for deploying database content on-top of MySQL DBMS middleware. 17

Example 6 - Basic two-tier application (web application and database server tiers). 19

Example 7 - Providing a custom relationship script to establish a connection. 22

Example 8 - A web application Node Template requiring a custom database connection type. 23

Example 9 - Defining a custom relationship type. 24

Example 10 - Simple dependency relationship between two nodes. 25

Example 11 - An abstract "host" requirement using a node filter. 26

Example 12 - An abstract Compute node template with a node filter. 27

Example 13 - An abstract database requirement using a node filter. 28

Example 14 - An abstract database node template. 29

Example 15 - Referencing an abstract database node template. 31

Example 16 - Using substitution mappings to export a database implementation. 33

Example 17 - Declaring a transaction subsystem as a chain of substitutable node templates. 35

Example 18 - Defining a TransactionSubsystem node type. 36

Example 19 - Implementation of a TransactionSubsytem node type using substitution mappings. 38

Example 20 - Grouping Node Templates for possible policy application. 40

Example 21 - Grouping nodes for anti-colocation policy application. 41

Example 22 - Using YAML anchors in TOSCA templates. 42

Example 23 - Properties reflected as attributes. 45


Table of Figures

Figure 1: Using template substitution to implement a database tier. 31

Figure 2: Substitution mappings. 33

Figure 3: Chaining of subsystems in a service template. 35

Figure 4: Defining subsystem details in a service template. 37

Figure‑5: Typical 3-Tier Network. 181

Figure‑6: Generic Service Template. 190

Figure‑7: Service template with network template A.. 190

Figure‑8: Service template with network template B. 191

 

1      Introduction

1.1 Objective

The TOSCA Simple Profile in YAML specifies a rendering of TOSCA which aims to provide a more accessible syntax as well as a more concise and incremental expressiveness of the TOSCA DSL in order to minimize the learning curve and speed the adoption of the use of TOSCA to portably describe cloud applications.

This proposal describes a YAML rendering for TOSCA. YAML is a human friendly data serialization standard (http://yaml.org/) with a syntax much easier to read and edit than XML. As there are a number of DSLs encoded in YAML, a YAML encoding of the TOSCA DSL makes TOSCA more accessible by these communities.

This proposal prescribes an isomorphic rendering in YAML of a subset of the TOSCA v1.0 ensuring that TOSCA semantics are preserved and can be transformed from XML to YAML or from YAML to XML. Additionally, in order to streamline the expression of TOSCA semantics, the YAML rendering is sought to be more concise and compact through the use of the YAML syntax.

1.2 Summary of key TOSCA concepts

The TOSCA metamodel uses the concept of service templates to describe cloud workloads as a topology template, which is a graph of node templates modeling the components a workload is made up of and as relationship templates modeling the relations between those components. TOSCA further provides a type system of node types to describe the possible building blocks for constructing a service template, as well as relationship type to describe possible kinds of relations. Both node and relationship types may define lifecycle operations to implement the behavior an orchestration engine can invoke when instantiating a service template. For example, a node type for some software product might provide a ‘create’ operation to handle the creation of an instance of a component at runtime, or a ‘start’ or ‘stop’ operation to handle a start or stop event triggered by an orchestration engine. Those lifecycle operations are backed by implementation artifacts such as scripts or Chef recipes that implement the actual behavior.

An orchestration engine processing a TOSCA service template uses the mentioned lifecycle operations to instantiate single components at runtime, and it uses the relationship between components to derive the order of component instantiation. For example, during the instantiation of a two-tier application that includes a web application that depends on a database, an orchestration engine would first invoke the ‘create’ operation on the database component to install and configure the database, and it would then invoke the ‘create’ operation of the web application to install and configure the application (which includes configuration of the database connection).

The TOSCA simple profile assumes a number of base types (node types and relationship types) to be supported by each compliant environment such as a ‘Compute’ node type, a ‘Network’ node type or a generic ‘Database’ node type. Furthermore, it is envisioned that a large number of additional types for use in service templates will be defined by a community over time. Therefore, template authors in many cases will not have to define types themselves but can simply start writing service templates that use existing types. In addition, the simple profile will provide means for easily customizing and extending existing types, for example by providing a customized ‘create’ script for some software.

1.3 Implementations

Different kinds of processors and artifacts qualify as implementations of the TOSCA simple profile. Those that this specification is explicitly mentioning or referring to fall into the following categories:

·         TOSCA YAML service template (or “service template”): A YAML document artifact containing a (TOSCA) service template (see sections 3.9 “Service template definition”) that represents a Cloud application. (see sections 3.8 “Topology template definition”)

·         TOSCA processor (or “processor”): An engine or tool that is capable of parsing and interpreting a TOSCA service template for a particular purpose. For example, the purpose could be validation, translation or visual rendering.

·         TOSCA orchestrator (also called orchestration engine): A TOSCA processor that interprets a TOSCA service template or a TOSCA CSAR in order to instantiate and deploy the described application in a Cloud.

·         TOSCA generator: A tool that generates a TOSCA service template. An example of generator is a modeling tool capable of generating or editing a TOSCA service template (often such a tool would also be a TOSCA processor).

·         TOSCA archive (or TOSCA Cloud Service Archive, or “CSAR”): a package artifact that contains a TOSCA service template and other artifacts usable by a TOSCA orchestrator to deploy an application.

The above list is not exclusive. The above definitions should be understood as referring to and implementing the TOSCA simple profile as described in this document (abbreviated here as “TOSCA” for simplicity).

1.4 Terminology

The TOSCA language introduces a YAML grammar for describing service templates by means of Topology Templates and towards enablement of interaction with a TOSCA instance model perhaps by external APIs or plans. The primary currently is on design time aspects, i.e. the description of services to ensure their exchange between Cloud providers, TOSCA Orchestrators and tooling.

 

The language provides an extension mechanism that can be used to extend the definitions with additional vendor-specific or domain-specific information.

1.5 Notational Conventions

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].

1.5.1 Notes

·         Sections that are titled “Example” throughout this document are considered non-normative.

1.6 Normative References

[RFC2119]

S. Bradner, Key words for use in RFCs to Indicate Requirement Levels, http://www.ietf.org/rfc/rfc2119.txt, IETF RFC 2119, March 1997.

[TOSCA-1.0]

Topology and Orchestration Topology and Orchestration Specification for Cloud Applications (TOSCA) Version 1.0, an OASIS Standard, 25 November 2013, http://docs.oasis-open.org/tosca/TOSCA/v1.0/os/TOSCA-v1.0-os.pdf

[YAML-1.2]

YAML, Version 1.2, 3rd Edition, Patched at 2009-10-01, Oren Ben-Kiki, Clark Evans, Ingy döt Net http://www.yaml.org/spec/1.2/spec.html

[YAML-TS-1.1]

Timestamp Language-Independent Type for YAML Version 1.1, Working Draft 2005-01-18, http://yaml.org/type/timestamp.html

1.7 Non-Normative References

 

 

[Apache]

Apache Server, https://httpd.apache.org/

[Chef]

Chef, https://wiki.opscode.com/display/chef/Home

[NodeJS]

Node.js, https://nodejs.org/

[Puppet]

Puppet, http://puppetlabs.com/

[WordPress]

WordPress, https://wordpress.org/

[Maven-Version]

 

Apache Maven version policy draft:

https://cwiki.apache.org/confluence/display/MAVEN/Version+number+policy

1.8 Glossary

The following terms are used throughout this specification and have the following definitions when used in context of this document.

Term

Definition

Instance Model

A deployed service is a running instance of a Service Template. More precisely, the instance is derived by instantiating the Topology Template of its Service Template, most often by running a special plan defined for the Service Template, often referred to as build plan.

Node Template

A Relationship Template specifies the occurrence of a software component node as part of a Topology Template. Each Node Template refers to a Node Type that defines the semantics of the node (e.g., properties, attributes, requirements, capabilities, interfaces). Node Types are defined separately for reuse purposes.

Relationship Template

A Relationship Template specifies the occurrence of a relationship between nodes in a Topology Template. Each Relationship Template refers to a Relationship Type that defines the semantics relationship (e.g., properties, attributes, interfaces, etc.). Relationship Types are defined separately for reuse purposes.

Service Template

A Service Template is typically used to specify the “topology” (or structure) and “orchestration” (or invocation of management behavior) of IT services so that they can be provisioned and managed in accordance with constraints and policies.

 

Specifically, TOSCA Service Templates optionally allow definitions of a TOSCA Topology Template, TOSCA types (e.g., Node, Relationship, Capability, Artifact, etc.), groupings, policies and constraints along with any input or output declarations.

 

Topology Model

The term Topology Model is often used synonymously with the term Topology Template with the use of “model” being prevalent when considering a Service Template’s topology definition as an abstract representation of an application or service to facilitate understanding of its functional components and by eliminating unnecessary details.

Topology Template

A Topology Template defines the structure of a service in the context of a Service Template. A Topology Template consists of a set of Node Template and Relationship Template definitions that together define the topology model of a service as a (not necessarily connected) directed graph.

 

The term Topology Template is often used synonymously with the term Topology Model.  The distinction is that a topology template can be used to instantiate and orchestrate the model as a reusable pattern and includes all details necessary to accomplish it.

 

 

2      TOSCA by example

This non-normative section contains several sections that show how to model applications with TOSCA Simple Profile using YAML by example starting with a “Hello World” template up through examples that show complex composition modeling.

2.1 A “hello world” template for TOSCA Simple Profile in YAML

As mentioned before, the TOSCA simple profile assumes the existence of a small set of pre-defined, normative set of node types (e.g., a ‘Compute’ node) along with other types, which will be introduced through the course of this document, for creating TOSCA Service Templates. It is envisioned that many additional node types for building service templates will be created by communities some may be published as profiles that build upon the TOSCA Simple Profile specification. Using the normative TOSCA Compute node type, a very basic “Hello World” TOSCA template for deploying just a single server would look as follows:

Example 1 - TOSCA Simple "Hello World"

tosca_definitions_version: tosca_simple_yaml_1_0

 

description: Template for deploying a single server with predefined properties.

 

topology_template:

  node_templates:

    my_server:

      type: tosca.nodes.Compute

      capabilities:

        # Host container properties

        host:

         properties:

           num_cpus: 1

           disk_size: 10 GB

           mem_size: 4096 MB

        # Guest Operating System properties

        os:

          properties:

            # host Operating System image properties

            architecture: x86_64

            type: linux 

            distribution: rhel 

            version: 6.5 

The template above contains a very simple topology template with only a single ‘Compute’ node template that declares some basic values for properties within two of the several capabilities that are built into the Compute node type definition.  All TOSCA Orchestrators are expected to know how to instantiate a Compute node since it is normative and expected to represent a well-known function that is portable across TOSCA implementations.  This expectation is true for all normative TOSCA Node and Relationship types that are defined in the Simple Profile specification. This means, with TOSCA’s approach, that the application developer does not need to provide any deployment or implementation artifacts that contain code or logic to orchestrate these common software components.  TOSCA orchestrators simply select or allocate the correct node (resource) type that fulfills the application topologies requirements using the properties declared in the node and its capabilities.

In the above example, the “host” capability contains properties that allow application developers to optionally supply the number of CPUs, memory size and disk size they believe they need when the Compute node is instantiated in order to run their applications. Similarly, the “os” capability is used to provide values to indicate what host operating system the Compute node should have when it is instantiated.

The logical diagram of the “hello world” Compute node would look as follows:

 

As you can see, the Compute node also has attributes and other built-in capabilities, such as Bindable and Endpoint, each with additional properties that will be discussed in other examples later in this document.  Although the Compute node has no direct properties apart from those in its capabilities, other TOSCA node type definitions may have properties that are part of the node type itself in addition to having Capabilities.  TOSCA orchestration engines are expected to validate all property values provided in a node template against the property definitions in their respective node type definitions referenced in the service template.  The tosca_definitions_version keyname in the TOSCA service template identifies the versioned set of normative TOSCA type definitions to use for validating those types defined in the TOSCA Simple Profile including the Compute node type. Specifically, the value tosca_simple_yaml_1_0 indicates Simple Profile v1.0.0 definitions would be used for validation.  Other type definitions may be imported from other service templates using the import keyword discussed later.

2.1.1 Requesting input parameters and providing output

Typically, one would want to allow users to customize deployments by providing input parameters instead of using hardcoded values inside a template. In addition, output values are provided to pass information that perhaps describes the state of the deployed template to the user who deployed it (such as the private IP address of the deployed server). A refined service template with corresponding inputs and outputs sections is shown below.

Example 2 - Template with input and output parameter sections

tosca_definitions_version: tosca_simple_yaml_1_0

 

description: Template for deploying a single server with predefined properties.

 

topology_template:

  inputs:

    cpus:

      type: integer

      description: Number of CPUs for the server.

      constraints:

        - valid_values: [ 1, 2, 4, 8 ]

 

  node_templates:

    my_server:

      type: tosca.nodes.Compute

      capabilities:

        # Host container properties

        host:

          properties:

            # Compute properties

            num_cpus: { get_input: cpus }

            mem_size: 2048  MB

            disk_size: 10 GB

 

  outputs:

    server_ip:

      description: The private IP address of the provisioned server.

      value: { get_attribute: [ my_server, private_address ] }

The inputs and outputs sections are contained in the topology_template element of the TOSCA template, meaning that they are scoped to node templates within the topology template. Input parameters defined in the inputs section can be assigned to properties of node template within the containing topology template; output parameters can be obtained from attributes of node templates within the containing topology template.

Note that the inputs section of a TOSCA template allows for defining optional constraints on each input parameter to restrict possible user input. Further note that TOSCA provides for a set of intrinsic functions like get_input, get_property or get_attribute to reference elements within the template or to retrieve runtime values.

2.2 TOSCA template for a simple software installation

Software installations can be modeled in TOSCA as node templates that get related to the node template for a server on which the software shall be installed. With a number of existing software node types (e.g. either created by the TOSCA work group or a community) template authors can just use those node types for writing service templates as shown below.

Example 3 - Simple (MySQL) software installation on a TOSCA Compute node

tosca_definitions_version: tosca_simple_yaml_1_0

description: Template for deploying a single server with MySQL software on top.

 

topology_template:

  inputs:

    # omitted here for brevity

 

  node_templates:

    mysql:

      type: tosca.nodes.DBMS.MySQL

      properties:

        root_password: { get_input: my_mysql_rootpw }

        port: { get_input: my_mysql_port }

      requirements:

        - host: db_server

 

    db_server:

      type: tosca.nodes.Compute

      capabilities:

        # omitted here for brevity

The example above makes use of a node type tosca.nodes.DBMS.MySQL for the mysql node template to install MySQL on a server. This node type allows for setting a property root_password to adapt the password of the MySQL root user at deployment. The set of properties and their schema has been defined in the node type definition. By means of the get_input function, a value provided by the user at deployment time is used as value for the root_password property. The same is true for the port property.

The mysql node template is related to the db_server node template (of type tosca.nodes.Compute) via the requirements section to indicate where MySQL is to be installed. In the TOSCA metamodel, nodes get related to each other when one node has a requirement against some feature provided by another node. What kinds of requirements exist is defined by the respective node type. In case of MySQL, which is software that needs to be installed or hosted on a compute resource, the underlying node type named DBMS has a predefined requirement called host, which needs to be fulfilled by pointing to a node template of type tosca.nodes.Compute.

The logical relationship between the mysql node and its host db_server node would appear as follows:

Within the requirements section, all entries simple entries are a map which contains the symbolic name of a requirement definition as the key and the identifier of the fulfilling node as the value. The value is essentially the symbolic name of the other node template; specifically, or the example above, the host requirement is fulfilled by referencing the db_server node template.  The underlying TOSCA DBMS node type already defines a complete requirement definition for the host requirement of type Container and assures that a HostedOn TOSCA relationship will automatically be created and will only allow a valid target host node is of type Compute.  This approach allows the template author to simply provide the name of a valid Compute node (i.e., db_server) as the value for the mysql node’s host requirement and not worry about defining anything more complex if they do not want to.

2.3 Overriding behavior of predefined node types

Node types in TOSCA have associated implementations that provide the automation (e.g. in the form of scripts such as Bash, Chef or Python) for the normative lifecycle operations of a node. For example, the node type implementation for a MySQL database would associate scripts to TOSCA node operations like configure, start, or stop to manage the state of MySQL at runtime.

Many node types may already come with a set of operational scripts that contain basic commands that can manage the state of that specific node. If it is desired, template authors can provide a custom script for one or more of the operation defined by a node type in their node template which will override the default implementation in the type.  The following example shows a mysql node template where the template author provides their own configure script:

Example 4 - Node Template overriding its Node Type's "configure" interface

tosca_definitions_version: tosca_simple_yaml_1_0

 

description: Template for deploying a single server with MySQL software on top.

 

topology_template:

  inputs:

    # omitted here for brevity

 

  node_templates:

    mysql:

      type: tosca.nodes.DBMS.MySQL

      properties:

        root_password: { get_input: my_mysql_rootpw }

        port: { get_input: my_mysql_port }

      requirements:

        - host: db_server

      interfaces:

        Standard:

          configure: scripts/my_own_configure.sh

 

    db_server:

      type: tosca.nodes.Compute

      capabilities:

        # omitted here for brevity

In the example above, the my_own_configure.sh script is provided for the configure operation of the MySQL node type’s Standard lifecycle interface. The path given in the example above (i.e., ‘scripts/’) is interpreted relative to the template file, but it would also be possible to provide an absolute URI to the location of the script.

In other words, operations defined by node types can be thought of as “hooks” into which automation can be injected. Typically, node type implementations provide the automation for those “hooks”. However, within a template, custom automation can be injected to run in a hook in the context of the one, specific node template (i.e. without changing the node type).

2.4 TOSCA template for database content deployment

In the example shown in section 4 the deployment of the MySQL middleware only, i.e. without actual database content was shown. The following example shows how such a template can be extended to also contain the definition of custom database content on-top of the MySQL DBMS software.

Example 5 - Template for deploying database content on-top of MySQL DBMS middleware

tosca_definitions_version: tosca_simple_yaml_1_0

 

description: Template for deploying MySQL and database content.

 

topology_template:

  inputs:

    # omitted here for brevity

 

  node_templates:

    my_db:

      type: tosca.nodes.Database.MySQL

      properties:

        name: { get_input: database_name }

        user: { get_input: database_user }

        password: { get_input: database_password }

        port: { get_input: database_port }

      artifacts:

        db_content:

          file: files/my_db_content.txt

          type: tosca.artifacts.File

      requirements:

        - host: mysql

      interfaces:

        Standard:

          create:

            implementation: db_create.sh

            inputs:

              # Copy DB file artifact to server’s staging area

              db_data: { get_artifact: [ SELF, db_content ] }

 

    mysql:

      type: tosca.nodes.DBMS.MySQL

      properties:

        root_password: { get_input: mysql_rootpw }

        port: { get_input: mysql_port }

      requirements:

        - host: db_server

 

    db_server:

      type: tosca.nodes.Compute

      capabilities:

        # omitted here for brevity

In the example above, the my_db node template or type tosca.nodes.Database.MySQL represents an actual MySQL database instance managed by a MySQL DBMS installation. The requirements section of the my_db node template expresses that the database it represents is to be hosted on a MySQL DBMS node template named mysql which is also declared in this template.

In its artifacts section of the my_db the node template, there is an artifact definition named db_content which represents a text file  my_db_content.txt which in turn will be used to add content to the SQL database as part of the create operation. The requirements section of the my_db node template expresses that the database is hosted on a MySQL DBMS represented by the mysql node.

As you can see above, a script is associated with the create operation with the name db_create.sh.  The TOSCA Orchestrator sees that this is not a named artifact declared in the node’s artifact section, but instead a filename for a normative TOSCA implementation artifact script type (i.e., tosca.artifacts.Implementation.Bash). Since this is an implementation type for TOSCA, the orchestrator will execute the script automatically to create the node on db_server, but first it will prepare the local environment with the declared inputs for the operation. In this case, the orchestrator would see that the db_data input is using the get_artifact function to retrieve the file (my_db_content.txt) which is associated with the db_content artifact name prior to executing the db_create.sh script.

 

The logical diagram for this example would appear as follows:

Note that while it would be possible to define one node type and corresponding node templates that represent both the DBMS middleware and actual database content as one entity, TOSCA normative node types distinguish between middleware (container) and application (containee) node types. This allows on one hand to have better re-use of generic middleware node types without binding them to content running on top of them, and on the other hand this allows for better substitutability of, for example, middleware components like a DBMS during the deployment of TOSCA models.

2.5 TOSCA template for a two-tier application

The definition of multi-tier applications in TOSCA is quite similar to the example shown in section 2.2, with the only difference that multiple software node stacks (i.e., node templates for middleware and application layer components), typically hosted on different servers, are defined and related to each other. The example below defines a web application stack hosted on the web_server “compute” resource, and a database software stack similar to the one shown earlier in section 6 hosted on the db_server compute resource.

Example 6 - Basic two-tier application (web application and database server tiers)

tosca_definitions_version: tosca_simple_yaml_1_0

 

description: Template for deploying a two-tier application servers on two

 

topology_template:

  inputs:

    # Admin user name and password to use with the WordPress application

    wp_admin_username:

      type: string

    wp_admin_password:

      type: string

    wp_db_name:

      type: string

    wp_db_user:

      type: string

    wp_db_password:

      type: string

    wp_db_port:

      type: integer

    mysql_root_password:

      type: string

    mysql_port:

      type: integer

    context_root:

      type: string

 

  node_templates:

    wordpress:

      type: tosca.nodes.WebApplication.WordPress

      properties:

        context_root: { get_input: context_root }

        admin_user: { get_input: wp_admin_username }

        admin_password: { get_input: wp_admin_password }

        db_host: { get_attribute: [ db_server, private_address ] }

      requirements:

        - host: apache

        - database_endpoint: wordpress_db

      interfaces:

        Standard:

          inputs:

            db_host: { get_attribute: [ db_server, private_address ] }

            db_port: { get_property: [ wordpress_db, port ] }

            db_name: { get_property: [ wordpress_db, name ] }

            db_user: { get_property: [ wordpress_db, user ] }

            db_password: { get_property: [ wordpress_db, password ] }  

 

    apache:

      type: tosca.nodes.WebServer.Apache

      properties:

        # omitted here for brevity

      requirements:

        - host: web_server

 

    web_server:

      type: tosca.nodes.Compute

      capabilities:

        # omitted here for brevity

 

    wordpress_db:

      type: tosca.nodes.Database.MySQL

      properties:

        name: { get_input: wp_db_name }

        user: { get_input: wp_db_user }

        password: { get_input: wp_db_password }

        port: { get_input: wp_db_port }

      requirements:

        - host: mysql

 

    mysql:

      type: tosca.nodes.DBMS.MySQL

      properties:

        root_password: { get_input: mysql_root_password }

        port: { get_input: mysql_port }

      requirements:

        - host: db_server

 

    db_server:

      type: tosca.nodes.Compute

      capabilities:

        # omitted here for brevity

The web application stack consists of the wordpress [WordPress], the apache [Apache] and the web_server node templates. The wordpress node template represents a custom web application of type tosca.nodes.WebApplication.WordPress which is hosted on an Apache web server represented by the apache node template. This hosting relationship is expressed via the host entry in the requirements section of the wordpress node template. The apache node template, finally, is hosted on the web_server compute node.

The database stack consists of the wordpress_db, the mysql and the db_server node templates. The wordpress_db node represents a custom database of type tosca.nodes.Database.MySQL which is hosted on a MySQL DBMS represented by the mysql node template. This node, in turn, is hosted on the db_server compute node.

The wordpress node requires a connection to the wordpress_db node, since the WordPress application needs a database to store its data in. This relationship is established through the database_endpoint entry in the requirements section of the wordpress node template’s declared node type. For configuring the WordPress web application, information about the database to connect to is required as input to the configure operation. Therefore, the input parameters are defined and values for them are retrieved from the properties and attributes of the wordpress_db node via the get_property and get_attribute functions. In the above example, these inputs are defined at the interface-level and would be available to all operations of the Standard interface (i.e., the tosca.interfaces.node.lifecycle.Standard interface) within the wordpress node template and not just the configure operation.

2.6 Using a custom script to establish a relationship in a template

In previous examples, the template author did not have to think about explicit relationship types to be used to link a requirement of a node to another node of a model, nor did the template author have to think about special logic to establish those links. For example, the host requirement in previous examples just pointed to another node template and based on metadata in the corresponding node type definition the relationship type to be established is implicitly given.

In some cases it might be necessary to provide special processing logic to be executed when establishing relationships between nodes at runtime. For example, when connecting the WordPress application from previous examples to the MySQL database, it might be desired to apply custom configuration logic in addition to that already implemented in the application node type.  In such a case, it is possible for the template author to provide a custom script as implementation for an operation to be executed at runtime as shown in the following example.

Example 7 - Providing a custom relationship script to establish a connection

tosca_definitions_version: tosca_simple_yaml_1_0

 

description: Template for deploying a two-tier application on two servers.

 

topology_template:

  inputs:

    # omitted here for brevity

 

  node_templates:

    wordpress:

      type: tosca.nodes.WebApplication.WordPress

      properties:

        # omitted here for brevity

      requirements:

        - host: apache

        - database_endpoint:

            node: wordpress_db

            relationship: my_custom_database_connection

 

    wordpress_db:

      type: tosca.nodes.Database.MySQL

      properties:

        # omitted here for the brevity

      requirements:

        - host: mysql

 

  relationship_templates:

    my_custom_database_connection:

      type: ConnectsTo

      interfaces:

        Configure:

          pre_configure_source: scripts/wp_db_configure.sh

 

   # other resources not shown for this example ...

The node type definition for the wordpress node template is WordPress which declares the complete database_endpoint requirement definition. This database_endpoint declaration indicates it must be fulfilled by any node template that provides an Endpoint.Database Capability Type using a ConnectsTo relationship. The wordpress_db node template’s underlying MySQL type definition indeed provides the Endpoint.Database Capability type.  In this example however, no explicit relationship template is declared; therefore TOSCA orchestrators would automatically create a ConnectsTo relationship to establish the link between the wordpress node and the wordpress_db node at runtime.

 

The ConnectsTo relationship (see 5.6.4) also provides a default Configure interface with operations that optionally get executed when the orchestrator establishes the relationship. In the above example, the author has provided the custom script wp_db_configure.sh to be executed for the operation called pre_configure_source. The script file is assumed to be located relative to the referencing service template such as a relative directory within the TOSCA Cloud Service Archive (CSAR) packaging format. This approach allows for conveniently hooking in custom behavior without having to define a completely new derived relationship type.

2.7 Using custom relationship types in a TOSCA template

In the previous section it was shown how custom behavior can be injected by specifying scripts inline in the requirements section of node templates. When the same custom behavior is required in many templates, it does make sense to define a new relationship type that encapsulates the custom behavior in a re-usable way instead of repeating the same reference to a script (or even references to multiple scripts) in many places.

Such a custom relationship type can then be used in templates as shown in the following example.

Example 8 - A web application Node Template requiring a custom database connection type

tosca_definitions_version: tosca_simple_yaml_1_0

 

description: Template for deploying a two-tier application on two servers.

 

topology_template:

  inputs:

    # omitted here for brevity

 

  node_templates:

    wordpress:

      type: tosca.nodes.WebApplication.WordPress

      properties:

        # omitted here for brevity

      requirements:

        - host: apache

        - database_endpoint:

            node: wordpress_db
           
relationship: my.types.WordpressDbConnection

 

    wordpress_db:

      type: tosca.nodes.Database.MySQL

      properties:

        # omitted here for the brevity

      requirements:

        - host: mysql

 

   # other resources not shown here ...

In the example above, a special relationship type my.types.WordpressDbConnection is specified for establishing the link between the wordpress node and the wordpress_db node through the use of the relationship (keyword) attribute in the database reference. It is assumed, that this special relationship type provides some extra behavior (e.g., an operation with a script) in addition to what a generic “connects to” relationship would provide. The definition of this custom relationship type is shown in the following section.

2.7.1 Definition of a custom relationship type

The following YAML snippet shows the definition of the custom relationship type used in the previous section. This type derives from the base “ConnectsTo” and overrides one operation defined by that base relationship type. For the pre_configure_source operation defined in the Configure interface of the ConnectsTo relationship type, a script implementation is provided. It is again assumed that the custom configure script is located at a location relative to the referencing service template, perhaps provided in some application packaging format (e.g., the TOSCA Cloud Service Archive (CSAR) format).

Example 9 - Defining a custom relationship type

tosca_definitions_version: tosca_simple_yaml_1_0

 

description: Definition of custom WordpressDbConnection relationship type

 

relationship_types:

  my.types.WordpressDbConnection:

    derived_from: tosca.relationships.ConnectsTo

    interfaces:

      Configure:

        pre_configure_source: scripts/wp_db_configure.sh

In the above example, the Configure interface is the specified alias or shorthand name for the TOSCA interface type with the full name of tosca.interfaces.relationship.Configure which is defined in the appendix.

2.8 Defining generic dependencies between nodes in a template

In some cases it can be necessary to define a generic dependency between two nodes in a template to influence orchestration behavior, i.e. to first have one node processed before another dependent node gets processed. This can be done by using the generic dependency requirement which is defined by the TOSCA Root Node Type and thus gets inherited by all other node types in TOSCA (see section 5.8.1).

Example 10 - Simple dependency relationship between two nodes

tosca_definitions_version: tosca_simple_yaml_1_0

 

description: Template with a generic dependency between two nodes.

 

topology_template:

  inputs:

    # omitted here for brevity

 

  node_templates:

    my_app:

      type: my.types.MyApplication

      properties:

        # omitted here for brevity

      requirements:

        - dependency: some_service

 

    some_service:

      type: some.nodetype.SomeService

      properties:

        # omitted here for brevity

As in previous examples, the relation that one node depends on another node  is expressed in the requirements section using the built-in requirement named dependency that exists for all node types in TOSCA. Even if the creator of the MyApplication node type did not define a specific requirement for SomeService (similar to the database requirement in the example in section 2.6), the template author who knows that there is a timing dependency and can use the generic dependency requirement to express that constraint using the very same syntax as used for all other references.

2.9 Describing abstract requirements for nodes and capabilities in a TOSCA template

In TOSCA templates, nodes are either:

·         Concrete: meaning that they have a deployment and/or one or more implementation artifacts that are declared on the “create” operation of the node’s Standard lifecycle interface, or they are

·         Abstract: where the template describes the node type along with its required capabilities and properties that must be satisfied.

 

TOSCA Orchestrators, by default, when finding an abstract node in TOSCA Service Template during deployment will attempt to “select” a concrete implementation for the abstract node type that best matches and fulfills the requirements and property constraints the template author provided for that abstract node. The concrete implementation of the node could be provided by another TOSCA Service Template (perhaps located in a catalog or repository known to the TOSCA Orchestrator) or by an existing resource or service available within the target Cloud Provider’s platform that the TOSCA Orchestrator already has knowledge of.

 

TOSCA supports two methods for template authors to express requirements for an abstract node within a TOSCA service template. 

 

1.       Using a target node_filter: where a node template can describe a requirement (relationship) for another node without including it in the topology. Instead, the node provides a node_filter to describe the target node type along with its capabilities and property constrains

 

2.       Using an abstract node template: that describes the abstract node’s type along with its property constraints and any requirements and capabilities it also exports.  This first method you have already seen in examples from previous chapters where the Compute node is abstract and selectable by the TOSCA Orchestrator using the supplied Container and OperatingSystem capabilities property constraints.

 

These approaches allows architects and developers to create TOSCA service templates that are composable and can be reused by allowing flexible matching of one template’s requirements to another’s capabilities. Examples of both these approaches are shown below.

2.9.1 Using a node_filter to define hosting infrastructure requirements for a software

Using TOSCA, it is possible to define only the software components of an application in a template and just express constrained requirements against the hosting infrastructure. At deployment time, the provider can then do a late binding and dynamically allocate or assign the required hosting infrastructure and place software components on top.

This example shows how a single software component (i.e., the mysql node template) can define its host requirements that the TOSCA Orchestrator and provider will use to select or allocate an appropriate host Compute node by using matching criteria provided on a node_filter.

Example 11 - An abstract "host" requirement using a node filter

tosca_definitions_version: tosca_simple_yaml_1_0

 

description: Template with requirements against hosting infrastructure.

 

topology_template:

  inputs:

    # omitted here for brevity

 

  node_templates:

    mysql:

      type: tosca.nodes.DBMS.MySQL

      properties:

        # omitted here for brevity

      requirements:

        - host:

            node_filter:

              capabilities:

                # Constraints for selecting “host” (Container Capability)

                - host:

                    properties:

                      - num_cpus: { in_range: [ 1, 4 ] }

                      - mem_size: { greater_or_equal: 2 GB }

                # Constraints for selecting “os” (OperatingSystem Capability)

                - os:

                    properties:

                      - architecture: { equal: x86_64 }

                      - type: linux

                      - distribution: ubuntu

In the example above, the mysql component contains a host requirement for a node of type Compute which it inherits from its parent DBMS node type definition; however, there is no declaration or reference to any node template of type Compute. Instead, the mysql node template augments the abstract “host” requirement with a node_filter which contains additional selection criteria (in the form of property constraints that the provider must use when selecting or allocating a host Compute node. 

Some of the constraints shown above narrow down the boundaries of allowed values for certain properties such as mem_size or num_cpus for the “host” capability by means of qualifier functions such as greater_or_equal. Other constraints, express specific values such as for the architecture or distribution properties of the “os” capability which will require the provider to find a precise match. 

Note that when no qualifier function is provided for a property (filter), such as for the distribution property, it is interpreted to mean the equal operator as shown on the architecture property.

2.9.2 Using an abstract node template to define infrastructure requirements for software

This previous approach works well if no other component (i.e., another node template) other than mysql node template wants to reference the same Compute node the orchestrator would instantiate. However, perhaps another component wants to also be deployed on the same host, yet still allow the flexible matching achieved using a node-filter.  The alternative to the above approach is to create an abstract node template that represents the Compute node in the topology as follows:

Example 12 - An abstract Compute node template with a node filter

tosca_definitions_version: tosca_simple_yaml_1_0

                  

description: Template with requirements against hosting infrastructure.

 

topology_template:

  inputs:

    # omitted here for brevity

 

  node_templates:

    mysql:

      type: tosca.nodes.DBMS.MySQL

      properties:

        # omitted here for brevity

      requirements:

        - host: mysql_compute

 

    # Abstract node template (placeholder) to be selected by provider

    mysql_compute:

      type: Compute

      node_filter:

        capabilities:

          - host:

              properties:

                num_cpus: { equal: 2 }

                mem_size: { greater_or_equal: 2 GB }

          - os:

              properties:

                architecture: { equal: x86_64 }

                type: linux

                distribution: ubuntu

As you can see the resulting mysql_compute node template looks very much like the “hello world” template as shown in Chapter 2.1 (where the Compute node template was abstract), but this one also allows the TOSCA orchestrator more flexibility when “selecting” a host Compute node by providing flexible constraints for properties like mem_size.

As we proceed, you will see that TOSCA provides many normative node types like Compute for commonly found services (e.g., BlockStorage, WebServer, Network, etc.).  When these TOSCA normative node types are used in your application’s topology they are always assumed to be “selectable” by TOSCA Orchestrators which work with target infrastructure providers to find or allocate the best match for them based upon your application’s requirements and constraints.

2.9.3 Using a node_filter to define requirements on a database for an application

In the same way requirements can be defined on the hosting infrastructure (as shown above) for an application, it is possible to express requirements against application or middleware components such as a database that is not defined in the same template. The provider may then allocate a database by any means, (e.g. using a database-as-a-service solution).

Example 13 - An abstract database requirement using a node filter

tosca_definitions_version: tosca_simple_yaml_1_0

 

description: Template with a TOSCA Orchestrator selectable database requirement using a node_filter.

 

topology_template:

  inputs:

    # omitted here for brevity

 

  node_templates:

    my_app:

      type: my.types.MyApplication

      properties:

        admin_user: { get_input: admin_username }

        admin_password: { get_input: admin_password }

        db_endpoint_url: { get_property: [SELF, database_endpoint, url_path ] }         

      requirements:

        - database_endpoint:

            node: my.types.nodes.MyDatabase

            node_filter:

              properties:

                - db_version: { greater_or_equal: 5.5 }

In the example above, the application my_app requires a database node of type MyDatabase which has a db_version property value of greater_or_equal to the value 5.5.

This example also shows how the get_property intrinsic function can be used to retrieve the url_path property from the database node that will be selected by the provider and connected to my_app at runtime due to fulfillment of the database_endpoint requirement. To locate the property, the get_property’s first argument is set to the keyword SELF which indicates the property is being referenced from something in the node itself. The second parameter is the name of the requirement named database_endpoint which contains the property we are looking for. The last argument is the name of the property itself (i.e., url_path) which contains the  value we want to retrieve and assign to db_endpoint_url.

The alternative representation, which includes a node template in the topology for database that is still selectable by the TOSCA orchestrator for the above example, is as follows:

Example 14 - An abstract database node template

tosca_definitions_version: tosca_simple_yaml_1_0

 

description: Template with a TOSCA Orchestrator selectable database using node template.

 

topology_template:

  inputs:

    # omitted here for brevity

 

  node_templates:

    my_app:

      type: my.types.MyApplication

      properties:

        admin_user: { get_input: admin_username }

        admin_password: { get_input: admin_password }

        db_endpoint_url: { get_property: [SELF, database_endpoint, url_path ] }         

      requirements:

        - database_endpoint: my_abstract_database

 

    my_abstract_database:

      type: my.types.nodes.MyDatabase

      properties:

        - db_version: { greater_or_equal: 5.5 }

2.10 Using node template substitution for model composition

From an application perspective, it is often not necessary or desired to dive into platform details, but the platform/runtime for an application is abstracted. In such cases, the template for an application can use generic representations of platform components. The details for such platform components, such as the underlying hosting infrastructure at its configuration, can then be defined in separate template files that can be used for substituting the more abstract representations in the application level template file.

2.10.1 Understanding node template instantiation through a TOSCA Orchestrator

When a topology template is instantiated by a TOSCA Orchestrator, the orchestrator has to look for realizations of the single node templates according to the node types specified for each node template. Such realizations can either be node types that include the appropriate implementation artifacts and deployment artifacts that can be used by the orchestrator to bring to life the real-world resource modeled by a node template. Alternatively, separate topology templates may be annotated as being suitable for realizing a node template in the top-level topology template.

In the latter case, a TOSCA Orchestrator will use additional substitution mapping information provided as part of the substituting topology templates to derive how the substituted part get “wired” into the overall deployment, for example, how capabilities of a node template in the top-level topology template get bound to capabilities of node templates in the substituting topology template.

Thus, in cases where no “normal” node type implementation is available, or the node type corresponds to a whole subsystem that cannot be implemented as a single node, additional topology templates can be used for filling in more abstract placeholders in top level application templates.

2.10.2 Definition of the top-level service template

The following sample defines a web application web_app connected to a database db. In this example, the complete hosting stack for the application is defined within the same topology template: the web application is hosted on a web server web_server, which in turn is installed (hosted) on a compute node server.

The hosting stack for the database db, in contrast, is not defined within the same file but only the database is represented as a node template of type tosca.nodes.Database. The underlying hosting stack for the database is defined in a separate template file, which is shown later in this section. Within the current template, only a number of properties (user, password, name) are assigned to the database using hardcoded values in this simple example.

Figure 1: Using template substitution to implement a database tier

When a node template is to be substituted by another service template, this has to be indicated to an orchestrator by means of a special “substitutable” directive. This directive causes, for example, special processing behavior when validating the left-hand service template in Figure 1. The hosting requirement of the db node template is not bound to any capability defined within the service template, which would normally cause a validation error. When the “substitutable” directive is present, the orchestrator will however first try to perform substitution of the respective node template and after that validate if all mandatory requirements of all nodes in the resulting graph are fulfilled.

Note that in contrast to the use case described in section 0 (where a database was abstractly referred to in the requirements section of a node and the database itself was not represented as a node template), the approach shown here allows for some additional modeling capabilities in cases where this is required.
For example, if multiple components shall use the same database (or any other sub-system of the overall service), this can be expressed by means of normal relations between node templates, whereas such modeling would not be possible in requirements sections of disjoint node templates.

Example 15 - Referencing an abstract database node template

tosca_definitions_version: tosca_simple_yaml_1_0

 

topology_template:

  description: Template of an application connecting to a database.

 

  node_templates:

    web_app:

      type: tosca.nodes.WebApplication.MyWebApp

      requirements:

        - host: web_server

        - database_endpoint: db

 

    web_server:

      type: tosca.nodes.WebServer

      requirements:

        - host: server

 

    server:

      type: tosca.nodes.Compute

      # details omitted for brevity

 

    db:

      # This node is abstract (no Deploment or Implemenation artifacts on create)

      # and can be substituted with a topology provided by another template

      # that exports a Database type’s capabilities.

      type: tosca.nodes.Database

      properties:

        user: my_db_user

        password: secret

        name: my_db_name

2.10.3 Definition of the database stack in a service template

The following sample defines a template for a database including its complete hosting stack, i.e. the template includes a database node template, a template for the database management system (dbms) hosting the database, as well as a computer node server on which the DBMS is installed.

This service template can be used standalone for deploying just a database and its hosting stack. In the context of the current use case, though, this template can also substitute the database node template in the previous snippet and thus fill in the details of how to deploy the database.

In order to enable such a substitution, an additional metadata section substitution_mappings is added to the topology template to tell a TOSCA Orchestrator how exactly the topology template will fit into the context where it gets used. For example, requirements or capabilities of the node that gets substituted by the topology template have to be mapped to requirements or capabilities of internal node templates for allow for a proper wiring of the resulting overall graph of node templates.

In short, the substitution_mappings section provides the following information:

1.       It defines what node templates, i.e. node templates of which type, can be substituted by the topology template.

2.       It defines how capabilities of the substituted node (or the capabilities defined by the node type of the substituted node template, respectively) are bound to capabilities of node templates defined in the topology template.

3.       It defines how requirements of the substituted node (or the requirements defined by the node type of the substituted node template, respectively) are bound to requirements of node templates defined in the topology template.

Figure 2: Substitution mappings

The substitution_mappings section in the sample below denotes that this topology template can be used for substituting node templates of type tosca.nodes.Database. It further denotes that the database_endpoint capability of the substituted node gets fulfilled by the database_endpoint capability of the database node contained in the topology template.

Example 16 - Using substitution mappings to export a database implementation

tosca_definitions_version: tosca_simple_yaml_1_0

 

topology_template:

  description: Template of a database including its hosting stack.

 

  inputs:

    db_user:

      type: string

    db_password:

      type: string

    # other inputs omitted for brevity

 

  substitution_mappings:

    node_type: tosca.nodes.Database

    capabilities:

      database_endpoint: [ database, database_endpoint ]

 

  node_templates:

    database:

      type: tosca.nodes.Database

      properties:

        user: { get_input: db_user }

        # other properties omitted for brevity

      requirements:

        - host: dbms

 

    dbms:

      type: tosca.nodes.DBMS

      # details omitted for brevity

 

    server:

      type: tosca.nodes.Compute

      # details omitted for brevity

Note that the substitution_mappings section does not define any mappings for requirements of the Database node type, since all requirements are fulfilled by other nodes templates in the current topology template. In cases where a requirement of a substituted node is bound in the top-level service template as well as in the substituting topology template, a TOSCA Orchestrator should raise a validation error.

Further note that no mappings for properties or attributes of the substituted node are defined. Instead, the inputs and outputs defined by the topology template have to match the properties and attributes or the substituted node. If there are more inputs than the substituted node has properties, default values must be defined for those inputs, since no values can be assigned through properties in a substitution case.

2.11 Using node template substitution for chaining subsystems

A common use case when providing an end-to-end service is to define a chain of several subsystems that together implement the overall service. Those subsystems are typically defined as separate service templates to (1) keep the complexity of the end-to-end service template at a manageable level and to (2) allow for the re-use of the respective subsystem templates in many different contexts. The type of subsystems may be specific to the targeted workload, application domain, or custom use case. For example, a company or a certain industry might define a subsystem type for company- or industry specific data processing and then use that subsystem type for various end-user services. In addition, there might be generic subsystem types like a database subsystem that are applicable to a wide range of use cases.

2.11.1 Defining the overall subsystem chain

Figure 3 shows the chaining of three subsystem types – a message queuing subsystem, a transaction processing subsystem, and a databank subsystem – that support, for example, an online booking application. On the front end, this chain provides a capability of receiving messages for handling in the message queuing subsystem. The message queuing subsystem in turn requires a number of receivers, which in the current example are two transaction processing subsystems. The two instances of the transaction processing subsystem might be deployed on two different hosting infrastructures or datacenters for high-availability reasons. The transaction processing subsystems finally require a database subsystem for accessing and storing application specific data. The database subsystem in the backend does not require any further component and is therefore the end of the chain in this example.

Figure 3: Chaining of subsystems in a service template

All of the node templates in the service template shown above are abstract and considered substitutable where each can be treated as their own subsystem; therefore, when instantiating the overall service, the orchestrator would realize each substitutable node template using other TOSCA service templates.  These service templates would include more nodes and relationships that include the details for each subsystem. A simplified version of a TOSCA service template for the overall service is given in the following listing.

 

Example 17 - Declaring a transaction subsystem as a chain of substitutable node templates

tosca_definitions_version: tosca_simple_yaml_1_0

 

topology_template:

  description: Template of online transaction processing service.

 

  node_templates:

    mq:

      type: example.QueuingSubsystem

      properties:

        # properties omitted for brevity

      capabilities:

        message_queue_endpoint:

          # details omitted for brevity

      requirements:

        - receiver: trans1

        - receiver: trans2

 

    trans1:

      type: example.TransactionSubsystem

      properties:

        mq_service_ip: { get_attribute: [ mq, service_ip ] }

        receiver_port: 8080

      capabilities:

        message_receiver:

          # details omitted for brevity

      requirements:

        - database_endpoint: dbsys

 

    trans2:

      type: example.TransactionSubsystem

      properties:

        mq_service_ip: { get_attribute: [ mq, service_ip ] }

        receiver_port: 8080

      capabilities:

        message_receiver:

          # details omitted for brevity

      requirements:

        - database_endpoint: dbsys

 

    dbsys:

      type: example.DatabaseSubsystem

      properties:

        # properties omitted for brevity

      capabilities:

        database_endpoint:

          # details omitted for brevity

 

As can be seen in the example above, the subsystems are chained to each other by binding requirements of one subsystem node template to other subsystem node templates that provide the respective capabilities. For example, the receiver requirement of the message queuing subsystem node template mq is bound to transaction processing subsystem node templates trans1 and trans2.

Subsystems can be parameterized by providing properties. In the listing above, for example, the IP address of the message queuing server is provided as property mq_service_ip to the transaction processing subsystems and the desired port for receiving messages is specified by means of the receiver_port property.

If attributes of the instantiated subsystems shall be obtained, this would be possible by using the get_attribute intrinsic function on the respective subsystem node templates.

2.11.2 Defining a subsystem (node) type

The types of subsystems that are required for a certain end-to-end service are defined as TOSCA node types as shown in the following example. Node templates of those node types can then be used in the end-to-end service template to define subsystems to be instantiated and chained for establishing the end-to-end service.

The realization of the defined node type will be given in the form of a whole separate service template as outlined in the following section.

 

Example 18 - Defining a TransactionSubsystem node type

tosca_definitions_version: tosca_simple_yaml_1_0

 

node_types:

  example.TransactionSubsystem:

    properties:

      mq_service_ip:

        type: string

      receiver_port:

        type: integer

    attributes:

      receiver_ip:

        type: string

      receiver_port:

        type: integer

    capabilities:

      message_receiver: tosca.capabilities.Endpoint

    requirements:

      - database_endpoint: tosca.capabilities.Endpoint.Database

 

Configuration parameters that shall be allowed for customizing the instantiation of any subsystem are defined as properties of the node type. In the current example, those are the properties mq_service_ip and receiver_port that had been used in the end-to-end service template in section 2.11.1.

Observable attributes of the resulting subsystem instances are defined as attributes of the node type. In the current case, those are the IP address of the message receiver as well as the actually allocated port of the message receiver endpoint.

2.11.3 Defining the details of a subsystem

The details of a subsystem, i.e. the software components and their hosting infrastructure, are defined as node templates and relationships in a service template. By means of substitution mappings that have been introduced in section 2.10.2, the service template is annotated to indicate to an orchestrator that it can be used as realization of a node template of certain type, as well as how characteristics of the node type are mapped to internal elements of the service template.

 

Figure 4: Defining subsystem details in a service template

Figure 1 illustrates how a transaction processing subsystem as outlined in the previous section could be defined in a service template. In this example, it simply consists of a custom application app of type SomeApp that is hosted on a web server websrv, which in turn is running on a compute node.

The application named app provides a capability to receive messages, which is bound to the message_receiver capability of the substitutable node type. It further requires access to a database, so the application’s database_endpoint requirement is mapped to the database_endpoint requirement of the TransactionSubsystem node type.

Properties of the TransactionSubsystem node type are used to customize the instantiation of a subsystem. Those properties can be mapped to any node template for which the author of the subsystem service template wants to expose configurability. In the current example, the application app and the web server middleware websrv get configured through properties of the TransactionSubsystem node type. All properties of that node type are defined as inputs of the service template. The input parameters in turn get mapped to node templates by means of get_input function calls in the respective sections of the service template.

Similarly, attributes of the whole subsystem can be obtained from attributes of particular node templates. In the current example, attributes of the web server and the hosting compute node will be exposed as subsystem attributes. All exposed attributes that are defined as attributes of the substitutable TransactionSubsystem node type are defined as outputs of the subsystem service template.

An outline of the subsystem service template is shown in the listing below. Note that this service template could be used for stand-alone deployment of a transaction processing system as well, i.e. it is not restricted just for use in substitution scenarios. Only the presence of the substitution_mappings metadata section in the topology_template enables the service template for substitution use cases.

 

Example 19 - Implementation of a TransactionSubsytem node type using substitution mappings

tosca_definitions_version: tosca_simple_yaml_1_0

 

topology_template:

  description: Template of a database including its hosting stack.

 

  inputs:

    mq_service_ip:

      type: string

      description: IP address of the message queuing server to receive messages from

    receiver_port:

      type: string

      description: Port to be used for receiving messages

    # other inputs omitted for brevity

 

  substitution_mappings:

    node_type: example.TransactionSubsystem

    capabilities:

      message_receiver: [ app, message_receiver ]

    requirements:

      database_endpoint: [ app, database ]

 

  node_templates:

    app:

      type: example.SomeApp

      properties:

        # properties omitted for brevity

      capabilities:

        message_receiver:

          properties:

            service_ip: { get_input: mq_service_ip }

            # other properties omitted for brevity

      requirements:

        - database:

            # details omitted for brevity

        - host: websrv

 

    websrv:

      type: tosca.nodes.WebServer

      properties:

        # properties omitted for brevity

      capabilities:

        data_endpoint:

          properties:

            port_name: { get_input: receiver_port }

            # other properties omitted for brevity

      requirements:

        - host: server

 

    server:

      type: tosca.nodes.Compute

      # details omitted for brevity

 

  outputs:

    receiver_ip:

      description: private IP address of the message receiver application

      value: { get_attribute: [ server, private_address ] }

    receiver_port:

      description: Port of the message receiver endpoint

      value: { get_attribute: [ app, app_endpoint, port ] }

2.12 Grouping node templates

In designing applications composed of several interdependent software components (or nodes) it is often desirable to manage these components as a named group.  This can provide an effective way of associating policies (e.g., scaling, placement, security or other) that orchestration tools can apply to all the components of group during deployment or during other lifecycle stages.

In many realistic scenarios it is desirable to include scaling capabilities into an application to be able to react on load variations at runtime. The example below shows the definition of a scaling web server stack, where a variable number of servers with apache installed on them can exist, depending on the load on the servers.

Example 20 - Grouping Node Templates for possible policy application

tosca_definitions_version: tosca_simple_yaml_1_0

 

description: Template for a scaling web server.

 

topology_template:

  inputs:

    # omitted here for brevity

 

  node_templates:

    apache:

      type: tosca.nodes.WebServer.Apache

      properties:

        # Details omitted for brevity

      requirements:

        - host: server

 

    server:

      type: tosca.nodes.Compute

        # details omitted for brevity

 

  groups:

    webserver_group:

      type: tosca.groups.Root

      members: [ apache, server ]

The example first of all uses the concept of grouping to express which components (node templates) need to be scaled as a unit – i.e. the compute nodes and the software on-top of each compute node. This is done by defining the webserver_group in the groups section of the template and by adding both the apache node template and the server node template as a member to the group.

Furthermore, a scaling policy is defined for the group to express that the group as a whole (i.e. pairs of server node and the apache component installed on top) should scale up or down under certain conditions.

In cases where no explicit binding between software components and their hosting compute resources is defined in a template, but only requirements are defined as has been shown in section 2.9, a provider could decide to place software components on the same host if their hosting requirements match, or to place them onto different hosts.

It is often desired, though, to influence placement at deployment time to make sure components get collocation or anti-collocated. This can be expressed via grouping and policies as shown in the example below.

Example 21 - Grouping nodes for anti-colocation policy application

tosca_definitions_version: tosca_simple_yaml_1_0

 

description: Template hosting requirements and placement policy.

 

topology_template:

  inputs:

    # omitted here for brevity

 

  node_templates:

    wordpress_server:

      type: tosca.nodes.WebServer

      properties:

        # omitted here for brevity

      requirements:

        - host:

            # Find a Compute node that fulfills these additional filter reqs.

            node_filter:

              capabilities:

                - host:

                    properties:

                      - mem_size: { greater_or_equal: 512 MB }

                      - disk_size: { greater_or_equal: 2 GB }

                - os:

                    properties:

                      - architecture: x86_64

                      - type: linux

 

    mysql:

      type: tosca.nodes.DBMS.MySQL

      properties:

        # omitted here for brevity

      requirements:

        - host:

            node: tosca.nodes.Compute

            node_filter:

              capabilities:

                - host:

                    properties:

                      - disk_size: { greater_or_equal: 1 GB }

                - os:

                    properties:

                      - architecture: x86_64

                      - type: linux

 

  groups:

    my_co_location_group:

      type: tosca.groups.Root

      members: [ wordpress_server, mysql ]

 

  policies:

    - my_anti_collocation_policy:

        type: my.policies.anticolocateion

        targets: [ my_co_location_group ]

        # For this example, specific policy definitions are considered

        # domain specific and are not included here

In the example above, both software components wordpress_server and mysql have similar hosting requirements. Therefore, a provider could decide to put both on the same server as long as both their respective requirements can be fulfilled. By defining a group of the two components and attaching an anti-collocation policy to the group it can be made sure, though, that both components are put onto different hosts at deployment time.

2.13 Using YAML Macros to simplify templates

The YAML 1.2 specification allows for defining of aliases, which allow for authoring a block of YAML (or node) once and indicating it is an “anchor” and then referencing it elsewhere in the same document as an “alias”.  Effectively, YAML parsers treat this as a “macro” and copy the anchor block’s code to wherever it is referenced.  Use of this feature is especially helpful when authoring TOSCA Service Templates where similar definitions and property settings may be repeated multiple times when describing a multi-tier application.

 

For example, an application that has a web server and database (i.e., a two-tier application) may be described using two Compute nodes (one to host the web server and another to host the database).  The author may want both Compute nodes to be instantiated with similar properties such as operating system, distribution, version, etc.

To accomplish this, the author would describe the reusable properties using a named anchor in the “dsl_definitions” section of the TOSCA Service Template and reference the anchor name as an alias in any Compute node templates where these properties may need to be reused.  For example:

Example 22 - Using YAML anchors in TOSCA templates

tosca_definitions_version: tosca_simple_yaml_1_0

 

description: >

  TOSCA simple profile that just defines a YAML macro for commonly reused Compute

  properties.

 

dsl_definitions:

  my_compute_node_props: &my_compute_node_props

    disk_size: 10 GB

    num_cpus: 1

    mem_size: 2 GB

 

topology_template:

  node_templates:

    my_server:

      type: Compute

      capabilities:

        - host:

            properties: *my_compute_node_props

 

    my_database:

      type: Compute

      capabilities:

        - host:

            properties: *my_compute_node_props

2.14 Passing information as inputs to Nodes and Relationships

It is possible for type and template authors to declare input variables within an inputs block on interfaces to nodes or relationships in order to pass along information needed by their operations (scripts).  These declarations can be scoped such as to make these variable values available to all operations on a node or relationships interfaces or to individual operations.  TOSCA orchestrators will make these values available as environment variables within the execution environments in which the scripts associated with lifecycle operations are run.

2.14.1 Example: declaring input variables for all operations on a single interface

node_templates: 

  wordpress:

    type: tosca.nodes.WebApplication.WordPress

    requirements:

      ...

      - database_endpoint: mysql_database

    interfaces:

      Standard:

        inputs:

          wp_db_port: { get_property: [ SELF, database_endpoint, port ] }

2.14.2 Example: declaring input variables for a single operation

node_templates: 

  wordpress:

    type: tosca.nodes.WebApplication.WordPress

    requirements:

      ...

      - database_endpoint: mysql_database

    interfaces:

      Standard:

        create: wordpress_install.sh

        configure:

          implementation: wordpress_configure.sh           

          inputs:

            wp_db_port: { get_property: [ SELF, database_endpoint, port ] }

In the case where an input variable name is defined at more than one scope within the same interfaces section of a node or template definition, the lowest (or innermost) scoped declaration would override those declared at higher (or more outer) levels of the definition.

2.14.3 Example: setting output variables to an attribute

node_templates:

  frontend: 
    type: MyTypes.SomeNodeType    

    attributes: 
      url: { get_operation_output: [ SELF, Standard, create, generated_url ] } 
    interfaces: 
      Standard: 
        create: 
          implementation: scripts/frontend/create.sh

 

In this example, the Standard create operation exposes / exports an environment variable named “generated_url” attribute which will be assigned to the WordPress node’s url attribute.

2.14.4 Example: passing output variables between operations

node_templates:

  frontend: 
    type: MyTypes.SomeNodeType 
    interfaces: 
      Standard: 
        create: 
          implementation: scripts/frontend/create.sh

        configure: 
          implementation: scripts/frontend/configure.sh 
          inputs: 
            data_dir: {
get_operation_output: [ SELF, Standard, create, data_dir ] }

In this example, the Standard lifecycle’s create operation exposes / exports an environment variable named “data_dir” which will be passed as an input to the Standard lifecycle’s configure operation.

2.15 Topology Template Model versus Instance Model

A TOSCA service template contains a topology template, which models the components of an application, their relationships and dependencies (a.k.a., a topology model) that get interpreted and instantiated by TOSCA Orchestrators.  The actual node and relationship instances that are created represent a set of resources distinct from the template itself, called a topology instance (model). The direction of this specification is to provide access to the instances of these resources for management and operational control by external administrators.  This model can also be accessed by an orchestration engine during deployment – i.e. during the actual process of instantiating the template in an incremental fashion, That is, the orchestrator can choose the order of resources to instantiate (i.e., establishing a partial set of node and relationship instances) and have the ability, as they are being created, to access them in order to facilitate instantiating the remaining resources of the complete topology template.

2.16 Using attributes implicitly reflected from properties

Most entity types in TOSCA (e.g., Node, Relationship, Requirement and Capability Types) have property definitions, which allow template authors to set the values for as inputs when these entities are instantiated by an orchestrator.  These property values are considered to reflect the desired state of the entity by the author.   Once instantiated, the actual values for these properties on the realized (instantiated) entity are obtainable via attributes on the entity with the same name as the corresponding property.

In other words, TOSCA orchestrators will automatically reflect (i.e., make available) any property defined on an entity making it available as an attribute of the entity with the same name as the property.

 

Use of this feature is shown in the example below where a source node named my_client, of type ClientNode, requires a connection to another node named my_server of type ServerNode.  As you can see, the ServerNode type defines a property named notification_port which defines a dedicated port number which instances of my_client may use to post asynchronous notifications to it during runtime.  In this case, the TOSCA Simple Profile assures that the notification_port property is implicitly reflected as an attribute in the my_server node (also with the name notification_port) when its node template is instantiated. 

 

Example 23 - Properties reflected as attributes

tosca_definitions_version: tosca_simple_yaml_1_0

                        

description: >

  TOSCA simple profile that shows how the (notification_port) property is reflected as an attribute and can be referenced elsewhere.

 

node_types:

  ServerNode:

    derived_from: SoftwareComponent

    properties:

      notification_port:

        type: integer

    capabilities:

      # omitted here for brevity

 

  ClientNode:

    derived_from: SoftwareComponent

    properties:

      # omitted here for brevity

    requirements:

      - server:

          capability: Endpoint

          node: ServerNode 

          relationship: ConnectsTo

 

topology_template:          

  node_templates:

 

    my_server:

      type: ServerNode 

      properties:

        notification_port: 8000

 

    my_client:

      type: ClientNode

      requirements:

        - server:

            node: my_server

            relationship: my_connection

 

  relationship_templates:

    my_connection:

      type: ConnectsTo

      interfaces:

        Configure:

          inputs:

            targ_notify_port: { get_attribute: [ TARGET, notification_port ] }

            # other operation definitions omitted here for brevity

 

Specifically, the above example shows that the ClientNode type needs the notification_port value anytime a node of ServerType is connected to it using the ConnectsTo relationship in order to make it available to its Configure operations (scripts). It does this by using the get_attribute function to retrieve the notification_port attribute from the TARGET node of the ConnectsTo relationship (which is a node of type ServerNode) and assigning it to an environment variable named targ_notify_port.

 

It should be noted that the actual port value of the notification_port attribute may or may not be the value 8000 as requested on the property; therefore, any node that is dependent on knowing its actual “runtime” value would use the get_attribute function instead of the get_property function. 

3      TOSCA Simple Profile definitions in YAML

Except for the examples, this section is normative and describes all of the YAML grammar, definitions and block structure for all keys and mappings that are defined for the TOSCA Version 1.0 Simple Profile specification that are needed to describe a TOSCA Service Template (in YAML).

3.1 TOSCA Namespace URI and alias

The following TOSCA Namespace URI alias and TOSCA Namespace Alias are reserved values which SHALL be used when identifying the TOSCA Simple Profile version 1.0 specification.

Namespace Alias

Namespace URI

Specification Description

tosca_simple_yaml_1_0

http://docs.oasis-open.org/tosca/ns/simple/yaml/1.0

The TOSCA Simple Profile v1.0 (YAML) target namespace and namespace alias.

3.1.1 TOSCA Namespace prefix

The following TOSCA Namespace prefix is a reserved value and SHALL be used to reference the default TOSCA Namespace URI as declared in TOSCA Service Templates.

Namespace Prefix

Specification Description

tosca

The reserved TOSCA Simple Profile Specification prefix that can be associated with the default TOSCA Namespace URI

3.1.2 TOSCA Namespacing in TOSCA Service Templates

In the TOSCA Simple Profile, TOSCA Service Templates MUST always have, as the first line of YAML, the keyword “tosca_definitions_version” with an associated TOSCA Namespace Alias value.  This single line accomplishes the following:

1.       Establishes the TOSCA Simple Profile Specification version whose grammar MUST be used to parse and interpret the contents for the remainder of the TOSCA Service Template.

2.       Establishes the default TOSCA Namespace URI and Namespace Prefix for all types found in the document that are not explicitly namespaced.

3.       Automatically imports (without the use of an explicit import statement) the normative type definitions (e.g., Node, Relationship, Capability, Artifact, etc.) that are associated with the TOSCA Simple Profile Specification the TOSCA Namespace Alias value identifies.

4.       Associates the TOSCA Namespace URI and Namespace Prefix to the automatically imported TOSCA type definitions.

3.1.3 Rules to avoid namespace collisions

TOSCA Simple Profiles allows template authors to declare their own types and templates and assign them simple names with no apparent namespaces.  Since TOSCA Service Templates can import other service templates to introduce new types and topologies of templates that can be used to provide concrete implementations (or substitute) for abstract nodes.  Rules are needed so that TOSCA Orchestrators know how to avoid collisions and apply their own namespaces when import and nesting occur.

3.1.3.1 Additional Requirements

·         Since TOSCA Service Templates can import (or substitute in) other Service Templates, TOSCA Orchestrators and tooling will encounter the “tosca_definitions_version” statement for each imported template.  In these cases, the following additional requirements apply:

o   Imported type definitions with the same Namespace URI, local name and version SHALL be equivalent.

o   If different values of the “tosca_definitions_version” are encountered, their corresponding type definitions MUST be uniquely identifiable using their corresponding Namespace URI using a different Namespace prefix.

·         Duplicate local names (i.e., within the same Service Template SHALL be considered an error.  These include, but are not limited to duplicate names found for the following definitions:

o   Repositories (repositories)

o   Data Types (data_types)

o   Node Types (node_types)

o   Relationship Types (relationship_types)

o   Capability Types (capability_types)

o   Artifact Types (artifact_types)

o   Interface Types (interface_types)

·         Duplicate Template names within a Service Template’s Topology Template SHALL be considered an error.  These include, but are not limited to duplicate names found for the following template types:

o   Node Templates (node_templates)

o   Relationship Templates (relationship_templates)

o   Inputs (inputs)

o   Outputs (outputs)

o   Groups (groups)

·         Duplicate names for the following keynames within Types or Templates SHALL be considered an error.  These include, but are not limited to duplicate names found for the following keynames:

o   Properties (properties)

o   Attributes (attributes)

o   Artifacts (artifacts)

o   Requirements (requirements)

o   Capabilities (capabilities)

o   Interfaces (interfaces)

3.2 Parameter and property types

This clause describes the primitive types that are used for declaring normative properties, parameters and grammar elements throughout this specification.

3.2.1 Referenced YAML Types

Many of the types we use in this profile are built-in types from the YAML 1.2 specification (i.e., those identified by the “tag:yaml.org,2002” version tag) [YAML-1.2].

The following table declares the valid YAML type URIs and aliases that SHALL be used when possible when defining parameters or properties within TOSCA Service Templates using this specification:

Valid aliases

Type URI

string

tag:yaml.org,2002:str (default)

integer

tag:yaml.org,2002:int

float

tag:yaml.org,2002:float

boolean

tag:yaml.org,2002:bool (i.e., a value either ‘true’ or ‘false’)

timestamp

tag:yaml.org,2002:timestamp  [YAML-TS-1.1]

null

tag:yaml.org,2002:null

3.2.1.1 Notes

·         The “string” type is the default type when not specified on a parameter or property declaration.

·         While YAML supports further type aliases, such as “str” for “string”, the TOSCA Simple Profile specification promotes the fully expressed alias name for clarity.

3.2.2 TOSCA version

TOSCA supports the concept of “reuse” of type definitions, as well as template definitions which could be version and change over time.  It is important to provide a reliable, normative means to represent a version string which enables the comparison and management of types and templates over time. Therefore, the TOSCA TC intends to provide a normative version type (string) for this purpose in future Working Drafts of this specification.

Shorthand Name

version

Type Qualified Name

tosca:version

3.2.2.1 Grammar

TOSCA version strings have the following grammar:

<major_version>.<minor_version>[.<fix_version>[.<qualifier>[-<build_version] ] ]

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

·         major_version: is a required integer value greater than or equal to 0 (zero)

·         minor_version: is a required integer value greater than or equal to 0 (zero).

·         fix_version: is an optional integer value greater than or equal to 0 (zero).

·         qualifier: is an optional string that indicates a named, pre-release version of the associated code that has been derived from the version of the code identified by the combination major_version, minor_version and fix_version numbers.

·         build_version: is an optional integer value greater than or equal to 0 (zero) that can be used to further qualify different build versions of the code that has the same qualifer_string.

3.2.2.2 Version Comparison

·         When comparing TOSCA versions, all component versions (i.e., major, minor and fix) are compared in sequence from left to right.

·         TOSCA versions that include the optional qualifier are considered older than those without a qualifier.

·         TOSCA versions with the same major, minor, and fix versions and have the same qualifier string, but with different build versions can be compared based upon the build version.

·         Qualifier strings are considered domain-specific. Therefore,  this specification makes no recommendation on how to compare TOSCA versions with the same major, minor and fix versions, but with different qualifiers strings and simply considers them different named branches derived from the same code.

3.2.2.3 Examples

Example of a version with

# basic version strings

6.1

2.0.1

 

# version string with optional qualifier

3.1.0.beta

 

# version string with optional qualifier and build version

1.0.0.alpha-10

3.2.2.4 Notes

·         [Maven-Version] The TOSCA version type is compatible with the Apache Maven versioning policy.

3.2.2.5 Additional Requirements

·         A version value of zero (i.e., ‘0’, ‘0.0’, or ‘0.0.0’) SHALL indicate there no version provided.

·         A version value of zero used with any qualifiers SHALL NOT be valid.

3.2.3 TOCSA range type

The range type can be used to define numeric ranges with a lower and upper boundary. For example, this allows for specifying a range of ports to be opened in a firewall.

Shorthand Name

range

Type Qualified Name

tosca:range

3.2.3.1 Grammar

TOSCA range values have the following grammar:

[<lower_bound>, <upper_bound>]  

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

·         lower_bound: is a required integer value that denotes the lower boundary of the range.

·         upper_bound: is a required integer value that denotes the upper boundary of the range. This value MUST be greater than lower_bound.

3.2.3.2 Keywords

The following Keywords may be used in the TOSCA range type:

Keyword

Applicable Types

Description

UNBOUNDED

scalar

Used to represent an unbounded upper bounds (positive) value in a set for a scalar type.

3.2.3.3 Examples

Example of a node template property with a range value:

# numeric range between 1 and 100

a_range_property: [ 1, 100 ]

 

# a property that has allows any number 0 or greater

num_connections: [ 0, UNBOUNDED ]

3.2.4 TOSCA list type

The list type allows for specifying multiple values for a parameter of property. For example, if an application allows for being configured to listen on multiple ports, a list of ports could be configured using the list data type.

Note that entries in a list for one property or parameter must be of the same type. The type (for simple entries) or schema (for complex entries) is defined by the entry_schema attribute of the respective property definition, attribute definitions, or input or output parameter definitions.

Shorthand Name

list

Type Qualified Name

tosca:list

3.2.4.1 Grammar

TOSCA lists are essentially normal YAML lists with the following grammars:

3.2.4.1.1  Square bracket notation

 [ <list_entry_1>, <list_entry_2>, ... ]

3.2.4.1.2 Bulleted (sequenced) list notation

- <list_entry_1>

- ...

- <list_entry_n>

In the above grammars, the pseudo values that appear in angle brackets have the following meaning:

·         <list_entry_*>: represents one entry of the list.

3.2.4.2 Declaration Examples

3.2.4.2.1 List declaration using a simple type

The following example shows a list declaration with an entry schema based upon a simple integer type (which has additional constraints):

<some_entity>:

  ...

  properties:  

    listen_ports:

      type: list

      entry_schema:

        description: listen port entry (simple integer type)

        type: integer

        constraints:

          - max_length: 128

3.2.4.2.2 List declaration using a complex type

The following example shows a list declaration with an entry schema based upon a complex type:

<some_entity>:

  ...

  properties:  

    products:

      type: list

      entry_schema:

        description: Product information entry (complex type) defined elsewhere

        type: ProductInfo

3.2.4.3 Definition Examples

These examples show two notation options for defining lists:

·         A single-line option which is useful for only short lists with simple entries.

·         A multi-line option where each list entry is on a separate line; this option is typically useful or more readable if there is a large number of entries, or if the entries are complex.

3.2.4.3.1 Square bracket notation

listen_ports: [ 80, 8080 ]

3.2.4.3.2 Bulleted list notation

listen_ports:

  - 80

  - 8080

3.2.5 TOSCA map type

The map type allows for specifying multiple values for a parameter of property as a map. In contrast to the list type, where each entry can only be addressed by its index in the list, entries in a map are named elements that can be addressed by their keys.

Note that entries in a map for one property or parameter must be of the same type. The type (for simple entries) or schema (for complex entries) is defined by the entry_schema attribute of the respective property definition, attribute definition, or input or output parameter definition.

Shorthand Name

map

Type Qualified Name

tosca:map

3.2.5.1 Grammar

TOSCA maps are normal YAML dictionaries with following grammar:

3.2.5.1.1 Single-line grammar

{ <entry_key_1>: <entry_value_1>, ..., <entry_key_n>: <entry_value_n> }

...

<entry_key_n>: <entry_value_n>

3.2.5.1.2 Multi-line grammar

<entry_key_1>: <entry_value_1>

...

<entry_key_n>: <entry_value_n>

In the above grammars, the pseudo values that appear in angle brackets have the following meaning:

·         entry_key_*: is the required key for an entry in the map

·         entry_value_*: is the value of the respective entry in the map

3.2.5.2 Declaration Examples

3.2.5.2.1 Map declaration using a simple type

The following example shows a map with an entry schema definition based upon an existing string type (which has additional constraints):

<some_entity>:

  ...

  properties:  

    emails:

      type: map

      entry_schema:

        description: basic email address

        type: string

        constraints:

          - max_length: 128

3.2.5.2.2 Map declaration using a complex type

The following example shows a map with an entry schema definition for contact information:

<some_entity>:

  ...

  properties:  

    contacts:

      type: map

      entry_schema:

        description: simple contact information

        type: ContactInfo

3.2.5.3 Definition Examples

These examples show two notation options for defining maps:

·         A single-line option which is useful for only short maps with simple entries.

·         A multi-line option where each map entry is on a separate line; this option is typically useful or more readable if there is a large number of entries, or if the entries are complex.

3.2.5.3.1 Single-line notation

# notation option for shorter maps

user_name_to_id_map: { user1: 1001, user2: 1002 }

3.2.5.3.2 Multi-line notation

# notation for longer maps

user_name_to_id_map:

  user1: 1001

  user2: 1002

3.2.6 TOCSA scalar-unit type

The scalar-unit type can be used to define scalar values along with a unit from the list of recognized units provided below.

3.2.6.1 Grammar

TOSCA scalar-unit typed values have the following grammar:

<scalar> <unit>  

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

·         scalar: is a required scalar value.

·         unit: is a required unit value. The unit value MUST be type-compatible with the scalar.

3.2.6.2 Additional requirements

·         Whitespace: any number of spaces (including zero or none) SHALL be allowed between the scalar value and the unit value.

·         It SHALL be considered an error if either the scalar or unit portion is missing on a property or attribute declaration derived from any scalar-unit type.

·         When performing constraint clause evaluation on values of the scalar-unit type, both the scalar value portion and unit value portion SHALL be compared together (i.e., both are treated as a single value). For example, if we have a property called storage_size. which is of type scalar-unit, a valid range constraint would appear as follows:

o    storage_size: in_range [ 4 GB, 20 GB ]

where storage_size’s range would be evaluated using both the numeric and unit values (combined together), in this case ‘4 GB’ and ’20 GB’.

3.2.6.3 Concrete Types

Shorthand Names

scalar-unit.size, scalar-unit.size

Type Qualified Names

tosca:scalar-unit.size, tosca:scalar-unit.time

 

The scalar-unit type grammar is abstract and has two recognized concrete types in TOSCA:

·         scalar-unit.size – used to define properties that have scalar values measured in size units.

·         scalar-unit.time – used to define properties that have scalar values measured in size units.

·         scalar-unit.frequency – used to define properties that have scalar values measured in units per second.

These types and their allowed unit values are defined below.

3.2.6.4 scalar-unit.size

3.2.6.4.1 Recognized Units

Unit

Usage

Description

B

size

byte

kB

size

kilobyte (1000 bytes)

KiB

size

kibibytes (1024 bytes)

MB

size

megabyte (1000000 bytes)

MiB

size

mebibyte (1048576 bytes)

GB

size

gigabyte (1000000000 bytes)

GiB

size

gibibytes (1073741824 bytes)

TB

size

terabyte (1000000000000 bytes)

TiB

size

tebibyte (1099511627776 bytes)

3.2.6.4.2 Examples

# Storage size in Gigabytes

properties:

  storage_size: 10 GB

3.2.6.4.3 Notes

·         The unit values recognized by TOSCA Simple Profile for size-type units are based upon a subset of those defined by GNU at http://www.gnu.org/software/parted/manual/html_node/unit.html, which is a non-normative reference to this specification.

·         TOSCA treats these unit values as case-insensitive (e.g., a value of ‘kB’, ‘KB’ or ‘kb’ would be equivalent), but it is considered best practice to use the case of these units as prescribed by GNU.

·         Some Cloud providers may not support byte-level granularity for storage size allocations. In those cases, these values could be treated as desired sizes and actual allocations would be based upon individual provider capabilities.

3.2.6.5 scalar-unit.time

3.2.6.5.1 Recognized Units

Unit

Usage

Description

d

time

days

h

time

hours

m

time

minutes

s

time

seconds

ms

time

milliseconds

us

time

microseconds

ns

time

nanoseconds

3.2.6.5.2 Examples

# Response time in milliseconds

properties:

  respone_time: 10 ms

3.2.6.5.3 Notes

·         The unit values recognized by TOSCA Simple Profile for time-type units are based upon a subset of those defined by International System of Units whose recognized abbreviations are defined within the following reference: 

o    http://www.ewh.ieee.org/soc/ias/pub-dept/abbreviation.pdf

o    This document is a non-normative reference to this specification and intended for publications or grammars enabled for Latin characters which are not accessible in typical programming languages

3.2.6.6 scalar-unit.frequency

3.2.6.6.1 Recognized Units

Unit

Usage

Description

Hz

frequency

Hertz, or Hz. equals one cycle per second.

kHz

frequency

Kilohertz, or kHz, equals to 1,000 Hertz

MHz

frequency

Megahertz, or MHz, equals to 1,000,000 Hertz or 1,000 kHz

GHz

frequency

Gigahertz, or GHz, equals to 1,000,000,000 Hertz, or 1,000,000 kHz, or 1,000 MHz.

3.2.6.6.2 Examples

# Processor raw clock rate

properties:

  clock_rate: 2.4 GHz

3.2.6.6.3 Notes

·         The value for Hertz (Hz) is the International Standard Unit (ISU) as described by the Bureau International des Poids et Mesures (BIPM) in the SI Brochure: The International System of Units (SI) [8th edition, 2006; updated in 2014]”, http://www.bipm.org/en/publications/si-brochure/

3.3 Normative values

3.3.1 Node States

As components (i.e., nodes) of TOSCA applications are deployed, instantiated and orchestrated over their lifecycle using normative lifecycle operations (see section 5.7 for normative lifecycle definitions) it is important define normative values for communicating the states of these components normatively between orchestration and workflow engines and any managers of these applications.

The following table provides the list of recognized node states for TOSCA Simple Profile that would be set by the orchestrator to describe a node instance’s state:

Node State

Value

Transitional

Description

initial

no

Node is not yet created.  Node only exists as a template definition.

creating

yes

Node is transitioning from initial state to created state.

created

no

Node software has been installed.

configuring

yes

Node is transitioning from created state to configured state.

configured

no

Node has been configured prior to being started.

starting

yes

Node is transitioning from configured state to started state.

started

no

Node is started.

stopping

yes

Node is transitioning from its current state to a configured state.

deleting

yes

Node is transitioning from its current state to one where it is deleted and its state is no longer tracked by the instance model.

error

no

Node is in an error state.

3.3.2 Relationship States

Similar to the Node States described in the previous section, Relationships have state relative to their (normative) lifecycle operations.

The following table provides the list of recognized relationship states for TOSCA Simple Profile that would be set by the orchestrator to describe a node instance’s state:

Node State

Value

Transitional

Description

initial

no

Relationship is not yet created.  Relationship only exists as a template definition.

3.3.2.1 Notes

·         Additional states may be defined in future versions of the TOSCA Simple Profile in YAML specification.

3.3.3 Directives

There are currently no directive values defined for this version of the TOSCA Simple Profile.

3.3.4 Network Name aliases

The following are recognized values that may be used as aliases to reference types of networks within an application model without knowing their actual name (or identifier) which may be assigned by the underlying Cloud platform at runtime.

Alias value

Description

PRIVATE

An alias used to reference the first private network within a property or attribute of a Node or Capability which would be assigned to them by the underlying platform at runtime.

 

A private network contains IP addresses and ports typically used to listen for incoming traffic to an application or service from the Intranet and not accessible to the public internet.

PUBLIC

An alias used to reference the first public network within a property or attribute of a Node or Capability which would be assigned to them by the underlying platform at runtime.

 

A public network contains IP addresses and ports typically used to listen for incoming traffic to an application or service from the Internet.

3.3.4.1 Usage

These aliases would be used in the tosca.capabilities.Endpoint Capability type (and types derived from it) within the network_name field for template authors to use to indicate the type of network the Endpoint is supposed to be assigned an IP address from.

3.4 TOSCA Metamodel

This section defines all modelable entities that comprise the TOSCA Version 1.0 Simple Profile specification along with their keynames, grammar and requirements.

3.4.1 Required Keynames

The TOSCA metamodel includes complex types (e.g., Node Types, Relationship Types, Capability Types, Data Types, etc.) each of which  include their own list of reserved keynames that are sometimes marked as required.  These types may be used to derive other types.  These derived types (e.g., child types) do not have to provide required keynames as long as they have been specified in the type they have been derived from (i.e., their parent type).

3.5 Reusable modeling definitions

3.5.1 Description definition

This optional element provides a means include single or multiline descriptions within a TOSCA Simple Profile template as a scalar string value.

3.5.1.1 Keyname

The following keyname is used to provide a description within the TOSCA Simple Profile specification:

description

3.5.1.2 Grammar

Description definitions have the following grammar:

description: <string>

3.5.1.3 Examples

Simple descriptions are treated as a single literal that includes the entire contents of the line that immediately follows the description key:

description: This is an example of a single line description (no folding).

The YAML “folded” style may also be used for multi-line descriptions which “folds” line breaks as space characters.

description: >

  This is an example of a multi-line description using YAML. It permits for line       

  breaks for easier readability...

 

  if needed.  However, (multiple) line breaks are folded into a single space  

  character when processed into a single string value.

3.5.1.4 Notes

3.5.2 Constraint clause

A constraint clause defines an operation along with one or more compatible values that can be used to define a constraint on a property or parameter’s allowed values when it is defined in a TOSCA Service Template or one of its entities.

3.5.2.1 Operator keynames

The following is the list of recognized operators (keynames) when defining constraint clauses:

Operator

Type

Value Type

Description

equal

scalar

any

Constrains a property or parameter to a value equal to (‘=’) the value declared.

greater_than

scalar

comparable

Constrains a property or parameter to a value greater than (‘>’) the value declared.

greater_or_equal

scalar

comparable

Constrains a property or parameter to a value greater than or equal to (‘>=’) the value declared.

less_than

scalar

comparable

Constrains a property or parameter to a value less than (‘<’) the value declared.

less_or_equal

scalar

comparable

Constrains a property or parameter to a value less than or equal to (‘<=’) the value declared.

in_range

dual scalar

comparable, range

Constrains a property or parameter to a value in range of (inclusive) the two values declared.

 

Note: subclasses or templates of types that declare a property with the in_range constraint MAY only further restrict the range specified by the parent type.

valid_values

list

any

Constrains a property or parameter to a value that is in the list of declared values.

length

scalar

string, list, map

Constrains the property or parameter to a value of a given length.

min_length

scalar

string, list, map

Constrains the property or parameter to a value to a minimum length.

max_length

scalar

string, list, map

Constrains the property or parameter to a value to a maximum length.

pattern

regex

string

Constrains the property or parameter to a value that is allowed by the provided regular expression.


Note: Future drafts of this specification will detail the use of regular expressions and reference an appropriate standardized grammar.

3.5.2.1.1 Comparable value types

In the Value Type column above, an entry of “comparable” includes integer, float, timestamp, string, version, and scalar-unit types while an entry of “any” refers to any type allowed in the TOSCA simple profile in YAML.

3.5.2.2 Additional Requirements

·         If no operator is present for a simple scalar-value on a constraint clause, it SHALL be interpreted as being equivalent to having the “equal” operator provided; however, the “equal” operator may be used for clarity when expressing a constraint clause.

·         The “length” operator SHALL be interpreted mean “size” for set types (i.e., list, map, etc.).

3.5.2.3 Grammar

Constraint clauses have one of the following grammars:

# Scalar grammar

<operator>: <scalar_value>

 

# Dual scalar grammar

<operator>: [ <scalar_value_1>, <scalar_value_2> ]

 

# List grammar

<operator> [ <value_1>, <value_2>, ..., <value_n> ]

 

# Regular expression (regex) grammar

pattern: <regular_expression_value>

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

·         operator: represents a required operator from the specified list shown above (see section 3.5.2.1 “Operator keynames”).

·         scalar_value, scalar_value_*: represents a required scalar (or atomic quantity) that can hold only one value at a time.  This will be a value of a primitive type, such as an integer or string that is allowed by this specification.

·         value_*: represents a required value of the operator that is not limited to scalars.

·         reqular_expression_value: represents a regular expression (string) value.

3.5.2.4 Examples

Constraint clauses used on parameter or property definitions:

# equal

equal: 2

 

# greater_than

greater_than: 1

 

# greater_or_equal

greater_or_equal: 2

 

# less_than

less_than: 5

 

# less_or_equal

less_or_equal: 4

 

# in_range

in_range: [ 1, 4 ]

 

# valid_values

valid_values: [ 1, 2, 4 ]

# specific length (in characters)

length: 32

 

# min_length (in characters)

min_length: 8

 

# max_length (in characters)

max_length: 64

3.5.3 Property Filter definition

A property filter definition defines criteria, using constraint clauses, for selection of a TOSCA entity based upon it property values.

3.5.3.1 Grammar

Property filter definitions have one of the following grammars:

3.5.3.1.1 Short notation:

The following single-line grammar may be used when only a single constraint is needed on a property:

<property_name>: <property_constraint_clause>

3.5.3.1.2 Extended notation:

The following multi-line grammar may be used when multiple constraints are needed on a property:

<property_name>:

  - <property_constraint_clause_1>

  - ...

  - <property_constraint_clause_n>

In the above grammars, the pseudo values that appear in angle brackets have the following meaning:

·         property_name: represents the name of property that would be used to select a property definition with the same name (property_name) on a TOSCA entity (e.g., a Node Type, Node Template, Capability Type, etc.). 

·         property_constraint_clause_*: represents constraint clause(s) that would be used to filter entities based upon the named property’s value(s).

3.5.3.2 Additional Requirements

·         Property constraint clauses must be type compatible with the property definitions (of the same name) as defined on the target TOSCA entity that the clause would be applied against.

3.5.4 Node Filter definition

A node filter definition defines criteria for selection of a TOSCA Node Template based upon the template’s property values, capabilities and capability properties.

3.5.4.1 Keynames

The following is the list of recognized keynames for a TOSCA node filter definition:

Keyname

Required

Type

Description

properties

no

list of

property filter definition

An optional sequenced list of property filters that would be used to select (filter) matching TOSCA entities (e.g., Node Template, Node Type, Capability Types, etc.) based upon their property definitions’ values.

capabilities

no

list of capability names or capability type names

An optional sequenced list of capability names or types that would be used to select (filter) matching TOSCA entities based upon their existence.

3.5.4.2 Additional filtering on named Capability properties

Capabilities used as filters often have their own sets of properties which also can be used to construct a filter.

Keyname

Required

Type

Description

<capability   name_or_type>  

  name>:

   properties

no

list of

property filter definitions

An optional sequenced list of property filters that would be used to select (filter) matching TOSCA entities (e.g., Node Template, Node Type, Capability Types, etc.) based upon their capabilities’ property definitions’ values.

3.5.4.3 Grammar

Node filter definitions have following grammar:

<filter_name>:

  properties:

    - <property_filter_def_1>

    - ...

    - <property_filter_def_n>

  capabilities:

    - <capability_name_or_type_1>:

        properties:

          - <cap_1_property_filter_def_1>

          - ...

          - <cap_m_property_filter_def_n>

    -  ...

    - <capability_name_or_type_n>:

        properties:

          - <cap_1_property_filter_def_1>

          - ...

          - <cap_m_property_filter_def_n>

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

·         property_filter_def_*: represents a property filter definition that would be used to select (filter) matching TOSCA entities (e.g., Node Template, Node Type, Capability Types, etc.) based upon their property definitions’ values. 

·         capability_name_or_type_*: represents the type or name of a capability that would be used to select (filter) matching TOSCA entities based upon their existence.

·         cap_*_property_def_*: represents a property filter definition that would be used to select (filter) matching TOSCA entities (e.g., Node Template, Node Type, Capability Types, etc.) based upon their capabilities’ property definitions’ values.

3.5.4.4 Additional requirements

·         TOSCA orchestrators SHALL search for matching capabilities listed on a target filter by assuming the capability name is first a symbolic name and secondly it is a type name (in order to avoid namespace collisions).

3.5.4.5 Example

The following example is a filter that would be used to select a TOSCA Compute node based upon the values of its defined capabilities. Specifically, this filter would select Compute nodes that supported a specific range of CPUs (i.e., num_cpus value between 1 and 4) and memory size (i.e., mem_size of 2 or greater) from its declared “host” capability. 

                                                                                                     

my_node_template:

  # other details omitted for brevity

  requirements:

    - host:

        node_filter:

          capabilities:

            # My “host” Compute node needs these properties:     

            - host:

                properties:

                  - num_cpus: { in_range: [ 1, 4 ] }

                  - mem_size: { greater_or_equal: 512 MB }

3.5.5 Repository definition

A repository definition defines a named external repository which contains deployment and implementation artifacts that are referenced within the TOSCA Service Template.

3.5.5.1 Keynames

The following is the list of recognized keynames for a TOSCA repository definition:

Keyname

Required

Type

Constraints

Description

description

no

description

None

The optional description for the repository.

url

yes

string

None

The required URL or network address used to access the repository.

credential

no

Credential

None

The optional Credential used to authorize access to the repository.

3.5.5.2 Grammar

Repository definitions have one the following grammars:

3.5.5.2.1 Single-line grammar (no credential):

<repository_name>: <repository_address>

3.5.5.2.2 Multi-line grammar

<repository_name>:

  description: <repository_description>

  url: <repository_address>

  credential: <authorization_credential>

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

·         repository_name: represents the required symbolic name of the repository as a string.

·         repository_description: contains an optional description of the repository.

·         repository_address: represents the required URL of the repository as a string.

·         authorization_credential: represents the optional credentials (e.g., user ID and password) used to authorize access to the repository.

3.5.5.3 Example

The following represents a repository definition:

repositories:

  my_code_repo:

    description: My project’s code repository in GitHub

    url: https://github.com/my-project/

3.5.6 Artifact definition

An artifact definition defines a named, typed file that can be associated with Node Type or Node Template and used by orchestration engine to facilitate deployment and implementation of interface operations.

3.5.6.1 Keynames

The following is the list of recognized keynames for a TOSCA artifact definition when using the extended notation:

Keyname

Required

Type

Description

type

yes

string

The required artifact type for the artifact definition.

file

yes

string

The required URI string (relative or absolute) which can be used to locate the artifact’s file.

repository

no

string

The optional name of the repository definition which contains the location of the external repository that contains the artifact.  The artifact is expected to be referenceable by its file URI within the repository.

description

no

description

The optional description for the artifact definition.

deploy_path

no

string

The file path the associated file would be deployed into within the target node’s container.

3.5.6.2 Grammar

Artifact definitions have one of the following grammars:

3.5.6.2.1 Short notation

The following single-line grammar may be used when the artifact’s type and mime type can be inferred from the file URI:

<artifact_name>: <artifact_file_URI>

3.5.6.2.2 Extended notation:

The following multi-line grammar may be used when the artifact’s definition’s type and mime type need to be explicitly declared:

<artifact_name>:

  description: <artifact_description>

  type: <artifact_type_name>

  file: <artifact_file_URI>

  repository: <artifact_repository_name>

  deploy_path: <file_deployment_path>

In the above grammars, the pseudo values that appear in angle brackets have the following meaning:

·         artifact_name: represents the required symbolic name of the artifact as a string.

·         artifact_description: represents the optional description for the artifact.

·         artifact_type_name: represents the required artifact type the artifact definition is based upon.

·         artifact_file_URI: represents the required URI string (relative or absolute) which can be used to locate the artifact’s file.

·         artifact_repository_name: represents the optional name of the repository definition to use to retrieve the associated artifact (file) from.

·         file_deployement_path: represents the optional path the artifact_file_URI would be copied into within the target node’s container.

3.5.6.3 Example

The following represents an artifact definition:

my_file_artifact: ../my_apps_files/operation_artifact.txt

3.5.7 Import definition

An import definition is used within a TOSCA Service Template to locate and uniquely name another TOSCA Service Template file which has type and template definitions to be imported (included) and referenced within another Service Template.

3.5.7.1 Keynames

The following is the list of recognized keynames for a TOSCA import definition:

Keyname

Required

Type

Constraints

Description

file

yes

string

None

The required symbolic name for the imported file.

repository

no

string

None

The optional symbolic name of the repository definition where the imported file can be found as a string.

namespace_uri

no

string

None

The optional namespace URI to that will be applied to type definitions found within the imported file as a string.

namespace_prefix

no

string

None

The optional namespace prefix (alias) that will be used to indicate the namespace_uri when forming a qualified name (i.e., qname) when referencing type definitions from the imported file.

3.5.7.2 Grammar

Import definitions have one the following grammars:

3.5.7.2.1 Single-line grammar:

<import_name>: <file_URI>

3.5.7.2.2 Multi-line grammar

<import_name>:

  file: <file_URI>

  repository: <repository_name>

  namespace_uri: <definition_namespace_uri>

  namespace_prefix: <definition_namespace_prefix>

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

·         import_name: represents the required symbolic name for the imported file as a string.

·         file_uri: contains the required name (i.e., URI) of the file to be imported as a string.

·         repository_name: represents the optional symbolic name of the repository definition where the imported file can be found as a string.

·         namespace_uri: represents the optional namespace URI to that will be applied to type definitions found within the imported file as a string.

·         namespace_prefix: represents the optional namespace prefix (alias) that will be used to indicate the namespace_uri when forming a qualified name (i.e., qname) when referencing type definitions from the imported file as a string.

3.5.7.3 Example

The following represents how import definitions would be used for the imports keyname within a TOSCA Service Template:

imports:

  - some_definition_file: path1/path2/some_defs.yaml

  - another_definition_file:

      file: path1/path2/file2.yaml

      repository: my_service_catalog

      namespace_uri: http://mycompany.com/tosca/1.0/platform

      namespace_prefix: mycompany

3.5.8 Property definition

A property definition defines a named, typed value and related data that can be associated with an entity defined in this specification (e.g., Node Types, Relationship Types, Capability Types, etc.).  Properties are used by template authors to provide input values to TOSCA entities which indicate their “desired state” when they are instantiated.  The value of a property can be retrieved using the get_property function within TOSCA Service Templates.

3.5.8.1.1 Attribute and Property reflection

The actual state of the entity, at any point in its lifecycle once instantiated, is reflected by Attribute definitions.  TOSCA orchestrators automatically create an attribute for every declared property (with the same symbolic name) to allow introspection of both the desired state (property) and actual state (attribute).

3.5.8.2 Keynames

The following is the list of recognized keynames for a TOSCA property definition:

Keyname

Required

Type

Constraints

Description

type

yes

string

None

The required data type for the property.

description

no

description

None

The optional description for the property.

required

no

 

boolean

default: true

An optional key that declares a property as required (true) or not (false).

default

no

<any>

None

An optional key that may provide a value to be used as a default if not provided by another means.

status

no

 

string

default: supported

The optional status of the property relative to the specification or implementation. See table below for valid values.

constraints

no

list of

constraint clauses

None

The optional list of sequenced constraint clauses for the property.

entry_schema

no

string

None

The optional key that is used to declare the name of the Datatype definition for entries of set types such as the TOSCA list or map.

3.5.8.3 Status values

The following property status values are supported:

Value

Description

supported

Indicates the property is supported.  This is the default value for all property definitions.

unsupported

Indicates the property is not supported.

experimental

Indicates the property is experimental and has no official standing.

deprecated

Indicates the property has been deprecated by a new specification version.

3.5.8.4 Grammar

Named property definitions have the following grammar:

<property_name>:

  type: <property_type>

  description: <property_description>

  required: <property_required>

  default: <default_value>

  status: <status_value>

  constraints:

    - <property_constraints>

  entry_schema:

    description: <entry_description>

    type: <entry_type>

    constraints:

      - <entry_constraints>

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

·         property_name: represents the required symbolic name of the property as a string.

·         property_description: represents the optional description of the property.

·         property_type: represents the required data type of the property.

·         property_required: represents an optional boolean value (true or false) indicating whether or not the property is required.  If this keyname is not present on a property definition, then the property SHALL be considered required (i.e., true) by default.

·         default_value: contains a type-compatible value that may be used as a default if not provided by another means.

·         status_value: a string that contains a keyword that indicates the status of the property relative to the specification or implementation. 

·         property_constraints: represents the optional sequenced list of one or more constraint clauses on the property definition.

·         entry_description: represents the optional description of the entry schema.

·         entry_type: represents the required type name for entries in a list or map  property type.

·         entry_constraints: represents the optional sequenced list of one or more constraint clauses on entries in a list or map property type.

3.5.8.5 Additional Requirements

·         Implementations of the TOSCA Simple Profile SHALL automatically reflect (i.e., make available) any property defined on an entity as an attribute of the entity with the same name as the property.

·         A property SHALL be considered required by default (i.e., as if the required keyname on the definition is set to true) unless the definition’s required keyname is explicitly set to false.

·         The value provided on a property definition’s default keyname SHALL be type compatible with the type declared on the definition’s type keyname.

3.5.8.6 Notes

·         This element directly maps to the PropertiesDefinition element defined as part of the schema for most type and entities defined in the TOSCA v1.0 specification.

3.5.8.7 Example

The following represents an example of a property definition with constraints:

properties:

  num_cpus:

    type: integer

    description: Number of CPUs requested for a software node instance.

    default: 1

    required: true

    constraints:

      - valid_values: [ 1, 2, 4, 8 ]

3.5.9 Property assignment

This section defines the grammar for assigning values to named properties within TOSCA Node and Relationship templates that are defined in their corresponding named types.

3.5.9.1 Keynames

The TOSCA property assignment has no keynames.

3.5.9.2 Grammar

Property assignments have the following grammar:

3.5.9.2.1 Short notation:

The following single-line grammar may be used when a simple value assignment is needed:

<property_name>: <property_value> | { <property_value_expression> }

In the above grammars, the pseudo values that appear in angle brackets have the following meaning:

·         property_name: represents the name of a property that would be used to select a property definition with the same name within on a TOSCA entity (e.g., Node Template, Relationship Template, etc.,) which is declared in its declared type (e.g., a Node Type, Node Template, Capability Type, etc.). 

·         property_value, property_value_expression: represent the type-compatible value to assign to the named property.  Property values may be provided as the result from the evaluation of an expression or a function.

3.5.10 Attribute definition

An attribute definition defines a named, typed value that can be associated with an entity defined in this specification (e.g., a Node, Relationship or Capability Type).  Specifically, it is used to expose the “actual state” of some property of a TOSCA entity after it has been deployed and instantiated (as set by the TOSCA orchestrator).  Attribute values can be retrieved via the get_attribute function from the instance model and used as values to other entities within TOSCA Service Templates.

3.5.10.1 Attribute and Property reflection

TOSCA orchestrators automatically create Attribute definitions for any Property definitions declared on the same TOSCA entity (e.g., nodes, node capabilities and relationships) in order to make accessible the actual (i.e., the current state) value from the running instance of the entity.

3.5.10.2 Keynames

The following is the list of recognized keynames for a TOSCA attribute definition:

Keyname

Required

Type

Constraints

Description

type

yes

string

None

The required data type for the attribute.

description

no

description

None

The optional description for the attribute.

default

no

<any>

None

An optional key that may provide a value to be used as a default if not provided by another means.

 

This value SHALL be type compatible with the type declared by the property definition’s type keyname.

status

no

string

default: supported

The optional status of the attribute relative to the specification or implementation.  See supported status values defined under the Property definition section.

entry_schema

no

string

None

The optional key that is used to declare the name of the Datatype definition for entries of set types such as the TOSCA list or map.

3.5.10.3 Grammar

Attribute definitions have the following grammar:

attributes:

  <attribute_name>:

    type: <attribute_type>

    description: <attribute_description>

    default: <default_value>

    status: <status_value>

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

·         attribute_name: represents the required symbolic name of the attribute as a string.

·         attribute_type: represents the required data type of the attribute.

·         attribute_description: represents the optional description of the attribute.

·         default_value: contains a type-compatible value that may be used as a default if not provided by another means.

·         status_value: contains a value indicating the attribute’s status relative to the specification version (e.g., supported, deprecated, etc.). Supported status values for this keyname are defined under Property definition.

3.5.10.4 Additional Requirements

·         In addition to any explicitly defined attributes on a TOSCA entity (e.g., Node Type, RelationshipType, etc.), implementations of the TOSCA Simple Profile MUST automatically reflect (i.e., make available) any property defined on an entity as an attribute of the entity with the same name as the property.

·         Values for the default keyname MUST be derived or calculated from other attribute or operation output values (that reflect the actual state of the instance of the corresponding resource) and not hard-coded or derived from a property settings or inputs (i.e., desired state).

3.5.10.5 Notes

·         Attribute definitions are very similar to Property definitions; however, properties of entities reflect an input that carries the template author’s requested or desired value (i.e., desired state) which the orchestrator (attempts to) use when instantiating the entity whereas attributes reflect the actual value (i.e., actual state) that provides the actual instantiated value. 

o   For example, a property can be used to request the IP address of a node using a property (setting); however, the actual IP address after the node is instantiated may by different and made available by an attribute.

3.5.10.6 Example

The following represents a required attribute definition:

actual_cpus:

  type: integer

  description: Actual number of CPUs allocated to the node instance.

3.5.11 Attribute assignment

This section defines the grammar for assigning values to named attributes within TOSCA Node and Relationship templates which are defined in their corresponding named types.

3.5.11.1 Keynames

The TOSCA attribute assignment has no keynames.

3.5.11.2 Grammar

Attribute assignments have the following grammar:

3.5.11.2.1 Short notation:

The following single-line grammar may be used when a simple value assignment is needed:

<attribute_name>: <attribute_value> | { <attribute_value_expression> }

3.5.11.2.2 Extended notation:

The following multi-line grammar may be used when a value assignment requires keys in addition to a simple value assignment:

<attribute_name>:

  description: <attribute_description>

  value: <attribute_value> | { <attribute_value_expression> }

In the above grammars, the pseudo values that appear in angle brackets have the following meaning:

·         attribute_name: represents the name of an attribute that would be used to select an attribute definition with the same name within on a TOSCA entity (e.g., Node Template, Relationship Template, etc.) which is declared (or reflected from a Property definition) in its declared type (e.g., a Node Type, Node Template, Capability Type, etc.). 

·         attribute_value, attribute_value_expresssion: represent the type-compatible value to assign to the named attribute.  Attribute values may be provided as the result from the evaluation of an expression or a function.

·         attribute_description: represents the optional description of the attribute.

3.5.11.3 Additional requirements

·         Attribute values MAY be provided by the underlying implementation at runtime when requested by the get_attribute function or it MAY be provided through the evaluation of expressions and/or functions that derive the values from other TOSCA attributes (also at runtime).

3.5.12 Parameter definition

A parameter definition is essentially a TOSCA property definition; however, it also allows a value to be assigned to it (as for a TOSCA property assignment). In addition, in the case of output parameters, it can optionally inherit the data type of the value assigned to it rather than have an explicit data type defined for it.

3.5.12.1 Keynames

The TOSCA parameter definition has all the keynames of a TOSCA Property definition, but in addition includes the following additional or changed keynames:

Keyname

Required

Type

Constraints

Description

type

no

string

None

The required data type for the parameter.

 

Note: This keyname is required for a TOSCA Property definition, but is not for a TOSCA Parameter definition.

value

no

<any>

N/A

The type-compatible value to assign to the named parameter.  Parameter values may be provided as the result from the evaluation of an expression or a function.

 

3.5.12.2 Grammar

Named parameter definitions have the following grammar:

<parameter_name>:

  type: <parameter_type>

  description: <parameter_description>

  value: <parameter_value> | { <parameter_value_expression> }

  required: <parameter_required>

  default: <parameter_default_value>

  status: <status_value>

  constraints:

    - <parameter_constraints>

  entry_schema:

    description: <entry_description>

    type: <entry_type>

    constraints:

      - <entry_constraints>

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

·         parameter_name: represents the required symbolic name of the parameter as a string.

·         parameter_description: represents the optional description of the parameter.

·         parameter_type: represents the optional data type of the parameter.  Note, this keyname is required for a TOSCA Property definition, but is not for a TOSCA Parameter definition.

·         parameter_value, parameter_value_expresssion: represent the type-compatible value to assign to the named parameter.  Parameter values may be provided as the result from the evaluation of an expression or a function.

·         parameter_required: represents an optional boolean value (true or false) indicating whether or not the parameter is required.  If this keyname is not present on a parameter definition, then the property SHALL be considered required (i.e., true) by default.

·         default_value: contains a type-compatible value that may be used as a default if not provided by another means.

·         status_value: a string that contains a keyword that indicates the status of the parameter relative to the specification or implementation. 

·         parameter_constraints: represents the optional sequenced list of one or more constraint clauses on the parameter definition.

·         entry_description: represents the optional description of the entry schema.

·         entry_type: represents the required type name for entries in a list or map  parameter type.

·         entry_constraints: represents the optional sequenced list of one or more constraint clauses on entries in a list or map parameter type.

3.5.12.3 Additional Requirements

·         A parameter SHALL be considered required by default (i.e., as if the required keyname on the definition is set to true) unless the definition’s required keyname is explicitly set to false.

·         The value provided on a parameter definition’s default keyname SHALL be type compatible with the type declared on the definition’s type keyname.

3.5.12.4 Example

The following represents an example of an input parameter definition with constraints:

inputs:

  cpus:

    type: integer

    description: Number of CPUs for the server.

    constraints:

      - valid_values: [ 1, 2, 4, 8 ]

The following represents an example of an (untyped) output parameter definition:

outputs:

  server_ip:

    description: The private IP address of the provisioned server.

    value: { get_attribute: [ my_server, private_address ] }

 

3.5.13 Operation definition

An operation definition defines a named function or procedure that can be bound to an implementation artifact (e.g., a script).

3.5.13.1 Keynames

The following is the list of recognized keynames for a TOSCA operation definition:

Keyname

Required

Type

Description

description

no

description

The optional description string for the associated named operation.

implementation

no

string

The optional implementation artifact name (e.g., a script file name within a TOSCA CSAR file). 

inputs

no

list of

property definitions

The optional list of input properties definitions (i.e., parameter definitions) for operation definitions that are within TOSCA Node or Relationship Type definitions. This includes when operation definitions are included as part of a Requirement definition in a Node Type.

no

list of

property assignments

The optional list of input property assignments (i.e., parameters assignments) for operation definitions that are within TOSCA Node or Relationship Template definitions. This includes when operation definitions are included as part of a Requirement assignment in a Node Template.

The following is the list of recognized keynames to be used with the implementation keyname within a TOSCA operation definition:

Keyname

Required

Type

Description

primary

no

string

The optional implementation artifact name (i.e., the primary script file name within a TOSCA CSAR file). 

dependencies

no

list of

string

The optional ordered list of one or more dependent or secondary implementation artifact name which are referenced by the primary implementation artifact (e.g., a library the script installs or a secondary script). 

3.5.13.2 Grammar

Operation definitions have the following grammars:

3.5.13.2.1 Short notation

The following single-line grammar may be used when only an operation’s implementation artifact is needed:

<operation_name>: <implementation_artifact_name>

3.5.13.2.2 Extended notation for use in Type definitions

The following multi-line grammar may be used in Node or Relationship Type definitions when additional information about the operation is needed:

<operation_name>:

   description: <operation_description>

   implementation: <implementation_artifact_name>

   inputs:

     <property_definitions>

3.5.13.2.3 Extended notation for use in Template definitions

The following multi-line grammar may be used in Node or Relationship Template definitions when there are multiple artifacts that may be needed for the operation to be implemented:

<operation_name>:

   description: <operation_description>

   implementation:

     primary: <implementation_artifact_name>  

     dependencies:

       - <list_of_dependent_artifact_names>

   inputs:

     <property_assignments>

In the above grammars, the pseudo values that appear in angle brackets have the following meaning:

·         operation_name: represents the required symbolic name of the operation as a string.

·         operation_description: represents the optional description string for the corresponding operation_name.

·         implementation_artifact_name: represents the optional name (string) of an implementation artifact definition (defined elsewhere), or the direct name of an implementation artifact’s relative filename (e.g., a service template-relative, path-inclusive filename or absolute file location using a URL).

·         property_definitions: represents the optional list of property definitions which the TOSCA orchestrator would make available (i.e., or pass) to the corresponding implementation artifact during its execution.

·         property_assignments: represents the optional list of property assignments for passing parameters to Node or Relationship Template operations providing values for properties defined in their respective type definitions.

·         list_of_dependent_artifact_names: represents the optional ordered list of one or more dependent or secondary implementation artifact names (as strings) which are referenced by the primary implementation artifact.  TOSCA orchestrators will copy these files to the same location as the primary artifact on the target node so as to make them accessible to the primary implementation artifact when it is executed.

3.5.13.3 Additional requirements

·         The default sub-classing behavior for implementations of operations SHALL be override.  That is, implementation artifacts assigned in subclasses override any defined in its parent class.

·         Template authors MAY provide property assignments on operation inputs on templates that do not necessarily have a property definition defined in its corresponding type.

·         Implementation artifact file names (e.g., script filenames) may include file directory path names that are relative to the TOSCA service template file itself when packaged within a TOSCA Cloud Service ARchive (CSAR) file.

3.5.13.4 Examples

3.5.13.4.1 Single-line implementation example

interfaces:

  Standard:

    start: scripts/start_server.sh

3.5.13.4.2 Multi-line implementation example

interfaces:

  Configure:

    pre_configure_source:

      implementation:

        primary: scripts/pre_configure_source.sh

        dependencies:

          - scripts/setup.sh

          - binaries/library.rpm

          - scripts/register.py

3.5.14 Interface definition

An interface definition defines a named interface that can be associated with a Node or Relationship Type

3.5.14.1 Keynames

The following is the list of recognized keynames for a TOSCA interface definition:

Keyname

Required

Type

Description

inputs

no

list of

property definitions

The optional list of input property definitions available to all defined operations for interface definitions that are within TOSCA Node or Relationship Type definitions. This includes when interface definitions are included as part of a Requirement definition in a Node Type.

no

list of

property assignments

The optional list of input property assignments (i.e., parameters assignments) for interface definitions that are within TOSCA Node or Relationship Template definitions. This includes when interface definitions are referenced as part of a Requirement assignment in a Node Template.

3.5.14.2 Grammar

Interface definitions have the following grammar:

3.5.14.2.1 Extended notation for use in Type definitions

The following multi-line grammar may be used in Node or Relationship Type definitions:

<interface_definition_name>:

  type: <interface_type_name>

  inputs:

    <property_definitions>

  <operation_definitions>

3.5.14.2.2 Extended notation for use in Template definitions

The following multi-line grammar may be used in Node or Relationship Type definitions:

<interface_definition_name>:

  inputs:

    <property_assignments>

  <operation_definitions>

In the above grammars, the pseudo values that appear in angle brackets have the following meaning:

·         interface_definition_name: represents the required symbolic name of the interface as a string.

·         interface_type_name: represents the required name of the Interface Type for the interface definition.

·         property_definitions: represents the optional list of property definitions (i.e., parameters) which the TOSCA orchestrator would make available (i.e., or pass) to all defined operations. 

-       This means these properties and their values would be accessible to the implementation artifacts (e.g., scripts) associated to each operation during their execution.

·         property_assignments: represents the optional list of property assignments for passing parameters to Node or Relationship Template operations providing values for properties defined in their respective type definitions.

·         operation_definitions: represents the required name of one or more operation definitions.

3.6 Type-specific definitions

3.6.1 Capability definition

A capability definition defines a named, typed set of data that can be associated with Node Type or Node Template to describe a transparent capability or feature of the software component the node describes.

3.6.1.1 Keynames

The following is the list of recognized keynames for a TOSCA capability definition:

Keyname

Required

Type

Constraints

Description

type

yes

string

N/A

The required name of the Capability Type the capability definition is based upon.

description

no

description

N/A

The optional description of the Capability definition.

properties

no

list of

property definitions

N/A

An optional list of property definitions for the Capability definition.

attributes

no

list of

attribute definitions

N/A

An optional list of attribute definitions for the Capability definition.

valid_source_types

no

string[]

N/A

An optional list of one or more valid names of Node Types that are supported as valid sources of any relationship established to the declared Capability Type.

occurrences

no

range of integer

implied default of [1,UNBOUNDED]

The optional minimum and maximum occurrences for the capability. By default, an exported Capability should allow at least one relationship to be formed with it with a maximum of UNBOUNDED relationships.

Note: the keyword UNBOUNDED is also supported to represent any positive integer.

3.6.1.2 Grammar

Capability definitions have one of the following grammars:

3.6.1.2.1 Short notation

The following grammar may be used when only a list of capability definition names needs to be declared:

<capability_definition_name>: <capability_type>

3.6.1.2.2 Extended notation

The following multi-line grammar may be used when additional information on the capability definition is needed:

<capability_definition_name>:

  type: <capability_type>

  description: <capability_description>

  properties:

    <property_definitions>

  attributes:

    <attribute_definitions>

  valid_source_types: [ <node type_names> ]

In the above grammars, the pseudo values that appear in angle brackets have the following meaning:

·         capability_definition_name: represents the symbolic name of the capability as a string.

·         capability_type: represents the required name of a capability type the capability definition is based upon.

·         capability_description: represents the optional description of the capability definition.

·         property_definitions: represents the optional list of property definitions for the capability definition.

·         attribute_definitions: represents the optional list of attribute definitions for the capability definition.

·         node_type_names: represents the optional list of one or more names of Node Types that the Capability definition supports as valid sources for a successful relationship to be established to itself.

3.6.1.3 Examples

The following examples show capability definitions in both simple and full forms:

3.6.1.3.1 Simple notation example

# Simple notation, no properties defined or augmented

some_capability: mytypes.mycapabilities.MyCapabilityTypeName

3.6.1.3.2 Full notation example

# Full notation, augmenting properties of the referenced capability type

some_capability:

  type: mytypes.mycapabilities.MyCapabilityTypeName

  properties:

    limit:

      type: integer

      default: 100

3.6.1.4 Additional requirements

·         Any Node Type (names) provides as values for the valid_source_types keyname SHALL be type-compatible (i.e., derived from the same parent Node Type) with any Node Types defined using the same keyname in the parent Capability Type. 

·         Capability symbolic names SHALL be unique; it is an error if a capability name is found to occur more than once.

3.6.1.5 Notes

3.6.2 Requirement definition

The Requirement definition describes a named requirement (dependencies) of a TOSCA Node Type or Node template which needs to be fulfilled by a matching Capability definition declared by another TOSCA modelable entity.  The requirement definition may itself include the specific name of the fulfilling entity (explicitly) or provide an abstract type, along with additional filtering characteristics, that a TOSCA orchestrator can use to fulfill the capability at runtime (implicitly).

3.6.2.1 Keynames

The following is the list of recognized keynames for a TOSCA requirement definition:

Keyname

Required

Type

Constraints

Description

capability

yes

string

N/A

The required reserved keyname used that can be used to provide the name of a valid Capability Type  that can fulfill the requirement.

node

no

string

N/A

The optional reserved keyname used to provide the name of a valid Node Type that contains the capability definition that can be used to fulfill the requirement.

relationship

no

string

N/A

The optional reserved keyname used to provide the name of a valid Relationship Type to construct when fulfilling the requirement.

occurrences

no

range of integer

implied default of [1,1]

The optional minimum and maximum occurrences for the requirement.

Note: the keyword UNBOUNDED is also supported to represent any positive integer.

3.6.2.1.1 Additional Keynames for multi-line relationship grammar

The Requirement definition contains the Relationship Type information needed by TOSCA Orchestrators to construct relationships to other TOSCA nodes with matching capabilities; however, it is sometimes recognized that additional properties may need to be passed to the relationship (perhaps for configuration).  In these cases, additional grammar is provided so that the Node Type may declare additional Property definitions to be used as inputs to the Relationship Type’s declared interfaces (or specific operations of those interfaces). 

Keyname

Required

Type

Constraints

Description

type

yes

string

N/A

The optional reserved keyname used to provide the name of the Relationship Type for the requirement definition’s relationship keyname.

interfaces

no

list of interface definitions

N/A

The optional reserved keyname used to reference declared (named) interface definitions of the corresponding Relationship Type in order to declare additional Property definitions for these interfaces or operations of these interfaces.

3.6.2.2 Grammar

Requirement definitions have one of the following grammars:

3.6.2.2.1 Simple grammar (Capability Type only)

<requirement_name>: <capability_type_name>

3.6.2.2.2 Extended grammar (with Node and Relationship Types)

<requirement_name>:

  capability: <capability_type_name>

  node: <node_type_name>

  relationship: <relationship_type_name>

  occurrences: [ <min_occurrences>, <max_occurrences> ]

3.6.2.2.3 Extended grammar for declaring Property Definitions on the relationship’s Interfaces

The following additional multi-line grammar is provided for the relationship keyname in order to declare new Property definitions for inputs of known Interface definitions of the declared Relationship Type. 

<requirement_name>:

  # Other keynames omitted for brevity

  relationship:

    type: <relationship_type_name>

    interfaces:

      <interface_definitions>

In the above grammars, the pseudo values that appear in angle brackets have the following meaning:

·         requirement_name: represents the required symbolic name of the requirement definition as a string.

·         capability_type_name: represents the required name of a Capability type that can be used to fulfill the requirement.

·         node_type_name: represents the optional name of a TOSCA Node Type that contains the Capability Type definition the requirement can be fulfilled by. 

·         relationship_type_name: represents the optional name of a Relationship Type to be used to construct a relationship between this requirement definition (i.e., in the source node) to a matching capability definition (in a target node).

·         min_occurrences, max_occurrences: represents the optional minimum and maximum occurrences of the requirement (i.e., its cardinality).

·         interface_definitions: represents one or more already declared interface definitions in the Relationship Type (as declared on the type keyname) allowing for the declaration of new Property definition for these interfaces or for specific Operation definitions of these interfaces.

3.6.2.3 Additional Requirements

·         Requirement symbolic names SHALL be unique; it is an error if a requirement name is found to occur more than once.

·         If the occurrences keyname is not present, then the occurrence of the requirement SHALL be one and only one; that is a default declaration as follows would be assumed: 

o    occurrences: [1,1]

3.6.2.4 Notes

·         This element directly maps to the RequirementsDefinition of the Node Type entity as defined in the TOSCA v1.0 specification.

·         The requirement symbolic name is used for identification of the requirement definition only and not relied upon for establishing any relationships in the topology.

3.6.2.5 Requirement Type definition is a tuple

A requirement definition allows type designers to govern which types are allowed (valid) for fulfillment using three levels of specificity with only the Capability Type being required.

1.       Node Type (optional)

2.       Relationship Type (optional)

3.       Capability Type (required)

The first level allows selection, as shown in both the simple or complex grammar, simply providing the node’s type using the node keyname. The second level allows specification of the relationship type to use when connecting the requirement to the capability using the relationship keyname.  Finally, the specific named capability type on the target node is provided using the capability keyname.

3.6.2.5.1 Property filter

In addition to the node, relationship and capability types, a filter, with the keyname node_filter, may be provided to constrain the allowed set of potential target nodes based upon their properties and their capabilities’ properties.  This allows TOSCA orchestrators to help find the “best fit” when selecting among multiple potential target nodes for the expressed requirements.

3.6.3 Artifact Type

An Artifact Type is a reusable entity that defines the type of one or more files that are used to define implementation or deployment artifacts that are referenced by nodes or relationships on their operations.

3.6.3.1 Keynames

The following is the list of recognized keynames for a TOSCA Artifact Type definition:

Keyname

Required

Type

Description

derived_from

no

string

An optional parent Artifact Type name the Artifact Type derives from.

version

no

version

An optional version for the Artifact Type definition.

description

no

description

An optional description for the Artifact Type.

mime_type

no

string

The required mime type property for the Artifact Type.

file_ext

no

string[]

The required file extension property for the Artifact Type.

properties

no

list of

property definitions

An optional list of property definitions for the Artifact Type.

3.6.3.2 Grammar

Artifact Types have following grammar:

<artifact_type_name>:

  derived_from: <parent_artifact_type_name>

  version: <version_number>

  description: <artifact_description>

  mime_type: <mime_type_string>

  file_ext: [ <file_extensions> ]

  properties:

    <property_definitions>

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

·         artifact_type_name: represents the name of the Artifact Type being declared as a string.

·         parent_artifact_type_name: represents the name of the Artifact Type this Artifact Type definition derives from (i.e., its “parent” type).

·         version_number: represents the optional TOSCA version number for the Artifact Type.

·         artifact_description: represents the optional description string for the Artifact Type.

·         mime_type_string: represents the optional Multipurpose Internet Mail Extensions (MIME) standard string value that describes the file contents for this type of Artifact Type as a string.

·         file_extensions: represents the optional list of one or more recognized file extensions for this type of artifact type as strings.

·         property_definitions: represents the optional list of property definitions for the artifact type.

3.6.3.3 Examples

my_artifact_type:

  description: Java Archive artifact type

  derived_from: tosca.artifact.Root

  mime_type: application/java-archive

  file_ext: [ jar ]

3.6.4 Interface Type

An Interface Type is a reusable entity that describes a set of operations that can be used to interact with or manage a node or relationship in a TOSCA topology.

3.6.4.1 Keynames

The following is the list of recognized keynames for a TOSCA Interface Type definition:

Keyname

Required

Type

Description

derived_from

no

string

An optional parent Interface  Type name this new Interface Type derives from.

version

no

version

An optional version for the Interface Type definition.

description

no

description

An optional description for the Interface Type.

inputs

no

list of

property definitions

The optional list of input parameter definitions.

3.6.4.2 Grammar

Interface Types have following grammar:

<interface_type_name>:

  derived_from: <parent_interface_type_name>

  version: <version_number>

  description: <interface_description>

  inputs:

    <property_definitions>

  <operation_definitions>

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

·         parent_interface_type_name: represents the name of the Interface Type this Interface Type definition derives from (i.e., its “parent” type).

·         version_number: represents the optional TOSCA version number for the Interface Type.

·         interface_description: represents the optional description string for the Interface Type.

3.6.4.3 Example

The following example shows a custom interface used to define multiple configure operations.

mycompany.mytypes.myinterfaces.MyConfigure:

  derived_from: tosca.interfaces.Root

  description: My custom configure Interface Type

  inputs:

    mode:

      type: string

  pre_configure_service:

    description: pre-configure operation for my service

  post_configure_service:

    description: post-configure operation for my service

3.6.4.4 Additional Requirements

·         Interface Types MUST NOT include any implementations for defined operations; that is, the implementation keyname is invalid.

·         The inputs keyname is reserved and SHALL NOT be used for an operation name.

3.6.4.5 Notes

·         The TOSCA Simple Profile specification does not yet provide a means to derive or extend an Interface Type from another Interface Type.

3.6.5 Data Type

A Data Type definition defines the schema for new named datatypes in TOSCA. 

3.6.5.1 Keynames

The following is the list of recognized keynames for a TOSCA Data Type definition:

Keyname

Required

Type

Description

derived_from

no

string

The optional key used when a datatype is derived from an existing TOSCA Data Type.

version

no

version

An optional version for the Data Type definition.

description

no

description

The optional description for the Data Type.

constraints

no

list of

constraint clauses

The optional list of sequenced constraint clauses for the Data Type. 

properties

no

list of

property definitions

The optional list property definitions that comprise the schema for a complex Data Type in TOSCA.

3.6.5.2 Grammar

Data Types have the following grammar:

<data_type_name>:

  derived_from: <existing_type_name>

  version: <version_number>

  description: <datatype_description>

  constraints:

    - <type_constraints>

  properties:

    <property_definitions>

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

·         data_type_name: represents the required symbolic name of the Data Type as a string.

·         version_number: represents the optional TOSCA version number for the Data Type.

·         datatype_description: represents the optional description for the Data Type.

·         existing_type_name: represents the optional name of a valid TOSCA type this new Data Type would derive from.

·         type_constraints: represents the optional sequenced list of one or more type-compatible constraint clauses that restrict the Data Type.

·         property_definitions: represents the optional list of one or more property definitions that provide the schema for the Data Type.

3.6.5.3 Additional Requirements

·         A valid datatype definition MUST have either a valid derived_from declaration or at least one valid property definition.

·         Any constraint clauses SHALL be type-compatible with the type declared by the derived_from keyname.

·         If a properties keyname is provided, it SHALL contain one or more valid property definitions.

3.6.5.4 Examples

The following example represents a Data Type definition based upon an existing string type:

3.6.5.4.1 Defining a complex datatype

# define a new complex datatype

mytypes.phonenumber:

  description: my phone number datatype

  properties:

    countrycode:

      type: integer

    areacode:

      type: integer

    number:

      type: integer

3.6.5.4.2 Defining a datatype derived from an existing datatype

# define a new datatype that derives from existing type and extends it

mytypes.phonenumber.extended:

  derived_from: mytypes.phonenumber

  description: custom phone number type that extends the basic phonenumber type

  properties:

    phone_description:

      type: string

      constraints:

        - max_length: 128

3.6.6 Capability Type

A Capability Type is a reusable entity that describes a kind of capability that a Node Type can declare to expose.  Requirements (implicit or explicit) that are declared as part of one node can be matched to (i.e., fulfilled by) the Capabilities declared by another node.

3.6.6.1 Keynames

The following is the list of recognized keynames for a TOSCA Capability Type definition:

Keyname

Required

Type

Description

derived_from

no

string

An optional parent capability type name this new Capability Type derives from.

version

no

version

An optional version for the Capability Type definition.

description

no

description

An optional description for the Capability Type.

properties

no

list of
property definitions

An optional list of property definitions for the Capability Type.

attributes

no

list of

attribute definitions

An optional list of attribute definitions for the Capability Type.

valid_source_types

no

string[]

An optional list of one or more valid names of Node Types that are supported as valid sources of any relationship established to the declared Capability Type.

3.6.6.2 Grammar

Capability Types have following grammar:

<capability_type_name>:

  derived_from: <parent_capability_type_name>

  version: <version_number>

  description: <capability_description>

  properties:

    <property_definitions>

  attributes:

    <attribute_definitions>

  valid_source_types: [ <node type_names> ]

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

·         capability_type_name: represents the required name of the Capability Type being declared as a string.

·         parent_capability_type_name: represents the name of the Capability Type this Capability Type definition derives from (i.e., its “parent” type).

·         version_number: represents the optional TOSCA version number for the Capability Type.

·         capability_description: represents the optional description string for the corresponding capability_type_name.

·         property_definitions: represents an optional list of property definitions that the Capability type exports.

·         attribute_definitions: represents the optional list of attribute definitions for the Capability Type.

·         node_type_names: represents the optional list of one or more names of Node Types that the Capability Type supports as valid sources for a successful relationship to be established to itself.

3.6.6.3 Example

mycompany.mytypes.myapplication.MyFeature:

  derived_from: tosca.capabilities.Root

  description: a custom feature of my company’s application

  properties:

    my_feature_setting:

      type: string

    my_feature_value:

      type: integer

3.6.7 Requirement Type

A Requirement Type is a reusable entity that describes a kind of requirement that a Node Type can declare to expose.  The TOSCA Simple Profile seeks to simplify the need for declaring specific Requirement Types from nodes and instead rely upon nodes declaring their features sets using TOSCA Capability Types along with a named Feature notation.

Currently, there are no use cases in this TOSCA Simple Profile in YAML specification that utilize an independently defined Requirement Type.  This is a desired effect as part of the simplification of the TOSCA v1.0 specification.

3.6.8 Node Type

A Node Type is a reusable entity that defines the type of one or more Node Templates. As such, a Node Type defines the structure of observable properties via a Properties Definition, the Requirements and Capabilities of the node as well as its supported interfaces.

3.6.8.1 Keynames

The following is the list of recognized keynames for a TOSCA Node Type definition:

Keyname

Required

Definition/Type

Description

derived_from

no

string

An optional parent Node Type name this new Node Type derives from.

version

no

version

An optional version for the Node Type definition.

description

no

description

An optional description for the Node Type.

properties

no

list of

property definitions

An optional list of property definitions for the Node Type.

attributes

no

list of

attribute definitions

An optional list of attribute definitions for the Node Type.

requirements

no

list of

requirement definitions

An optional sequenced list of requirement definitions for the Node Type.

capabilities

no

list of

capability definitions

An optional list of capability definitions for the Node Type.

interfaces

no

list of

interface definitions

An optional list of interface definitions supported by the Node Type.

artifacts

no

list of

artifact definitions

An optional list of named artifact definitions for the Node Type.

3.6.8.2 Grammar

Node Types have following grammar:

<node_type_name>: 

  derived_from: <parent_node_type_name>

  version: <version_number>

  description: <node_type_description>

  properties:

    <property_definitions>

  attributes:

    <attribute_definitions>

  requirements:

    - <requirement_definitions>

  capabilities:

    <capability_definitions>

  interfaces:

    <interface_definitions>

  artifacts:

    <artifact_definitions>

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

·         node_type_name: represents the required symbolic name of the Node Type being declared.

·         parent_node_type_name: represents the name (string) of the Node Type this Node Type definition derives from (i.e., its “parent” type).

·         version_number: represents the optional TOSCA version number for the Node Type.

·         node_type_description: represents the optional description string for the corresponding node_type_name.

·         property_definitions: represents the optional list of property definitions for the Node Type.

·         attribute_definitions: represents the optional list of attribute definitions for the Node Type.

·         requirement_definitions: represents the optional sequenced list of requirement definitions for the Node Type.

·         capability_definitions: represents the optional list of capability definitions for the Node Type.

·         interface_definitions: represents the optional list of one or more interface definitions supported by the Node Type.

·         artifact_definitions: represents the optional list of artifact definitions for the Node Type.

3.6.8.3 Additional Requirements

·         Requirements are intentionally expressed as a sequenced list of TOSCA Requirement definitions which SHOULD be resolved (processed) in sequence order by TOSCA Orchestrators. .

3.6.8.4 Best Practices

·         It is recommended that all Node Types SHOULD derive directly (as a parent) or indirectly (as an ancestor) of the TOSCA Root Node Type (i.e., tosca.nodes.Root) to promote compatibility and portability.  However, it is permitted to author Node Types that do not do so.

·         TOSCA Orchestrators, having a full view of the complete application topology template and its resultant dependency graph of nodes and relationships, MAY prioritize how they instantiate the nodes and relationships for the application (perhaps in parallel where possible) to achieve the greatest efficiency

3.6.8.5 Example

my_company.my_types.my_app_node_type:

  derived_from: tosca.nodes.SoftwareComponent

  description: My company’s custom applicaton

  properties:

    my_app_password:

      type: string

      description: application password

      constraints:

        - min_length: 6

        - max_length: 10

  attributes:

    my_app_port:

      type: integer

      description: application port number

  requirements:

    - some_database:

        capability: EndPoint.Database

        node: Database   

        relationship: ConnectsTo

3.6.9 Relationship Type

A Relationship Type is a reusable entity that defines the type of one or more relationships between Node Types or Node Templates.

3.6.9.1 Keynames

The following is the list of recognized keynames for a TOSCA Relationship Type definition:

Keyname

Required

Definition/Type

Description

derived_from

no

string

An optional parent Relationship Type name the Relationship Type derives from.

version

no

version

An optional version for the Relationship Type definition.

description

no

description

An optional description for the Relationship Type.

properties

no

list of

property definitions

An optional list of property definitions for the Relationship Type.

attributes

no

list of

attribute definitions

An optional list of attribute definitions for the Relationship Type.

interfaces

no

list of

interface definitions

An optional list of interface definitions interfaces supported by the Relationship Type.

valid_target_types

no

string[]

An optional list of one or more names of Capability Types that are valid targets for this relationship.

3.6.9.2 Grammar

Relationship Types have following grammar:

<relationship_type_name>:

  derived_from: <parent_relationship_type_name>

  version: <version_number>

  description: <relationship_description>

  properties:

    <property_definitions>

  attributes:

    <attribute_definitions>

  interfaces:

    <interface_definitions>

  valid_target_types: [ <capability_type_names> ]

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

·         relationship_type_name: represents the required symbolic name of the Relationship Type being declared as a string.

·         parent_relationship_type_name: represents the name (string) of the Relationship Type this Relationship Type definition derives from (i.e., its “parent” type).

·         relationship_description: represents the optional description string for the corresponding relationship_type_name.

·         version_number: represents the optional TOSCA version number for the Relationship Type.

·         property_definitions: represents the optional list of property definitions for the Relationship Type.

·         attribute_definitions: represents the optional list of attribute definitions for the Relationship Type.

·         interface_definitions: represents the optional list of one or more names of valid interface definitions supported by the Relationship Type.

·         capability_type_names: represents one or more names of valid target types for the relationship (i.e., Capability Types).

3.6.9.3 Best Practices

·         For TOSCA application portability, it is recommended that designers use the normative Relationship types defined in this specification where possible and derive from them for customization purposes.

·         The TOSCA Root Relationship Type (tosca.relationships.Root) SHOULD be used to derive new types where possible when defining new relationships types.  This assures that its normative configuration interface (tosca.interfaces.relationship.Configure) can be used in a deterministic way by TOSCA orchestrators.

3.6.9.4 Examples

mycompanytypes.myrelationships.AppDependency:

  derived_from: tosca.relationships.DependsOn

  valid_target_types: [ mycompanytypes.mycapabilities.SomeAppCapability ]

3.6.10 Group Type

A Group Type defines logical grouping types for nodes, typically for different management purposes. Groups can effectively be viewed as logical nodes that are not part of the physical deployment topology of an application, yet can have capabilities and the ability to attach policies and interfaces that can be applied (depending on the group type) to its member nodes.

 

Conceptually, group definitions allow the creation of logical “membership” relationships to nodes in a service template that are not a part of the application’s explicit requirement dependencies in the topology template (i.e. those required to actually get the application deployed and running). Instead, such logical membership allows for the introduction of things such as group management and uniform application of policies (i.e., requirements that are also not bound to the application itself) to the group’s members.

3.6.10.1 Keynames

The following is the list of recognized keynames for a TOSCA Group Type definition:

Keyname

Required

Type

Description

derived_from

no

string

An optional parent Group Type name the Group Type derives from.

version

no

version

An optional version for the Group Type definition.

description

no

description

The optional description for the Group Type.

properties

no

list of

property definitions

An optional list of property definitions for the Group Type.

members

no

string[]

An optional list of one or more names of Node Types that  are valid (allowed) as members of the Group Type. 

 

Note: This can be viewed by TOSCA Orchestrators as an implied relationship from the listed members nodes to the group, but one that does not have operational lifecycle considerations.  For example, if we were to name this as an explicit Relationship Type we might call this “MemberOf” (group).

interfaces

no

list of

interface definitions

An optional list of interface definitions supported by the Group Type.

3.6.10.2 Grammar

Group Types have one the following grammars:

<group_type_name>:

  derived_from: <parent_group_type_name>

  version: <version_number>

  description: <group_description>

  properties:

    <property_definitions>

  members: [ <list_of_valid_member_types> ]

  interfaces:

    <interface_definitions>

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

·         group_type_name: represents the required symbolic name of the Group Type being declared as a string.

·         parent_group_type_name: represents the name (string) of the Group Type this Group Type definition derives from (i.e., its “parent” type).

·         version_number: represents the optional TOSCA version number for the Group Type.

·         group_description: represents the optional description string for the corresponding group_type_name.

·         property_definitions: represents the optional list of property definitions for the Group Type.

·         list_of_valid_member_types: represents the optional list of TOSCA types (i.e., Node or Capability Types) that are valid member types for being added to (i.e., members of) the Group Type.

·         interface_definitions: represents the optional list of one or more interface definitions supported by the Group Type.

3.6.10.3 Additional Requirements

·         Group definitions SHOULD NOT be used to define or redefine relationships (dependencies) for an application that can be expressed using normative TOSCA Relationships within a TOSCA topology template.

·         The list of values associated with the “members” keyname MUST only contain types that or homogenous (i.e., derive from the same type hierarchy).

3.6.10.4 Example

The following represents a Group Type definition:

group_types:

  mycompany.mytypes.groups.placement:

    description: My company’s group type for placing nodes of type Compute

    members: [ tosca.nodes.Compute ]

3.6.11 Policy Type

A Policy Type defines a type of requirement that affects or governs an application or service’s topology at some stage of its lifecycle, but is not explicitly part of the topology itself (i.e., it does not prevent the application or service from being deployed or run if it did not exist).

3.6.11.1 Keynames

The following is the list of recognized keynames for a TOSCA Policy Type definition:

Keyname

Required

Type

Description

derived_from

no

string

An optional parent Policy Type name the Policy Type derives from.

version

no

version

An optional version for the Policy Type definition.

description

no

description

The optional description for the Policy Type.

properties

no

list of

property definitions

An optional list of property definitions for the Policy Type.

targets

 

no

string[]

An optional list of valid Node Types or Group Types the Policy Type can be applied to.

 

Note: This can be viewed by TOSCA Orchestrators as an implied relationship to the target nodes, but one that does not have operational lifecycle considerations.  For example, if we were to name this as an explicit Relationship Type we might call this “AppliesTo” (node or group).

3.6.11.2 Grammar

Policy Types have one the following grammars:

<policy_type_name>:

  derived_from: <parent_policy_type_name>

  version: <version_number>

  description: <policy_description>

  properties:

    <property_definitions>

  targets: [ <list_of_valid_target_types> ]

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

·         policy_type_name: represents the required symbolic name of the Policy Type being declared as a string.

·         parent_policy_type_name: represents the name (string) of the Policy Type this Policy Type definition derives from (i.e., its “parent” type).

·         version_number: represents the optional TOSCA version number for the Policy Type.

·         policy_description: represents the optional description string for the corresponding policy_type_name.

·         property_definitions: represents the optional list of property definitions for the Policy Type.

·         list_of_valid_target_types: represents the optional list of TOSCA types (i.e., Group or Node Types) that are valid targets for this Policy Type.

3.6.11.3 Additional Requirements

·         None

3.6.11.4 Example

The following represents a Policy Type definition:

policy_types:

  mycompany.mytypes.policies.placement.Container.Linux:

    description: My company’s placement policy for linux

    derived_from: tosca.policies.Root

3.7 Template-specific definitions

The definitions in this section provide reusable modeling element grammars that are specific to the Node or Relationship templates.

3.7.1 Capability assignment

A capability assignment allows node template authors to assign values to properties and attributes for a named capability definition that is part of a Node Template’s type definition.

3.7.1.1 Keynames

The following is the list of recognized keynames for a TOSCA capability assignment:

Keyname

Required

Type

Description

properties

no

list of

property assignments

An optional list of property definitions for the Capability definition.

attributes

no

list of

attribute assignments

An optional list of attribute definitions for the Capability definition.

3.7.1.2 Grammar

Capability assignments have one of the following grammars:

<capability_definition_name>:

  properties:

    <property_assignments>

  attributes:

    <attribute_assignments>

In the above grammars, the pseudo values that appear in angle brackets have the following meaning:

·         capability_definition_name: represents the symbolic name of the capability as a string.

·         property_assignments: represents the optional list of property assignments for the capability definition.

·         attribute_assignments: represents the optional list of attribute assignments for the capability definition.

3.7.1.3 Example

The following example shows a capability assignment:

3.7.1.3.1 Notation example

node_templates:

  some_node_template:

    capabilities:

      some_capability:

        properties:

          limit: 100

3.7.2 Requirement assignment

A Requirement assignment allows template authors to provide either concrete names of TOSCA templates or provide abstract selection criteria for providers to use to find matching TOSCA templates that are used to fulfill a named requirement’s declared TOSCA Node Type.

3.7.2.1 Keynames

The following is the list of recognized keynames for a TOSCA requirement assignment:

Keyname

Required

Type

Description

capability

no

string

The optional reserved keyname used to provide the name of either a:

·         Capability definition within a target node template that can fulfill the requirement.

·         Capability Type that the provider will use to select a type-compatible target node template to fulfill the requirement at runtime.

node

no

string

The optional reserved keyname used to identify the target node of a relationship.  specifically, it is used to provide either a:

·         Node Template name that can fulfill the target node requirement.

·         Node Type name that the provider will use to select a type-compatible node template to fulfill the requirement at runtime.

relationship

no

string

The optional reserved keyname used to provide the name of either a:

·         Relationship Template to use to relate the source node to the (capability in the) target node when fulfilling the requirement.

·         Relationship Type that the provider will use to select a type-compatible relationship template to relate the source node to the target node at runtime.

node_filter

no

node filter

The optional filter definition that TOSCA orchestrators or providers would use to select a type-compatible target node that can fulfill the associated abstract requirement at runtime.

The following is the list of recognized keynames for a TOSCA requirement assignment’s relationship keyname which is used when Property assignments need to be provided to inputs of declared interfaces or their operations:

Keyname

Required

Type

Description

type

no

string

The optional reserved keyname used to provide the name of the Relationship Type for the requirement assignment’s relationship keyname.

properties

no

list of

interface definitions

The optional reserved keyname used to reference declared (named) interface definitions of the corresponding Relationship Type in order to provide Property assignments for these interfaces or operations of these interfaces.

3.7.2.2 Grammar

Named requirement assignments have one of the following grammars:

3.7.2.2.1 Short notation:

The following single-line grammar may be used if only a concrete Node Template for the target node needs to be declared in the requirement:

<requirement_name>: <node_template_name>

This notation is only valid if the corresponding Requirement definition in the Node Template’s parent Node Type declares (at a minimum) a valid Capability Type which can be found in the declared target Node Template. A valid capability definition always needs to be provided in the requirement declaration of the source node to identify a specific capability definition in the target node the requirement will form a TOSCA relationship with.

3.7.2.2.2 Extended notation:

The following grammar would be used if the requirement assignment needs to provide more information than just the Node Template name:

<requirement_name>:

  node: <node_template_name> | <node_type_name>

  relationship: <relationship_template_name> | <relationship_type_name>

  capability: <capability_symbolic_name> | <capability_type_name>

  node_filter:

    <node_filter_definition>

  occurrences: [ min_occurrences, max_occurrences ]

3.7.2.2.3 Extended grammar with Property Assignments for the relationship’s Interfaces

The following additional multi-line grammar is provided for the relationship keyname in order to provide new Property assignments for inputs of known Interface definitions of the declared Relationship Type. 

<requirement_name>:

  # Other keynames omitted for brevity

  relationship:

    type: <relationship_template_name> | <relationship_type_name>

    properties:

      <property_assignments>

    interfaces:

      <interface_assignments>

Examples of uses for the extended requirement assignment grammar include:

·         The need to allow runtime selection of the target node based upon an abstract Node Type rather than a concrete Node Template.  This may include use of the node_filter keyname to provide node and capability filtering information to find the “best match” of a concrete Node Template at runtime.

·         The need to further clarify the concrete Relationship Template or abstract Relationship Type to use when relating the source node’s requirement to the target node’s capability.

·         The need to further clarify the concrete capability (symbolic) name or abstract Capability Type in the target node to form a relationship between.

·         The need to (further) constrain the occurrences of the requirement in the instance model.

In the above grammars, the pseudo values that appear in angle brackets have the following meaning:

·         requirement_name: represents the symbolic name of a requirement assignment as a string.

·         node_template_name: represents the optional name of a Node Template that contains the capability this requirement will be fulfilled by.

·         relationship_template_name: represents the optional name of a Relationship Type to be used when relating the requirement appears to the capability in the target node.

·         capability_symbolic_name: represents the optional ordered list of specific, required capability type or named capability definition within the target Node Type or Template.

·         node_type_name: represents the optional name of a TOSCA Node Type the associated named requirement can be fulfilled by.  This must be a type that is compatible with the Node Type declared on the matching requirement (same symbolic name) the requirement’s Node Template is based upon.

·         relationship_type_name: represents the optional name of a Relationship Type that is compatible with the Capability Type in the target node.

·         property_assignments: represents the optional list of property value assignments for the declared relationship.

·         interface_assignments: represents the optional list of interface definitions for the declared relationship used to provide property assignments on inputs of interfaces and operations.

·         capability_type_name: represents the optional name of a Capability Type definition within the target Node Type this requirement needs to form a relationship with.

·         node_filter_definition: represents the optional node filter TOSCA orchestrators would use to fulfill the requirement for selecting a target node. Note that this SHALL only be valid if the node keyname’s value is a Node Type and is invalid if it is a Node Template.

3.7.2.3 Examples

3.7.2.3.1 Example 1 – Abstract hosting requirement on a Node Type

A web application node template named ‘my_application_node_template’ of type WebApplication declares a requirement named ‘host’ that needs to be fulfilled by any node that derives from the node type WebServer

# Example of a requirement fulfilled by a specific web server node template

node_templates:

  my_application_node_template:

    type: tosca.nodes.WebApplication

    ...

    requirements:

      - host:

          node: tosca.nodes.WebServer

In this case, the node template’s type is WebApplication which already declares the Relationship Type HostedOn to use to relate to the target node and the Capability Type of Container to be the specific target of the requirement in the target node.

3.7.2.3.2 Example  2 - Requirement with Node Template and a custom Relationship Type

This example is similar to the previous example; however, the requirement named ‘database’ describes a requirement for a connection to a database endpoint (Endpoint.Database) Capability Type in a named node template (my_database). However, the connection requires a custom Relationship Type (my.types.CustomDbConnection’) declared on the keyname ‘relationship’.

# Example of a (database) requirement that is fulfilled by a node template named

# “my_database”, but also requires a custom database connection relationship

my_application_node_template:

  requirements:

    - database:

        node: my_database

        capability: Endpoint.Database

        relationship: my.types.CustomDbConnection

3.7.2.3.3 Example 3 - Requirement for a Compute node with additional selection criteria (filter)

This example shows how to extend an abstract ‘host’ requirement for a Compute node with a filter definition that further constrains TOSCA orchestrators to include additional properties and capabilities on the target node when fulfilling the requirement.

node_templates:

  mysql:

   type: tosca.nodes.DBMS.MySQL

    properties:

      # omitted here for brevity

    requirements:

      - host:

          node: tosca.nodes.Compute

          node_filter:

            capabilities:

              - host:

                  properties:

                    - num_cpus: { in_range: [ 1, 4 ] }

                    - mem_size: { greater_or_equal: 512 MB }

              - os:

                  properties:

                    - architecture: { equal: x86_64 }

                    - type: { equal: linux }

                    - distribution: { equal: ubuntu }

              - mytypes.capabilities.compute.encryption:

                  properties:

                    - algorithm: { equal: aes }

                    - keylength: { valid_values: [ 128, 256 ] }

3.7.3 Node Template

A Node Template specifies the occurrence of a manageable software component as part of an application’s topology model which is defined in a TOSCA Service Template.  A Node template is an instance of a specified Node Type and can provide customized properties, constraints or operations which override the defaults provided by its Node Type and its implementations.

3.7.3.1 Keynames

The following is the list of recognized keynames for a TOSCA Node Template definition:

Keyname

Required

Type

Description

type

yes

string

The required name of the Node Type the Node Template is based upon.

description

no

description

An optional description for the Node Template.

directives

no

string[]

An optional list of directive values to provide processing instructions to orchestrators and tooling.

properties

no

list of

property assignments

An optional list of property value assignments for the Node Template.

attributes

no

list of

attribute assignments

An optional list of attribute value assignments for the Node Template.

requirements

no

list of

requirement assignments

An optional sequenced list of requirement assignments for the Node Template.

capabilities

no

list of

capability assignments

An optional list of capability assignments for the Node Template.

interfaces

no

list of

interface definitions

An optional list of named interface definitions for the Node Template.

artifacts

no

list of

artifact definitions

 

An optional list of named artifact definitions for the Node Template.

node_filter

no

node filter

The optional filter definition that TOSCA orchestrators would use to select the correct target node.  This keyname is only valid if the directive has the value of “selectable” set.

copy

no

string

The optional (symbolic) name of another node template to copy into (all keynames and values) and use as a basis for this node template.

3.7.3.2 Grammar

<node_template_name>:

  type: <node_type_name>

  description: <node_template_description>

  directives: [<directives>]

  properties:

    <property_assignments>

  attributes:

    <attribute_assignments>

  requirements:

    - <requirement_assignments>

  capabilities:

    <capability_assignments>

  interfaces:

    <interface_definitions>

  artifacts:

    <artifact_definitions>

  node_filter:

    <node_filter_definition>

  copy: <source_node_template_name>

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

·         node_template_name: represents the required symbolic name of the Node Template being declared.

·         node_type_name: represents the name of the Node Type the Node Template is based upon.

·         node_template_description: represents the optional description string for Node Template.

·         directives: represents the optional list of processing instruction keywords (as strings) for use by tooling and orchestrators.

·         property_assignments: represents the optional list of property assignments for the Node Template that provide values for properties defined in its declared Node Type.

·         attribute_assignments: represents the optional list of attribute assignments  for the Node Template that provide values for attributes defined in its declared Node Type.

·         requirement_assignments: represents the optional sequenced list of requirement assignments for the Node Template that allow assignment of type-compatible capabilities, target nodes, relationships and target (node filters) for use when fulfilling the requirement at runtime.

·         capability_assignments: represents the optional list of capability assignments for the Node Template that augment those provided by its declared Node Type.

·         interface_definitions: represents the optional list of interface definitions for the Node Template that augment those provided by its declared Node Type.

·         artifact_definitions: represents the optional list of artifact definitions for the Node Template that augment those provided by its declared Node Type.

·         node_filter_definition: represents the optional node filter TOSCA orchestrators would use for selecting a matching node template.

·         source_node_template_name: represents the optional (symbolic) name of another node template to copy into (all keynames and values) and use as a basis for this node template.

3.7.3.3 Additional requirements

·         The node_filter keyword (and supporting grammar) SHALL only be valid if the Node Template has a directive keyname with the value of “selectable” set.

·         The source node template provided as a value on the copy keyname MUST NOT itself use the copy keyname (i.e., it must itself be a complete node template description and not copied from another node template).

3.7.3.4 Example

node_templates:

  mysql:

    type: tosca.nodes.DBMS.MySQL

    properties:

      root_password: { get_input: my_mysql_rootpw }

      port: { get_input: my_mysql_port }

    requirements:

      - host: db_server

    interfaces:

      Standard:

        configure: scripts/my_own_configure.sh

3.7.4 Relationship Template

A Relationship Template specifies the occurrence of a manageable relationship between node templates as part of an application’s topology model that is defined in a TOSCA Service Template.  A Relationship template is an instance of a specified Relationship Type and can provide customized properties, constraints or operations which override the defaults provided by its Relationship Type and its implementations.

3.7.4.1 Keynames

The following is the list of recognized keynames for a TOSCA Relationship Template definition:

Keyname

Required

Type

Description

type

yes

string

The required name of the Relationship Type the Relationship Template is based upon.

description

no

description

An optional description for the Relationship Template.

properties

no

list of

property assignments

An optional list of property assignments for the Relationship Template.

attributes

no

list of

attribute assignments

An optional list of attribute assignments for the Relationship Template.

interfaces

no

list of

interface definitions

An optional list of named interface definitions for the Node Template.

copy

no

string

The optional (symbolic) name of another relationship template to copy into (all keynames and values) and use as a basis for this relationship template.

3.7.4.2 Grammar

<relationship_template_name>:

  type: <relationship_type_name>

  description: <relationship_type_description>

  properties:

    <property_assignments>

  attributes:

    <attribute_assignments>

  interfaces:

    <interface_definitions>

  copy:

    <source_relationship_template_name>

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

·         relationship_template_name: represents the required symbolic name of the Relationship Template being declared.

·         relationship_type_name: represents the name of the Relationship Type the Relationship Template is based upon.

·         relationship_template_description: represents the optional description string for the Relationship Template.

·         property_assignments: represents the optional list of property assignments for the Relationship Template that provide values for properties defined in its declared Relationship Type.

·         attribute_assignments: represents the optional list of attribute assignments  for the Relationship Template that provide values for attributes defined in its declared Relationship Type.

·         interface_definitions: represents the optional list of interface definitions for the Relationship Template that augment those provided by its declared Relationship Type.

·         source_relationship_template_name: represents the optional (symbolic) name of another relationship template to copy into (all keynames and values) and use as a basis for this relationship template.

3.7.4.3 Additional requirements

·         The source relationship template provided as a value on the copy keyname MUST NOT itself use the copy keyname (i.e., it must itself be a complete relationship template description and not copied from another relationship template).

3.7.4.4 Example

relationship_templates:

  storage_attachment:

    type: AttachesTo

    properties:

      location: /my_mount_point

3.7.5 Group definition

A group definition defines a logical grouping of node templates, typically for management purposes, but is separate from the application’s topology template.

3.7.5.1 Keynames

The following is the list of recognized keynames for a TOSCA group definition:

Keyname

Required

Type

Description

type

yes

string

The required name of the group type the group definition is based upon.

description

no

description

The optional description for the group definition.

properties

no

list of

property assignments

An optional list of property value assignments for the group definition.

members

no

list of string

The optional list of one or more node template names that are members of this group definition.

interfaces

no

list of

interface definitions

An optional list of named interface definitions for the group definition.

3.7.5.2 Grammar

Group definitions have one the following grammars:

<group_name>:

  type: <group_type_name>

  description: <group_description>

  properties:

    <property_assignments>

  members: [ <list_of_node_templates> ]

  interfaces:

    <interface_definitions>

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

·         group_name: represents the required symbolic name of the group as a string.

·         group_type_name: represents the name of the Group Type the definition is based upon.

·         group_description: contains an optional description of the group.

·         property_assignments: represents the optional list of property assignments for the group definition that provide values for properties defined in its declared Group Type.

·         list_of_node_templates: contains the required list of one or more node template names (within the same topology template) that are members of this logical group.

·         interface_definitions: represents the optional list of interface definitions for the group definition that augment those provided by its declared Group Type.

3.7.5.3 Additional Requirements

·         Group definitions SHOULD NOT be used to define or redefine relationships (dependencies) for an application that can be expressed using normative TOSCA Relationships within a TOSCA topology template.

3.7.5.4 Example

The following represents a group definition:

groups:

  my_app_placement_group:

    type: tosca.groups.Root

    description: My application’s logical component grouping for placement

    members: [ my_web_server, my_sql_database ]

3.7.6 Policy definition

A policy definition defines a policy that can be associated with a TOSCA topology or top-level entity definition (e.g., group definition, node template, etc.).

3.7.6.1 Keynames

The following is the list of recognized keynames for a TOSCA policy definition:

Keyname

Required

Type

Description

type

yes

string

The required name of the policy type the policy definition is based upon.

description

no

description

The optional description for the policy definition.

properties

no

list of

property assignments

An optional list of property value assignments for the policy definition.

targets

 

no

string[]

An optional list of valid Node Templates or Groups the Policy can be applied to.

3.7.6.2 Grammar

Policy definitions have one the following grammars:

<policy_name>:

  type: <policy_type_name>

  description: <policy_description>

  properties:

    <property_assignments>

  targets: [<list_of_policy_targets>]

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

·         policy_name: represents the required symbolic name of the policy as a string.

·         policy_type_name: represents the name of the policy the definition is based upon.

·         policy_description: contains an optional description of the policy.

·         property_assignments: represents the optional list of property assignments for the policy definition  that provide values for properties defined in its declared Policy Type.

·         list_of_policy_targets: represents the optional list of names of node templates or groups that the policy is to applied to.

3.7.6.3 Example

The following represents a policy definition:

policies:

  - my_compute_placement_policy:

      type: tosca.policies.placement

      description: Apply my placement policy to my application’s servers

      targets: [ my_server_1, my_server_2 ]

3.8 Topology Template definition

This section defines the topology template of a cloud application. The main ingredients of the topology template are node templates representing components of the application and relationship templates representing links between the components. These elements are defined in the nested node_templates section and the nested relationship_templates sections, respectively.  Furthermore, a topology template allows for defining input parameters, output parameters as well as grouping of node templates.

3.8.1 Keynames

The following is the list of recognized keynames for a TOSCA Topology Template:

Keyname

Required

Type

Description

description

no

description

The optional description for the Topology Template.

inputs

no

list of

parameter definitions

An optional list of input parameters (i.e., as parameter definitions) for the Topology Template.

node_templates

no

list of

node templates

An optional list of node template definitions for the Topology Template.

relationship_templates

no

list of

relationship templates

An optional list of relationship templates for the Topology Template.

groups

no

list of

group definitions

An optional list of Group definitions whose members are node templates defined within this same Topology Template.

policies

no

list of

policy definitions

An optional list of Policy definitions for the Topology Template.

outputs

no

list of

parameter definitions

An optional list of output parameters (i.e., as parameter definitions) for the Topology Template.

substitution_mappings

no

N/A

An optional declaration that exports the topology template as an implementation of a Node type.

 

This also includes the mappings between the external Node Types named capabilities and requirements to existing implementations of those capabilities and requirements on Node templates declared within the topology template.

3.8.2 Grammar

The overall grammar of the topology_template section is shown below.–Detailed grammar definitions of the each sub-sections are provided in subsequent subsections.

topology_template:

  description: <template_description>

  inputs: <input_parameter_list>

  outputs: <output_parameter_list>

  node_templates: <node_template_list>

  relationship_templates: <relationship_template_list>

  groups: <group_definition_list>

  policies:

    - <policy_definition_list>

 

  # Optional declaration that exports the Topology Template

  # as an implementation of a Node Type.

  substitution_mappings:

    node_type: <node_type_name>

    capabilities:

      <map_of_capability_mappings_to_expose>

    requirements:

      <map_of_requirement_mapping_to_expose>

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

·         template_description: represents the optional description string for Topology Template.

·         input_parameter_list: represents the optional list of input parameters (i.e., as property definitions) for the Topology Template.

·         output_parameter_list: represents the optional list of output parameters (i.e., as property definitions) for the Topology Template.

·         group_definition_list: represents the optional list of group definitions whose members are node templates that also are defined within this Topology Template.

·         policy_definition_list: represents the optional sequenced list of policy definitions for the Topology Template.

·         node_template_list: represents the optional list of node template definitions for the Topology Template.

·         relationship_template_list: represents the optional list of relationship templates for the Topology Template.

·         node_type_name: represents the optional name of a Node Type that the Topology Template implements as part of the substitution_mappings.

·         map_of_capability_mappings_to_expose: represents the mappings that expose internal capabilities from node templates (within the topology template) as capabilities of the Node Type definition that is declared as part of the substitution_mappings.

·         map_of_requirement_mappings_to_expose: represents the mappings of link requirements of the Node Type definition that is declared as part of the substitution_mappings to internal requirements implementations within node templates (declared within the topology template).

 

More detailed explanations for each of the Topology Template grammar’s keynames appears in the sections below.

3.8.2.1 inputs

The inputs section provides a means to define parameters using TOSCA parameter definitions, their allowed values via constraints and default values within a TOSCA Simple Profile template. Input parameters defined in the inputs section of a topology template can be mapped to properties of node templates or relationship templates within the same topology template and can thus be used for parameterizing the instantiation of the topology template.

 

This section defines topology template-level input parameter section.

·         Inputs here would ideally be mapped to BoundaryDefinitions in TOSCA v1.0.

·         Treat input parameters as fixed global variables (not settable within template)

·         If not in input take default (nodes use default)

3.8.2.1.1 Grammar

The grammar of the inputs section is as follows:

inputs:

  <parameter_definition_list>

3.8.2.1.2 Examples

This section provides a set of examples for the single elements of a topology template.

Simple inputs example without any constraints:

inputs:

  fooName:

    type: string

    description: Simple string typed property definition with no constraints.

    default: bar

Example of inputs with constraints:

inputs:

  SiteName:

    type: string

    description: string typed property definition with constraints

    default: My Site

    constraints:

      - min_length: 9

3.8.2.2 node_templates

The node_templates section lists the Node Templates that describe the (software) components that are used to compose cloud applications.

3.8.2.2.1 grammar

The grammar of the node_templates section is a follows:

node_templates:

  <node_template_defn_1>

  ...

  <node_template_defn_n>

3.8.2.2.2 Example

Example of node_templates section:

node_templates:

  my_webapp_node_template:

    type: WebApplication

 

  my_database_node_template:

    type: Database

3.8.2.3 relationship_templates

The relationship_templates section lists the Relationship Templates that describe the relations between components that are used to compose cloud applications.

 

Note that in the TOSCA Simple Profile, the explicit definition of relationship templates as it was required in TOSCA v1.0 is optional, since relationships between nodes get implicitly defined by referencing other node templates in the requirements sections of node templates.

3.8.2.3.1 Grammar

The grammar of the relationship_templates section is as follows:

relationship_templates:

  <relationship_template_defn_1>

  ...

  <relationship_template_defn_n>

3.8.2.3.2 Example

Example of relationship_templates section:

relationship_templates:

  my_connectsto_relationship:

    type: tosca.relationships.ConnectsTo

    interfaces:

      Configure:

        inputs:

          speed: { get_attribute: [ SOURCE, connect_speed ] }     

3.8.2.4 outputs

The outputs section provides a means to define the output parameters that are available from a TOSCA Simple Profile service template. It allows for exposing attributes of node templates or relationship templates within the containing topology_template to users of a service.

3.8.2.4.1 Grammar

The grammar of the outputs section is as follows:

outputs:

  <parameter_def_list>

3.8.2.4.2 Example

Example of the outputs section:

outputs:

  server_address:

    description: The first private IP address for the provisioned server.

    value: { get_attribute: [ HOST, networks, private, addresses, 0 ] }

3.8.2.5 groups

The groups section allows for grouping one or more node templates within a TOSCA Service Template and for assigning special attributes like policies to the group.

3.8.2.5.1 Grammar

The grammar of the groups section is as follows:

groups:

  <group_defn_1>

  ...

  <group_defn_n>

3.8.2.5.2 Example

The following example shows the definition of three Compute nodes in the node_templates section of a topology_template as well as the grouping of two of the Compute nodes in a group server_group_1.

node_templates:

  server1:

    type: tosca.nodes.Compute

    # more details ...

 

  server2:

    type: tosca.nodes.Compute

    # more details ...

 

  server3:

    type: tosca.nodes.Compute

    # more details ...

 

groups:

  # server2 and server3 are part of the same group

  server_group_1:

    type: tosca.groups.Root

    members: [ server2, server3 ]

3.8.2.6 policies

The policies section allows for declaring policies that can be applied to entities in the topology template.

3.8.2.6.1 Grammar

The grammar of the policies section is as follows:

policies:

  - <policy_defn_1>

  - ...

  - <policy_defn_n>

3.8.2.6.2 Example

The following example shows the definition of a placement policy.

policies:

  - my_placement_policy:

      type: mycompany.mytypes.policy.placement

3.8.2.7 Notes

·         The parameters (properties) that are listed as part of the inputs block can be mapped to PropertyMappings provided as part of BoundaryDefinitions as described by the TOSCA v1.0 specification.

·         The node templates listed as part of the node_templates block can be mapped to the list of NodeTemplate definitions provided as part of TopologyTemplate of a ServiceTemplate as described by the TOSCA v1.0 specification.

·         The relationship templates listed as part of the relationship_templates block can be mapped to the list of RelationshipTemplate definitions provided as part of TopologyTemplate of a ServiceTemplate as described by the TOSCA v1.0 specification.

·         The output parameters that are listed as part of the outputs section of a topology template can be mapped to PropertyMappings provided as part of BoundaryDefinitions as described by the TOSCA v1.0 specification.

o   Note, however, that TOSCA v1.0 does not define a direction (input vs. output) for those mappings, i.e. TOSCA v1.0 PropertyMappings are underspecified in that respect and TOSCA Simple Profile’s inputs and outputs provide a more concrete definition of input and output parameters.

3.9 Service Template definition

A TOSCA Service Template (YAML) document contains element definitions of building blocks for cloud application, or complete models of cloud applications. This section describes the top-level structural elements (TOSCA keynames) along with their grammars, which are allowed to appear in a TOSCA Service Template document.

3.9.1 Keynames

The following is the list of recognized keynames for a TOSCA Service Template definition:

Keyname

Required

Type

Description

tosca_definitions_version

yes

string

Defines the version of the TOSCA Simple Profile specification the template (grammar) complies with.

metadata

no

map of string

Defines a section used to declare additional metadata information.  Domain-specific TOSCA profile specifications may define keynames that are required for their implementations.

description

no

description

Declares a description for this Service Template and its contents.

dsl_definitions

no

N/A

Declares optional DSL-specific definitions and conventions.  For example, in YAML, this allows defining reusable YAML macros (i.e., YAML alias anchors) for use throughout the TOSCA Service Template.

repositories

no

list of

Repository definitions

Declares the list of external repositories which contain artifacts that are referenced in the service template along with their addresses and necessary credential information used to connect to them in order to retrieve the artifacts.

imports

no

list of

Import Definitions

Declares import statements external TOSCA Definitions documents. For example, these may be file location or URIs relative to the service template file within the same TOSCA CSAR file.

artifact_types

no

list of

Artifact Types

This section contains an optional list of artifact type definitions for use in the service template

data_types

no

list of

Data Types

Declares a list of optional TOSCA Data Type definitions.

capability_types

no

list of

Capability Types

This section contains an optional list of capability type definitions for use in the service template.

interface_types

no

list of

Interface Types

This section contains an optional list of interface type definitions for use in the service template.

relationship_types

no

list of

Relationship Types

This section contains a set of relationship type definitions for use in the service template.

node_types

no

list of

Node Types

This section contains a set of node type definitions for use in the service template.

group_types

no

list of

Group Types

This section contains a list of group type definitions for use in the service template.

policy_types

no

list of

Policy Types

This section contains a list of policy type definitions for use in the service template.

topology_template

no

Topology Template definition

Defines the topology template of an application or service, consisting of node templates that represent the application’s or service’s components, as well as relationship templates representing relations between the components.

3.9.1.1 Metadata keynames

The following is the list of recognized metadata keynames for a TOSCA Service Template definition:

Keyname

Required

Type

Description

template_name

no

string

Declares a descriptive name for the template. 

template_author

no

string

Declares the author(s) or owner of the template.

template_version

no

string

Declares the version string for the template.

3.9.2 Grammar

The overall structure of a TOSCA Service Template and its top-level key collations using the TOSCA Simple Profile is shown below:

tosca_definitions_version: # Required TOSCA Definitions version string

 

# Optional metadata keyname: value pairs

metadata:

  template_name:             # Optional name of this service template

  template_author:           # Optional author of this service template

  template_version:          # Optional version of this service template

  #  Optional list of domain or profile specific metadata keynames

 

# Optional description of the definitions inside the file.

description: <template_type_description>

 

dsl_definitions:

  # list of YAML alias anchors (or macros)

 

repositories:

  # list of external repository definitions which host TOSCA artifacts

 

imports:

  # ordered list of import definitions

 

artifact_types:

  # list of artifact type definitions

 

data_types:

  # list of datatype definitions

 

capability_types:

  # list of capability type definitions

 

interface_types

  # list of interface type definitions

 

relationship_types:

  # list of relationship type definitions

 

node_types:

  # list of node type definitions

 

group_types:

  # list of group type definitions

 

policy_types:

  # list of policy type definitions

 

topology_template:

  # topology template definition of the cloud application or service

3.9.2.1 Notes

·         TOSCA Service Templates do not have to contain a topology_template and MAY contain simply type definitions (e.g., Artifact, Interface, Capability, Node, Relationship Types, etc.) and be imported for use as type definitions in other TOSCA Service Templates.

3.9.3 Top-level keyname definitions

3.9.3.1 tosca_definitions_version

This required element provides a means to include a reference to the TOSCA Simple Profile specification within the TOSCA Definitions YAML file.  It is an indicator for the version of the TOSCA grammar that should be used to parse the remainder of the document.

3.9.3.1.1 Keyname

tosca_definitions_version

3.9.3.1.2 Grammar

Single-line form:

tosca_definitions_version: <tosca_simple_profile_version>

3.9.3.1.3 Examples:

TOSCA Simple Profile version 1.0 specification using the defined namespace alias (see Section 3.1):

tosca_definitions_version: tosca_simple_yaml_1_0

TOSCA Simple Profile version 1.0 specification using the fully defined (target) namespace (see Section 3.1):

tosca_definitions_version: http://docs.oasis-open.org/tosca/ns/simple/yaml/1.0

3.9.3.2 metadata

This keyname is used to associate domain-specific metadata with the Service Template.  The metadata keyname allows a declaration of a map of keynames with string values.

3.9.3.2.1 Keyname

metadata

3.9.3.2.2 Grammar

metadata:

  <map_of_string_values>

3.9.3.2.3 Example

metadata:

  creation_date: 2015-04-14

  date_updated: 2015-05-01

  status: developmental 

 

3.9.3.3 template_name

This optional metadata keyname can be used to declare the name of service template as a single-line string value.

3.9.3.3.1 Keyname

template_name

3.9.3.3.2 Grammar

template_name: <name string>

3.9.3.3.3 Example

template_name: My service template

3.9.3.3.4 Notes

·         Some service templates are designed to be referenced and reused by other service templates.  Therefore, in these cases, the template_name value SHOULD be designed to be used as a unique identifier through the use of namespacing techniques. 

3.9.3.4 template_author

This optional metadata keyname can be used to declare the author(s) of the service template as a single-line string value.

3.9.3.4.1 Keyname

template_author

3.9.3.4.2 Grammar

template_author: <author string>

3.9.3.4.3 Example

template_author: My service template

3.9.3.5 template_version

This optional metadata keyname can be used to declare a domain specific version of the service template as a single-line string value.

3.9.3.5.1 Keyname

template_version

3.9.3.5.2 Grammar

template_version: <version>

3.9.3.5.3 Example

template_version: 2.0.17

3.9.3.5.4 Notes:

·         Some service templates are designed to be referenced and reused by other service templates and have a lifecycle of their own.  Therefore, in these cases, a template_version value SHOULD be included and used in conjunction with a unique template_name value to enable lifecycle management of the service template and its contents. 

3.9.3.6 description

This optional keyname provides a means to include single or multiline descriptions within a TOSCA Simple Profile template as a scalar string value.

3.9.3.6.1 Keyname

description

3.9.3.7 dsl_definitions

This optional keyname provides a section to define macros (e.g., YAML-style macros when using the TOSCA Simple Profile in YAML specification).

3.9.3.7.1 Keyname

dsl_definitions

3.9.3.7.2 Grammar

dsl_definitions:

   <dsl_definition_1>

   ...

   <dsl_definition_n>

3.9.3.7.3 Example

dsl_definitions:

    ubuntu_image_props: &ubuntu_image_props

      architecture: x86_64

      type: linux

      distribution: ubuntu

      os_version: 14.04

 

    redhat_image_props: &redhat_image_props

      architecture: x86_64

      type: linux

      distribution: rhel

      os_version: 6.6

3.9.3.8 repositories

This optional keyname provides a section to define external repositories which may contain artifacts or other TOSCA Service Templates which might be referenced or imported by the TOSCA Service Template definition.

3.9.3.8.1 Keyname

repositories

3.9.3.8.2 Grammar

repositories:

   <repository_definition_1>

   ...

   <repository_definition_n>

3.9.3.8.3 Example

repositories:

  my_project_artifact_repo:

    description: development repository for TAR archives and Bash scripts

    url: http://mycompany.com/repository/myproject/

3.9.3.9 imports

This optional keyname provides a way to import a block sequence of one or more TOSCA Definitions documents.  TOSCA Definitions documents can contain reusable TOSCA type definitions (e.g., Node Types, Relationship Types, Artifact Types, etc.) defined by other authors.  This mechanism provides an effective way for companies and organizations to define normative types and/or describe their software applications for reuse in other TOSCA Service Templates.

3.9.3.9.1 Keyname

imports

3.9.3.9.2 Grammar

imports:

   - <import_definition_1>

   - ...

   - <import_definition_n>

3.9.3.9.3 Example

# An example import of definitions files from a location relative to the

# file location of the service template declaring the import.

imports:

  - some_definitions: relative_path/my_defns/my_typesdefs_1.yaml

  - more_definitions:

      file: my_defns/my_typesdefs_n.yaml   

      repository: my_company_repo

      namespace_uri: http://mycompany.com/ns/tosca/2.0

      namespace_prefix: mycompany

3.9.3.10 artifact_types

This optional keyname lists the Artifact Types that are defined by this Service Template.

3.9.3.10.1 Keyname

artifact_types

3.9.3.10.2 Grammar

artifact_types:

  <artifact_type_defn_1>

  ...

  <artifact type_defn_n>

3.9.3.10.3 Example

artifact_types:

  mycompany.artifacttypes.myFileType:

    derived_from: tosca.artifacts.File

3.9.3.11 data_types

This optional keyname provides a section to define new data types in TOSCA.

3.9.3.11.1 Keyname

data_types

3.9.3.11.2 Grammar

data_types:

   <tosca_datatype_def_1>

   ...

   <tosca_datatype_def_n>

3.9.3.11.3 Example

data_types:

  # A complex datatype definition

  simple_contactinfo_type:

    properties:

      name:

        type: string

      email:

        type: string

      phone:

        type: string

 

  # datatype definition derived from an existing type

  full_contact_info:

    derived_from: simple_contact_info

    properties:

      street_address:

        type: string

      city:

        type: string

      state:

        type: string

      postalcode:

        type: string

3.9.3.12 capability_types

This optional keyname lists the Capability Types that provide the reusable type definitions that can be used to describe features Node Templates or Node Types can declare they support.

3.9.3.12.1 Keyname

capability_types

3.9.3.12.2 Grammar

capability_types:

  <capability_type_defn_1>

  ...

  <capability type_defn_n>

3.9.3.12.3 Example

capability_types:

  mycompany.mytypes.myCustomEndpoint:

    derived_from: tosca.capabilities.Endpoint

    properties:

      # more details ...

 

  mycompany.mytypes.myCustomFeature:

    derived_from: tosca.capabilities.Feature

    properties:

      # more details ...

3.9.3.13 interface_types

This optional keyname lists the Interface Types that provide the reusable type definitions that can be used to describe operations for on TOSCA entities such as Relationship Types and Node Types.

3.9.3.13.1 Keyname

interface_types

3.9.3.13.2 Grammar

interface_types:

  <interface_type_defn_1>

  ...

  <interface type_defn_n>

3.9.3.13.3 Example

interface_types:

  mycompany.interfaces.service.Signal:

    signal_begin_receive:

      description: Operation to signal start of some message processing.

    signal_end_receive:

      description: Operation to signal end of some message processed.

3.9.3.14 relationship_types

This optional keyname lists the Relationship Types that provide the reusable type definitions that can be used to describe dependent relationships between Node Templates or Node Types.

3.9.3.14.1 Keyname

relationship_types

3.9.3.14.2 Grammar

relationship_types:

  <relationship_type_defn_1>

  ...

  <relationship type_defn_n>

3.9.3.14.3 Example

relationship_types:

  mycompany.mytypes.myCustomClientServerType:

    derived_from: tosca.relationships.HostedOn

    properties:

      # more details ...

  mycompany.mytypes.myCustomConnectionType:

    derived_from: tosca.relationships.ConnectsTo

    properties:

      # more details ...

3.9.3.15 node_types

This optional keyname lists the Node Types that provide the reusable type definitions for software components that Node Templates can be based upon.

3.9.3.15.1 Keyname

node_types

3.9.3.15.2 Grammar

node_types:

  <node_type_defn_1>

  ...

  <node_type_defn_n>

3.9.3.15.3 Example

node_types:

  my_webapp_node_type:

    derived_from: WebApplication

    properties:

      my_port:

        type: integer

 

  my_database_node_type:

    derived_from: Database

    capabilities:

      mytypes.myfeatures.transactSQL

3.9.3.15.4 Notes

·         The node types listed as part of the node_types block can be mapped to the list of NodeType definitions as described by the TOSCA v1.0 specification. 

3.9.3.16 group_types

This optional keyname lists the Group Types that are defined by this Service Template.

3.9.3.16.1 Keyname

group_types

3.9.3.16.2 Grammar

group_types:

  <group_type_defn_1>

  ...

  <group type_defn_n>

3.9.3.16.3 Example

group_types:

  mycompany.mytypes.myScalingGroup:

    derived_from: tosca.groups.Root

3.9.3.17 policy_types

This optional keyname lists the Policy Types that are defined by this Service Template.

3.9.3.17.1 Keyname

policy_types

3.9.3.17.2 Grammar

policy_types:

  <policy_type_defn_1>

  ...

  <policy type_defn_n>

3.9.3.17.3 Example

policy_types:

  mycompany.mytypes.myScalingPolicy:

    derived_from: tosca.policies.Scaling

4      TOSCA functions

Except for the examples, this section is normative and includes functions that are supported for use within a TOSCA Service Template.

4.1 Reserved Function Keywords

The following keywords MAY be used in some TOSCA function in place of a TOSCA Node or Relationship Template name.  A TOSCA orchestrator will interpret them at the time the function would be evaluated at runtime as described in the table below.  Note that some keywords are only valid in the context of a certain TOSCA entity as also denoted in the table.

 

Keyword

Valid Contexts

Description

SELF

Node Template or Relationship Template

A TOSCA orchestrator will interpret this keyword as the Node or Relationship Template instance that contains the function at the time the function is evaluated.

SOURCE

Relationship Template only.

A TOSCA orchestrator will interpret this keyword as the Node Template instance that is at the source end of the relationship that contains the referencing function.

TARGET

Relationship Template only.

A TOSCA orchestrator will interpret this keyword as the Node Template instance that is at the target end of the relationship that contains the referencing function.

HOST

Node Template only

A TOSCA orchestrator will interpret this keyword to refer to the all nodes that “host” the node using this reference (i.e., as identified by its HostedOn relationship).

 

Specifically, TOSCA orchestrators that encounter this keyword when evaluating the get_attribute or get_property functions SHALL search each node along the “HostedOn” relationship chain starting at the immediate node that hosts the node where the function was evaluated (and then that node’s host node, and so forth) until a match is found or the “HostedOn” relationship chain ends.

 

4.2 Environment Variable Conventions

4.2.1 Reserved Environment Variable Names and Usage

TOSCA orchestrators utilize certain reserved keywords in the execution environments that implementation artifacts for Node or Relationship Templates operations are executed in. They are used to provide information to these implementation artifacts such as the results of TOSCA function evaluation or information about the instance model of the TOSCA application

 

The following keywords are reserved environment variable names in any TOSCA supported execution environment:

Keyword

Valid Contexts

Description

TARGETS

Relationship Template only.

·   For an implementation artifact that is executed in the context of a relationship, this keyword, if present, is used to supply a list of Node Template instances in a TOSCA application’s instance model that are currently target of the context relationship. 

·   The value of this environment variable will be a comma-separated list of identifiers of the single target node instances (i.e., the tosca_id attribute of the node).

TARGET

Relationship Template only.

·   For an implementation artifact that is executed in the context of a relationship, this keyword, if present, identifies a Node Template instance in a TOSCA application’s instance model that is a target of the context relationship, and which is being acted upon in the current operation. 

·   The value of this environment variable will be the identifier of the single target node instance (i.e., the tosca_id attribute of the node).

SOURCES

Relationship Template only.

·   For an implementation artifact that is executed in the context of a relationship, this keyword, if present, is used to supply a list of Node Template instances in a TOSCA application’s instance model that are currently source of the context relationship. 

·   The value of this environment variable will be a comma-separated list of identifiers of the single source node instances (i.e., the tosca_id attribute of the node).

SOURCE

Relationship Template only.

·   For an implementation artifact that is executed in the context of a relationship, this keyword, if present, identifies a Node Template instance in a TOSCA application’s instance model that is a source of the context relationship, and which is being acted upon in the current operation. 

·   The value of this environment variable will be the identifier of the single source node instance (i.e., the tosca_id attribute of the node).

 

For scripts (or implementation artifacts in general) that run in the context of relationship operations, select properties and attributes of both the relationship itself as well as select properties and attributes of the source and target node(s) of the relationship can be provided to the environment by declaring respective operation inputs.

 

Declared inputs from mapped properties or attributes of the source or target node (selected via the SOURCE or TARGET keyword) will be provided to the environment as variables having the exact same name as the inputs. In addition, the same values will be provided for the complete set of source or target nodes, however prefixed with the ID if the respective nodes. By means of the SOURCES or TARGETS variables holding the complete set of source or target node IDs, scripts will be able to iterate over corresponding inputs for each provided ID prefix.

 

The following example snippet shows an imaginary relationship definition from a load-balancer node to worker nodes. A script is defined for the add_target operation of the Configure interface of the relationship, and the ip_address attribute of the target is specified as input to the script:

 

node_templates:

  load_balancer:

    type: some.vendor.LoadBalancer

    requirements:

      - member:

          relationship: some.vendor.LoadBalancerToMember

            interfaces:

              Configure:

                add_target:

                  inputs:

                    member_ip: { get_attribute: [ TARGET, ip_address ] }

                  implementation: scripts/configure_members.py

The add_target operation will be invoked, whenever a new target member is being added to the load-balancer. With the above inputs declaration, a member_ip environment variable that will hold the IP address of the target being added will be provided to the configure_members.py script. In addition, the IP addresses of all current load-balancer members will be provided as environment variables with a naming scheme of <target node ID>_member_ip. This will allow, for example, scripts that always just write the complete list of load-balancer members into a configuration file to do so instead of updating existing list, which might be more complicated.

Assuming that the TOSCA application instance includes five load-balancer members, node1 through node5, where node5 is the current target being added, the following environment variables (plus potentially more variables) would be provided to the script:

# the ID of the current target and the IDs of all targets    

TARGET=node5

TARGETS=node1,node2,node3,node4,node5

 

# the input for the current target and the inputs of all targets

member_ip=10.0.0.5

node1_member_ip=10.0.0.1

node2_member_ip=10.0.0.2

node3_member_ip=10.0.0.3

node4_member_ip=10.0.0.4

node5_member_ip=10.0.0.5

With code like shown in the snippet below, scripts could then iterate of all provided member_ip inputs:

#!/usr/bin/python

import os

 

targets = os.environ['TARGETS'].split(',')

 

for t in targets:

  target_ip = os.environ.get('%s_member_ip' % t)

  # do something with target_ip ...

4.2.2 Prefixed vs. Unprefixed TARGET names

The list target node types assigned to the TARGETS key in an execution environment would have names prefixed by unique IDs that distinguish different instances of a node in a running model  Future drafts of this specification will show examples of how these names/IDs will be expressed.

4.2.2.1 Notes

·         Target of interest is always un-prefixed. Prefix is the target opaque ID.  The IDs can be used to find the environment var. for the corresponding target. Need an example here.

·         If you have one node that contains multiple targets this would also be used (add or remove target operations would also use this you would get set of all current targets).

4.3 Intrinsic functions

These functions are supported within the TOSCA template for manipulation of template data. 

4.3.1 concat

The concat function is used to concatenate two or more string values within a TOSCA service template.

4.3.1.1 Grammar

concat: [<string_value_expressions_*> ]

4.3.1.2 Parameters

Parameter

Required

Type

Description

<string_value_expressions_*>

yes

list of

string or

string value expressions

A list of one or more strings (or expressions that result in a string value) which can be concatenated together into a single string.

4.3.1.3 Examples

outputs:

  description: Concatenate the URL for a server from other template values

  server_url:

  value: { concat: [ 'http://',

                     get_attribute: [ server, public_address ],

                     ':',

                     get_attribute: [ server, port ] ] }

4.3.2 token

The token function is used within a TOSCA service template on a string to parse out (tokenize) substrings separated by one or more token characters within a larger string.

4.3.2.1 Grammar

token: [ <string_with_tokens>, <string_of_token_chars>, <substring_index> ]

4.3.2.2 Parameters

Parameter

Required

Type

Description

string_with_tokens

yes

string

The composite string that contains one or more substrings separated by token characters.

string_of_token_chars

yes

string

The string that contains one or more token characters that separate substrings within the composite string.

substring_index

yes

integer

The integer indicates the index of the substring to return from the composite string.  Note that the first substring is denoted by using the ‘0’ (zero) integer value.

4.3.2.3 Examples

outputs:

   webserver_port:

     description: the port provided at the end of my server’s endpoint’s IP address

     value: { token: [ get_attribute: [ my_server, data_endpoint, ip_address ],

                       ‘:’,

                       1 ] }

4.4 Property functions

These functions are used within a service template to obtain property values from property definitions declared elsewhere in the same service template.  These property definitions can appear either directly in the service template itself (e.g., in the inputs section) or on entities (e.g., node or relationship templates) that have been modeled within the template.

 

Note that the get_input and get_property functions may only retrieve the static values of property definitions of a TOSCA application as defined in the TOSCA Service Template.  The get_attribute function should be used to retrieve values for attribute definitions (or property definitions reflected as attribute definitions) from the runtime instance model of the TOSCA application (as realized by the TOSCA orchestrator).

4.4.1 get_input

The get_input function is used to retrieve the values of properties declared within the inputs section of a TOSCA Service Template.

4.4.1.1 Grammar

get_input: <input_property_name>

4.4.1.2 Parameters

Parameter

Required

Type

Description

<input_property_name>

yes

string

The name of the property as defined in the inputs section of the service template.

4.4.1.3 Examples

inputs:

  cpus:

    type: integer

 

node_templates:

  my_server:

    type: tosca.nodes.Compute

    capabilities:

      host:

        properties:

          num_cpus: { get_input: cpus }

4.4.2 get_property

The get_property function is used to retrieve property values between modelable entities defined in the same service template.

4.4.2.1 Grammar

get_property: [ <modelable_entity_name>, <optional_req_or_cap_name>, <property_name>, <nested_property_name_or_index_1>, ..., <nested_property_name_or_index_n> ]

4.4.2.2 Parameters

Parameter

Required

Type

Description

<modelable entity name> | SELF | SOURCE | TARGET | HOST

yes

string

The required name of a modelable entity (e.g., Node Template or Relationship Template name) as declared in the service template that contains the named property definition the function will return the value from. See section B.1 for valid keywords.

<optional_req_or_cap_name>

no

string

The optional name of the requirement or capability name within the modelable entity (i.e., the <modelable_entity_name> which contains the named property definition the function will return the value from.

 

Note:  If the property definition is located in the modelable entity directly, then this parameter MAY be omitted.

<property_name>

yes

string

The name of the property definition the function will return the value from.

<nested_property_name_or_index_*>

no

string| integer

Some TOSCA properties are complex (i.e., composed as nested structures).  These parameters are used to dereference into the names of these nested structures when needed. 

 

Some properties represent list types. In these cases, an index may be provided to reference a specific entry in the list (as named in the previous parameter) to return.

4.4.2.3 Examples

The following example shows how to use the get_property function with an actual Node Template name:

node_templates:

 

  mysql_database:

    type: tosca.nodes.Database

    properties:

      name: sql_database1

 

  wordpress:

    type: tosca.nodes.WebApplication.WordPress

    ...

    interfaces:

      Standard:

        configure:

          inputs:

            wp_db_name: { get_property: [ mysql_database, name ] }

The following example shows how to use the get_property function using the SELF keyword:

node_templates: 

 

  mysql_database:

    type: tosca.nodes.Database

    ...

    capabilities:

      database_endpoint:

        properties:

          port: 3306

 

  wordpress:

    type: tosca.nodes.WebApplication.WordPress

    requirements:

      ...

      - database_endpoint: mysql_database

    interfaces:

      Standard:

        create: wordpress_install.sh

        configure:

          implementation: wordpress_configure.sh           

          inputs:

            ...

            wp_db_port: { get_property: [ SELF, database_endpoint, port ] }

The following example shows how to use the get_property function using the TARGET keyword:

relationship_templates:

    my_connection:

      type: ConnectsTo

      interfaces:

        Configure:

          inputs:

            targets_value: { get_property: [ TARGET, value ] }

4.5 Attribute functions

These functions (attribute functions) are used within an instance model to obtain attribute values from instances of nodes and relationships that have been created from an application model described in a service template.  The instances of nodes or relationships can be referenced by their name as assigned in the service template or relative to the context where they are being invoked.

4.5.1 get_attribute

The get_attribute function is used to retrieve the values of named attributes declared by the referenced node or relationship template name.

4.5.1.1 Grammar

get_attribute: [ <modelable_entity_name>, <optional_req_or_cap_name>, <attribute_name>, <nested_attribute_name_or_index_1>, ..., <nested_attribute_name_or_index_n> ]

4.5.1.2 Parameters

Parameter

Required

Type

Description

<modelable entity name> | SELF | SOURCE | TARGET | HOST

yes

string

The required name of a modelable entity (e.g., Node Template or Relationship Template name) as declared in the service template that contains the named attribute definition the function will return the value from.  See section B.1 for valid keywords.

<optional_req_or_cap_name>

no

string

The optional name of the requirement or capability name within the modelable entity (i.e., the <modelable_entity_name> which contains the named attribute definition the function will return the value from.

 

Note:  If the attribute definition is located in the modelable entity directly, then this parameter MAY be omitted.

<attribute_name>

yes

string

The name of the attribute definition the function will return the value from.

<nested_attribute_name_or_index_*>

no

string| integer

Some TOSCA attributes are complex (i.e., composed as nested structures).  These parameters are used to dereference into the names of these nested structures when needed.   

 

Some attributes represent list types. In these cases, an index may be provided to reference a specific entry in the list (as named in the previous parameter) to return.

4.5.1.3 Examples:

The attribute functions are used in the same way as the equivalent Property functions described above.  Please see their examples and replace “get_property” with “get_attribute” function name.

4.5.1.4 Notes

These functions are used to obtain attributes from instances of node or relationship templates by the names they were given within the service template that described the application model (pattern).

4.6 Operation functions

These functions are used within an instance model to obtain values from interface operations. These can be used in order to set an attribute of a node instance at runtime or to pass values from one operation to another.

4.6.1 get_operation_output

The get_operation_output function is used to retrieve the values of variables exposed / exported from an interface operation.

4.6.1.1 Grammar

get_operation_output: <modelable_entity_name>, <interface_name>, <operation_name>, <output_variable_name>

4.6.1.2 Parameters

Parameter

Required

Type

Description

<modelable entity name> | SELF | SOURCE | TARGET

yes

string

The required name of a modelable entity (e.g., Node Template or Relationship Template name) as declared in the service template that implements the named interface and operation.

<interface_name>

Yes

string

The required name of the interface which defines the operation.

<operation_name>

yes

string

The required name of the operation whose value we would like to retrieve.

<output_variable_name>

Yes

string

The required name of the variable that is exposed / exported by the operation.

 

4.6.1.3 Notes

·         If operation failed, then ignore its outputs.  Orchestrators should allow orchestrators to continue running when possible past deployment in the lifecycle.  For example, if an update fails, the application should be allowed to continue running and some other method would be used to alert administrators of the failure.

4.7 Navigation functions

·         This version of the TOSCA Simple Profile does not define any model navigation functions.

4.7.1 get_nodes_of_type

The get_nodes_of_type function can be used to retrieve a list of all known instances of nodes of the declared Node Type.

4.7.1.1 Grammar

get_nodes_of_type: <node_type_name>

4.7.1.2 Parameters

Parameter

Required

Type

Description

<node_type_name>

yes

string

The required name of a Node Type that a TOSCA orchestrator would use to search a running application instance in order to return all unique, named node instances of that type.

4.7.1.3 Returns

Return Key

Type

Description

TARGETS

<see above>

The list of node instances from the current application instance that match the node_type_name supplied as an input parameter of this function.

4.8 Artifact functions

4.8.1 get_artifact

The get_artifact function is used to retrieve artifact location between modelable entities defined in the same service template.

4.8.1.1 Grammar

get_artifact: [ <modelable_entity_name>, <artifact_name>, <location>, <remove> ]

4.8.1.2 Parameters

Parameter

Required

Type

Description

<modelable entity name> | SELF | SOURCE | TARGET | HOST

yes

string

The required name of a modelable entity (e.g., Node Template or Relationship Template name) as declared in the service template that contains the named property definition the function will return the value from. See section B.1 for valid keywords.

<artifact_name>

yes

string

The name of the artifact definition the function will return the value from.

<location> | LOCAL_FILE

no

string

Location value must be either a valid path e.g. ‘/etc/var/my_file’ or ‘LOCAL_FILE’.

 

If the value is LOCAL_FILE the orchestrator is responsible for providing a path as the result of the get_artifact call where the artifact file can be accessed. The orchestrator will also remove the artifact from this location at the end of the operation.

 

If the location is a path specified by the user the orchestrator is responsible to copy the artifact to the specified location. The orchestrator will return the path as the value of the get_artifact function and leave the file here after the execution of the operation.

remove

no