TOSCA Simple Profile in YAML Version 1.3

Committee Specification 01

18 September 2019

This version:

https://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.3/cs01/TOSCA-Simple-Profile-YAML-v1.3-cs01.pdf (Authoritative)

https://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.3/cs01/TOSCA-Simple-Profile-YAML-v1.3-cs01.html

https://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.3/cs01/TOSCA-Simple-Profile-YAML-v1.3-cs01.docx

Previous version:

https://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.3/csprd01/TOSCA-Simple-Profile-YAML-v1.3-csprd01.pdf (Authoritative)

https://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.3/csprd01/TOSCA-Simple-Profile-YAML-v1.3-csprd01.html

https://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.3/csprd01/TOSCA-Simple-Profile-YAML-v1.3-csprd01.docx

Latest version:

https://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.3/TOSCA-Simple-Profile-YAML-v1.3.pdf (Authoritative)

https://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.3/TOSCA-Simple-Profile-YAML-v1.3.html

https://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.3/TOSCA-Simple-Profile-YAML-v1.3.docx

Technical Committee:

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

Chairs:

Paul Lipton (paul.lipton@live.com), Individual Member

Chris Lauwers (lauwers@ubicity.com), Individual Member

Editors:

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

Chris Lauwers (lauwers@ubicity.com), Individual Member

Claude Noshpitz (claude.noshpitz@att.com), AT&T

Calin Curescu (calin.curescu@ericsson.com), Ericsson

Related work:

This specification replaces or supersedes:

·         TOSCA Simple Profile in YAML Version 1.2. Edited by Matt Rutkowski, Luc Boutier, and Chris Lauwers. OASIS Standard. Latest version: https://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.2/TOSCA-Simple-Profile-YAML-v1.2.html.

This specification is related to:

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

Declared XML namespaces:

·         http://docs.oasis-open.org/tosca/ns/simple/yaml/1.3

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 membership of OASIS 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/.

This specification is provided under the RF on Limited Terms Mode of the OASIS IPR Policy, the mode chosen when the Technical Committee was established. 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).

Note that any machine-readable content (Computer Language Definitions) declared Normative for this Work Product is provided in separate plain text files. In the event of a discrepancy between any such plain text file and display content in the Work Product's prose narrative document(s), the content in the separate plain text file prevails.

Citation format:

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

[TOSCA-Simple-Profile-YAML-v1.3]

TOSCA Simple Profile in YAML Version 1.3. Edited by Matt Rutkowski, Chris Lauwers, Claude Noshpitz, and Calin Curescu. 18 September 2019. OASIS Committee Specification 01. https://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.3/cs01/TOSCA-Simple-Profile-YAML-v1.3-cs01.html. Latest version: https://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.3/TOSCA-Simple-Profile-YAML-v1.3.html.

Notices

Copyright © OASIS Open 2019. All Rights Reserved.

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Table of Contents

Table of Examples. 7

Table of Figures. 8

1        Introduction. 9

1.1 IPR Policy. 9

1.2 Objective. 9

1.3 Summary of key TOSCA concepts. 9

1.4 Implementations. 10

1.5 Terminology. 10

1.6 Notational Conventions. 10

1.7 Normative References. 11

1.8 Non-Normative References. 11

1.9 Glossary. 12

2        TOSCA by example. 14

2.1 A “hello world” template for TOSCA Simple Profile in YAML. 14

2.2 TOSCA template for a simple software installation. 17

2.3 Overriding behavior of predefined node types. 18

2.4 TOSCA template for database content deployment 19

2.5 TOSCA template for a two-tier application. 22

2.6 Using a custom script to establish a relationship in a template. 24

2.7 Using custom relationship types in a TOSCA template. 26

2.8 Defining generic dependencies between nodes in a template. 27

2.9 Describing abstract requirements for nodes and capabilities in a TOSCA template. 28

2.10 Using node template substitution for model composition. 33

2.11 Using node template substitution for chaining subsystems. 37

2.12 Using node template substitution to provide product choice. 43

2.13 Grouping node templates. 47

2.14 Using YAML Macros to simplify templates. 49

2.15 Passing information as inputs to Interfaces and Operations. 50

2.16 Returning output values from operations. 51

2.17 Receiving asynchronous notifications. 52

2.18 Topology Template Model versus Instance Model 53

2.19 Using attributes implicitly reflected from properties. 53

2.20 Creating Multiple Node Instances from the Same Node Template. 55

3        TOSCA Simple Profile definitions in YAML. 59

3.1 TOSCA Namespace URI and alias. 59

3.2 Using Namespaces. 60

3.3 Parameter and property types. 64

3.4 Normative values. 74

3.5 TOSCA Metamodel 76

3.6 Reusable modeling definitions. 76

3.7 Type-specific definitions. 119

3.8 Template-specific definitions. 138

3.9 Topology Template definition. 157

3.10 Service Template definition. 165

4        TOSCA functions. 178

4.1 Reserved Function Keywords. 178

4.2 Environment Variable Conventions. 178

4.3 Intrinsic functions. 181

4.4 Property functions. 183

4.5 Attribute functions. 187

4.6 Operation functions. 188

4.7 Navigation functions. 188

4.8 Artifact functions. 189

4.9 Context-based Entity names (global) 192

5        TOSCA normative type definitions. 193

5.1 Assumptions. 193

5.2 TOSCA normative type names. 193

5.3 Data Types. 193

5.4 Artifact Types. 205

5.5 Capabilities Types. 208

5.6 Requirement Types. 219

5.7 Relationship Types. 219

5.8 Interface Types. 222

5.9 Node Types. 229

5.10 Group Types. 243

5.11 Policy Types. 244

6        TOSCA Cloud Service Archive (CSAR) format 246

6.1 Overall Structure of a CSAR. 246

6.2 TOSCA Meta File. 246

6.3 Archive without TOSCA-Metadata. 247

7        TOSCA workflows. 249

7.1 Normative workflows. 249

7.2 Declarative workflows. 249

7.3 Imperative workflows. 253

8        TOSCA networking. 269

8.1 Networking and Service Template Portability. 269

8.2 Connectivity semantics. 269

8.3 Expressing connectivity semantics. 270

8.4 Network provisioning. 272

8.5 Network Types. 276

8.6 Network modeling approaches. 282

9        Non-normative type definitions. 287

9.1 Artifact Types. 287

9.2 Capability Types. 289

9.3 Node Types. 290

10      Component Modeling Use Cases. 294

11      Application Modeling Use Cases. 301

11.1 Use cases. 301

12      TOSCA Policies. 350

12.1 A declarative approach. 350

12.2 Consideration of Event, Condition and Action. 350

12.3 Types of policies. 350

12.4 Policy relationship considerations. 351

12.5 Use Cases. 352

13      Artifact Processing and creating Portable Service Templates. 355

13.1 CSAR Onboarding. 355

13.2 Artifacts Processing. 356

13.3 Dynamic Artifacts. 360

13.4 Discussion of Examples. 360

13.5 Artifact Types and Metadata. 367

14      Conformance. 368

14.1 Conformance Targets. 368

14.2 Conformance Clause 1: TOSCA YAML service template. 368

14.3 Conformance Clause 2: TOSCA processor 368

14.4 Conformance Clause 3: TOSCA orchestrator 368

14.5 Conformance Clause 4: TOSCA generator 369

14.6 Conformance Clause 5: TOSCA archive. 369

Appendix A. Known Extensions to TOSCA v1.0. 370

A.1 Model Changes. 370

A.2 Normative Types. 370

Appendix B. Acknowledgments. 372

Appendix C. Revision History. 374

 

 


Table of Examples

Example 1 - TOSCA Simple "Hello World" 14

Example 2 - Template with input and output parameter sections. 15

Example 3 - Simple (MySQL) software installation on a TOSCA Compute node. 17

Example 4 - Node Template overriding its Node Type's "configure" interface. 19

Example 5 - Template for deploying database content on-top of MySQL DBMS middleware. 20

Example 6 - Basic two-tier application (web application and database server tiers) 22

Example 7 - Providing a custom relationship script to establish a connection. 24

Example 8 - A web application Node Template requiring a custom database connection type. 26

Example 9 - Defining a custom relationship type. 27

Example 10 - Simple dependency relationship between two nodes. 27

Example 11 - An abstract "host" requirement using a node filter 29

Example 12 - An abstract Compute node template with a node filter 30

Example 13 - An abstract database requirement using a node filter 31

Example 14 - An abstract database node template. 32

Example 15 - Referencing an abstract database node template. 34

Example 16 - Using substitution mappings to export a database implementation. 36

Example 17 - Declaring a transaction subsystem as a chain of substitutable node templates. 38

Example 18 - Defining a TransactionSubsystem node type. 40

Example 19 - Implementation of a TransactionSubsytem node type using substitution mappings. 41

Example 20 - Grouping Node Templates for possible policy application. 47

Example 21 - Grouping nodes for anti-colocation policy application. 48

Example 22 - Using YAML anchors in TOSCA templates. 49

Example 23 - Properties reflected as attributes. 54

Example 24 – TOSCA SD-WAN Service Template. 56

Example 25 – TOSCA SD-WAN Service Template. 57

Example 26 – TOSCA SD-WAN Service Template. 58

 

Table of Figures

Figure 1: Using template substitution to implement a database tier 34

Figure 2: Substitution mappings. 36

Figure 3: Chaining of subsystems in a service template. 38

Figure 4: Defining subsystem details in a service template. 41

Figure‑5: Typical 3-Tier Network. 273

Figure‑6: Generic Service Template. 282

Figure‑7: Service template with network template A. 283

Figure‑8: Service template with network template B. 283

 

1      Introduction

1.1 IPR Policy

This specification is provided under the RF on Limited Terms Mode of the OASIS IPR Policy, the mode chosen when the Technical Committee was established. 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).

1.2 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 XML specification 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.

1.3 Summary of key TOSCA concepts

The TOSCA metamodel uses the concept of service templates that describe cloud workloads as a topology template, which is a graph of node templates modeling the components a workload is made up of and of 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 types 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.

1.4 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) topology 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, deploy, and manage 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).

1.5 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 focus 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.

1.6 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].

1.6.1 Notes

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

·         A feature marked as deprecated in a particular version will be removed in the subsequent version of the specification.

1.7 Normative References

Reference Tag

Description

[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

1.8 Non-Normative References

Reference Tag

Description

[Apache]

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

[Chef]

Chef, https://chef.io

[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

[JSON-Spec]

The JSON Data Interchange Format (ECMA and IETF versions):

·         http://www.ecma-international.org/publications/files/ECMA-ST/ECMA-404.pdf

·         https://tools.ietf.org/html/rfc7158

[JSON-Schema]

JSON Schema specification:

·         http://json-schema.org/documentation.html

[XMLSpec]

 

XML Specification, W3C Recommendation, February 1998,

http://www.w3.org/TR/1998/REC-xml-19980210

[XML Schema Part 1]

XML Schema Part 1: Structures, W3C Recommendation, October 2004,

http://www.w3.org/TR/xmlschema-1/

[XML Schema Part 2]

XML Schema Part 2: Datatypes, W3C Recommendation, October 2004,

http://www.w3.org/TR/xmlschema-2/

[IANA register for Hash Function Textual Names]

https://www.iana.org/assignments/hash-function-text-names/hash-function-text-names.xhtml

[Jinja2]

Jinja2, jinja.pocoo.org/

[Twig]

Twig, https://twig.symfony.com

1.9 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 declarative workflow that is automatically generated based on the node templates and relationship templates defined in the Topology Template.

Node Template

A Node Template specifies the occurrence of a 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.

Abstract Node Template

An abstract node template is a node template that doesn’t define any implementations for the TOSCA lifecycle management operations. Service designers explicitly mark node templates as abstract using the substitute directive. TOSCA orchestrators provide implementations for abstract node templates by finding substituting templates for those node templates.

No-Op Node Template

A No-Op node template is a node template that does not specify implementations for any of its operations, but is not marked as abstract. No-op templates only act as placeholders for information to be used by other node templates and do not need to be orchestrated.

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_3tosca_simple_yaml_1_3

 

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

 

topology_template:

  node_templates:

    db_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 named “db_server 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_3 indicates Simple Profile v1.3.0 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_3

 

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

 

topology_template:

  inputs:

     db_server_num_cpus:

      type: integer

      description: Number of CPUs for the server.

      constraints:

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

 

  node_templates:

    db_server:

      type: tosca.nodes.Compute

      capabilities:

        # Host container properties

        host:

          properties:

            # Compute properties

            num_cpus: { get_input: db_server_num_cpus }

            mem_size: 2048  MB

            disk_size: 10 GB

            mem_size: 4096 MB

        # Guest Operating System properties

        os:

          # omitted for brevity

 

  outputs:

    server_ip:

      description: The private IP address of the provisioned server.

      value: { get_attribute: [ db_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 would 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_3

 

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

 

topology_template:

  inputs:

    mysql_rootpw:

      type: string

    mysql_port:

      type: integer

    # rest omitted here for brevity

 

  node_templates:

    db_server:

      type: tosca.nodes.Compute

      # rest omitted here for brevity

 

    mysql:

      type: tosca.nodes.DBMS.MySQL

      properties:

        root_password: { get_input: mysql_rootpw }

        port: { get_input: mysql_port }

      requirements:

        - host: db_server

 

  outputs:

    # 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 the 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 capability 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 tosca.nodes.SoftwareComponent 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 list of requirements, each list entry is a map that contains a single key/value pair where the symbolic name of a requirement definition is the key and the identifier of the fulfilling node is 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 has a complete requirement definition for the host requirement of type Compute 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 operations 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_3

 

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

 

topology_template:

  inputs:

    # omitted here for brevity

 

  node_templates:

    db_server:

      type: tosca.nodes.Compute

      # rest omitted here for brevity

 

    mysql:

      type: tosca.nodes.DBMS.MySQL

      properties:

        root_password: { get_input: mysql_rootpw }

        port: { get_input: mysql_port }

      requirements:

        - host: db_server

      interfaces:

        Standard:

          configure: scripts/my_own_configure.sh

 

  outputs:

    # 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 4, shown above, 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_3

 

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

 

topology_template:

  inputs:

    wordpress_db_name:

      type: string

    wordpress_db_user:

      type: string

    wordpress_db_password:

      type: string

    # rest omitted here for brevity

 

  node_templates:

    db_server:

      type: tosca.nodes.Compute

      # rest omitted here for brevity

 

    mysql:

      type: tosca.nodes.DBMS.MySQL

      # rest omitted here for brevity

 

    wordpress_db:

      type: tosca.nodes.Database.MySQL

      properties:

        name: { get_input: wordpress_db_name }

        user: { get_input: wordpress_db_user }

        password: { get_input: wordpress_db_password }

      artifacts:

        db_content:

          file: files/wordpress_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 ] }

 

  outputs:

    # omitted here for brevity

In the example above, the wordpress_db node template of type tosca.nodes.Database.MySQL represents an actual MySQL database instance managed by a MySQL DBMS installation. The requirements section of the wordpress_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 the artifacts section of the wordpress_db the node template, there is an artifact definition named db_content which represents a text file  wordpress_db_content.txt which in turn will be used to add content to the SQL database as part of the create operation.

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 (wordpress_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_3

 

description: Template for deploying a two-tier application servers on 2 servers.

 

topology_template:

  inputs:

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

    wp_admin_username:

      type: string

    wp_admin_password:

      type: string

    mysql_root_password:

      type: string

    context_root:

      type: string

    # rest omitted here for brevity

 

 

  node_templates:

    db_server:

      type: tosca.nodes.Compute

      # rest omitted here for brevity

 

    mysql:

      type: tosca.nodes.DBMS.MySQL

      # rest omitted here for brevity

 

    wordpress_db:

      type: tosca.nodes.Database.MySQL

      # rest omitted here for brevity

 

    web_server:

      type: tosca.nodes.Compute

      # rest omitted here for brevity

 

    apache:

      type: tosca.nodes.WebServer.Apache

      requirements:

        - host: web_server

      # rest omitted here for brevity

 

    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: [ mysql, port ] }

            db_name: { get_property: [ wordpress_db, name ] }

            db_user: { get_property: [ wordpress_db, user ] }

            db_password: { get_property: [ wordpress_db, password ] }

 

  outputs:

    # 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_3

 

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

 

topology_template:

  inputs:

    # omitted here for brevity

 

  node_templates:

    db_server:

      type: tosca.nodes.Compute

      # rest omitted here for brevity

 

    mysql:

      type: tosca.nodes.DBMS.MySQL

      # rest omitted here for brevity

 

    wordpress_db:

      type: tosca.nodes.Database.MySQL

      # rest omitted here for brevity

 

    web_server:

      type: tosca.nodes.Compute

      # rest omitted here for brevity

 

    apache:

      type: tosca.nodes.WebServer.Apache

      requirements:

        - host: web_server

      # rest omitted here for brevity

 

    wordpress:

      type: tosca.nodes.WebApplication.WordPress

      properties:

        # omitted here for brevity

      requirements:

        - host: apache

        - database_endpoint:

            node: wordpress_db

            relationship: wp_db_connection

      # rest omitted here for brevity

 

    wordpress_db:

      type: tosca.nodes.Database.MySQL

      properties:

        # omitted here for the brevity

      requirements:

        - host: mysql

 

  relationship_templates:

    wp_db_connection:

      type: ConnectsTo

      interfaces:

        Configure:

          pre_configure_source: scripts/wp_db_configure.sh

 

  outputs:

    # omitted here for brevity

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 5.7.4) 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_3

 

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 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_3

 

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

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 5.9.1).

Example 10 - Simple dependency relationship between two nodes

tosca_definitions_version: tosca_simple_yaml_1_3

 

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 only 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 allow 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.

 

The following section describe how a user can define a requirement for an orchestrator to select an implementation and replace a node. For more details on how an orchestrator may perform matching and select a node from it’s catalog(s) you may look at section 14 of the specification.

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_3

 

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_3

                  

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

      directives: [ select ]

      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

In this node template, the msql_compute node template is marked as abstract using the select directive. As you can see the resulting mysql_compute node template looks very much like the “hello world” template as shown in Chapter 2.1 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 “implementable” 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_3

 

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_3

 

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 and 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. Service designers use the substitute directive to declare node templates as abstract. At deployment time, TOSCA orchestrators are expected to substitute abstract node templates in a service template before service orchestration can be performed.

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 first look for abstract node templates in the topology template. Abstract node templates are node templates that include the substitute directive.  These abstract node templates must then be realized using substituting service templates that are compatible with  the node types specified for each abstract 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 gets “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 marking he node template as abstract using the substitute directive. Orchestrators can only instantiate abstract node templates by substituting them with a service template that consists entirely of concrete nodes. Note that abstract node template substitution may need to happen recursively before a service template is obtained that consists only of concrete nodes.

Note that in contrast to the use case described in section 2.9.2 (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 need to 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_3

 

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 as specified by the substitute directive

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

      # that exports a Database type’s capabilities.

      type: tosca.nodes.Database

      directives:

        - substitute

      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_3

 

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 are mapped to the appropriate 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_3

 

topology_template:

  description: Template of online transaction processing service.

 

  node_templates:

    mq:

      type: example.QueuingSubsystem

      directives:

        - substitute

      properties:

        # properties omitted for brevity

      capabilities:

        message_queue_endpoint:

          # details omitted for brevity

      requirements:

        - receiver: trans1

        - receiver: trans2

 

    trans1:

      type: example.TransactionSubsystem

      directives:

        - substitute

      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

      directives:

        - substitute

      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

      directives:

        - substitute

      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 need to 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_3

 

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 would 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 a 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_3

 

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 Using node template substitution to provide product choice

Some service templates might include abstract node templates that model specific functionality without fully specifying the exact product or technology that provides that functionality. The objective of such service templates is to allow the end-user of the service to decide at service deployment time which specific product component to use.

2.12.1 Defining a service template with vendor-independent component

For example, let’s assume an abstract security service that includes a firewall component where the choice of firewall product is left to the end-user at service deployment time. The following template shows an example of such a service: it  includes an abstract firewall node template that has a vendor property that represents the firewall vendor. The value of this property is obtained from a topology input variable that allows end-users to specify the desired firewall vendor at deployment time.

Defining a security service with a vendor-independent firewall component

tosca_definitions_version: tosca_simple_yaml_1_3

 

description: Service template for an abstract security service

 

topology_template:

 

  inputs:

    vendorInput:

      type: string

    rulesInput:

      type: list

      entry_schema: FirewallRules

   

  node_templates:

    firewall:

      type: abstract.Firewall

      directives:

        - substitute

      properties:

        vendor: { get_input: vendorInput }

        rules: { get_input: rulesInput }

The abstract firewall node type is defined in the following code snippet. The abstract firewall node type defines a rules property to hold the configured firewall rules. In addition, it also defines a property for capturing the name of the vendor of the firewall.

Node type defining an abstract firewall component

tosca_definitions_version: tosca_simple_yaml_1_3

 

description: Template defining an abstract firewall component

 

node_types:

  abstract.Firewall:

    derived_from: tosca.nodes.Root

    properties:

      vendor:

        type: string

      rules:

        type: list

        entry_schema: FirewallRules

2.12.2 Defining vendor-specific component options

In the above example, the firewall node template is abstract, which means that it needs to be substituted with a substituting firewall template. Let’s assume we have two firewall vendors—ACME Firewalls and Simple Firewalls—who each provide implementations for the abstract firewall component. Their respective implementations are defined in vendor-specific service templates. ACME Firewall’s service template might look as follows:

Service template for an ACME firewall

tosca_definitions_version: tosca_simple_yaml_1_3

 

description: Service template for an ACME firewall

 

topology_template:

 

  inputs:

    rulesInput:

      type: list

      entry_schema: FirewallRules

   

  substitution_mappings:

    node_type: abstract.Firewall

    properties:

      rules: [ rulesInput ]

 

  node_templates:

    acme:

      type: ACMEFirewall

      properties:

        rules: { get_input: rulesInput }

        acmeConfig: # any ACME-specific properties go here.

 

In this example the node type ACMEFirewall is an ACME-specific node type that models the internals of the ACME firewall product. The ACMEFirewall node type definition is omitted here for brevity since it is not relevant for the example.

Similarly, Simple Firewall’s service template looks as follows:

Service template for a Simple Firewall

tosca_definitions_version: tosca_simple_yaml_1_3

 

description: Service template for a Simple Corp. firewall

 

topology_template:

 

  inputs:

    rulesInput:

      type: list

      entry_schema: FirewallRules

   

  substitution_mappings:

    node_type: abstract.Firewall

    properties:

      rules: [ rulesInput ]

 

  node_templates:

    acme:

      type: SimpleFirewall

      properties:

        rules: { get_input: rulesInput }

 

As the substitution mappings section in the service templates show, either firewall service template can be used to implement the abstract firewall component defined above.

2.12.3 Substitution matching using substitution filters

Since both the ACME Firewall and the Simple Firewall can substitute for abstract node templates of type abstract.Firewall, either firewall is a valid candidate to substitute the abstract firewall node template. When multiple matching templates are available, the orchestrator must provide mechanisms to allow the end-user to drive the decision about which matching template must be selected.

TOSCA uses a substitution_filter in the substitution mappings section of a service template to further constrain the abstract nodes for which a service template can be a valid substitution. Using substitution filters, a service template is a valid candidate to substitute an abstract node template if the following two conditions are met:

1.     The type advertised in the substitution_mappings section of the service template matches the type of the abstract node template.

2.     The property values of the abstract node template satisfy the constraints defined in the substitution_filtter of the substituting service template.

In the security service example used in this section, the value of the vendor property of the abstract firewall node template is provide by the end-user using a topology input parameter. Substituting templates use a substitution_filter to match the appropriate vendor-specific service templates with the abstract firewall node template based on the value of the vendor property.

The following code snippet shows an updated version of the ACME Firewall service template. This version includes a substitution_filter that specifies that this service template only matches abstract firewall nodes with a vendor property equal to ‘ACME’.

Service template for an ACME firewall with a substitution filter

tosca_definitions_version: tosca_simple_yaml_1_3

 

description: Service template for an ACME firewall

 

topology_template:

 

  inputs:

    rulesInput:

      type: list

      entry_schema: FirewallRules

   

  substitution_mappings:

    node_type: abstract.Firewall

    substitution_filter:

      properties:

-    vendor: { equal: ACME }

    properties:

      rules: [ rulesInput ]

 

  node_templates:

    acme:

      type: ACMEFirewall

      properties:

        rules: { get_input: rulesInput }

        acmeConfig: # any ACME-specific properties go here.

 

Similarly, an updated service template for Simple Corp’s firewall looks as follows:

Service template for a Simple firewall with a substitution filter

tosca_definitions_version: tosca_simple_yaml_1_3

 

description: Service template for a Simple Corp. firewall

 

topology_template:

 

  inputs:

    rulesInput:

      type: list

      entry_schema: FirewallRules

   

  substitution_mappings:

    node_type: abstract.Firewall

    substitution_filter:

      properties:

-    vendor: { equal: Simple }

    properties:

      rules: [ rulesInput ]

 

  node_templates:

    acme:

      type: SimpleFirewall

      properties:

        rules: { get_input: rulesInput }

 

As specified in this example, only abstract firewall node templates that have the vendor property set to ‘Simple’ can be substituted by this service template.

2.13 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_3

 

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_3

 

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.

2.14 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_3

 

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

2.15 Passing information as inputs to Interfaces and Operations

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 using the appropriate mechanisms depending on the type of implementation artifact used for each operation. For example, when using script artifacts, input values are passed as environment variables within the execution environments in which the scripts associated with lifecycle operations are run.

2.15.1 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 ] }

2.15.2 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.

2.16 Returning output values from operations

Service template designers have the ability to define operation outputs that specify named output values that are expected to be returned by interface operations as well as the attributes on nodes or relationships into which these output values must be stored.

 

2.16.1 Example: setting output values to a node attribute

The service template below shows an example service template that is used to create a compute node. The config operation of the Standard lifecycle returns both the private and the public IP addresses of the config node. The attribute mappings grammar is used to reflect these addresses into the appropriate Compute node attributes:

 

tosca_definitions_version: tosca_simple_yaml_1_3

 

description: Template for creating compute node

 

topology_template:

 

  node_templates:

 

    node:

      type: tosca.nodes.Compute

      interfaces:

        Standard:

          configure:

            outputs:

              ip1: [ SELF, private_address ]

              ip2: [ SELF, public_address ]

 

2.16.2 Example: setting output values to a capability attribute

Some operation outputs may need to be reflected into attributes of capabilities of nodes, rather than in attributes of the nodes themselves. The following example shows how an IP address returned by a config operation is stored in the ip_address attribute of the endpoint capability of a Compute node:

 

tosca_definitions_version: tosca_simple_yaml_1_2_0

 

description: Template for creating compute node

 

topology_template:

 

  node_templates:

 

    compute:

      type: tosca.nodes.Compute

      interfaces:

        Standard:

          config:

            outputs:

              ip1: [ SELF, endpoint, ip_address ]

 

2.17 Receiving asynchronous notifications

As shown in the previous section, TOSCA allows service template designers to reflect the results of executing interface operations into node or relationship artifacts using output mappings. However, there are many situations where components modeled by a node can change independently as a result of external events (e.g. load changes, failures, mode changes, etc.) rather than as a result of executing lifecycle management operations. To support those situations, TOSCA includes support for notifications that allow service template designers to specify how to asynchronously receive external events and how those events should result in node or relationship attribute changes.

Just like operations, notifications are specified as part of interface definitions. The major difference between notifications and operations is that the former are called from the outside world to on the orchestrator, and not the other way around. As a result, notifications do not have inputs defined (since they are called asynchronously from the outside). Information carried in notifications is pushed to the orchestrator via notification outputs (similar to operation outputs).

The following example shows how a health monitoring interface is used to allow the orchestrator to monitor the health of a database node by listening for heartbeats as well as by waiting for asynchronous failure alerts:

 

tosca_definitions_version: tosca_simple_yaml_1_3

 

description: Template showing a health monitoring interface

 

topology_template:

  node_templates:

    db_1:

      type: org.ego.nodes.Database

      interfaces:

        HealthMonitor:

          notifications:

            heartbeat:

              outputs:

                tick: [ SELF, still_alive ]

            failure_report:

              outputs:

                level: [SELF, failure_level]

                time: [SELF, failure_time]

                environment: [SELF, failure_context]   

 

2.18 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.

2.19 Using attributes implicitly reflected from properties

Most entity types in TOSCA (e.g., Node, Relationship, Capability Types, etc.) 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 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_3

                        

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. 

2.20 Creating Multiple Node Instances from the Same Node Template

TOSCA service templates specify a set of nodes that need to be instantiated at service deployment time. Some service templates may include multiple nodes that perform the same role. For example, a template that models an SD-WAN service might contain multiple VPN Site nodes, one for each location that accesses the SD-WAN. Rather than having to create a separate service template for each possible number of VPN sites, it would be preferable to have a single service template that allows the number of VPN sites to be specified as an input to the template at deployment time. This section introduces experimental TOSCA language extensions in support of this functionality.It is expected that these extensions will be formally standardized in a future version of this specifications.

The discussion in this section uses an example SD-WAN deployment to three sites as shown in the following figure:

Example SD-WAN Service Deployment

The following code snippet shows a TOSCA service template from which this service could have been deployed:

Example 24 – TOSCA SD-WAN Service Template

tosca_definitions_version: tosca_simple_yaml_1_3

 

description: Template for deploying SD-WAN with three sites.

 

topology_template:

  inputs:

    location1:

      type: Location

    location2:

      type: Location

    location3:

      type: Location

  node_templates:

    sdwan:

      type: VPN

    site1:

      type: VPNSite

      properties:

        location: { get_input: location1 }

      requirements:

        - vpn: sdwan

    site2:

      type: VPNSite

      properties:

        location: { get_input: location2 }

      requirements:

        - vpn: sdwan

    site3:

      type: VPNSite

      properties:

        location: { get_input: location3 }

      requirements:

        - vpn: sdwan

 

 

Unfortunately, this template can only be used to deploy an SD-WAN with three sites. To deploy a different number of sites, additional service templates would have t be created, one for each number of possible SD-WAN sites. This leads to template proliferation, which is undesirable. The next section explores alternatives.

2.20.1 Specifying Number of Occurrences

To avoid the need for multiple service templates, TOSCA must provide a mechanism that allows all VPN Site nodes to be created from the same Site node template in the topology, and allow the number of sites to be specified at deployment time. Specifically, this functionality must:

-       Allow service template designers to specify that multiple node instances can be created from a single node template

-       Allow service template designers to constrain how many node instances can be created from a single node template

-       Allow users to specify at deployment time the exact number of instances that need to be created from the single node template.

To provide this functionality, the TOSCA node template definition grammar is extended with an occurrences keyword that specifies the minimum and maximum number of instances that can be created from this node template. If occurrences is not specified, only one single instance can be created. In addition, an instance_count keyword is used to specify the requested number of runtime instances of this node template. It is expected that the value of the instance_count is provided as an input to the topology template. These extensions enable the creation of a simplified SD-WAN service template that contains only one single VPN Site node as shown in the following code snippet:

 

Example 25 – TOSCA SD-WAN Service Template

tosca_definitions_version: tosca_simple_yaml_1_3

 

description: Template for deploying SD-WAN with a variable number of sites.

 

topology_template:

  inputs:

    numberOfSites:

      type: integer

 

  node_templates:

    sdwan:

      type: VPN

    site:

      type: VPNSite

      occurrences: [1, UNBOUNDED]

      instance_count: { get_input: numberOfSites }

      requirements:

        - vpn: sdwan

 

2.20.2 Specifying Inputs

The service template in the previous section conveniently ignores the location property of the Site node. As shown earlier, the location property is expected to be provided as an input value. If Site node templates can be instantiated multiple times, then it follows that multiple input values are required to initialize the location property for each of the Site node instances.

To allow specific input values to be matched with specific node template instances, a new reserved keyword called INDEX is introduced. A TOSCA orchestrator will interpret this keyword as the runtime index in the list of node instances created from a single node template.

The following service template shows how the INDEX keyword is used to retrieve specific values from a list of input values in a service template:

Example 26 – TOSCA SD-WAN Service Template

tosca_definitions_version: tosca_simple_yaml_1_3

 

description: Template for deploying SD-WAN with a variable number of sites.

 

topology_template:

  inputs:

    numberOfSites:

      type: integer

    locations:

      type: list

      entry_schema: Location

 

  node_templates:

    sdwan:

      type: VPN

    site:

      type: VPNSite

      occurrences: [1, UNBOUNDED]

      instance_count: { get_input: numberOfSites }

      properties:

        location: { get_input: [ locations, INDEX ] }

      requirements:

        - vpn: sdwan

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 1.3 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 1.3 specification.

Namespace Alias

Namespace URI

Specification Description

tosca_simple_yaml_1_3

http://docs.oasis-open.org/tosca/ns/simple/yaml/1.3

The TOSCA Simple Profile v1.3 (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

·         The URI value “http://docs.oasis-open.org/tosca”, as well as all (path) extensions to it, SHALL be reserved for TOSCA approved specifications and work.  That means Service Templates that do not originate from a TOSCA approved work product MUST NOT use it, in any form, when declaring a (default) Namespace.

·         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)

·         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)

o    Policies (policies)

o    Groups (groups)

3.2 Using Namespaces

As of TOSCA version 1.2, Service template authors may declare a namespace within a Service Template that would be used as the default namespace for any types (e.g., Node Type, Relationship Type, Data Type, etc.) defined within the same Service template.  

 

Specifically, a Service Template’s namespace declaration’s URI would be used to form a unique, fully qualified Type name when combined with the locally defined, unqualified name of any Type in the same Service Template.  The resulatant, fully qualified Type name would be used by TOSCA Orchestrators, Processors and tooling when that Service Template was imported into another Service Template to avoid Type name collision.

 

If a default namespace for the Service Template is declared, then it should be declared immediately after the “tosca_definitions_version” declaration, to ensure that the namespace is clearly visible.

 

3.2.1 Example – Importing a Service Template and Namespaces

For example, let say we have two Service Templates, A and B, both of which define Types and a Namespace.  Service Template B contains a Node Type definition for “MyNode” and declares its (default) Namespace to be “http://companyB.com/service/namespace/”:

Service Template B

 

tosca_definitions_version: tosca_simple_yaml_1_2

description: Service Template B

namespace: http://companyB.com/service/namespace/ 

 

node_types:

  MyNode:

    derived_from: SoftwareComponent

    properties:

      # omitted here for brevity

    capabilities:

      # omitted here for brevity

 

Service Template A has its own, completely different, Node Type definition also named “MyNode“. 

 

Service Template A

 

tosca_definitions_version: tosca_simple_yaml_1_2

description: Service Template A

namespace: http://companyA.com/product/ns/ 

 

imports:

  - file: csar/templates/ServiceTemplateB.yaml

    namespace_prefix: templateB

 

node_types:

  MyNode:

    derived_from: Root

    properties:

      # omitted here for brevity

    capabilities:

      # omitted here for brevity

As you can see, Service Template A also “imports“ Service Template B (i.e., “ServiceTemplateB.yaml“) bringing in its Type defintions to the global namespace using the Namespace URI declared in Service Template B to fully qualify all of its imported types.  

 

In addition, the import includes a “namespace_prefix“ value (i.e., “templateB“ ), that can be used to qualify and disambiguate any Type reference from from Service Template B within Service Template A.  This prefix is effectively the local alias for the corresponding Namespace URI declared within Service Template B (i.e., “http://companyB.com/service/namespace/“).

 

To illustrate conceptually what a TOSCA Orchestrator, for example, would track for their global namespace upon processing Service Template A (and by import Service Template B) would be a list of global Namespace URIs and their associated Namespace prefixes, as well as a list of fully qualified Type names that comprises the overall global namespace.

3.2.1.1 Conceptual Global Namespace URI and Namespace Prefix tracking

 

Entry#

Namespace URI

Namespace Prefix

Added by Key (Source file)

1

http://open.org/tosca/ns/simple/yaml/1.3/

tosca

· tosca_definitions_version:

-    from Service Template A

2

http://companyA.com/product/ns/ 

<None>

·  namespace:

-    from Service Template A

3

http://companyB.com/service/namespace/ 

templateB

·  namespace:

-    from Service Template B

·  namespace_prefix:

-   from Service Template A, during import

 

In the above table,

·         Entry 1: is an entry for the default TOSCA namespace, which is required to exist for it to be a valid Service template.  It is established by the “tosca_definitions_version” key’s value.  By default, it also gets assigned the “tosca” Namespace prefix.

·         Entry 2: is the entry for the local default namespace for Service Template A as declared by the “namespace” key. 

o    Note that no Namespace prefix is needed; any locally defined types that are not qualified (i.e., not a full URI or using a Namespace Prefix) will default to this namespace if not found first in the TOSCA namespace.

·         Entry 3: is the entry for default Namespace URI for any type imported from Service Template B.  The author of Service Template A has assigned the local Namespace Prefix “templateB” that can be used to qualify reference to any Type from Service Template B.

 

As per TOSCA specification, any Type, that is not qualified with the ‘tosca’ prefix or full URI name, should be first resolved by its unqualified name within the TOSCA namespace.  If it not found there, then it may be resolved within the local Service Template’s default namespace.

 

3.2.1.2 Conceptual Global Namespace and Type tracking

 

Entry#

Namespace URI

Unqualified Full Name

 

Unqualified Short Name

Type Classification

1

http://open.org/tosca/ns/simple/yaml/1.3/

tosca.nodes.Compute

Compute

node

2

http://open.org/tosca/ns/simple/yaml/1.3/

tosca.nodes.SoftwareComponent

 

SoftwareComponent

 

3

http://open.org/tosca/ns/simple/yaml/1.3/

tosca.relationships.ConnectsTo

ConnectsTo

relationship

...

...

 

 

 

100

http://companyA.com/product/ns/ 

N/A

MyNode

node

...

...

 

 

 

200

http://companyB.com/service/namespace/ 

N/A

MyNode

node

...

...

 

 

 

 

In the above table,

·         Entry 1: is an example of one of the TOSCA standard Node Types (i.e., “Compute”) that is brought into the global namespace via the “tosca_definitions_version” key.

o    It also has two forms, full and short that are unique to TOSCA types for historical reasons.  Reference to a TOSCA type by either its unqualified short or full names is viewed as equivalent as a reference to the same fully qualified Type name (i.e., its full URI).

o    In this example, use of either “tosca.nodes.Compute” or “Compute” (i.e., an unqualified full and short name Type) in a Service Template would be treated as its fully qualified URI equivalent of:

§   “http://docs.oasis-open.org/tosca/ns/simple/yaml/1.3/tosca.nodes.Compute”.

·         Entry 2: is an example of a standard TOSCA Relationship Type

·         Entry 100: contains the unique Type identifer for the Node Type “MyNode” from Service Template A.

·         Entry 200: contains the unique Type identifer for the Node Type “MyNode” from Service Template B.

 

As you can see, although both templates defined a NodeType with an unqualified name of “MyNode”, the TOSCA Orchestrator, processor or tool tracks them by their unique fully qualified Type Name (URI).

 

The classification column is included as an example on how to logically differentiate a “Compute” Node Type and “Compute” capability type if the table would be used to “search” for a match based upon context in a Service Template.  

 

For example, if the short name “Compute” were used in a template on a Requirements clause, then the matching type would not be the Compute Node Type, but instead the Compute Capability Type based upon the Requirement clause being the context for Type reference.

3.3 Parameter and property types

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

3.3.1 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

3.3.1.1 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.

3.3.2 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

3.3.2.1 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.

3.3.2.2 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.

3.3.2.3 Examples

Examples of valid TOSCA version strings:

# 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

3.3.2.4 Notes

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

3.3.2.5 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.

3.3.3 TOSCA 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

3.3.3.1 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 or equal to lower_bound.

3.3.3.2 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.

3.3.3.3 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 ]

 

3.3.4 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

3.3.4.1 Grammar

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

3.3.4.1.1  Square bracket notation

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

3.3.4.1.2 Bulleted 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.

3.3.4.2 Declaration Examples

3.3.4.2.1 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

3.3.4.2.2 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

3.3.4.3 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.

3.3.4.3.1 Square bracket notation

listen_ports: [ 80, 8080 ]

3.3.4.3.2 Bulleted list notation

listen_ports:

  - 80

  - 8080

3.3.5 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. In addition, the keys that identify entries in a map must be of the same type as well. The type of these keys is defined by the key_schema attribute of the respective property_definition, attribute_definition, or input or output parameter_definition. If the key_schema is not specified, keys are assumed to be of type string.

Shorthand Name

map

Type Qualified Name

tosca:map

3.3.5.1 Grammar

TOSCA maps are normal YAML dictionaries with following grammar:

3.3.5.1.1 Single-line grammar

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

3.3.5.1.2 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

3.3.5.2 Declaration Examples

3.3.5.2.1 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

3.3.5.2.2 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

3.3.5.3 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.

3.3.5.3.1 Single-line notation

# notation option for shorter maps

user_name_to_id_map: { user1: 1001, user2: 1002 }

3.3.5.3.2 Multi-line notation

# notation for longer maps

user_name_to_id_map:

  user1: 1001

  user2: 1002

3.3.6 TOSCA 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.

3.3.6.1 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.

3.3.6.2 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’.

3.3.6.3 Concrete Types

Shorthand Names

scalar-unit.size, scalar-unit.time, scalar-unit.frequency, scalar-unit.bitrate

Type Qualified Names

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

 

The scalar-unit type grammar is abstract and has four 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.

·         scalar-unit.bitrate – used to define properties that have scalar values measured in bits or bytes per second

These types and their allowed unit values are defined below.

3.3.6.4 scalar-unit.size

3.3.6.4.1 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)

3.3.6.4.2 Examples

# Storage size in Gigabytes

properties:

  storage_size: 10 GB

3.3.6.4.3 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.

3.3.6.5 scalar-unit.time

3.3.6.5.1 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

3.3.6.5.2 Examples

# Response time in milliseconds

properties:

  respone_time: 10 ms

3.3.6.5.3 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

3.3.6.6 scalar-unit.frequency

3.3.6.6.1 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.

3.3.6.6.2 Examples

# Processor raw clock rate

properties:

  clock_rate: 2.4 GHz

3.3.6.6.3 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/

3.3.6.7 scalar-unit.bitrate

3.3.6.7.1 Recognized Units

Unit

Usage

Description

bps

bitrate

bit per second

Kbps

bitrate

kilobit (1000 bits) per second

Kibps

bitrate

kibibits (1024 bits) per second

Mbps

bitrate

megabit (1000000 bits) per second

Mibps

bitrate

mebibit (1048576 bits) per second

Gbps

bitrate

gigabit (1000000000 bits) per second

Gibps

bitrate

gibibits (1073741824 bits) per second

Tbps

bitrate

terabit (1000000000000 bits) per second

Tibps

bitrate

tebibits (1099511627776 bits) per second

Bps

bitrate

byte per second

KBps

bitrate

kilobyte (1000 bytes) per second

KiBps

bitrate

kibibytes (1024 bytes) per second

MBps

bitrate

megabyte (1000000 bytes) per second

MiBps

bitrate

mebibyte (1048576 bytes) per second

GBps

bitrate

gigabyte (1000000000 bytes) per second

GiBps

bitrate

gibibytes (1073741824 bytes) per second

TBps

bitrate

terabytes (1000000000000 bits) per second

TiBps

bitrate

tebibytes (1099511627776 bits) per second

3.3.6.7.2 Examples

#### Somewhere in a node template definition

requirements:

    - link:

        node_filter:

          capabilities:

            - myLinkable

                properties:

                  bitrate:

                   - greater_or_equal: 10 Kbps # 10 * 1000 bits per second at least

3.3.6.7.3 Notes

·         Unlike with the scalar-unit.size type, TOSCA treats scalar-unit.bitrate values as case-sensitive (e.g., a value of ‘KBs’ means kilobyte per second, whereas ‘Kb’ means kilobit per second).

·         For comparison purposes, 1 byte is the same as 8 bits.

 

3.4 Normative values

3.4.1 Node States

As components (i.e., nodes) of TOSCA applications are deployed, instantiated and orchestrated over their lifecycle using normative lifecycle operations (see section 5.8 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.

3.4.2 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.

3.4.2.1 Notes

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

3.4.3 Directives

The following directive values are defined for this version of the TOSCA Simple Profile:

Directive

Description

substitute

Marks a node template as abstract and instructs the TOSCA Orchestrator to substitute this node template with an appropriate substituting template.

substitutable

This deprecated directive is synonymous to the substitute directive.

select

Marks a node template as abstract and instructs the TOSCA Orchestrator to select a node of this type from its inventory (based on constraints specified in the optional node_filter in the node template)

selectable

This deprecated directive is synonymous to the select directive.

 

3.4.4 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.

3.4.4.1 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.

3.5 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.

3.5.1 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).

3.6 Reusable modeling definitions

3.6.1 Description definition

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

3.6.1.1 Keyname

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

description

3.6.1.2 Grammar

Description definitions have the following grammar:

description: <string>

3.6.1.3 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.

3.6.1.4 Notes

3.6.2 Metadata

This optional element provides a means to include optional metadata as a map of strings.

3.6.2.1 Keyname

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

metadata

3.6.2.2 Grammar

Metadata definitions have the following grammar:

metadata:

  map of <string>

3.6.2.3 Examples

metadata:

  foo1: bar1

  foo2: bar2

  ...

3.6.2.4 Notes

3.6.3 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.

3.6.3.1 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.

schema

string

string

Constrains the property or parameter to a value that is allowed by the referenced schema.

3.6.3.1.1 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.

3.6.3.2 Schema Constraint purpose

TOSCA recognizes that there are external data-interchange formats that are widely used within Cloud service APIs and messaging (e.g., JSON, XML, etc.). 

The ‘schema’ Constraint was added so that, when TOSCA types utilize types from these externally defined data (interchange) formats on Properties or Parameters, their corresponding Property definitions’ values can be optionally validated by TOSCA Orchestrators using the schema string provided on this operator.

3.6.3.3 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.).

3.6.3.4 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>

 

# Schema grammar

schema: <schema_definition>

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.

·         schema_definition: represents a schema definition as a string.

3.6.3.5 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

 

# schema

schema: <

  { 

     # Some schema syntax that matches corresponding property or parameter.

  }

3.6.4 Property Filter definition

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

3.6.4.1 Grammar

Property filter definitions have one of the following grammars:

3.6.4.1.1 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>

3.6.4.1.2 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).

3.6.4.2 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.

3.6.5 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.

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

3.6.5.2 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 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.

3.6.5.3 Grammar

Node filter definitions have following grammar:

node_filter:

  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.

3.6.5.4 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).

3.6.5.5 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 }

3.6.6 Repository definition

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

3.6.6.1 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.

3.6.6.2 Grammar

Repository definitions have one the following grammars:

3.6.6.2.1 Single-line grammar (no credential):

<repository_name>: <repository_address>

3.6.6.2.2 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.

3.6.6.3 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/

3.6.7 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.

3.6.7.1 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.

artifact_version

no

string

The version of this artifact. One use of this artifact_version is to declare the particular version of this artifact type, in addition to its mime_type (that is declared in the artifact type definition). Together with the mime_type it may be used to select a particular artifact processor for this artifact. For example a python interpreter that can interpret python version 2.7.0

checksum

no

string

The checksum used to validate the integrity of the artifact.

checksum_algorithm

no

string

Algorithm used to calculate the artifact checksum (e.g. MD5, SHA [Ref]). Shall be specified if checksum is specified for an artifact.

 

properties

no

map of

property

assignments

The optional map of property assignments associated with the artifact.

3.6.7.2 Grammar

Artifact definitions have one of the following grammars:

3.6.7.2.1 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>

3.6.7.2.2 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>

  version: <artifact _version>

  checksum: <artifact_checksum>

  checksum_algorithm: <artifact_checksum_algorithm>

  properties: <property assignments>

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.

·         artifact_version: represents the version of artifact

·         artifact_checksum: represents the checksum of the Artifact

·         artifact_checksum_algorithm:represents the algorithm for verifying the checksum. Shall be specified if checksum is specified

·         properties: represents an optional map of property assignments associated with the artifact

 

3.6.7.3 Examples

The following represents an artifact definition:

my_file_artifact: ../my_apps_files/operation_artifact.txt

 

The following example represents an artifact definition with property assignments:

artifacts:

  sw_image:

    description: Image for virtual machine

    type: tosca.artifacts.Deployment.Image.VM

    file: http://10.10.86.141/images/Juniper_vSRX_15.1x49_D80_preconfigured.qcow2

    checksum: ba411cafee2f0f702572369da0b765e2

    version: 3.2

    checksum_algorithm: MD5

    properties:

      name: vSRX

      container_format: BARE

      disk_format: QCOW2

      min_disk: 1 GB

      size: 649 MB

3.6.8 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.

3.6.8.1 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_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.

namespace_uri

no

string

Deprecated

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

3.6.8.2 Grammar

Import definitions have one the following grammars:

3.6.8.2.1 Single-line grammar:

imports:

  - <URI_1>

  - <URI_2>

3.6.8.2.2 Multi-line grammar

imports: 

  - file: <file_URI>  

    repository: <repository_name>

    namespace_uri: <definition_namespace_uri>  # deprecated

    namespace_prefix: <definition_namespace_prefix>

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

·         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 default namespace as declared in the imported Service Template when forming a qualified name (i.e., qname) when referencing type definitions from the imported file as a string.

3.6.8.2.3 Requirements

·         The “file” keyname’s vlue MAY be an approved TOSCA Namespace alias.

·         The namespace prefix “tosca” Is reserved and SHALL NOT be used to as a value for “namespace_prefix” on import.

·         The imports key “namespace_uri” is now deprecated.  It was intended to be able to define a default namespace for any types that were defined within the Service Template being imported; however, with version 1.2, Service Templates MAY now declare their own default Namespace which SHALL be used in place of this key’s value.

o    Please note that TOSCA Orchestrators and Processors MAY still use the”namespace_uri” value if provided, if the imported Service Template has no declared default Namespace value.  Regardless it is up to the TOSCA Orchestrator or Processor to resolve Namespace collisions caused by imports as they see fit, for example, they may treat it as an error or dynamically generate a unique namepspace themselves on import.

3.6.8.2.4 Import URI processing requirements

TOSCA Orchestrators, Processors and tooling SHOULD treat the <file_URI> of an import as follows:

·         URI: If the <file_URI> is a known namespace URI (identifier), such as a well-known URI defined by a TOSCA specification, then it SHOULD cause the corresponding Type defintions to be imported.

o    This implies that there may or may not be an actual Service Template, perhaps it is a known set Types identified by the well-known URI.

o    This also implies that internet access is NOT needed to import.

·         Alias – If the <file_URI> is a reserved TOSCA Namespace alias, then it SHOULD cause the corresponding Type defintions to be imported, using the associated full, Namespace URI to uniquely identify the imported types.

·         URL - If the <file_URI> is a valid URL (i.e., network accessible as a remote resource) and the location contains a valid TOSCA Service Template, then it SHOULD cause the remote Service Template to be imported.

·         Relative path - If the <file_URI> is a relative path URL, perhaps pointing to a Service Template located in the same CSAR file, then it SHOULD cause the locally accessible Service Template to be imported.

o    If the “repository” key is supplied, this could also mean relative to the repository’s URL in a remote file system;

o    If the importing file located in a CSAR file, it should be treated as relative to the current document’s location within a CSAR file’s directory structure.

·         Otherwise, the import SHOULD be considered a failure.

3.6.8.3 Example

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

imports:

  - path1/path2/some_defs.yaml

  - file: path1/path2/file2.yaml

    repository: my_service_catalog

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

    namespace_prefix: mycompany

3.6.9 Schema Definition

All entries in a map or list for one property or parameter must be of the same type. Similarly, all keys for map entries for one property or parameter must be of the same type as well.  A TOSCA schema definition specifies the type (for simple entries) or schema (for complex entries) for keys and entries in TOSCA set types such as the TOSCA list or map.

3.6.9.1 Keynames

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

Keyname

Required

Type

Constraints

Description

type

yes

string

None

The required data type for the key or entry.

description

no

description

None

The optional description for the schema.

constraints

no

list of

constraint clauses

None

The optional list of sequenced constraint clauses for the property.

key_schema

no

schema_definition

None

When the schema itself is of type map, the optional schema definition that is used to specify the type of they keys of that map’s entries.

entry_schema

no

schema_definition

None

When the schema itself is of type map or list, the optional schema definition that is used to specify the type of the entries in that map or list

3.6.9.2  Grammar

Schema definitions have the following grammar:

<schema_definition>:

  type: <schema_type>

  description: <schema_description>

  constraints:

    - <schema_constraints>

  key_schema : <key_schema_definition>

  entry_schema: <entry_schema_definition>

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

·         schema_description: represents the optional description of the schema definition

·         schema_type: represents the required type name for entries of the specified schema.

·         schema_constraints: represents the optional list of one or more constraint clauses on on entries of the specified schema.

·         key_schema_definition: if the schema_type is map, represents the optional schema definition for they keys of that map’s entries.

·         entry_schema_definition: if the schema_type is map or list, represents the optional schema definition for the entries in that map or list.

3.6.10 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.

3.6.10.1 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).

3.6.10.2 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.

key_schema

no

schema_definition

None

The optional schema definition for the keys used to identify entries in properties of type TOSCA map.

entry_schema

no

schema_definition

None

The optional schema definition for the entries in properties of TOSCA set types such as list or map.

external-schema

no

string

None

The optional key that contains a schema definition that TOSCA Orchestrators MAY use for validation when the “type” key’s value indicates an External schema (e.g., “json”)

 

See section “External schema” below for further explanation and usage.

metadata

no

map of string

N/A

Defines a section used to declare additional metadata information.

3.6.10.3 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.

3.6.10.4 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>

  key_schema : <key_schema_definition>

  entry_schema: <entry_schema_definition>

  metadata:

    <metadata_map>

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 list of one or more sequenced constraint clauses on the property definition.

·         key_schema_definition: if the property_type is map, represents the optional schema definition for they keys used to identify entries in that map.

·         entry_schema_definition: if the property_type is map or list, represents the optional schema definition for the entries in that map or list.

·         metadata_map: represents the optional map of string.

3.6.10.5 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.

·         Constraints of a property definition SHALL be type-compatible with the type defined for that definition.

·         If a ‘schema’ keyname is provided, its value (string) MUST represent a valid schema definition that matches the recognized external type provided as the value for the ‘type’ keyname as described by its correspondig schema specification.

·         TOSCA Orchestrators MAY choose to validate the value of the ‘schema’ keyname in accordance with the corresponding schema specifcation for any recognized external types.

3.6.10.6 Refining Property Definitions

TOSCA allows derived types to refine properties defined in base types. A property definition in a derived type is considered a refinement when a property with the same name is already defined in one of the base types for that type.

Property definition refinements use parameter definition grammar rather than property definition grammar. Specifically, this means the following:

·         The type keyname is optional. If no type is specified, the property refinement reuses the type of the property it refines. If a type is specified, the type must be the same as the type of the refined property or it must derive from the type of the refined property.

·         Property definition refinements support the value keyname that specifies a fixed type-compatible value to assign to the property. These value assignments are considered final, meaning that it is not valid to change the property value later (e.g. using further refinements)..

Property refinement definitions can refine properties defined in one of base types by doing one or more of the following:

·         Assigning a new (compatible) type as per the rules outlined above.

·         Assigning a (final) fixed value

·         Adding a default value

·         Changing a default value

·         Adding constraints.

·         Turning an optional property into a required property.

No other refinements are allowed.

3.6.10.7 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.

3.6.10.8 Examples

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 ]

The following shows an example of a property refinement. Consider the definition of an Endpoint capability type:

tosca.capabilities.Endpoint:

  derived_from: tosca.capabilities.Root

  properties:

    protocol:

      type: string

      required: true

      default: tcp

    port:

      type: PortDef

      required: false

    secure:

      type: boolean

      required: false

      default: false

    # Other property definitions omitted for brevity

The Endpoint.Admin capability type refines the secure property of the Endpoint capability type from which it derives by forcing its value to always be true:

tosca.capabilities.Endpoint.Admin:

  derived_from: tosca.capabilities.Endpoint

  # Change Endpoint secure indicator to true from its default of false

  properties:

    secure: true

 

3.6.11 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.

3.6.11.1 Keynames

The TOSCA property assignment has no keynames.

3.6.11.2 Grammar

Property assignments have the following grammar:

3.6.11.2.1 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.

3.6.12 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.

3.6.12.1 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.

3.6.12.2 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.

key_schema

No

schema_definition

None

The optional schema definition for the keys used to identify entries in attributes of type TOSCA map.

entry_schema

no

schema_definition

None

The optional schema definition for the entries in attributes of TOSCA set types such as list or map.

3.6.12.3 Grammar

Attribute definitions have the following grammar:

attributes:

  <attribute_name>:

    type: <attribute_type>

    description: <attribute_description>

    default: <default_value>

    status: <status_value>

    key_schema : <key_schema_definition>

    entry_schema: <entry_schema_definition>

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.

·         key_schema_definition: if the attribute_type is map, represents the optional schema definition for they keys used to identify entries in that map.

·         entry_schema_definition: if the attribute_type is map or list, represents the optional schema definition for the entries in that map or list.

3.6.12.4 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).

3.6.12.5 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.

3.6.12.6 Example

The following represents a required attribute definition:

actual_cpus:

  type: integer

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

3.6.13 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.

3.6.13.1 Keynames

The TOSCA attribute assignment has no keynames.

3.6.13.2 Grammar

Attribute assignments have the following grammar:

3.6.13.2.1 Short notation:

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

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

3.6.13.2.2 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.

3.6.13.3 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).

3.6.14 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.

3.6.14.1 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.

 

3.6.14.2 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>

  key_schema : <key_schema_definition>

  entry_schema: <entry_schema_definition>

 

In addition, the following single-line grammar is supported when only a fixed value needs to be provided:

<parameter_name>: <parameter_value> | { <parameter_value_expression> }

This single-line grammar is equivalent to the following:

<parameter_name>:

    value : <parameter_value> | { <parameter_value_expression> }

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 list of one or more sequenced constraint clauses on the parameter definition.

·         key_schema_definition: if the parameter_type is map, represents the optional schema definition for they keys used to identify entries in that map.

·         entry_schema_definition: if the parameter_type is map or list, represents the optional schema definition for the entries in that map or list.

3.6.14.3 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.

3.6.14.4 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 ] }

 

3.6.15 Attribute Mapping definition

An attribute mapping defines a named output value that is expected to be returned by an operation implementations and a mapping that specifies the node or relationship attribute into which the returned output value must be stored.

3.6.15.1 Grammar

 

Attribute mappings have the following grammar :

 

output_name: [ <SELF | SOURCE | TARGET >, <optional_capability_name>, <attribute_name>, <nested_attribute_name_or_index_1>, ..., <nested_attribute_name_or_index_or_key_n> ]

 

The various entities in this grammar are defined as follows:

Parameter

Required

Type

Description

SELF | SOURCE | TARGET

yes

string

For operation outputs in interfaces on node templates, the only allowed keyname is SELF: output values must always be stored into attributes that belong to the node template that has the interface for which the output values are returned.

For operation outputs in interfaces on relationship templates, allowable keynames are SELF, SOURCE, or TARGET.

<optional_capability_name>

no

string

The optional name of the capability within the specified node template that contains the named attribute into which the output value must be stored.

<attribute_name>

yes

string

The name of the attribute into which the output value must be stored.

<nested_attribute_name_or_index_or_key_*>

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 or map types. In these cases, an index or key may be provided to reference a specific entry in the list or map (as named in the previous parameter) to return.

 

Note that it is possible for multiple operations to define outputs that map onto the same attribute value. For example, a create operation could include an output value that sets an attribute to an initial value, and the subsequence configure operation could then update that same attribute to a new value.

 

It is also possible that a node template assigns a value to an attribute that has an operation output mapped to it (including a value that is the result of calling an intrinsic function).  Orchestrators could use the assigned value for the attribute as its initial value. After the operation runs that maps an output value onto that attribute, the orchestrator must then use the updated value, and the value specified in the node template will no longer be used.

 

3.6.16 Operation implementation definition

An operation implementation definition specifies one or more artifacts (e.g. scripts) to be used as the implementation for an operation in an interface.

3.6.16.1 Keynames

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

Keyname

Required

Type

Description

primary

no

artifact definition

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

dependencies

no

list of

artifact definition

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

secondary script). 

timeout

No

integer

Timeout value in seconds

operation_host

no

string

The node on which operations should be executed (for TOSCA call_operation activities).

 

If the operation is associated with an interface on a node type or a relationship template, valid_values are SELF or HOST – referring to the node itself or to the node that is the target of the HostedOn relationship for that node.

 

If the operation is associated with a relationship type or a relationship template, valid_values are SOURCE or TARGET – referring to the relationship source or target node.

 

In both cases, the value can also be set to ORCHESTRATOR to indicated that the operation must be executed in the orchestrator environment rather than within the context of the service being orchestrated.

3.6.16.2 Grammar

Operation implementation definitions have the following grammars:

3.6.16.2.1 Short notation for use with single artifact

The following single-line grammar may be used when only a primary implementation artifact name is needed:

implementation: <primary_artifact_name>

This notation can be used when the primary artifact name uniquely identifies the artifact, either because it refers to a named artifact specified in the artifacts section of a type or template, or because it represents the name of a script in the CSAR file that contains the definition.

3.6.16.2.2 Short notation for use with multiple artifact

The following multi-line short-hand grammar may be used when multiple artifacts are needed, but each of the artifacts can be uniquely identified by name as before:

implementation:

  primary: <primary_artifact_name>

  dependencies:

    - <list_of_dependent_artifact_names>

  operation_host : SELF

  timeout : 60

3.6.16.2.3 Extended notation for use with single artifact

The following multi-line grammar may be used in Node or Relationship Type or Template definitions when only a single artifact is used but additional information about the primary artifact is needed (e.g. to specify the repository from which to obtain the artifact, or to specify the artifact type when it cannot be derived from the artifact file extension):

implementation:

  primary:

    <primary_artifact_definition>

  operation_host : HOST

  timeout : 100

3.6.16.2.4 Extended notation for use with multiple artifacts

The following multi-line grammar may be used in Node or Relationship Type or Template definitions when there are multiple artifacts that may be needed for the operation to be implemented and additional information about each of the artifacts is required:

implementation:

  primary:

    <primary_artifact_definition>  

  dependencies:

    - <list_of_dependent_artifact definitions>

  operation_host: HOST

  timeout: 120

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

·         primary_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).

·         primary_artifact_definition: represents a full inline definition of an implementation artifact.

·         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.

·         list_of_dependent_artifact_definitions: represents the ordered list of one or more inline definitions of dependent or secondary implementation artifacts. TOSCA orchestrators will copy these artifacts 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.

3.6.17 Operation definition

An operation definition defines a named function or procedure that can be bound to an operation implementation.

3.6.17.1 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

Operation implementation definition

The optional definition of the operation implementation 

inputs

no

map of

parameter definitions

The optional map 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

map of

property assignments

The optional map 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.

outputs

no

map of

attribute mappings

The optional map of attribute mappings that specify named operation output values and their mappings onto attributes of the node_type or relationship that contains the interface within which the operation is defined.

3.6.17.2 Grammar

Operation definitions have the following grammars:

3.6.17.2.1 Short notation

The following single-line grammar may be used when the operation’s implementation definition is the only keyname that is needed, and when the operation implementation definition itself can be specified using a single line grammar

<operation_name>: <implementation_artifact_name>

3.6.17.2.2 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: <Operation implementation definition>

   inputs:

     <property_definitions>

      outputs:

         <attribute mappings>

3.6.17.2.3 Extended notation for use in Template definitions

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

<operation_name>:

   description: <operation_description>

   implementation: <Operation implementation definition>

   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.

·         operation_implementation_definition: represents the optional specification of the operation’s implementation).

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

·         attribute_mappings: represents the optional map of of attribute_mappings that consists of named output values returned by operation implementations (i.e. artifacts) and associated mappings that specify the attribute into which this output value must be stored.

3.6.17.3 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.

3.6.17.4 Examples

3.6.17.4.1 Single-line example

interfaces:

  Standard:

    start: scripts/start_server.sh

3.6.17.4.2 Multi-line example with shorthand implementation definitions

interfaces:

  Configure:

    pre_configure_source:

      implementation:

        primary: scripts/pre_configure_source.sh

        dependencies:

          - scripts/setup.sh

          - binaries/library.rpm

          - scripts/register.py

3.6.17.4.3 Multi-line example with extended implementation definitions

interfaces:

  Configure:

    pre_configure_source:

      implementation:

        primary:

          file: scripts/pre_configure_source.sh

          type: tosca.artifacts.Implementation.Bash

          repository: my_service_catalog

        dependencies:           - file : scripts/setup.sh

             type : tosca.artifacts.Implementation.Bash

             Repository : my_service_catalog

       

3.6.18 Notification implementation definition

A notification implementation definition specifies one or more artifacts to be used by the orchestrator to subscribe to that particular notification. We use the primary and dependencies keynames as in the operation implementation definition.

3.6.18.1 Keynames

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

Keyname

Required

Type

Description

primary

no

artifact definition

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

dependencies

no

list of

artifact definition

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

secondary script). 

3.6.18.2 Grammar

Notification implementation definitions have the following grammars:

3.6.18.2.1 Short notation for use with single artifact

The following single-line grammar may be used when only a primary implementation artifact name is needed:

implementation: <primary_artifact_name>

This notation can be used when the primary artifact name uniquely identifies the artifact, either because it refers to a named artifact specified in the artifacts section of a type or template, or because it represents the name of a script in the CSAR file that contains the definition.

3.6.18.2.2 Short notation for use with multiple artifact

The following multi-line short-hand grammar may be used when multiple artifacts are needed, but each of the artifacts can be uniquely identified by name as before:

implementation:

  primary: <primary_artifact_name>

  dependencies:

    - <list_of_dependent_artifact_names>

3.6.19 Notification definition

A notification definition defines a named notification that can be associated with an interface. The notification is a way for an external event to be transmitted to the TOSCA orchestrator. Parameter values can be sent together with a notification and we can map them to node/relationship attributes imilarly to the way operation outputs are mapped to attributes. The artifact that the orchestrator is registering with in order to receive the notification is specified using the “implementation” keyname in a similar way to operations.

 

When the notification is received an event is generated within the orchestrator that can be associated to triggers in policies to call other internal operations and workflows. The notification name (the unqualified full name) itself identifies the event type that is generated and can be textually used when defining the associated triggers.

3.6.19.1 Keynames

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

Keyname

Required

Type

Description

description

no

description

The optional description string for the associated named notification.

implementation

no

notification implementation definition

The optional definition of the notification implementation.

outputs

no

map of attribute mappings

The optional map of property mappings that specify named notification output values and their mappings onto attributes of the node or relationship that contains the interface within which the notification is defined.

 

3.6.19.2 Grammar

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

<notification_name>:

  description: <notification_description>

  implementation: <notification_implementation_definition>

  outputs:

    <attribute_mappings>

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

·         notification_name: represents the required symbolic name of the notification as a string.

·         notification_description: represents the optional description string for the corresponding notification_name.

·         notification_implementation_definition: representes the optional specification of the notification implementation (i.e. the external artifact that is may send notifications)

·         attribute_mappings: represents the optional map of attribute assignments for mapping the outputs values to the respective attributes of the node or relationship.

3.6.20 Interface definition

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

3.6.20.1 Keynames

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

Keyname

Required

Type

Description

inputs

no

map of

property definitions

The optional map 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

map of

property assignments

The optional map 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.

operations

no

map of operation definitions

The optional map of operations defined for this interface.

notifications

no

map of notification definitions

The optional map of notifications defined for this interface.

3.6.20.2 Grammar

Interface definitions have the following grammar:

3.6.20.2.1 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>

  operations:

    <operation_definitions>

  notifications:

    <notification definitions>

3.6.20.2.2 Extended notation for use in Template definitions

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

<interface_definition_name>:

  inputs:

    <property_assignments>

  operations:

    <operation_definitions>

  notifications:

    <notification_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 map 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 map 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.

·         notification_definitions: represents the required name of one or more notification definitions.

3.6.20.3 Notes

Starting with Version 1.3 of this specification, interface definition grammar was changed to support notifications as well as operations. As a result, operations must now be specified under the newly-introduced operations keyname and the notifications under the new notifications keyname. For backward compatibility if neither the operations or notifications are specified then we assume the symbolic names in the interface definition to mean operations, but this use is deprecated. Operations and notifications names should not overlap.

3.6.21 Event Filter definition

An event filter definition defines criteria for selection of an attribute, for the purpose of monitoring it, within a TOSCA entity, or one its capabilities.

3.6.21.1 Keynames

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

Keyname

Required

Type

Description

node

yes

string

The required name of the node type or template that contains either the attribute to be monitored or contains the requirement  that references the node that contains the attribute to be monitored.

requirement

no

string

The optional name of the requirement within the filter’s node that can be used to locate a referenced node that contains an attribute to monitor.

capability

no

string

The optional name of a capability within the filter’s node or within the node referenced by its requirement that contains the attribute to monitor.

3.6.21.2 Grammar

Event filter definitions have following grammar:

node: <node_type_name> | <node_template_name>

requirement: <requirement_name>

capability: <capability_name>

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

·      node_type_name: represents the required name of the node type that would be used to select (filter) the node that contains the attribute to monitor or contains the requirement that references another node that contains the attribute to monitor. 

·      node_template_name: represents the required name of the node template that would be used to select (filter) the node that contains the attribute to monitor or contains the requirement that references another node that contains the attribute to monitor. 

·      requirement_name: represents the optional name of the requirement that would be used to select (filter) a referenced node that contains the attribute to monitor. 

·      capability_name: represents the optional name of a capability that would be used to select (filter) the attribute to monitor. If a requirement_name is specified, then the capability_name refers to a capability of the node that is targeted by the requirement.

3.6.22 Trigger definition

A trigger definition defines the event, condition and action that is used to “trigger” a policy it is associated with.

3.6.22.1 Keynames

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

Keyname

Required

Type

Description

description

no

description

The optional description string for the named trigger.

event

yes

string

The required name of the event that activates the trigger’s action. A deprecated form of this keyname is “event_type”.  

schedule

no

TimeInterval

The optional time interval during which the trigger is valid (i.e., during which the declared actions will be processed).

target_filter

no

event filter

The optional filter used to locate the attribute to monitor for the trigger’s defined condition. This filter helps locate the TOSCA entity (i.e., node or relationship) or further a specific capability of that entity that contains the attribute to monitor.

condition

no

condition clause definition

The optional condition which contains a condition clause definition specifying one or multiple attribute constraint that can be monitored.  Note: this is optional since sometimes the event occurrence itself  is enough to trigger the action.

action

yes

list of activity definition

The list of sequential activities to be performed when the event is triggered and the condition is met (i.e. evaluates to true).

3.6.22.2 Additional keynames for the extended condition notation

Keyname

Required

Type

Description

constraint

no

condition clause definition

The optional condition which contains a condition clause definition specifying one or multiple attribute constraint that can be monitored.  Note: this is optional since sometimes the event occurrence itself is enough to trigger the action.

period

no

scalar-unit.time

The optional period to use to evaluate for the condition.

evaluations

no

integer

The optional number of evaluations that must be performed over the period to assert the condition exists.

method

no

string

The optional statistical method name to use to perform the evaluation of the condition.

3.6.22.3 Grammar

Trigger definitions have the following grammars:

3.6.22.3.1 Short notation

 

<trigger_name>:

  description: <trigger_description>

  event: <event _name>

  schedule: <time_interval_for_trigger>

  target_filter:

    <event_filter_definition>

  condition:

    <condition_clause_definition>

  action:

    - <list_of_activity_definition>

3.6.22.3.2 Extended notation:

 

<trigger_name>:

  description: <trigger_description>

  event: <event _name>

  schedule: <time_interval_for_trigger>

  target_filter:

    <event_filter_definition>

  condition:

    constraint: <condition_clause_definition>

    period: <scalar-unit.time> # e.g., 60 sec

    evaluations: <integer> # e.g., 1

    method: <string> # e.g., average

  action:

    - <list_of_activity_definition>

 

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

·         trigger_name: represents the required symbolic name of the trigger as a string.

·         trigger_description: represents the optional description string for the corresponding trigger_name.

·         event_name: represents the required name of an event associated with an interface notification on the identified resource (node). 

·         time_interval_for_trigger: represents the optional time interval that the trigger is valid for.

·         event_filter_definition: represents the optional filter to use to locate the resource (node) or capability attribute to monitor. 

·         condition_clause_definition: represents one or multiple attribute constraint that can be monitored.and that would be used to test for a specific condition on the monitored resource.

·         list_of_activity_definition: represents the list of activities that are performed if the event and (optionally) condition are met. The activity definitions are the same as the ones used in a workflow step. One could regard these activities as an anonymous workflow that is invoked by this trigger and is applied to the target(s) of this trigger’s policy.

3.6.23 Activity definitions

An activity defines an operation to be performed in a TOSCA workflow step or in an action body of a policy trigger.

Activity definitions can be of the following types:

 

·         Delegate workflow activity definition

o    Defines the name of the delegate workflow and optional input assignments. This activity requires the target to be provided by the orchestrator (no-op node or relationship).

·         Set state activity definition

o    Sets the state of a node.

·         Call operation activity definition

o    Calls an operation defined on a TOSCA interface of a node, relationship or group. The operation name uses the <interface_name>.<operation_name> notation. Optionally, assignments for the operation inputs can also be provided. If provided, they will override for this operation call the operation inputs assignment in the node template.

·         Inline workflow activity definition

Inline another workflow defined in the topology (to allow reusability). The definition includes the name of a workflow to be inlined and optional workflow input assignments.

3.6.23.1 Delegate workflow activity definition

3.6.23.1.1 Keynames

The following is a list of recognized keynames for a delegate activity definition.

 

Keyname

Required

Type

Description

delegate

yes

string or empty

(see grammar below)

Defines the name of the delegate workflow and optional input assignments.

This activity requires the target to be provided by the orchestrator (no-op node or relationship).

workflow

no

string

The name of the delegate workflow. Required in the extended  notation.

inputs

no

map of

parameter assignments

The optional map of input parameter assignments for the delegate workflow.

 

3.6.23.1.2 Grammar

A delegate activity definition has the following grammar. The short notation can be used if no input assignments are provided.

3.6.23.1.2.1  Short notation

 

- delegate: <delegate_workflow_name>

3.6.23.1.2.2  Extended notation

- delegate:

   workflow: <delegate_workflow_name>

   inputs:

     <parameter_assignments>

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

3.6.23.2 Set state activity definition

Sets the state of the target node.

3.6.23.2.1 Keynames

The following is a list of recognized keynames for a set state activity definition.

 

Keyname

Required

Type

Description

set_state

yes

string

Value of the node state.

3.6.23.2.2 Grammar

A set state activity definition has the following grammar.

 

- set_state: <new_node_state>

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

·         new_node_state: represents the state that will be affected to the node once the activity is performed.

3.6.23.3 Call operation activity definition

This activity is used to call an operation on the target node. Operation input assignments can be optionally provided.

3.6.23.3.1 Keynames

The following is a list of recognized keynames for a call operation activity definition.

 

Keyname

Required

Type

Description

call_operation

yes

string or empty

(see grammar below)

Defines the opration call. The operation name uses the <interface_name>.<operation_name> notation.

Optionally, assignments for the operation inputs can also be provided. If provided, they will override for this operation call the operation inputs assignment in the node template.

operation

no

string

The name of the operation to call, using the <interface_name>.<operation_name> notation.

Required in the extended  notation.

inputs

no

map of

parameter assignments

The optional map of input parameter assignments for the called operation. Any provided input assignments will override the operation input assignment in the target node template for this operation call.

3.6.23.3.2 Grammar

A call operation activity definition has the following grammar. The short notation can be used if no input assignments are provided.

3.6.23.3.2.1  Short notation

- call_operation: <operation_name>

3.6.23.3.2.2  Extended notation

- call_operation:

   operation: <operation_name>

   inputs:

     <parameter_assignments>

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

·         operation_name: represents the name of the operation that will be called during the workflow execution. The notation used is <interface_sub_name>.<operation_sub_name>, where interface_sub_name is the interface name and the operation_sub_name is the name of the operation whitin this interface.

·         parameter_assignments: represents the optional map of property assignments for passing parameters as inputs to this workflow delegation.

3.6.23.4 Inline workflow activity definition

This activity is used to inline a workflow in the activities sequence. The definition includes the name of the inlined workflow and optional input assignments.

3.6.23.4.1 Keynames

The following is a list of recognized keynames for an inline workflow activity definition.

 

Keyname

Required

Type

Description

inline

yes

string or empty

(see grammar below)

The definition includes the name of a workflow to be inlined and optional workflow input assignments.

workflow

no

string

The name of the inlined workflow. Required in the extended  notation.

inputs

no

map of

parameter assignments

The optional map of input parameter assignments for the inlined workflow.

3.6.23.4.2 Grammar

An inline workflow activity definition has the following grammar. The short notation can be used if no input assignments are provided.

3.6.23.4.2.1  Short notation

- inline: <inlined_workflow_name>

3.6.23.4.2.2  Extended notation

- inline:

   workflow: <inlined_workflow_name>

   inputs:

     <parameter_assignments>

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

·         inlined_workflow_name: represents the name of the workflow to inline.

·         parameter_assignments: represents the optional map of property assignments for passing parameters as inputs to this workflow delegation.

3.6.23.5 Example

The following represents a list of activity definitions (using the short notation):

 - delegate: deploy

 - set_state: started

 - call_operation: tosca.interfaces.node.lifecycle.Standard.start

 - inline: my_workflow

 

3.6.24 Assertion definition

A workflow assertion is used to specify a single condition on a workflow filter definition. The assertion allows to assert the value of an attribute based on TOSCA constraints.

3.6.24.1 Keynames

The TOSCA workflow assertion definition has no keynames.

3.6.24.2 Grammar

Workflow assertion definitions have the following grammar:

<attribute_name>: <list_of_constraint_clauses>

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

·         attribute_name: represents the name of an attribute defined on the assertion context entity (node instance, relationship instance, group instance) and from which value will be evaluated against the defined constraint clauses.

·         list_of_constraint_clauses: represents the list of constraint clauses that will be used to validate the attribute assertion.

3.6.24.3 Example

Following represents a workflow assertion with a single equals constraint:

 my_attribute: [{equal : my_value}]

Following represents a workflow assertion with mutliple constraints:

 my_attribute:

  - min_length: 8

  - max_length : 10

3.6.25 Condition clause definition

A workflow condition clause definition is used to specify a condition that can be used within a workflow precondition or workflow filter.

3.6.25.1 Keynames

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

Keyname

Required

Type

Description

and

no

list of condition clause definition

An and clause allows to define sub-filter clause definitions that must all be evaluated truly so the and clause is considered as true.

or

no

list of condition clause definition

An or clause allows to define sub-filter clause definitions where one of them must all be evaluated truly so the or clause is considered as true.

not

no

list of condition clause definition

A not clause allows to define sub-filter clause definitions where one or more of them must be evaluated as false.

assert

no

deprecated list of assertion definition

An assert clause defines a list of filter assertions that must be evaluated on entity attributes. Assert acts as an and clause, i.e. every defined filter assertion must be true so the assertion is considered as true.Because assert and and are logically identical, the assert keyname has been deprecated.

 

Note : It is allowed to add direct assertion definitions directly to the condition clause definition without using any of the supported keynames. . In that case, an and clause is performed for all direct assertion definition.

3.6.25.2 Grammar

Condition clause definitions have the following grammars:

3.6.25.2.1 And clause

and: <list_of_condition_clause_definition>

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

·         list_of_condition_clause_definition: represents the list of condition clauses. All condition clauses MUST be asserted to true so that the and clause is asserted to true.

3.6.25.2.2 Or clause

or: <list_of_condition_clause_definition>

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

·         list_of_condition_clause_definition: represents the list of condition clauses. One of the condition clause have to be asserted to true so that the or clause is asserted to true.

3.6.25.2.3 Not clause

not: <list_of_condition_clause_definition>

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

·         list_of_condition_clause_definition: represents the list of condition clauses. One of the condition clause have to be asserted to false so that the not clause is asserted to true.

3.6.25.3 Direct assertion definition

<attribute_name>: <list_of_constraint_clauses>

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

·         attribute_name: represents the name of an attribute defined on the assertion context entity (node instance, relationship instance, group instance) and from which value will be evaluated against the defined constraint clauses.

·         list_of_constraint_clauses: represents the list of constraint clauses that will be used to validate the attribute assertion.

3.6.25.4 Additional Requirement

·         Keynames are mutually exclusive, i.e. a filter definition can define only one of and, or, or not keyname.

3.6.25.5 Notes

·         The TOSCA processor SHOULD perform assertion in the order of the list for every defined condition clause or direct assertion definition.

3.6.25.6 Example

Following represents a workflow condition clause with a single direct assertion definition:

condition:

  - my_attribute: [{equal: my_value}]

Following represents a workflow condition clause with single equals constraints on two different attributes.

condition:

  - my_attribute: [{equal: my_value}]

  - my_other_attribute: [{equal: my_other_value}]

Note that these two direct assertion constraints are logically and-ed. This means that the following is logically identical to the previous example:

condition:

  - and:

    - my_attribute: [{equal: my_value}]

    - my_other_attribute: [{equal: my_other_value}]

 

Following represents a workflow condition clause with a or constraint on two different assertions:

condition:

  - or:

    - my_attribute: [{equal: my_value}]

    - my_other_attribute: [{equal: my_other_value}]

The following shows an example of the not operator. The condition yields TRUE when the attribute my_attribute1 takes any value other than value1:

condition:

  - not:

    - my_attribute1: [{equal: value1}]}

The following condition yields TRUE when none of the attributes my_attribute1 and my_attribute2 is equal to value1.

condition:

  - not:

    - and:

      - my_attribute1: [{equal: value1}]

      - my_attribute2: [{equal: value1}]

The following condition is a functional equivalent of the previous example:

condition:

  - or:

    - not:

      - my_attribute1: [{equal: value1}]

    - not:

      - my_attribute2: [{equal: value1}]

Following represents multiple levels of condition clauses with direct assertion definitions to build the following logic: use http on port 80 or https on port 431:

condition:

  - or:

    -  and:

      - protocol: { equal: http }

      - port: { equal: 80 }

    -  and:

      - protocol: { equal: https }

      - port: { equal: 431 }

3.6.26 Workflow precondition definition

A workflow condition can be used as a filter or precondition to check if a workflow can be processed or not based on the state of the instances of a TOSCA topology deployment. When not met, the workflow will not be triggered.

3.6.26.1 Keynames

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

Keyname

Required

Type

Description

target

yes

string

The target of the precondition (this can be a node template name, a group name)

target_relationship

no

string

The optional name of a requirement of the target in case the precondition has to be processed on a relationship rather than a node or group. Note that this is applicable only if the target is a node.

condition

no

list of condition clause definitions

A list of workflow condition clause definitions. Assertion between elements of the condition are evaluated as an AND condition.

3.6.26.2 Grammar

Workflow precondition definitions have the following grammars:

  - target: <target_name>

    target_relationship: <target_requirement_name>

    condition:

      <list_of_condition_clause_definition>

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

·         target_name: represents the name of a node template or group in the topology.

·         target_requirement_name: represents the name of a requirement of the node template (in case target_name refers to a node template.

·         list_of_condition_clause_definition: represents the list of condition clauses to be evaluated. The value of the resulting condition is evaluated as an AND clause between the different elements.

3.6.27 Workflow step definition

A workflow step allows to define one or multiple sequenced activities in a workflow and how they are connected to other steps in the workflow. They are the building blocks of a declarative workflow.

3.6.27.1 Keynames

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

Keyname

Required

Type

Description

target

yes

string

The target of the step (this can be a node template name, a group name)

target_relationship

no

string

The optional name of a requirement of the target in case the step refers to a relationship rather than a node or group. Note that this is applicable only if the target is a node.

operation_host

no

string

The node on which operations should be executed (for TOSCA call_operation activities).

This element is required only for relationships and groups target.

 

If target is a relationships operation_host is required and valid_values are SOURCE or TARGET – referring to the relationship source or target node.

 

If target is a group operation_host is optional.

If not specified the operation will be triggered on every node of the group.

If specified the valid_value is a node_type or the name of a node template.

filter

no

list of constraint clauses

Filter is a map of attribute name, list of constraint clause that allows to provide a filtering logic.

activities

yes

list of activity definition

The list of sequential activities to be performed in this step.

on_success

no

list of string

The optional list of step names to be performed after this one has been completed with success (all activities has been correctly processed).

on_failure

no

list of string

The optional list of step names to be called after this one in case one of the step activity failed.

3.6.27.2 Grammar

Workflow step definitions have the following grammars:

steps:

  <step_name>

    target: <target_name>

    target_relationship: <target_requirement_name>

    operation_host: <operation_host_name>

    filter:

      - <list_of_condition_clause_definition>

    activities:

      - <list_of_activity_definition>

    on_success:

      - <target_step_name>

    on_failure:

      - <target_step_name>

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

·         target_name: represents the name of a node template or group in the topology.

·         target_requirement_name: represents the name of a requirement of the node template (in case target_name refers to a node template.

·         operation_host: the node on which the operation should be executed

·         list_of_condition_clause_definition: represents a list of condition clause definition.

·         list_of_activity_definition: represents a list of activity definition

·         target_step_name: represents the name of another step of the workflow.

3.7 Type-specific definitions

3.7.1 Entity Type Schema

An Entity Type is the common, base, polymorphic schema type which is extended by TOSCA base entity type schemas (e.g., Node Type, Relationship Type, Artifact Type, etc.) and serves to define once all the commonly shared keynames and their types. This is a “meta” type which is abstract and not directly instantiatable.

3.7.1.1 Keynames

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

Keyname

Required

Type

Constraints

Description

derived_from

no

string

‘None’

is the only allowed value

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

version

no

version

N/A

An optional version for the Entity Type definition.

metadata

no

map of string

N/A

Defines a section used to declare additional metadata information.

description

no

description

N/A

An optional description for the Entity Type.

3.7.1.2 Grammar

Entity Types have following grammar:

<entity_keyname>:

  # The only allowed value is ‘None’

  derived_from: None

  version: <version_number>

  metadata:

    <metadata_map>

  description: <interface_description>

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

·         version_number: represents the optional TOSCA version number for the entity.

·         entity_description: represents the optional description string for the entity.

·         metadata_map: represents the optional map of string.

3.7.1.3 Additional Requirements

·         The TOSCA Entity Type SHALL be the common base type used to derive all other top-level base TOSCA Types.

·         The TOSCA Entity Type SHALL NOT be used to derive or create new base types apart from those defined in this specification or a profile of this specification.

3.7.2 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.

3.7.2.1 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

map of

property definitions

N/A

An optional map of property definitions for the Capability definition.

attributes

no

map of

attribute definitions

N/A

An optional map 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.

3.7.2.2 Grammar

Capability definitions have one of the following grammars:

3.7.2.2.1 Short notation

The following single-line grammar may be used when only the capability definition name needs to be declared, without further refinement of the capability type definitions:

<capability_definition_name>: <capability_type>

3.7.2.2.2 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> ]

  occurrences : <range_of_occurrences>

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 map of property definitions for the capability definition.

·         attribute_definitions: represents the optional map 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.

·         Range_of_occurrences: represents he optional minimum and maximum occurrences for the capability.

3.7.2.3 Examples

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

3.7.2.3.1 Simple notation example

# Simple notation, no properties defined or augmented

some_capability: mytypes.mycapabilities.MyCapabilityTypeName

3.7.2.3.2 Full notation example

# Full notation, augmenting properties of the referenced capability type

some_capability:

  type: mytypes.mycapabilities.MyCapabilityTypeName

  properties:

    limit:

      type: integer

      default: 100

3.7.2.4 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.

3.7.2.5 Notes

3.7.3 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).

3.7.3.1 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.

3.7.3.1.1 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

map 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.

3.7.3.2 Grammar

Requirement definitions have one of the following grammars:

3.7.3.2.1 Simple grammar (Capability Type only)

<requirement_definition_name>: <capability_type_name>

3.7.3.2.2 Extended grammar (with Node and Relationship Types)

<requirement_definition_name>:

  capability: <capability_type_name>

  node: <node_type_name>

  relationship: <relationship_type_name>

  occurrences: [ <min_occurrences>, <max_occurrences> ]

3.7.3.2.3 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_definition_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_definition_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.

3.7.3.3 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]

3.7.3.4 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.

3.7.3.5 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.

3.7.3.5.1 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.

3.7.4 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.

3.7.4.1 Keynames

The Artifact Type is a TOSCA Entity and has the common keynames listed in section 3.7.1 TOSCA Entity Schema.

In addition, the Artifact Type has the following recognized keynames:

Keyname

Required

Type

Constraints

Description

mime_type

no

string

None

The required mime type property for the Artifact Type.

file_ext

no

string[]

None

The required file extension property for the Artifact Type.

properties

no

map of

property definitions

No

Anoptional map of property definitions for the Artifact Type.

3.7.4.2 Grammar

Artifact Types have following grammar:

<artifact_type_name>:

  derived_from: <parent_artifact_type_name>

  version: <version_number>

  metadata:

    <map of string>

  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 map of property definitions for the artifact type.

3.7.4.3 Examples

my_artifact_type:

  description: Java Archive artifact type

  derived_from: tosca.artifact.Root

  mime_type: application/java-archive

  file_ext: [ jar ]

  properties:

    id:

      description: Identifier of the jar

      type: string

      required: true

    creator:

      description: Vendor of the java implementation on which the jar is based

      type: string

      required: false

3.7.4.4 Additional Requirements

·         The ‘mime_type’ keyname  is meant to have values that are Apache mime types such as those defined here: http://svn.apache.org/repos/asf/httpd/httpd/trunk/docs/conf/mime.types

3.7.4.5 Notes

Information about artifacts can be broadly classified in two categories that serve different purposes :

 

1.     Selection of artifact processor – This category includes informational elements such as artifact version, checksum, checksum algorithm etc. and s used by TOSCA Orchestrator to select the correct artifact processor for the artifact. These informational elements are captured in TOSCA as keywords for the artifact.

2.     Properties processed by artifact processor - Some properties are not processed by the Orchestrator, but passed on to the artifact processor to assist with proper processing of the artifact. These informational elements are described through artifact properties.

·         .

3.7.5 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.

3.7.5.1 Keynames

The Interface Type is a TOSCA Entity and has the common keynames listed in section 3.7.1 TOSCA Entity Schema.

In addition, the Interface Type has the following recognized keynames:

Keyname

Required

Type

Description

inputs

no

map of

property definitions

The optional map of input parameter definitions.

operations

no

map of operation definitions

The optional map of operations defined for this interface.

notifications

no

map of notification definitions

The optional map of notifications defined for this interface.

3.7.5.2 Grammar

Interface Types have following grammar:

<interface_type_name>:

  derived_from: <parent_interface_type_name>

  version: <version_number>

  metadata:

    <map of string>

  description: <interface_description>

  inputs:

    <property_definitions>

  operations:

    <operation_definitions>

  notifications:

    <notification definitions>

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

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

·         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.

·         property_definitions: represents the optional map of property definitions (i.e., parameters) which the TOSCA orchestrator would make available (i.e., or pass) to all implementation artifacts for operations declared on the interface during their execution.

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

·         notification_definitions: represents the required name of one or more notification definitions.  

3.7.5.3 Example

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

mycompany.mytypes.myinterfaces.MyConfigure:

  derived_from: tosca.interfaces.relationship.Root

  description: My custom configure Interface Type

  inputs:

    mode:

      type: string

  operations:

    pre_configure_service:

      description: pre-configure operation for my service

    post_configure_service:

      description: post-configure operation for my service

3.7.5.4 Additional Requirements

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

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

3.7.5.5 Notes

Starting with Version 1.3 of this specification, interface type definition grammar was changed to support notifications as well as operations. As a result, operations must now be specified under the newly-introduced operations keyname and the notifications under the new notifications keyname. For backward compatibility if neither the operations or notifications are specified then we assume the symbolic names in the interface definition to mean operations, but this use is deprecated. Operations and notifications names should not overlap.

3.7.6 Data Type

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

3.7.6.1 Keynames

The Data Type is a TOSCA Entity and has the common keynames listed in section 3.7.1 TOSCA Entity Schema.

In addition, the Data Type has the following recognized keynames:

Keyname

Required

Type

Description

constraints

no

list of

constraint clauses

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

properties

no

map of

property definitions

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

key_schema

no

schema_definition

For data types that derive from the TOSCA map data type, the optional schema definition for the keys used to identify entries in properties of this data type.

entry_schema

no

schema_definition

For data types that derive from the TOSCA map or list data types, the optional schema definition for the entries in properties of this data type.

3.7.6.2 Grammar

Data Types have the following grammar:

<data_type_name>:

  derived_from: <existing_type_name>

  version: <version_number>

  metadata:

    <map of string>

  description: <datatype_description>

  constraints:

    - <type_constraints>

  properties:

    <property_definitions>

  key_schema : <key_schema_definition>

  entry_schema: <entry_schema_definition>

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 list of one or more type-compatible constraint clauses that restrict the Data Type.

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

·         key_schema_definition: if the data_type derives from the TOSCA map type (i.e existing_type_name is a map or derives from a map), represents the optional schema definition for they keys used to identify entries properties of this type..

·         entry_schema_definition: if the data_type derives from the TOSCA map or list types (i.e. existing_type name is a map or list or derives from a map or list), represents the optional schema definition for the entries in properties of this type.

3.7.6.3 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.

3.7.6.4 Examples

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

3.7.6.4.1 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

3.7.6.4.2 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

3.7.7 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.

3.7.7.1 Keynames

The Capability Type is a TOSCA Entity and has the common keynames listed in section 3.7.1 TOSCA Entity Schema.

In addition, the Capability Type has the following recognized keynames:

Keyname

Required

Type

Description

properties

no

map of
property definitions

An optional map of property definitions for the Capability Type.

attributes

no

map of

attribute definitions

An optional map 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.

3.7.7.2 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 map of property definitions that the Capability type exports.

·         attribute_definitions: represents the optional map 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.

3.7.7.3 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

3.7.8 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.

3.7.9 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.

3.7.9.1 Keynames

The Node Type is a TOSCA Entity and has the common keynames listed in section 3.7.1 TOSCA Entity Schema.

In addition, the Node Type has the following recognized keynames:

Keyname

Required

Type

Description

attributes

no

map of

attribute definitions

An optional map of attribute definitions for the Node Type.

properties

no

map of

property definitions

An optional map of property definitions for the Node Type.

requirements

no

list of

requirement definitions

An optional list of requirement definitions for the Node Type.

capabilities

no

map of

capability definitions

An optional map of capability definitions for the Node Type.

interfaces

no

map of

interface definitions

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

artifacts

no

map of

artifact definitions

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

3.7.9.2 Grammar

Node Types have following grammar:

<node_type_name>: 

  derived_from: <parent_node_type_name>

  version: <version_number>

  metadata:

    <map of string>

  description: <node_type_description>

  attributes:

    <attribute_definitions>

  properties:

    <property_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 map of property definitions for the Node Type.

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

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

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

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

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

3.7.9.3 Additional Requirements

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

3.7.9.4 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

3.7.9.5 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

3.7.10 Relationship Type

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

3.7.10.1 Keynames

The Relationship Type is a TOSCA Entity and has the common keynames listed in section 3.7.1 TOSCA Entity Schema.

In addition, the Relationship Type has the following recognized keynames:

Keyname

Required

Definition/Type

Description

properties

no

map of

property definitions

An optional map of property definitions for the Relationship Type.

attributes

no

map of

attribute definitions

An optional map of attribute definitions for the Relationship Type.

interfaces

no

map of

interface definitions

An optional map 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.

3.7.10.2 Grammar

Relationship Types have following grammar:

<relationship_type_name>:

  derived_from: <parent_relationship_type_name>

  version: <version_number>

  metadata:

    <map of string>

  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 map of property definitions for the Relationship Type.

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

·         interface_definitions: represents the optional map 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).

3.7.10.3 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.

3.7.10.4 Examples

mycompanytypes.myrelationships.AppDependency:

  derived_from: tosca.relationships.DependsOn

  valid_target_types: [ mycompanytypes.mycapabilities.SomeAppCapability ]

3.7.11 Group Type

A Group Type defines logical grouping types for nodes, typically for different management purposes. 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.

3.7.11.1 Keynames

The Group Type is a TOSCA Entity and has the common keynames listed in section 3.7.1 TOSCA Entity Schema.

In addition, the Group Type has the following recognized keynames:

Keyname

Required

Type

Description

attributes

no

map of

attribute definitions

An optional map of attribute definitions for the Group Type.

properties

no

map of

property definitions

An optional map 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).

3.7.11.2 Grammar

Group Types have one the following grammars:

<group_type_name>:

  derived_from: <parent_group_type_name>

  version: <version_number>

  metadata:

    <map of string>

  description: <group_description>

  attributes :

    <attribute_definitions>

  properties:

    <property_definitions>

  members: [ <list_of_valid_member_types> ]

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).

·