TOSCA Version 2.0

Committee Specification Draft 05

19 January 2023

This stage:

https://docs.oasis-open.org/tosca/TOSCA/v2.0/csd05/TOSCA-v2.0-csd05.docx (Authoritative)

https://docs.oasis-open.org/tosca/TOSCA/v2.0/csd05/TOSCA-v2.0-csd05.html

https://docs.oasis-open.org/tosca/TOSCA/v2.0/csd05/TOSCA-v2.0-csd05.pdf

Previous stage:

https://docs.oasis-open.org/tosca/TOSCA/v2.0/csd04/TOSCA-v2.0-csd04.docx (Authoritative)

https://docs.oasis-open.org/tosca/TOSCA/v2.0/csd04/TOSCA-v2.0-csd04.html

https://docs.oasis-open.org/tosca/TOSCA/v2.0/csd04/TOSCA-v2.0-csd04.pdf

Latest stage:

https://docs.oasis-open.org/tosca/TOSCA/v2.0/TOSCA-v2.0.docx (Authoritative)

https://docs.oasis-open.org/tosca/TOSCA/v2.0/TOSCA-v2.0.html

https://docs.oasis-open.org/tosca/TOSCA/v2.0/TOSCA-v2.0.pdf

Technical Committee:

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

Chair:

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

Editors:

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

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

Related work:

This specification replaces or supersedes:

·         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.

·         TOSCA Simple Profile in YAML Version 1.3. Edited by Matt Rutkowski, Chris Lauwers, Claude Noshpitz, and Calin Curescu. Latest version: https://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.3/TOSCA-Simple-Profile-YAML-v1.3.html.

This specification is related to:

·         Introduction to TOSCA Version 2.0. Edited by Chris Lauwers and Calin Curescu. Work in progress.

Declared XML namespace:

·         http://docs.oasis-open.org/tosca/ns/2.0

Abstract:

The OASIS TOSCA TC works to enhance the portability of cloud applications and services across their entire lifecycle. TOSCA will enable the interoperable description of application and infrastructure cloud services, the relationships between parts of the service, and the operational behavior of these services (e.g., deploy, patch, shutdown) independent of the supplier creating the service or of any particular cloud provider or hosting technology. TOSCA will also make it possible for higher-level operational behavior to be associated with cloud infrastructure management.

By increasing service and application portability in a vendor-neutral ecosystem, TOSCA will enable:

·         Portable deployment to any compliant cloud

·         Smoother migration of existing applications to the cloud

·         Flexible bursting (consumer choice)

·         Dynamic, multi-cloud provider applications

Status:

This document was last revised or approved by the OASIS Topology and Orchestration Specification for Cloud Applications (TOSCA) TC on the above date. The level of approval is also listed above. Check the “Latest stage” 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-v2.0]

TOSCA Version 2.0. Edited by Chris Lauwers and Calin Curescu. 19 January 2023. OASIS Committee Specification Draft 05. https://docs.oasis-open.org/tosca/TOSCA/v2.0/csd05/TOSCA-v2.0-csd05.html. Latest stage: https://docs.oasis-open.org/tosca/TOSCA/v2.0/TOSCA-v2.0.html.

Notices

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Table of Contents

1        Introduction. 18

1.1 IPR Policy. 18

1.2 Terminology. 18

1.3 Normative References. 18

1.4 Non-Normative References. 18

2        Overview. 20

2.1 Objective. 20

2.2 TOSCA Scope. 20

2.3 Application Domains. 20

2.4 Implementations. 21

2.5 Glossary. 21

3        TOSCA core concepts. 22

3.1 Service Templates, Node Templates, and Relationships. 22

3.2 Interfaces, Operations, and Artifacts. 23

3.3 Workflows. 23

3.4 Requirements and Capabilities. 23

3.5 Decomposition of Service Templates. 24

3.6 Policies in TOSCA. 25

3.7 Archive Format for Cloud Applications. 25

3.8 TOSCA Entities. 26

4        TOSCA Operational Model 27

4.1 TOSCA Processor 27

4.1.1 Parser 27

4.1.2 Resolver 27

4.1.2.1 Creating Service Representations. 28

4.1.2.2 Requirement Fulfillment 28

4.1.2.3 Substitution Mapping. 28

4.2 Orchestrator 28

5        TOSCA definitions. 29

5.1 TOSCA Metamodel 29

5.1.1 Modeling concepts and goals. 29

5.1.2 Modeling definitions and reuse. 29

5.1.3 Goal of the derivation and refinement rules. 30

5.1.4 Mandatory Keynames. 30

5.2 TOSCA Service. 30

5.2.1 TOSCA file definition. 30

5.2.1.1 Keynames. 30

5.2.1.2 Grammar 31

5.2.1.2.1 Requirements. 32

5.2.1.2.2 Notes. 32

5.2.1.3 Top-level keyname definitions. 33

5.2.1.3.1 tosca_definitions_version. 33

5.2.1.3.1.1     Keyname. 33

5.2.1.3.1.2     Grammar 33

5.2.1.3.1.3     Examples: 33

5.2.1.3.2 profile. 33

5.2.1.3.2.1     Keyname. 33

5.2.1.3.2.2     Grammar 33

5.2.1.3.2.3     Examples. 34

5.2.1.3.3 metadata. 34

5.2.1.3.3.1     Keyname. 34

5.2.1.3.3.2     Grammar 34

5.2.1.3.3.3     Example. 34

5.2.1.3.4 description. 34

5.2.1.3.4.1     Keyname. 34

5.2.1.3.4.2     Grammar 34

5.2.1.3.4.3     Example. 34

5.2.1.3.5 dsl_definitions. 34

5.2.1.3.5.1     Keyname. 35

5.2.1.3.5.2     Grammar 35

5.2.1.3.5.3     Example. 35

5.2.1.3.6 repositories. 35

5.2.1.3.6.1     Keyname. 35

5.2.1.3.6.2     Grammar 35

5.2.1.3.6.3     Example. 35

5.2.1.3.7 imports. 35

5.2.1.3.7.1     Keyname. 36

5.2.1.3.7.2     Grammar 36

5.2.1.3.7.3     Example. 36

5.2.1.3.8 artifact_types. 36

5.2.1.3.8.1     Keyname. 36

5.2.1.3.8.2     Grammar 36

5.2.1.3.8.3     Example. 36

5.2.1.3.9 data_types. 36

5.2.1.3.9.1     Keyname. 36

5.2.1.3.9.2     Grammar 36

5.2.1.3.9.3     Example. 37

5.2.1.3.10 capability_types. 37

5.2.1.3.10.1     Keyname. 37

5.2.1.3.10.2     Grammar 37

5.2.1.3.10.3     Example. 37

5.2.1.3.11 interface_types. 37

5.2.1.3.11.1     Keyname. 38

5.2.1.3.11.2     Grammar 38

5.2.1.3.11.3     Example. 38

5.2.1.3.12 relationship_types. 38

5.2.1.3.12.1     Keyname. 38

5.2.1.3.12.2     Grammar 38

5.2.1.3.12.3     Example. 38

5.2.1.3.13 node_types. 38

5.2.1.3.13.1     Keyname. 38

5.2.1.3.13.2     Grammar 39

5.2.1.3.13.3     Example. 39

5.2.1.3.14 group_types. 39

5.2.1.3.14.1     Keyname. 39

5.2.1.3.14.2     Grammar 39

5.2.1.3.14.3     Example. 39

5.2.1.3.15 policy_types. 39

5.2.1.3.15.1     Keyname. 39

5.2.1.3.15.2     Grammar 39

5.2.1.3.15.3     Example. 39

5.2.2 Profiles. 40

5.2.2.1 Examples. 40

5.2.2.2 Defining Profiles. 40

5.2.2.3 Profile Versions. 41

5.2.3 Imports and Namespaces. 43

5.2.3.1 Import definition. 43

5.2.3.1.1 Keynames. 43

5.2.3.1.2 Grammar 43

5.2.3.1.2.1     Single-line grammar: 43

5.2.3.1.2.2     Multi-line grammar 43

5.2.3.1.3 Import processing rules. 44

5.2.3.1.3.1     Importing profiles. 44

5.2.3.1.3.2     Importing service templates. 44

5.2.3.1.4 Examples. 44

5.2.3.2 Namespaces. 45

5.2.3.2.1 Additional Requirements. 47

5.2.3.3 Repository definition. 48

5.2.3.3.1 Keynames. 48

5.2.3.3.2 Grammar 48

5.2.3.3.2.1     Single-line grammar: 48

5.2.3.3.2.2     Multi-line grammar 49

5.2.3.3.3 Example. 49

5.2.4 Additional information definitions. 49

5.2.4.1 Description definition. 49

5.2.4.1.1 Keyname. 49

5.2.4.1.2 Grammar 49

5.2.4.1.3 Examples. 49

5.2.4.1.4 Notes. 50

5.2.4.2 Metadata. 50

5.2.4.2.1 Keyname. 50

5.2.4.2.2 Grammar 50

5.2.4.2.3 Examples. 50

5.2.4.2.4 Notes. 50

5.2.4.3 DSL Definitions. 50

5.2.5 Type definitions. 50

5.2.5.1 General derivation and refinement rules. 51

5.2.5.2 Common keynames in type definitions. 51

5.2.5.2.1 Keynames. 51

5.2.5.2.2 Grammar 51

5.2.5.2.3 Derivation rules. 52

5.2.6 Service template definition. 52

5.2.6.1 Keynames. 52

5.2.6.2 Grammar 53

5.2.6.2.1 inputs. 54

5.2.6.2.1.1     Grammar 54

5.2.6.2.1.2     Examples. 54

5.2.6.2.2 node_templates. 54

5.2.6.2.2.1     grammar 54

5.2.6.2.2.2     Example. 54

5.2.6.2.3 relationship_templates. 55

5.2.6.2.3.1     Grammar 55

5.2.6.2.3.2     Example. 55

5.2.6.2.4 outputs. 55

5.2.6.2.4.1     Grammar 55

5.2.6.2.4.2     Example. 55

5.2.6.2.5 groups. 55

5.2.6.2.5.1     Grammar 56

5.2.6.2.5.2     Example. 56

5.2.6.2.6 policies. 56

5.2.6.2.6.1     Grammar 56

5.2.6.2.6.2     Example. 56

5.2.6.2.7 substitution_mapping. 56

5.2.6.2.7.1     requirement_mapping. 56

5.2.6.2.7.2     Example. 57

5.3 Nodes and Relationships. 58

5.3.1 Node Type. 58

5.3.1.1 Keynames. 58

5.3.1.2 Grammar 58

5.3.1.3 Derivation rules. 59

5.3.1.4 Additional Requirements. 59

5.3.1.5 Example. 59

5.3.2 Node Template. 60

5.3.2.1 Keynames. 60

5.3.2.2 Grammar 61

5.3.2.3 Additional requirements. 61

5.3.2.4 Example. 62

5.3.3 Relationship Type. 62

5.3.3.1 Keynames. 62

5.3.3.2 Grammar 62

5.3.3.3 Derivation rules. 63

5.3.3.4 Examples. 63

5.3.4 Relationship Template. 64

5.3.4.1 Keynames. 64

5.3.4.2 Grammar 64

5.3.4.3 Additional requirements. 65

5.3.4.4 Example. 65

5.3.5 Capabilities and Requirements. 65

5.3.5.1 Capability Type. 65

5.3.5.1.1 Keynames. 65

5.3.5.1.2 Grammar 66

5.3.5.1.3 Derivation rules. 66

5.3.5.1.4 Example. 67

5.3.5.2 Capability definition. 67

5.3.5.2.1 Keynames. 67

5.3.5.2.2 Grammar 68

5.3.5.2.2.1     Short notation. 68

5.3.5.2.2.2     Extended notation. 68

5.3.5.2.3 Refinement rules. 69

5.3.5.2.4 Examples. 69

5.3.5.2.4.1     Simple notation example. 69

5.3.5.2.4.2     Full notation example. 69

5.3.5.2.5 Additional requirements. 69

5.3.5.2.6 Note. 69

5.3.5.3 Capability assignment 70

5.3.5.3.1 Keynames. 70

5.3.5.3.2 Grammar 70

5.3.5.3.3 Example. 71

5.3.5.3.3.1     Notation example. 71

5.3.5.3.4 Note. 71

5.3.5.4 Requirement Type. 71

5.3.5.5 Requirement definition. 71

5.3.5.5.1 Keynames. 71

5.3.5.5.1.1     Additional keynames for multi-line relationship grammar 72

5.3.5.5.2 Grammar 72

5.3.5.5.2.1     Simple grammar (Capability Type only) 72

5.3.5.5.2.2     Extended grammar (with Node and Relationship Types) 72

5.3.5.5.2.3     Extended grammar for declaring Parameter Definitions on the relationship’s Interfaces. 73

5.3.5.5.3 Refinement rules. 73

5.3.5.5.4 Additional requirements. 74

5.3.5.5.5 Notes. 74

5.3.5.5.6 Requirement definition is a tuple with a filter 74

5.3.5.6 Requirement assignment 74

5.3.5.6.1 Keynames. 75

5.3.5.6.2 Grammar 76

5.3.5.6.2.1     Short notation: 76

5.3.5.6.2.2     Extended notation: 77

5.3.5.6.2.3     Extended grammar with Property Assignments and Interface Assignments for the relationship  77

5.3.5.6.2.4     Extended grammar with capacity allocation. 77

5.3.5.6.3 Notes. 79

5.3.5.6.4 Examples. 80

5.3.5.6.4.1     Example 1 – Hosting requirement on a Node Type. 80

5.3.5.6.4.2     Example 2 - Requirement with Node Template and a custom Relationship Type. 80

5.3.5.6.4.3     Example 3 - Requirement for a Compute node with additional selection criteria (filter) 80

5.3.5.6.4.4     Example 4 - Requirement assignment for definition with count_range: [2,2] 81

5.3.5.6.4.5     Example 5 - Requirement assignment for definition with capacity allocation. 81

5.3.5.7 Node Filter definition. 82

5.3.5.7.1 Grammar 82

5.3.5.7.2 Example. 82

5.3.6 Interfaces. 82

5.3.6.1 Interface Type. 82

5.3.6.1.1 Keynames. 82

5.3.6.1.2 Grammar 83

5.3.6.1.3 Derivation rules. 83

5.3.6.1.4 Example. 83

5.3.6.1.5 Additional Requirements. 84

5.3.6.2 Interface definition. 84

5.3.6.2.1 Keynames. 84

5.3.6.2.2 Grammar 84

5.3.6.2.3 Refinement rules. 85

5.3.6.3 Interface assignment 85

5.3.6.3.1 Keynames. 85

5.3.6.3.2 Grammar 86

5.3.6.4 Operation definition. 86

5.3.6.4.1 Keynames. 86

5.3.6.4.2 Grammar 87

5.3.6.4.2.1     Short notation. 87

5.3.6.4.2.2     Extended notation. 87

5.3.6.4.3 Refinement rules. 87

5.3.6.4.4 Additional requirements. 88

5.3.6.4.5 Examples. 88

5.3.6.4.5.1     Single-line example. 88

5.3.6.4.5.2     Multi-line example with shorthand implementation definitions. 88

5.3.6.4.5.3     Multi-line example with extended implementation definitions. 88

5.3.6.5 Operation assignment 89

5.3.6.5.1 Keynames. 89

5.3.6.5.2 Grammar 89

5.3.6.5.2.1     Short notation. 89

5.3.6.5.2.2     Extended notation. 89

5.3.6.5.3 Additional requirements. 90

5.3.6.5.4 Examples. 90

5.3.6.6 Notification definition. 90

5.3.6.6.1 Keynames. 90

5.3.6.6.2 Grammar 91

5.3.6.6.2.1     Short notation. 91

5.3.6.6.2.2     Extended notation. 91

5.3.6.6.3 Refinement rules. 91

5.3.6.6.4 Additional requirements. 92

5.3.6.6.5 Examples. 92

5.3.6.7 Notification assignment 92

5.3.6.7.1 Keynames. 92

5.3.6.7.2 Grammar 92

5.3.6.7.2.1     Short notation. 93

5.3.6.7.2.2     Extended notation. 93

5.3.6.7.3 Additional requirements. 93

5.3.6.7.4 Examples. 93

5.3.6.8 Operation and notification implementation definition. 93

5.3.6.8.1 Keynames. 94

5.3.6.8.2 Grammar 94

5.3.6.8.2.1     Short notation for use with single artifact 94

5.3.6.8.2.2     Short notation for use with multiple artifacts. 94

5.3.6.8.2.3     Extended notation for use with single artifact 94

5.3.6.8.2.4     Extended notation for use with multiple artifacts. 94

5.3.7 Artifacts. 95

5.3.7.1 Artifact Type. 95

5.3.7.1.1 Keynames. 95

5.3.7.1.2 Grammar 95

5.3.7.1.3 Derivation rules. 96

5.3.7.1.4 Examples. 96

5.3.7.1.5 Additional Requirements. 96

5.3.7.1.6 Notes. 96

5.3.7.2 Artifact definition. 97

5.3.7.2.1 Keynames. 97

5.3.7.2.2 Grammar 97

5.3.7.2.2.1     Short notation. 97

5.3.7.2.2.2     Extended notation: 97

5.3.7.2.3 Refinement rules. 98

5.3.7.2.4 Examples. 98

5.4 Properties, Attributes, and Parameters. 99

5.4.1 Primitive Types. 100

5.4.1.1 string. 100

5.4.1.1.1 Notes: 100

5.4.1.2 integer 101

5.4.1.2.1 Notes. 101

5.4.1.3 float 101

5.4.1.3.1 Notes. 102

5.4.1.4 boolean. 102

5.4.1.5 bytes. 102

5.4.1.5.1 Notes. 102

5.4.1.6 nil 103

5.4.2 Special Types. 103

5.4.2.1 TOSCA version. 103

5.4.2.1.1 Grammar 103

5.4.2.1.2 Version Comparison. 104

5.4.2.1.3 Examples. 104

5.4.2.1.4 Notes. 104

5.4.2.1.5 Additional Requirements. 104

5.4.2.2 TOSCA range type. 104

5.4.2.2.1 Grammar 104

5.4.2.2.2 Keywords. 105

5.4.2.2.3 Examples. 105

5.4.2.3 TOSCA timestamp type. 105

5.4.2.3.1 Notes. 105

5.4.2.4 TOSCA scalar-unit type. 105

5.4.2.4.1 Grammar 106

5.4.2.4.2 Additional requirements. 106

5.4.2.4.3 Concrete Types. 106

5.4.2.4.4 scalar-unit.size. 106

5.4.2.4.4.1     Recognized Units. 106

5.4.2.4.4.2     Examples. 107

5.4.2.4.4.3     Notes. 107

5.4.2.4.5 scalar-unit.time. 107

5.4.2.4.5.1     Recognized Units. 107

5.4.2.4.5.2     Examples. 107

5.4.2.4.5.3     Notes. 108

5.4.2.4.6 scalar-unit.frequency. 108

5.4.2.4.6.1     Recognized Units. 108

5.4.2.4.6.2     Examples. 108

5.4.2.4.6.3     Notes. 108

5.4.2.4.7 scalar-unit.bitrate. 108

5.4.2.4.7.1     Recognized Units. 108

5.4.2.4.7.2     Examples. 109

5.4.3 Collection Types. 109

5.4.3.1 TOSCA list type. 109

5.4.3.1.1 Grammar 109

5.4.3.1.1.1     Square bracket notation. 109

5.4.3.1.1.2     Bulleted list notation. 109

5.4.3.1.2 Declaration Examples. 109

5.4.3.1.2.1     List declaration using a simple type. 109

5.4.3.1.2.2     List declaration using a complex type. 110

5.4.3.1.3 Definition Examples. 110

5.4.3.1.3.1     Square bracket notation. 110

5.4.3.1.3.2     Bulleted list notation. 110

5.4.3.2 TOSCA map type. 110

5.4.3.2.1 Grammar 110

5.4.3.2.1.1     Single-line grammar 110

5.4.3.2.1.2     Multi-line grammar 110

5.4.3.2.2 Declaration Examples. 111

5.4.3.2.2.1     Map declaration using a simple type. 111

5.4.3.2.2.2     Map declaration using a complex type. 111

5.4.3.2.3 Definition Examples. 111

5.4.3.2.3.1     Single-line notation. 111

5.4.3.2.3.2     Multi-line notation. 111

5.4.4 Data Type. 111

5.4.4.1 Keynames. 111

5.4.4.2 Grammar 112

5.4.4.3 Derivation rules. 112

5.4.4.4 Additional Requirements. 113

5.4.4.5 Examples. 113

5.4.4.5.1 Defining a complex datatype. 113

5.4.4.5.2 Defining a datatype derived from an existing datatype. 113

5.4.5 Schema definition. 113

5.4.5.1 Keynames. 114

5.4.5.2 Grammar 114

5.4.5.2.1 Short notation. 114

5.4.5.2.2 Extended Notation. 114

5.4.5.3 Refinement rules. 114

5.4.6 Validation clause definition. 115

5.4.6.1 Grammar 115

5.4.6.2 The $value Function. 115

5.4.6.3 Examples. 115

5.4.7 Property definition. 116

5.4.7.1 Attribute and Property reflection. 116

5.4.7.2 Keynames. 116

5.4.7.3 Status values. 117

5.4.7.4 Grammar 117

5.4.7.5 Refinement rules. 118

5.4.7.6 Additional Requirements. 119

5.4.7.7 Examples. 119

5.4.8 Property assignment 120

5.4.8.1 Keynames. 120

5.4.8.2 Grammar 120

5.4.8.2.1 Short notation: 120

5.4.8.3 Additional Requirements. 120

5.4.9 Attribute definition. 120

5.4.9.1 Attribute and Property reflection. 121

5.4.9.2 Keynames. 121

5.4.9.3 Grammar 121

5.4.9.4 Refinement rules. 122

5.4.9.5 Additional Requirements. 122

5.4.9.6 Notes. 123

5.4.9.7 Example. 123

5.4.10 Attribute assignment 123

5.4.10.1 Keynames. 123

5.4.10.2 Grammar 123

5.4.10.2.1 Short notation: 123

5.4.10.3 Additional requirements. 123

5.4.11 Parameter definition. 123

5.4.11.1 Keynames. 124

5.4.11.2 Grammar 124

5.4.11.3 Refinement rules. 126

5.4.11.4 Additional requirements. 126

5.4.11.5 Example. 126

5.4.12 Parameter value assignment 127

5.4.12.1 Keynames. 127

5.4.12.2 Grammar 127

5.4.12.3 Additional requirements. 127

5.4.13 Parameter mapping assignment 127

5.4.13.1 Keynames. 127

5.4.13.2 Grammar 127

5.4.13.3 Attribute selection format 128

5.4.13.4 Additional requirements. 128

5.4.14 Function syntax. 128

5.4.14.1 Parsing rule. 129

5.4.15 Function definitions. 130

5.4.15.1 Keynames. 130

5.4.15.2 Grammar 131

5.4.15.3 Refinement rules. 133

5.4.15.4 Examples. 133

5.4.15.4.1 Square root function with several signatures. 133

5.4.15.4.2 Function with list of arguments. 134

5.4.15.4.3 Function with no arguments. 134

5.4.15.4.4 Function with polymorphic arguments/result inside of lists. 134

5.4.15.4.5 Defining a list in a map argument 135

5.4.15.4.6 User-defined function usage. 135

5.5 Substitution. 135

5.5.1 Substitution mapping. 135

5.5.1.1 Keynames. 135

5.5.1.2 Grammar 136

5.5.1.3 Examples. 136

5.5.1.4 Additional requirements. 136

5.5.1.5 Notes. 136

5.5.2 Property mapping. 137

5.5.2.1 Keynames. 137

5.5.2.2 Grammar 137

5.5.2.3 Notes. 137

5.5.2.4 Additional constraints. 137

5.5.3 Attribute mapping. 138

5.5.3.1 Keynames. 138

5.5.3.2 Grammar 138

5.5.4 Capability mapping. 138

5.5.4.1 Keynames. 138

5.5.4.2 Grammar 138

5.5.5 Requirement mapping. 139

5.5.5.1 Keynames. 139

5.5.5.2 Grammar 139

5.5.6 Interface mapping. 140

5.5.6.1 Grammar 140

5.5.6.2 Notes. 140

5.6 Groups and Policies. 140

5.6.1 Group Type. 140

5.6.1.1 Keynames. 140

5.6.1.2 Grammar 141

5.6.1.3 Derivation rules. 141

5.6.1.4 Example. 141

5.6.2 Group definition. 142

5.6.2.1 Keynames. 142

5.6.2.2 Grammar 142

5.6.2.3 Example. 143

5.6.3 Policy Type. 143

5.6.3.1 Keynames. 143

5.6.3.2 Grammar 143

5.6.3.3 Derivation rules. 144

5.6.3.4 Example. 144

5.6.4 Policy definition. 144

5.6.4.1 Keynames. 144

5.6.4.2 Grammar 144

5.6.4.3 Example. 145

5.6.5 Trigger definition. 145

5.6.5.1 Keynames. 145

5.6.5.2 Grammar 146

5.6.6 Activity definitions. 146

5.6.6.1 Delegate workflow activity definition. 146

5.6.6.1.1 Keynames. 146

5.6.6.1.2 Grammar 147

5.6.6.1.2.1     Short notation. 147

5.6.6.1.2.2     Extended notation. 147

5.6.6.2 Set state activity definition. 147

5.6.6.2.1 Keynames. 147

5.6.6.2.2 Grammar 147

5.6.6.3 Call operation activity definition. 148

5.6.6.3.1 Keynames. 148

5.6.6.3.2 Grammar 148

5.6.6.3.2.1     Short notation. 148

5.6.6.3.2.2     Extended notation. 148

5.6.6.4 Inline workflow activity definition. 149

5.6.6.4.1 Keynames. 149

5.6.6.4.2 Grammar 149

5.6.6.4.2.1     Short notation. 149

5.6.6.4.2.2     Extended notation. 149

5.6.6.5 Example. 149

5.7 Workflows. 150

5.7.1 Imperative Workflow definition. 150

5.7.1.1 Keynames. 150

5.7.1.2 Grammar 150

5.7.2 Workflow precondition definition. 151

5.7.2.1 Examples. 151

5.7.3 Workflow step definition. 151

5.7.3.1 Keynames. 151

5.7.3.2 Grammar 152

6        TOSCA built-in functions. 153

6.1 Representation graph query functions. 153

6.1.1 get_input 153

6.1.1.1 Grammar 153

6.1.1.2 Arguments. 153

6.1.1.3 Examples. 153

6.1.2 get_property. 154

6.1.2.1 Grammar 154

6.1.2.2 Arguments. 154

6.1.2.2.1 The simplified TOSCA_PATH definition in BNF format 155

6.1.2.3 Note. 156

6.1.2.4 Examples. 156

6.1.3 get_attribute. 158

6.1.3.1 Grammar 158

6.1.3.2 Arguments. 158

6.1.3.3 Examples: 158

6.1.4 get_artifact 158

6.1.4.1 Grammar 159

6.1.4.2 Arguments. 159

6.1.4.3 Examples. 159

6.1.4.3.1 Example: Retrieving artifact without specified location. 159

6.1.4.3.2 Example: Retrieving artifact as a local path. 160

6.1.4.3.3 Example: Retrieving artifact in a specified location. 160

6.1.5 value. 160

6.1.5.1 Grammar 160

6.1.5.2 Arguments. 161

6.2 Boolean Functions. 161

6.2.1 Boolean Logic Functions. 161

6.2.1.1 and. 161

6.2.1.1.1 Grammar 161

6.2.1.1.2 Note. 161

6.2.1.2 or 161

6.2.1.2.1 Grammar 161

6.2.1.2.2 Note. 161

6.2.1.3 not 161

6.2.1.3.1 Grammar 161

6.2.1.4 xor 162

6.2.1.4.1 Grammar 162

6.2.2 Comparison Functions. 162

6.2.2.1 equal 162

6.2.2.1.1 Grammar 162

6.2.2.2 greater_than. 162

6.2.2.2.1 Grammar 162

6.2.2.3 greater_or_equal 162

6.2.2.3.1 Grammar 162

6.2.2.4 less_than. 162

6.2.2.4.1 Grammar 163

6.2.2.5 less_or_equal 163

6.2.2.5.1 Grammar 163

6.2.2.6 valid_values. 163

6.2.2.6.1 Grammar 163

6.2.2.7 matches. 163

6.2.2.7.1 Grammar 163

6.2.2.7.2 Note. 163

6.2.3 Boolean list, map and string functions. 164

6.2.3.1 has_suffix. 164

6.2.3.1.1 Grammar 164

6.2.3.2 has_prefix. 164

6.2.3.2.1 Grammar 164

6.2.3.3 contains. 164

6.2.3.3.1 Grammar 164

6.2.3.4 has_entry. 164

6.2.3.4.1 Grammar 164

6.2.3.5 has_key. 164

6.2.3.5.1 Grammar 165

6.2.3.6 has_all_entries. 165

6.2.3.6.1 Grammar 165

6.2.3.7 has_all_keys. 165

6.2.3.7.1 Grammar 165

6.2.3.8 has_any_entry. 165

6.2.3.8.1 Grammar 165

6.2.3.9 has_any_key. 165

6.2.3.9.1 Grammar 165

6.3 String, list, and map functions. 165

6.3.1 length. 165

6.3.1.1 Grammar 166

6.3.2 concat 166

6.3.2.1 Grammar 166

6.3.2.2 Examples. 166

6.3.3 join. 166

6.3.3.1 Grammar 166

6.3.3.2 Arguments. 166

6.3.3.3 Examples. 166

6.3.4 token. 167

6.3.4.1 Grammar 167

6.3.4.2 Arguments. 167

6.3.4.3 Examples. 167

6.4 Set functions. 167

6.4.1 union. 167

6.4.1.1 Grammar 167

6.4.1.2 Note. 167

6.4.2 intersection. 168

6.4.2.1 Grammar 168

6.4.2.2 Note. 168

6.5 Arithmetic functions. 168

6.5.1 sum.. 168

6.5.1.1 Grammar 168

6.5.2 difference. 168

6.5.2.1 Grammar 168

6.5.3 product 168

6.5.3.1 Grammar 168

6.5.4 quotient 169

6.5.4.1 Grammar 169

6.5.5 remainder 169

6.5.5.1 Grammar 169

6.5.6 round. 169

6.5.6.1 Grammar 169

6.5.7 floor 169

6.5.7.1 Grammar 169

6.5.8 ceil 169

6.5.8.1 Grammar 169

7        TOSCA Cloud Service Archive (CSAR) format 170

7.1 Overall Structure of a CSAR. 170

7.2 TOSCA Meta File. 170

7.2.1 Custom keynames in the TOSCA.meta file. 171

7.2.2 Example. 171

7.3 Archive without TOSCA-Metadata. 171

7.3.1 Example. 171

8        Security Considerations. 172

9        Conformance. 173

9.1 Conformance Targets. 173

9.2 Conformance Clause 1: TOSCA YAML service template. 173

9.3 Conformance Clause 2: TOSCA processor 173

9.4 Conformance Clause 3: TOSCA orchestrator 173

9.5 Conformance Clause 4: TOSCA generator 174

9.6 Conformance Clause 5: TOSCA archive. 174

Appendix A. Acknowledgments. 175

Appendix B. Revision History. 177

 

 


1      Introduction

[All text is normative unless otherwise labeled]

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 Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] and [RFC8174] when, and only when, they appear in all capitals, as shown here.

1.3 Normative References

[RFC2119]               Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <http://www.rfc-editor.org/info/rfc2119>.

[RFC8174]               Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, <http://www.rfc-editor.org/info/rfc8174>.

[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

[ISO-IEC-21320-1]    ISO/IEC 21320-1 "Document Container File — Part 1: Core", https://www.iso.org/standard/60101.html 

 

1.4 Non-Normative References

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

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

[NodeJS]                Node.js, https://nodejs.org/

[Puppet]                 Puppet, http://puppetlabs.com/

[WordPress]            WordPress, https://wordpress.org/

[Maven-Version]      Apache Maven version policy draft: https://cwiki.apache.org/confluence/display/MAVEN/Version+number+policy

[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

 

2      Overview

2.1 Objective

Cloud computing can become more valuable if the creation and lifecycle management of application, infrastructure, and network services can be fully automated and supported across a variety of deployment environments. The core TOSCA specification provides a language for describing service components and their relationships using a service topology, and it provides for specifying the lifecycle management procedures that allow for creation or modification of services using orchestration processes. The combination of topology and orchestration in a Service Template describes what is needed in different environments to enable automated deployment of services and their management throughout the complete service lifecycle (e.g. scaling, patching, monitoring, etc.).

2.2 TOSCA Scope

TOSCA is a domain-specific language for designing services and for defining the deployment and run-time management aspects of these services with the goal of enabling fully automated service management. As such, TOSCA is designed to support all three phases of the service lifecycle:

1.     Day 0—Service Design: Service designers use TOSCA to model services as topology graphs that consist of nodes and relationships. Nodes model the components of which a service is composed, and relationships model dependencies between these service components.

2.     Day 1—Service Deployment: TOSCA can also be used to define mechanisms for deploying TOSCA service topologies on external platforms.

3.     Day 2—Service Management: TOSCA can enable run-time management of services by providing support for updating and/or upgrading deployed services and by providing service assurance functionality.

Note that it is not mandatory for compliant TOSCA implementations to support all three service lifecycle phases. Some implementations may use TOSCA only for service design and delegate orchestration and ongoing lifecycle management functionality to external (non-TOSCA) orchestrators. Other implementations may decide to use TOSCA for all three phases of the service lifecycle.

2.3 Application Domains

TOSCA can be used to specify automated lifecycle management of the following:

·         Infrastructure-as-a-Service Clouds: automate the deployment and management of workloads in IaaS clouds such as OpenStack, Amazon Web Services, Microsoft Azure, and others.

·         Cloud-native applications: deploy containerized applications and micro-services, for example by interfacing to orchestration platforms such as Kubernetes.

·         Network Functions Virtualization: define the management of Virtual Network Functions and their composition into complex network services.

·         Software Defined Networking: support on-demand creation of network services (for example SD-WAN).

·         Functions-as-a-Service: define abstract software applications without any deployment or operational considerations.

·         IoT and Edge computing: deploy services at the network edge with the goal of minimizing latency.

·         Process automation: support open and interoperable process control architectures.

This list is by no means intended to be exhaustive and only serves to demonstrate the breadth of application domains that can benefit from TOSCA’s automated lifecycle management capabilities.

2.4 Implementations

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

·         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 file or a TOSCA CSAR in order to instantiate, deploy, and manage the described application in a Cloud.

·         TOSCA translator: A tool that translates TOSCA files into documents that use another language, such as Kubernetes Helm charts or Amazon CloudFormation templates.

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

The above list is not exclusive. The above definitions should be understood as referring to and implementing TOSCA as described in this document.

2.5 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. The instance is typically derived by running a declarative workflow that is automatically generated based on the node templates and relationship templates defined in the service template.

Node Template

A Node Template specifies the occurrence of a component node as part of a service 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 service 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.

Topology Model

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

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.

 

3      TOSCA core concepts

The TOSCA language introduces a YAML-based grammar for creating service templates that define the lifecycle management of application, infrastructure, and network services. The language defines a metamodel for specifying both the structure of a service as well as its management aspects. Within a TOSCA file, a Service Template defines the structure of a service. Interfaces, Operations, and Workflows define how service elements can be created and terminated as well as how they can be managed during their whole lifetimes. Policies specify operational behavior of the service such as quality-of-service objectives, performance objectives, and security constraints, and allow for closed-loop automation. The major elements defining a service are depicted in Figure 1.

3.1 Service Templates, Node Templates, and Relationships

Within a TOSCA file, a Service Template defines the topology model of a service as a directed acyclic graph. Each node in this graph is represented by a Node Template. A Node Template specifies the presence of an entity of a specific Node Type as a component of a service. A Node Type defines the properties of such a component (via Node Type Properties) and the operations (via Interfaces) available to manipulate the component. Node Types are defined separately for reuse purposes. In a service template a Node Template assigns values to the properties defined in the Node Type.

Figure 1: Structural Elements of a Service Template and their Relations

For example, consider a service that consists of an application server, a process engine, and a process model. A Service Template defining that service would include one Node Template of Node Type “application server”, another Node Template of Node Type “process engine”, and a third Node Template of Node Type “process model”. The application server Node Type defines properties like the IP address of an instance of this type, an operation for installing the application server with the corresponding IP address, and an operation for shutting down an instance of this application server. A constraint in the Node Template can specify a range of IP addresses available when making a concrete application server available.

Node templates may include one or more relationships to other node templates in the Service Template. Relationships represent the edges in the service topology graph. The node template that includes the relationship definition is implicitly defined as the source node of the relationship and the target node is explicitly specified as part of the relationship definition.  Each relationship definition refers to a Relationship Type that defines the semantics and any properties of the relationship. Relationship Types are defined separately for reuse purposes.

In the example above, a relationship can be established from the process engine Node Template to the application server Node Template with the meaning “hosted by”, and from the process model Node Template to the process engine Node Template with meaning “deployed on”.

3.2 Interfaces, Operations, and Artifacts

Both node and relationship types may define lifecycle operations that 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.

Operations that are related to the same management mission (e.g. lifecycle management) are grouped together in Interfaces that are defined by node and relationship types. Just like other TOSCA entities, interfaces refer to their corresponding Interface Type that defines the group of operations that are part of the interface. Interface Types can also define notifications that represent external events that are generated by the outside world and received by the orchestrator.

The implementations of interface operations can be provided as TOSCA artifacts. An artifact represents the content needed to provide an implementation for an interface operation. A TOSCA artifact could be an executable (e.g. a script, an executable program, an image), a configuration file or data file, or something that might be needed so that another executable can run (e.g. a library). Artifacts can be of different types, for example EJBs or python scripts. The content of an artifact depends on its type. Typically, descriptive metadata (such as properties) will also be provided along with the artifact. This metadata might be needed to properly process the artifact, for example by describing the appropriate execution environment.

3.3 Workflows

A deployed service is an instance of a service template. More precisely, the instance is created by instantiating the Service Template of its TOSCA file by running workflows that are most often automatically created by the orchestrator and that invoke the interface operations of the Node Types or the Node Templates. Orchestrators can automatically generate workflows by using 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).

Interface operations invoked by workflows must use actual values for the various properties of the various Node Templates and Relationship Templates of the Service Template. These values can come from input passed in by users as triggered by human interactions with the orchestrator or the templates can specify default values for some properties. For example, the application server Node Template will be instantiated by installing an actual application server at a concrete IP address considering the specified range of IP addresses. Next, the process engine Node Template will be instantiated by installing a concrete process engine on that application server (as indicated by the “hosted by” relationship template). Finally, the process model Node Template will be instantiated by deploying the process model on that process engine (as indicated by the “deployed on” relationship template).

3.4 Requirements and Capabilities

We discussed earlier how relationships are used to link node templates together into a service topology graph. However, it may not always be possible to define all node templates for a given service topology within a single service template. For example, modular design practices may dictate that different service subcomponents be modeled using separate service templates. This may result in relationships that need to be established across multiple service templates. Additionally, relationships may need to target components that already exist and do not need to be instantiated by an orchestrator. For example, relationships may reference physical resources that are managed in a resource inventory. Service templates may not include node templates for these resources.

TOSCA accommodates these scenarios using requirements and capabilities of node templates. A requirement expresses that one component depends on (requires) a feature provided by another component, or that a component has certain requirements against the hosting environment such as for the allocation of certain resources or the enablement of a specific mode of operation. Capabilities represent features exposed by components that can be used to fulfill requirements of other components.

Relationships are the result of fulfilling a requirement in one node template using a capability of a different node template. If both source and target node templates are defined in the same service template, service designers typically define the relationship between these node templates explicitly. Requirements that do not explicitly specify a target node must be fulfilled by the orchestrator at service deployment time. Orchestrators can take multiple service templates into account when fulfilling requirements, or they can attempt to use resources managed in an inventory, which will result in relationships that are established across service template boundaries.

Requirements and capabilities are modeled by annotating Node Types with Requirement Definitions and Capability Definitions. Capability Types are defined as reusable entities so that those definitions can be used in the context of several Node Types. Requirement definitions can specify the relationship type that will be used when creating the relationship that fulfills the requirement.

Figure 2: Requirements and Capabilities

 

Node Templates which have corresponding Node Types with Requirement Definitions or Capability Definitions will include representations of the respective Requirements and Capabilities with content specific to the respective Node Template.

Requirements can be matched in two ways as briefly indicated above: (1) requirements of a Node Template can be matched by capabilities of another Node Template in the same Service Template by connecting the respective requirement-capability-pairs via relationships; (2) requirements of a Node Template can be matched by the orchestrator, for example by allocating needed resources for a Node Template during instantiation.

3.5 Decomposition of Service Templates

TOSCA provides support for decomposing service components using the Substitution Mapping feature. For example, a Service Template for a business application that is hosted on an application server tier might focus on defining the structure and manageability behavior of the business application itself. The structure of the application server tier hosting the application can be provided in a separate Service Template built by another vendor specialized in deploying and managing application servers. This approach enables separation of concerns and re-use of common infrastructure templates.

Figure 3: Service Template Decomposition

From the point of view of a Service Template (e.g. the business application Service Template from the example above) that uses another Service Template, the other Service Template (e.g. the application server tier) “looks” like just a Node Template. During deployment, however, this Node Template can be substituted by the second Service Template if it exposes the same external façade (i.e. properties, capabilities, etc.) as the Node Template. Thus, a substitution with any Service Template that has the same facade as a certain Node Template in one Service Template becomes possible, allowing for a flexible composition of different Service Templates. This concept also allows for providing substitutable alternatives in the form of Service Templates. For example, a Service Template for a single node application server tier and a Service Template for a clustered application server tier might exist, and the appropriate option can be selected per deployment.

3.6 Policies in TOSCA

Non-functional behavior or quality-of-services are defined in TOSCA by means of policies. A Policy can express such diverse things like monitoring behavior, payment conditions, scalability, or continuous availability, for example.

A Node Template can be associated with a set of Policies collectively expressing the non-functional behavior or quality-of-services that each instance of the Node Template will expose. Each Policy specifies the actual properties of the non-functional behavior, like the concrete payment information (payment period, currency, amount etc.) about the individual instances of the Node Template.

These properties are defined by a Policy Type. Policy Types might be defined in hierarchies to properly reflect the structure of non-functional behavior or quality-of-services in particular domains. Furthermore, a Policy Type might be associated with a set of Node Types the non-functional behavior or quality-of-service it describes.

Policy Templates provide actual values of properties of the types defined by Policy Types. For example, a Policy Template for monthly payments for US customers will set the “payment period” property to “monthly” and the “currency” property to “US$”, leaving the “amount” property open. The “amount” property will be set when the corresponding Policy Template is used for a Policy within a Node Template. Thus, a Policy Template defines the invariant properties of a Policy, while the Policy sets the variant properties resulting from the actual usage of a Policy Template in a Node Template.

3.7 Archive Format for Cloud Applications

In order to support in a certain environment for the execution and management of the lifecycle of a cloud application, all corresponding artifacts have to be available in that environment. This means that beside the service template of the cloud application, the deployment artifacts and implementation artifacts have to be available in that environment. To ease the task of ensuring the availability of all of these, this specification defines a corresponding archive format called CSAR (Cloud Service ARchive).

A CSAR is a container file, i.e. it contains multiple files of possibly different file types. These files are typically organized in several subdirectories, each of which contains related files (and possibly other subdirectories etc.). The organization into subdirectories and their content is specific for a particular cloud application. CSARs are zip files, typically compressed. A CSAR may contain a file called TOSCA.meta that describes the organization of the CSAR.

3.8 TOSCA Entities

When defining services using TOSCA, we must distinguish between four kinds of entities:

1.     TOSCA Types: TOSCA types define re-usable building blocks that can be used during service design. For example, TOSCA Node Types define reusable service components, including their configurable properties.

2.     TOSCA Templates: TOSCA templates define (typed) components of a service. For example, service templates include node templates that assign specific values (often using TOSCA intrinsic functions) to the configurable properties defined in the corresponding node types. It is not uncommon to have multiple node templates of the same node type in a service template.

3.     Representations: At deployment time, TOSCA implementations combine TOSCA service templates with deployment-specific input values to create run-time representations of the service that is to be deployed and managed. Note that TOSCA does not standardize an object model for representations. Instead, such models are implementation specific.

4.     External Implementations: These are the actual entities in the external world that correspond to the representations managed by the orchestrator. TOSCA implementations that provide runtime service management must keep their internal service representations in sync with the actual state of the external implementations.

4      TOSCA Operational Model

This section presents a TOSCA Functional Architecture and an associated operational model that supports the three service lifecycle phases outline above. Note that this functional architecture is not intended to prescribe how TOSCA must be implemented. Instead, it aims to provide users of TOSCA with a mental model of how TOSCA implementations are expected to process TOSCA files.

While TOSCA does not mandate that compatible implementations must support all three lifecycle phases, a complete architecture must anticipate all three and must include support for all four kinds of TOSCA entities. The TOSCA architecture defined here illustrates how the various TOSCA entities are used and how they are related.

 

Timeline

Description automatically generated with medium confidence

Figure 1: TOSCA Functional Architecture

The functional architecture defines the following three blocks:

1.     TOSCA Processor: This functional block defines functionality that must be provided by all TOSCA implementations. TOSCA processors convert TOSCA-based service definitions into service representations that can be processed by an Orchestrator.

2.     Orchestrator: This functional block creates external implementations on various resource platforms based on the service representations created by a TOSCA processor. The orchestration functionality can itself be defined using TOSCA or can be provided by external (non-TOSCA) orchestration platforms.

3.     Platform: In the context of a TOSCA architecture, platforms represent external cloud, networking, or other infrastructure resources on top of which service entities can be created.

The remainder of this section describes each of these functional blocks in more detail.

4.1 TOSCA Processor

At the core of a compliant TOSCA implementation is a TOSCA Processor that can create service representations from TOSCA service templates. A TOSCA Processor contains the following functional blocks:

4.1.1 Parser

·         Accepts a single TOSCA file plus imported TOSCA files (files without a “service_template”)

·         Can (optionally) import these units from one or more repositories, either individually or as complete profiles

·         Outputs valid normalized node templates and unresolved requirements (one-to-one equivalency)

4.1.2 Resolver

A resolver performs the following functions

4.1.2.1 Creating Service Representations

·         Applies service inputs.

·         Converts normalized node templates to node representations (one-to-one equivalency [cardinality?]) [a full TOSCA orchestrator can manage these instead of the external orchestrator/platform]

·         Calls intrinsic functions (on demand for all the above) using the graph of node representations.

4.1.2.2 Requirement Fulfillment

·         Satisfies all requirements and creates the relationship graph (an unsatisfied requirement results in an error)

4.1.2.3 Substitution Mapping

4.2 Orchestrator

An orchestrator performs the following actions:

·         (Continuously) turns node representations into zero or more node implementations (one-to-any)

·         (Continuously) updates node representation attribute values (error if they do not adhere to TOSCA type validation clauses or property definition validation clauses) [we still don’t know how to handle multiplicity]

·         (Continuously) reactivates the resolver: outputs and even satisfaction of requirements may change.

·         (Optionally) changes the node representations themselves for day 2 transformations.

 

5      TOSCA definitions

Except for the examples, this section is normative and describes the YAML grammar, definitions, and semantics for all keynames that are defined in the TOSCA Version 2.0 specification.

5.1 TOSCA Metamodel

This section defines the models and the modeling goals that comprise the TOSCA Version 2.0 specification.

5.1.1 Modeling concepts and goals

TBD. Here we should have selected core concepts of TOSCA 1.0 from section “3   Core Concepts and Usage Pattern” and this section should be a more in-depth section than section 2.1 in this document.

Add a metamodel picture

Explain separation of concerns and different roles. Refer to email from Peter.

5.1.2 Modeling definitions and reuse

The TOSCA metamodel includes complex definitions used in types and templates. Reuse concepts simplify the design of TOSCA templates by allowing relevant TOSCA entities to use and/or modify definitions already specified during entity type design. The following four concepts are clarified next:

·         Definition:

      The TOSCA specification is based on defining modeling entities.

      Entity definitions are based on different sets of keynames (with specific syntax and semantics) that are associated with values (of a specific format).

·         Derivation:

      Specific TOSCA entities support a type definition.

      When defining a type, it can be derived from a parent type and inherit all the definitions of the parent type.

      The derivation rules describe what (keyname) definitions are inherited from the parent type and further if and how they can be expanded or modified. Note that some definitions (for example, “version”) and intrinsic to the type declaration and so are not inherited.

      A parent type can in turn be derived from a parent type. There is no limit to the depth of a chain of derivations.

·         Refinement:

      Definitions within a type definition consist of the definition of keynames and other TOSCA entities (e.g. properties, requirements, capabilities, etc.).  Definitions within a parent type can be refined (adjusted) to better suit the needs of the referencing type.

      The refinement rules pertaining to an entity describe how such entity definitions that are inherited from the parent type during a type derivation can be expanded or modified.

·         Augmentation:

      Definitions within a parent type can be expanded, which is the addition of properties, to better suit the requirements of the referencing type.

      The augmentation rules pertaining to an entity describe how the inherited parent type during a type derivation can be added to.

·         Assignment:

      When creating a service template, we specify several entities that are part of the template (e.g., nodes, relationships, groups, etc.).

      When adding such an entity in the service template, for some definitions that appear in the corresponding entity type (e.g., properties, operations, requirements, etc.) we may (or must) assign a certain specification (or value).

5.1.3 Goal of the derivation and refinement rules

The main reason for derivation and refinement rules is to create a framework useful for a consistent TOSCA type profile creation. The intuitive idea is that a derived type follows to a large extent the structure and behavior of a parent type, otherwise it would be better to define a new "not derived" type.

The guideline regarding the derivation rules is that a node of a derived type should be usable instead of a node of the parent type during the selection and substitution mechanisms. These two mechanisms are used by TOSCA templates to connect to TOSCA nodes and services defined by other TOSCA templates:

·         The selection mechanism allows a node instance created a-priori by another service template to be selected for usage (i.e., building relationships) to the current TOSCA template.

·         The substitution mechanism allows a node instance to be represented by a service created simultaneously via a substitution template.

It is relevant to emphasize the cross-template usage, as only in this case we deal with templates defined at different design time-points, with potentially different editing and maintenance restrictions.

5.1.4 Mandatory Keynames

The TOSCA metamodel includes complex definitions used in types (e.g., Node Types, Relationship Types, Capability Types, Data Types, etc.), definitions and refinements (e.g., Requirement Definitions, Capability Definitions, Property and Parameter Definitions, etc.) and templates (e.g., Service Template, Node Template, etc.) all of which include their own list of reserved keynames that are sometimes marked as mandatory. If a keyname is marked as mandatory it MUST be defined in that particular definition context. In some definitions, certain keywords may be mandatory depending on the value of other keywords in the definition. In that case, the keyword will be marked as conditional and the condition will be explained in the description column. Note that in the context of type definitions, types may be used to derive other types, and keyname definitions MAY be inherited from parent types (according to the derivation rules of that type entity). If a keyname definition is inherited, the derived type does not have to provide such definition.

5.2 TOSCA Service

A TOSCA Service is specified by a TOSCA Service Template.

5.2.1 TOSCA file definition

A TOSCA file contains definitions of building blocks for use in cloud applications or complete models of cloud applications. This section describes the top-level TOSCA keynames—along with their grammars—that are allowed to appear in a TOSCA file.

5.2.1.1 Keynames

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

Keyname

Mandatory

Type

Description

tosca_definitions_version

yes

string

Defines the version of the TOSCA specification used in the TOSCA file

profile

no

string

The profile name that can be used by other TOSCA files to import the type definitions in this document.

metadata

no

map of YAML values

Defines a section used to declare additional metadata information.  Domain-specific TOSCA profile specifications may define keynames that are mandatory for their implementations.

description

no

string

Declares a description for this TOSCA file and its contents.

dsl_definitions

no

N/A

Defines reusable YAML macros (i.e., YAML alias anchors) for use throughout the TOSCA file.

repositories

no

map of

Repository definitions

Declares the map of external repositories that contain artifacts that are referenced in the TOSCA file along with the addresses used to connect to them in order to retrieve the artifacts.

imports

no

list of

Import definitions

Declares a list of import statements pointing to external TOSCA files or well-known profiles. For example, these may be file locations or URIs relative to the TOSCA file within the same TOSCA CSAR file.

artifact_types

no

map of

Artifact Types

This section contains amap of artifact type definitions for use in the TOSCA file and/or external TOSCA files.

data_types

no

map of

Data Types

Declares a map of TOSCA Data Type definitions for use in the TOSCA file and/or external TOSCA files.

capability_types

no

map of

Capability Types

This section contains amap of capability type definitions for use in the TOSCA file and/or external TOSCA files.

interface_types

no

map of

Interface Types

This section contains amap of interface type definitions for use in the TOSCA file and/or external TOSCA files.

relationship_types

no

map of

Relationship Types

This section contains a map of relationship type definitions for use in the TOSCA file and/or external TOSCA files.

node_types

no

map of

Node Types

This section contains a map of node type definitions for use in the TOSCA file and/or external TOSCA files.

group_types

no

map of

Group Types

This section contains a map of group type definitions for use in the TOSCA file and/or external TOSCA files.

policy_types

no

map of

Policy Types

This section contains a map of policy type definitions for use in the TOSCA file and/or external TOSCA files.

service_template

no

service template definition

Defines a template from which to create a mode/representation of an application or service. Service templates consist of node templates that represent the application’s or service’s components, as well as relationship templates representing relations between these components.

Functions

no

map of function definitions

This section contains a map of function definitions for use in the TOSCA file and/or external TOSCA files.

5.2.1.2 Grammar

The overall structure of a TOSCA file and its top-level keynames is shown below:

# Mandatory TOSCA version string

tosca_definitions_version: <value>  # Mandatory, see section 3.1 for usage

profile: <string>                   # Optional, see section 3.2 for usage

 

# Optional metadata keyname: value pairs

metadata:

 

  # map of YAML values

 

# Optional description of the definitions inside the file.

description: <template_ description>

 

dsl_definitions:

  # map of YAML alias anchors (or macros)

 

repositories:

  # map of external repository definitions which host TOSCA artifacts

 

imports:

  # ordered list of import definitions

 

artifact_types:

  # map of artifact type definitions

 

data_types:

  # map of datatype definitions

 

capability_types:

  # map of capability type definitions

 

interface_types

  # map of interface type definitions

 

relationship_types:

  # map of relationship type definitions

 

node_types:

  # map of node type definitions

 

group_types:

  # map of group type definitions

 

policy_types:

  # map of policy type definitions

 

functions:

  # map of function definitions`

 

service_template:

  # service template definition of the cloud application or service

5.2.1.2.1 Requirements

·         The key “tosca_definitions_version” MUSTbe the first line of each TOSCA file..

5.2.1.2.2 Notes

·         TOSCA files do not have to contain a service_template and MAY contain simply type definitions (e.g., Artifact, Interface, Capability, Node, Relationship Types, etc.), repository definitions, function definitions, or other import statements and be imported for use in other TOSCA files.

5.2.1.3 Top-level keyname definitions

5.2.1.3.1 tosca_definitions_version

This mandatory element provides a means to specify the TOSCA version used within the TOSCA file.  It is an indicator for the version of the TOSCA grammar that should be used to parse the remainder of the TOSCA file.

5.2.1.3.1.1     Keyname

tosca_definitions_version

5.2.1.3.1.2     Grammar

tosca_definitions_version: <tosca_ version>

TOSCA uses the following version strings for the various revisions of the TOSCA specification:

Version String

TOSCA Specification

tosca_2_0

TOSCA Version 2.0

tosca_simple_yaml_1_3

TOSCA Simple Profile in YAML Version 1.3

tosca_simple_yaml_1_2

TOSCA Simple Profile in YAML Version 1.2

tosca_simple_yaml_1_1

TOSCA Simple Profile in YAML Version 1.1

tosca_simple_yaml_1_0

TOSCA Simple Profile in YAML Version 1.0

The version for this specification is tosca_2_0.

Note that it is not mandatory for TOSCA Version 2.0 implementations to support older versions of the TOSCA specifications.

5.2.1.3.1.3     Examples:

A TOSCA file designed using the TOSCA Version 2.0 specification:

tosca_definitions_version: tosca_2_0

5.2.1.3.2 profile

The profile keyword is used to assign a profile name to the collection of types defined in this TOSCA file. TOSCA implementations use profile names to register known profiles into an internal repository. These profiles can then be imported by other TOSCA files using the profile keyword in their import statement.

5.2.1.3.2.1     Keyname

profile

5.2.1.3.2.2     Grammar

profile: <string_value>

TOSCA does not place any restrictions on the value of the profile name string. However, we encourage a Java-style reverse-domain notation with version as a best-practice convention.

5.2.1.3.2.3     Examples

The following is an example of a TOSCA file that defines TOSCA Simple Profile Version 2.0 types:

profile: org.oasis-open.tosca.simple:2.0

The following defines a domain-specific profile for Kubernetes:

profile: io.kubernetes:1.18

5.2.1.3.3 metadata

This keyname is used to associate domain-specific metadata with the Service Template.  The metadata keyname allows a declaration of a map of keynames with values that can use all types supported by the YAML 1.2.2 recommended schemas [Yaml-1.2]. Specifically, the following types can be used for metadata values: map, seq, str, null, bool, int, float.

·          

5.2.1.3.3.1     Keyname

metadata

5.2.1.3.3.2     Grammar

metadata:

  <map_of_yaml_values>

5.2.1.3.3.3     Example

metadata:

  creation_date: 2015-04-14

  date_updated: 2015-05-01

  status: developmental 

5.2.1.3.4 description

This optional keyname provides a means to include single or multiline descriptions within a TOSCA template as a scalar string value.

5.2.1.3.4.1     Keyname

description

5.2.1.3.4.2     Grammar

description: <description>

5.2.1.3.4.3     Example

Single line example

description: A simple example service template

Multi-line example

description: "A multiline description

using a quoted string”

5.2.1.3.5 dsl_definitions

This optional keyname provides a section to define macros YAML-style macros for use in the TOSCA file.

5.2.1.3.5.1     Keyname

dsl_definitions

5.2.1.3.5.2     Grammar

dsl_definitions:

   <dsl_definition_1>

   ...

   <dsl_definition_n>

5.2.1.3.5.3     Example

dsl_definitions:

    ubuntu_image_props: &ubuntu_image_props

      architecture: x86_64

      type: linux

      distribution: ubuntu

      os_version: 14.04

 

    redhat_image_props: &redhat_image_props

      architecture: x86_64

      type: linux

      distribution: rhel

      os_version: 6.6

5.2.1.3.6 repositories

This optional keyname provides a section to define external repositories that may contain artifacts or other TOSCA files that might be referenced or imported by this TOSCA file.

5.2.1.3.6.1     Keyname

repositories

5.2.1.3.6.2     Grammar

repositories:

   <repository_definition_1>

   ...

   <repository_definition_n>

5.2.1.3.6.3     Example

repositories:

  my_project_artifact_repo:

    description: development repository for TAR archives and Bash scripts

    url: http://mycompany.com/repository/myproject/

  external_repo: https://foo.bar

5.2.1.3.7 imports

This optional keyname provides a way to import a one or more TOSCA profiles or other TOSCA files that contain reusable TOSCA type definitions (e.g., Node Types, Relationship Types, Artifact Types, etc.), function definitions, repository definitions, or other imports defined by other authors. This mechanism provides an effective way for companies and organizations to define domain-specific types and/or describe their software applications for reuse in other TOSCA files.

5.2.1.3.7.1     Keyname

imports

5.2.1.3.7.2     Grammar

imports:

   - <import_definition_1>

   - ...

   - <import_definition_n>

5.2.1.3.7.3     Example

# An example import of TOSCA files from a location relative to the

# file location of the TOSCA file declaring the import.

imports:

  - relative_path/my_defns/my_typesdefs_1.yaml

  - url: my_defns/my_typesdefs_n.yaml   

    repository: my_company_repo

    namespace: mycompany

5.2.1.3.8 artifact_types

This optional keyname lists the Artifact Types that are defined by this TOSCA file..

5.2.1.3.8.1     Keyname

artifact_types

5.2.1.3.8.2     Grammar

artifact_types:

  <artifact_type_defn_1>

  ...

  <artifact type_defn_n>

5.2.1.3.8.3     Example

artifact_types:

  mycompany.artifacttypes.myFileType:

    derived_from: tosca.artifacts.File

5.2.1.3.9 data_types

This optional keyname provides a section to define new data types in TOSCA.

5.2.1.3.9.1     Keyname

data_types

5.2.1.3.9.2     Grammar

data_types:

   <tosca_datatype_def_1>

   ...

   <tosca_datatype_def_n>

5.2.1.3.9.3     Example

data_types:

  # A complex datatype definition

  simple_contactinfo_type:

    properties:

      name:

        type: string

      email:

        type: string

      phone:

        type: string

 

  # datatype definition derived from an existing type

  full_contact_info:

    derived_from: simple_contact_info

    properties:

      street_address:

        type: string

      city:

        type: string

      state:

        type: string

      postalcode:

        type: string

5.2.1.3.10 capability_types

This optional keyname lists the Capability Types that provide the reusable type definitions that can be used to describe features of nodes that can be used to fulfill requirements of other nodes.

5.2.1.3.10.1   Keyname

capability_types

5.2.1.3.10.2   Grammar

capability_types:

  <capability_type_defn_1>

  ...

  <capability type_defn_n>

5.2.1.3.10.3   Example

capability_types:

  mycompany.mytypes.myCustomEndpoint:

    derived_from: tosca.capabilities.Endpoint

    properties:

      # more details ...

 

  mycompany.mytypes.myCustomFeature:

    derived_from: tosca.capabilities.Feature

    properties:

      # more details ...

5.2.1.3.11 interface_types

This optional keyname lists the Interface Types that provide the reusable type definitions that can be used to describe operations exposed by TOSCA relationships and nodes.

5.2.1.3.11.1   Keyname

interface_types

5.2.1.3.11.2   Grammar

interface_types:

  <interface_type_defn_1>

  ...

  <interface type_defn_n>

5.2.1.3.11.3   Example

interface_types:

  mycompany.interfaces.service.Signal:

    operations:

      signal_begin_receive:

        description: Operation to signal start of some message processing.

      signal_end_receive:

        description: Operation to signal end of some message processed.

5.2.1.3.12 relationship_types

This optional keyname lists the Relationship Types that provide the reusable type definitions that can be used to describe dependent relationships between nodes.

5.2.1.3.12.1   Keyname

relationship_types

5.2.1.3.12.2   Grammar

relationship_types:

  <relationship_type_defn_1>

  ...

  <relationship type_defn_n>

5.2.1.3.12.3   Example

relationship_types:

  mycompany.mytypes.myCustomClientServerType:

    derived_from: tosca.relationships.HostedOn

    properties:

      # more details ...

  mycompany.mytypes.myCustomConnectionType:

    derived_from: tosca.relationships.ConnectsTo

    properties:

      # more details ...

5.2.1.3.13 node_types

This optional keyname lists the Node Types that provide the reusable type definitions for nodes in a service.

5.2.1.3.13.1   Keyname

node_types

5.2.1.3.13.2   Grammar

node_types:

  <node_type_defn_1>

  ...

  <node_type_defn_n>

5.2.1.3.13.3   Example

node_types:

  my_webapp_node_type:

    derived_from: WebApplication

    properties:

      my_port:

        type: integer

 

  my_database_node_type:

    derived_from: Database

    capabilities:

      mytypes.myfeatures.transactSQL

5.2.1.3.14 group_types

This optional keyname lists the Group Types that are defined by this TOSCA file.

5.2.1.3.14.1   Keyname

group_types

5.2.1.3.14.2   Grammar

group_types:

  <group_type_defn_1>

  ...

  <group type_defn_n>

5.2.1.3.14.3   Example

group_types:

  mycompany.mytypes.myScalingGroup:

    derived_from: tosca.groups.Root

5.2.1.3.15 policy_types

This optional keyname lists the Policy Types that are defined by this TOSCA file.

5.2.1.3.15.1   Keyname

policy_types

5.2.1.3.15.2   Grammar

policy_types:

  <policy_type_defn_1>

  ...

  <policy type_defn_n>

5.2.1.3.15.3   Example

policy_types:

  mycompany.mytypes.myScalingPolicy:

    derived_from: tosca.policies.Scaling

5.2.2 Profiles

A profile is a named collection of TOSCA type definitions, artifacts, and service templates that logically belong together. One can think of TOSCA profiles as platform libraries exposed by the TOSCA orchestration platform and made available to all services that use that platform. Profiles in TOSCA are similar to libraries in traditional computer programming languages.

Profiles contain a collection of pre-defined components that can be used by service designers to compose complex service templates, Entities defined in TOSCA profiles are used as follows:

·         Types defined in a TOSCA profile provide reusable building blocks from which services can be composed.

·         Artifacts and service templates defined in a TOSCA profile provide implementations for the TOSCA types defined in the profile. Whereas artifacts provide interface operation implementations for concrete nodes and relationships, service templates defined in TOSCA profiles are intended to implement abstract nodes through substitution mapping.

TOSCA implementations can organize supported profiles in a catalog to allow other service templates to import those profiles by profile name. This avoids the need for every service that use those profiles to include the profile type definitions in their service definition packages.

5.2.2.1 Examples

Version 1.x of the TOSCA specification included a collection of normative type definitions for building cloud applications. This collection of type definitions was defined as the TOSCA Simple Profile. Implementations of TOSCA Version 1.x were expected to include implementations for the types defined in the TOSCA Simple Profile, and service templates defined using TOSCA Version 1.x implicitly imported the corresponding TOSCA Simple Profile version.

Starting with TOSCA Version 2.0, the TOSCA Simple Profile type definitions are no longer part of the TOSCA standard and support for the TOSCA Simple Profile is no longer mandatory. Instead, the definition of the TOSCA Simple Profile has been moved to an OASIS Open Github repository with the goal of being maintained by the TOSCA community and governed as an open-source project. In addition, TOSCA Version 2.0 removes the implicit import of the TOSCA Simple Profile. Service templates that want to continue to use the TOSCA Simple Profile type definitions must explicitly import that profile.

Eliminating mandatory support for the TOSCA Simple Profile makes it easier for TOSCA to be used for additional application domains. For example, the European Telecommunications Standards Institute (ETSI) has introduced a TOSCA profile for Network Functions Virtualization defines Virtualized Network Function Descriptors (VNFDs), Network Service Descriptors (NSDs) and a Physical Network Function Descriptors (PNFDs).

We should give a couple of additional examples.

5.2.2.2 Defining Profiles

A TOSCA file defines a TOSCA Profile if the profile keyword is used in that service template. The value of the profile keyword defines the name for the profile, which allows other service templates to import the profile by name.

TOSCA does not impose naming conventions for profile names, but as a best practice we recommend a domain-name-like structure as used for Java package naming. For example, the following profile statement is used to define TOSCA Simple Profile Version 2.0 types:

profile: org.oasis-open.tosca.simple:2.0

 

TOSCA parsers MUST process profile definitions according to the following rules:

·         TOSCA files that define a profile (i.e., that contain a profile keyname) MUST NOT also define a service template.

·         If the parser encounters the profile keyname in a TOSCA file, then the corresponding profile name will be applied to all types defined in that file as well as to types defined in any imported TOSCA files.

·         If one of those imported files also defines the profile keyname—and that profile name is different from the name of the importing profile—then that profile name overrides the profile name value from that point in the import tree onward, recursively.

·         TOSCA service templates defined in profiles MUST advertise substitution mapping to allow them to be used as implementations for abstract nodes defined using profile types.

5.2.2.3 Profile Versions

TOSCA Profiles are likely to evolve over time and profile designers will release different versions of their profiles. For example, the TOSCA Simple Profile has gone through minor revisions with each release of the TOSCA Version 1 standard. It is expected that profile designers will use a version qualifier to distinguish between different versions of their profiles, and service template designers must use the proper string name to make sure they import the desired versions of these profiles.

Do we impose a structure on profile names that distinguishes the version qualifier from the base profile name? If so, is there a specific separator character or string (in which case the use of the separator must be escaped somehow (or disallowed) in profile names.

When multiple versions of the same profile exist, it is possibly that service templates could mix and match different versions of a profile in the same service definition. The following code snippets illustrate this scenario:

Assume a profile designer creates version 1 of a base profile that defines (among other things) a Host capability type and a corresponding HostedOn relationship type as follows:

tosca_definitions_version: tosca_2_0

profile: org.base.v1

capability_types:

  Host:

    description: Hosting capability

relationship_types:

  HostedOn:

    valid_capability_types: [ Host ]

Now let’s assume a different profile designer creates a platform-specific profile that defines (among other things) a Platform node type. The Platform node type defines a capability of type Host. Since the Host capability is defined in the org.base.v1 profile, that profile must be imported as shown in the snippet below:

tosca_definitions_version: tosca_2_0

profile: org.platform

imports:

  - profile: org.base.v1

    namespace: p1

node_types:

  Platform:

    capabilities:

      host:

        type: p1:Host

At some later point of time, the original profile designer updates the org.base profile to Version 2. The updated version of this profile just adds a Credential data type (in addition to defining the Host capability type and the HostedOn relationship type), as follows:

tosca_definitions_version: tosca_2_0

profile: org.base.v2

capability_types:

  Host:

    description: Hosting capability

relationship_types:

  HostedOn:

    valid_capability_types: [ Host ]

data_types:

  Credential:

    properties:

      key:

        type: string

Finally, let’s assume a service designer creates a template for a service that is to be hosted on the platform defined in the org.platform profile. The template introduces a Service node type that has a requirement for the platform’s Host capability. It also has a credential property of type Credential as defined in org.base.v2:

tosca_definitions_version: tosca_2_0

imports:

  - profile: org.base.v2

    namespace: p2

  - profile: org.platform

    namespace: pl

node_types:

  Service:

    properties:

      credential:

        type: p2:Credential

    requirements:

      - host:

          capability: p2:Host

          relationship: p2:HostedOn

service_template:

  node_templates:

    service:

      type: Service

      properties:

        credential:

          key: password

      requirements:

        - host: platform

    platform:

      type: pl:Platform

 

This service template is invalid, since the platform node template does not define a capability of a type that is compatible with the valid_capability_types specified by the host requirement in the service node template. TOSCA grammar extensions are needed to specify that the Host capability type defined in org.base.v2 is the same as the Host capability type defined in org.base.v1

The example in this section illustrates a general version compatibility issue that exists when different versions of the same profile are used in a TOSCA service.

A number of suggestions for these extensions are currently being discussed. Grammar extensions will be included in this document one they are agreed upon.

5.2.3 Imports and Namespaces

5.2.3.1 Import definition

An import definition is used within a TOSCA file to locate and uniquely name another TOSCA file or TOSCA profile that has type, repository, and function definitions to be imported (included) into another TOSCA file.

5.2.3.1.1 Keynames

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

Keyname

Mandatory

Type

Description

url

conditional

string

The url that references a service template to be imported. An import statement must include either a url or a profile, but not both.

profile

conditional

string

The profile name that references a named type profile to be imported. An import statement must include either a url or a profile, but not both.

repository

conditional

string

The optional symbolic name of the repository definition where the imported file can be found as a string. The repository name can only be used when a url is specified.

namespace

no

string

The optional name of the namespace into which to import the type definitions from the imported template or profile.

5.2.3.1.2 Grammar

Import definitions have one the following grammars:

5.2.3.1.2.1     Single-line grammar:

When using the single-line grammar, the url keyword is assumed:

imports:

  - <URI_1>

  - <URI_2>

5.2.3.1.2.2     Multi-line grammar

The following multi-line grammar can be used for importing TOSCA files:

imports: 

  - url: <file_URI>  

    repository: <repository_name>

    namespace: <namespace_name>

The following multi-line grammar can be used for importing TOSCA profiles:

imports: 

  - profile: <profile_name>  

    namespace: <namespace_name>

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

·         file_uri: contains the URL that references the service template 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.

·         profile_name: the name of the well-known profile to be imported.

·         namespace_name: represents the optional name of the namespace into which type definitions will be imported. The namespace name can be used to form a namespace-qualified name that uniquely references type definitions from the imported file or profile. If no namespace name is specified, type definitions will be imported into the root namespace.

5.2.3.1.3 Import processing rules

TOSCA Orchestrators, Processors and tooling SHOULD handle import statements as follows:

5.2.3.1.3.1     Importing profiles

If the profile keyname is used in the import definition, then the TOSCA orchestrator or processor SHOULD attempt to import the profile by name:

·         If <profile_name> represents the name of a profile that is known to the TOSCA orchestrator or processor, then it SHOULD cause the Profile Type definitions to be imported.

·         If <profile_name> is not known, the import SHOULD be considered a failure.

5.2.3.1.3.2     Importing service templates

If the url keyname is used, the TOSCA orchestrator or processor SHOULD attempt to import the file referenced by <file_URI> as follows:

·         If the <file_URI> includes a URL scheme (e.g. file: or https:) then<file_URI> is considered to be a network accessible resource. If the resource identified by <file_URL> represents a valid TOSCA file, then it SHOULD cause the remote Service Template to be imported.

      Note that if in addition to a URL with a URL scheme, the import definition also specifies a <repository_name> (using the repository key), then that import definition SHOULD be considered invalid.

·         If the <file_URI> does not include a URL scheme, it is a considered a relative path URL. The TOSCA orchestrator or processor SHOULD handle such a <file_URI> as follows:

      If the import definition also specifies a <repository_name> (using the repository keyname), then <file_URI> refers to the path name of a file relative to the root of the named repository

      If the import definition does not specify a <profile_name> then <file_URI> refers to a TOSCA file located in the repository that contains the Service Template file that includes the import definition. If the importing service template is located in a CSAR file, then that CSAR file should be treated as the repository in which to locate the service template file that must be imported.

·         If <file_URI> starts with a leading slash (‘/’) then <file_URI> specifies a path name starting at the root of the repository.

·         If <file_URI> does not start with a leading slash, then <file_URI> specifies a path that is relative to the importing document’s location within the repository. Double dot notation (‘../’) can be used to refer to parent directories in a file path name.

·         If <file_URI> does not reference a valid TOSCA file file, then the import SHOULD be considered a failure.

5.2.3.1.4 Examples

The first example shows how to use an import definition import a well-known profile by name:

# Importing a profile

imports:

- profile: org.oasis-open.tosca.simple:2.0

The next example shows an import definition used to import a network-accessible resource using the https protocol:

# Absolute URL with scheme

imports:

- url: https://myorg.org/tosca/types/mytypes.yaml

The following represents shows an import definition used to import a service template in the same repository as the importing template. The template to be imported is referenced using a path name that is relative to the location of the importing template. This example shows the short notation:

# Short notation supported

imports:

- ../types/mytypes.yaml

The following shows the same example but using the long notation:

# Long notation

imports:

- url: ../types/mytypes.yaml

The following example shows how to import service templates using absolute path names (i.e. path names that start at the root of the repository):

# Root file

imports:

- url: /base.yaml

And finally, the following shows how to import templates from a repository that is different than the repository that contains the importing template:

# External repository

imports:

- url: types/mytypes.yaml

  repository: my_repository

5.2.3.2 Namespaces

When importing TOSCA files or TOSCA profiles, there exists a possibility for name collision. For example, an imported file may define a node type with the same name as a node type defined in the importing file.

For example, let say we have two TOSCA files, A and B, both of which contain a Node Type definition for “MyNode”:

TOSCA File B

tosca_definitions_version: tosca_2_0

description: TOSCA File B

 

node_types:

  MyNode:

    derived_from: SoftwareComponent

    properties:

      # omitted here for brevity

    capabilities:

      # omitted here for brevity

TOSCA File A

tosca_definitions_version: tosca_2_0

description: TOSCA File A

 

imports:

  - url: /templates/ServiceTemplateB.yaml

 

node_types:

  MyNode:

    derived_from: Root

    properties:

      # omitted here for brevity

    capabilities:

      # omitted here for brevity

 

service_template:

  node_templates:

    my_node:

      type: MyNode

As you can see, TOSCA file A imports TOSCA file B which results in duplicate definitions of the MyNode node type. In this example, it is not clear which type is intended to be used for the my_node node template.

To address this issue, TOSCA uses the concept of namespaces:

·         Each TOSCA file defines a root namespace for all type definitions defined in that template. Root namespaces are unnamed.

·         When a TOSCA file imports other templates, it has two options:

      It can import any type definitions from the imported templates into its root namespace

      Or it can import type definitions from the imported templates into a separate named namespace. This is done using the namespace keyname in the associated import statement. When using types imported into a named namespace, those type names must be qualified using the namespace name.

The following snippets update the previous example using namespaces to disambiguate between the two MyNode type definitions. This first snippet shows the scenario where the MyNode definition from TOSCA file B is intended to be used:

tosca_definitions_version: tosca_2_0

description: TOSCA file A

 

imports:

  - url: /templates/ServiceTemplateB.yaml

    namespace: templateB

 

node_types:

  MyNode:

    derived_from: Root

    properties:

      # omitted here for brevity

    capabilities:

      # omitted here for brevity

 

service_template:

  node_templates:

    my_node:

      type: templateB:MyNode

The second snippet shows the scenario where the MyNode definition from TOSCA file A is intended to be used:

tosca_definitions_version: tosca_2_0

description: TOSCA file A

 

imports:

  - url: /templates/ServiceTemplateB.yaml

    namespace: templateB

 

node_types:

  MyNode:

    derived_from: Root

    properties:

      # omitted here for brevity

    capabilities:

      # omitted here for brevity

 

service_template:

  node_templates:

    my_node:

      type: MyNode

 

In many scenarios, imported TOSCA files may in turn import their own TOSCA files, and introduce their own namespaces to avoid name collisions. In those scenarios, nested namespace names are used to uniquely identify type definitions in the import tree.

The following example shows a mytypes.yaml TOSCA file that imports a Kubernetes profile into the k8s namespace. It defines a SuperPod node type that derives from the Pod node type defined in that Kubernetes profile:

tosca_definitions_version: tosca_2_0

description: mytypes.yaml

 

imports:

- profile: io.kubernetes:1.18

  namespace: k8s

 

node_types:

  MyNode: {}

  SuperPod:

    derived_from: k8s:Pod

The mytypes.yaml template is then imported into the main.yaml TOSCA file, which defines both a node template of type SuperPod as well as a node template of type Pod. Nested namespace names are used to identify the Pod node type from the Kubernetes profile:

tosca_definitions_version: tosca_2_0

description: main.yaml

 

imports:

- url: mytypes.yaml

  namespace: my

 

service_template:

  node_templates:

    mynode:

      type: my:MyType

    pod:

      type: my:k8s:Pod

5.2.3.2.1 Additional Requirements

Within each namespace, names must be unique. This means the following:

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

      Repositories (repositories)

      Data Types (data_types)

      Node Types (node_types)

      Relationship Types (relationship_types)

      Capability Types (capability_types)

      Artifact Types (artifact_types)

      Interface Types (interface_types)

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

      Node Templates (node_templates)

      Relationship Templates (relationship_templates)

      Inputs (inputs)

      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:

      Properties (properties)

      Attributes (attributes)

      Artifacts (artifacts)

      Requirements (requirements)

      Capabilities (capabilities)

      Interfaces (interfaces)

      Policies (policies)

      Groups (groups)

5.2.3.3 Repository definition

A repository definition defines an external repository which contains deployment and implementation artifacts that are referenced within the TOSCA file.

5.2.3.3.1 Keynames

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

Keyname

Mandatory

Type

Description

description

no

string

The optional description for the repository.

url

yes

string

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

5.2.3.3.2 Grammar

Repository definitions have one the following grammars:

5.2.3.3.2.1     Single-line grammar:

<repository_name>: <repository_address>

5.2.3.3.2.2     Multi-line grammar

<repository_name>:

  description: <repository_description>

  url: <repository_address>

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

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

·         repository_description: contains an optional description of the repository.

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

5.2.3.3.3 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/

 

5.2.4 Additional information definitions

5.2.4.1 Description definition

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

5.2.4.1.1 Keyname

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

description

5.2.4.1.2 Grammar

Description definitions have the following grammar:

description: <description_string>

5.2.4.1.3 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.

5.2.4.1.4 Notes

·         Use of “folded” style is discouraged for the YAML string type apart from when used with the description keyname. .

5.2.4.2 Metadata

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

5.2.4.2.1 Keyname

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

metadata

5.2.4.2.2 Grammar

Metadata definitions have the following grammar:

metadata:

  map of <string>

5.2.4.2.3 Examples

metadata:

  foo1: bar1

  foo2: bar2

  ...

5.2.4.2.4 Notes

·         Data provided within metadata, wherever it appears, MAY be ignored by TOSCA Orchestrators and SHOULD NOT affect runtime behavior.

5.2.4.3 DSL Definitions

TBD.

5.2.5 Type definitions

TOSCA provides a type system to describe possible building blocks to construct a service template (i.e. for the nodes, relationship, group and policy templates, and the data, capabilities, interfaces, and artifacts used in the node and relationship templates). TOSCA types are reusable TOSCA entities and are defined in their specific sections in the service template, see Section 4.2.1 Service Template definition.

Next, in Section 4.2.5.2 Common keynames in type definitions we present the definitions of common keynames that are used by all TOSCA types. Type-specific definitions for the different TOSCA type entities are presented further in the document:

·         Node Type in Section 4.3.1 Node Type.

·         Relationship Type in Section 4.3.3 Relationship Type.

·         Interface Type in Section 4.3.6.1 Interface Type.

·         Capability Type in Section 4.3.5.1 Capability Type.

·         Requirement Type in Section 4.3.5.4 Requirement Type.

·         Data Type in Section 4.4.4 Data Type.

·         Artifact Type in Section 4.3.7.1 Artifact Type.

·         Group Type in Section 4.6.1 Group Type.

·         Policy Type in Section 4.6.3 Policy Type.

5.2.5.1 General derivation and refinement rules

To simplify type creation and to promote type extensibility TOSCA allows the definition of a new type (the derived type) based on another type (the parent type). The derivation process can be applied recursively, where a type may be derived from a long list of ancestor types (the parent, the parent of the parent, etc).

Unless specifically stated in the derivation rules, when deriving new types from parent types the keyname definitions are inherited from the parent type. Moreover, the inherited definitions may be refined according to the derivation rules of that particular type entity.

For definitions that are not inherited, a new definition MUST be provided (if the keyname is mandatory) or MAY be provided (if the keyname is not mandatory). If not provided, the keyname remains undefined. For definitions that are inherited, a refinement of the inherited definition is not mandatory even for mandatory keynames (since it has been inherited). A definition refinement that is exactly the same as the definition in the parent type does not change in any way the inherited definition. While unnecessary, it is not wrong.

The following are some generic derivation rules used during type derivation (the specific rules of each TOSCA type entity are presented in their respective sections):

·         If not refined, usually a keyname/entity definition, is inherited unchanged from the parent type, unless explicitly specified in the rules that it is “not inherited”.

·         New entities (such as properties, attributes, capabilities, requirements, interfaces, operations, notification, parameters) may be added during derivation.

·         Already defined entities that have a type may be redefined to have a type derived from the original type.

·         New validation clauses are added to already defined keynames/entities (i.e. the defined validation clauses do not replace the validation clause defined in the parent type but are added to it).

·         Some definitions must be totally flexible, so they will overwrite the definition in the parent type.

·         Some definitions must not be changed at all once defined (i.e. they represent some sort of “signature” fundamental to the type).

 

5.2.5.2 Common keynames in type definitions

The following keynames are used by all TOSCA type entities in the same way. This section serves to define them at once.

5.2.5.2.1 Keynames

The following is the list of recognized keynames used by all TOSCA type definitions:

Keyname

Mandatory

Type

Description

derived_from

no

string

An optional parent type name from which this type derives.

version

no

version

An optional version for the type definition.

metadata

no

map of string

Defines a section used to declare additional metadata information.

description

no

string

An optional description for the type.

5.2.5.2.2 Grammar

The common keynames in type definitions have the following grammar:

<type_name>:

  derived_from: <parent_type_name>

  version: <version_number>

  metadata:

    <metadata_map>

  description: <type_description>

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

·         parent_type_name: represents the optional parent type name.

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

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

·         metadata_map: represents the optional metadata map of string.

5.2.5.2.3 Derivation rules

During type derivation the common keyname definitions use the following rules:

·         derived_from: obviously, the definition is not inherited from the parent type. If not defined, it remains undefined and this type does not derive from another type. If defined, then this type derives from another type, and all its keyname definitions must respect the derivation rules of the type entity.

·         version: the definition is not inherited from the parent type. If undefined, it remains undefined.

·         metadata: the definition is not inherited from the parent type. If undefined, it remains undefined.

·         description: the definition is not inherited from the parent type. If undefined, it remains undefined.

5.2.6 Service template definition

This section defines the service template of a TOSCA file. The main ingredients of the service template are node templates representing components of the application and relationship templates representing links between the components. These elements are defined in the nested node_templates section and the nested relationship_templates sections, respectively.  Furthermore, a service template allows for defining input parameters, output parameters as well as grouping of node templates.

5.2.6.1 Keynames

The following is the list of recognized keynames for a TOSCA service template:

Keyname

Mandatory

Type

Description

description

no

string

The optional description for the service template.

inputs

no

map of

parameter definitions

An optional map of input parameters (i.e., as parameter definitions) for the service template.

node_templates

yes

map of

node templates

A mandatory map of node template definitions for the service template.

relationship_templates

no

map of

relationship templates

An optional map of relationship templates for the service template.

groups

no

map of

group definitions

An optional map of Group definitions whose members are node templates defined within this same service template.

policies

no

list of

policy definitions

An optional list of Policy definitions for the service template.

outputs

no

map of

parameter definitions

An optional map of output parameters (i.e., as parameter definitions) for the service template.

substitution_mappings

no

substitution_mapping

An optional declaration that exports the service template as an implementation of a Node type.

 

This also includes the mappings between the external Node Types capabilities and requirements to existing implementations of those capabilities and requirements on Node templates declared within the service template.

workflows

no

map of imperative workflow definitions

An optional map of imperative workflow definition for the service template.

5.2.6.2 Grammar

The overall grammar of the service_template section is shown below.Detailed grammar definitions are provided in subsequent subsections.

service_template:

  description: <template_description>

  inputs: <input_parameters>

  outputs: <output_parameters>

  node_templates: <node_templates>

  relationship_templates: <relationship_templates>

  groups: <group_definitions>

  policies:

    - <policy_definition_list>

  workflows: <workflows>

  # Optional declaration that exports the service template

  # as an implementation of a Node Type.

  substitution_mappings:

    <substitution_mappings>

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

·         template_description: represents the optional description string for service template.

·         input_parameters: represents the optional map of input parameter definitions for the service template.

·         output_parameters: represents the optional map of output parameter definitions for the service template.

·         group_definitions: represents the optional map of group definitions whose members are node templates that also are defined within this service template.

·         policy_definition_list: represents the optional list of sequenced policy definitions for the service template.

·         workflows: represents the optional map of imperative workflow definitions for the service template.

·         node_templates: represents the mandatory map of node template definitions for the service template.

·         relationship_templates: represents the optional map of relationship templates for the service template.

·         node_type_name: represents the optional name of a Node Type that the service template implements as part of the substitution_mappings.

·         map_of_capability_mappings_to_expose: represents the mappings that expose internal capabilities from node templates (within the service template) as capabilities of the Node Type definition that is declared as part of the substitution_mappings.

·         map_of_requirement_mappings_to_expose: represents the mappings of link requirements of the Node Type definition that is declared as part of the substitution_mappings to internal requirements implementations within node templates (declared within the service template).

More detailed explanations for each of the service template grammar’s keynames appears in the sections below.

5.2.6.2.1 inputs

The inputs section provides a means to define parameters using TOSCA parameter definitions, their allowed values via validation clauses and default values within a TOSCA template. Input parameters defined in the inputs section of a service template can be mapped to properties of node templates or relationship templates within the same service template and can thus be used for parameterizing the instantiation of the service template.

When deploying a service from the service template, values must be provided for all mandatory input parameters that have no default value defined. If no input is provided, then the default value is used.

5.2.6.2.1.1     Grammar

The grammar of the inputs section is as follows:

inputs:

  <parameter_definitions>

5.2.6.2.1.2     Examples

This section provides a set of examples for the single elements of a service template.

Simple inputs example without any validation clauses:

inputs:

  fooName:

    type: string

    description: Simple string parameter without a validation clause.

    default: bar

Example of inputs with a validation clause:

inputs:

  SiteName:

    type: string

    description: String parameter with validation clause.

    default: My Site

    validation: { $min_length: [ $value, 9 ] }

5.2.6.2.2 node_templates

The node_templates section lists the Node Templates that describe the (software) components that are used to compose cloud applications.

5.2.6.2.2.1     grammar

The grammar of the node_templates section is a follows:

node_templates:

  <node_template_defn_1>

  ...

  <node_template_defn_n>

5.2.6.2.2.2     Example

Example of node_templates section:

node_templates:

  my_webapp_node_template:

    type: WebApplication

 

  my_database_node_template:

    type: Database

5.2.6.2.3 relationship_templates

The relationship_templates section lists the Relationship Templates that describe the relations between components that are used to compose cloud applications.

Note that in TOSCA, the explicit definition of relationship templates as it was required in TOSCA v1.0 is optional, since relationships between nodes get implicitly defined by referencing other node templates in the requirements sections of node templates.

5.2.6.2.3.1     Grammar

The grammar of the relationship_templates section is as follows:

relationship_templates:

  <relationship_template_defn_1>

  ...

  <relationship_template_defn_n>

5.2.6.2.3.2     Example

Example of relationship_templates section:

relationship_templates:

  my_connectsto_relationship:

    type: tosca.relationships.ConnectsTo

    interfaces:

      Configure:

        inputs:

          speed: { $$get_attribute: [ SELF, SOURCE, connect_speed ] }     

5.2.6.2.4 outputs

The outputs section provides a means to define the output parameters that are available from a TOSCA service template. It allows for exposing attributes of node templates or relationship templates within the containing service_template to users of a service.

5.2.6.2.4.1     Grammar

The grammar of the outputs section is as follows:

outputs:

  <parameter_definitions>

5.2.6.2.4.2     Example

Example of the outputs section:

outputs:

  server_address:

    description: The first private IP address for the provisioned server.

    value: { $get_attribute: [ node5, networks, private, addresses, 0 ] }

5.2.6.2.5 groups

The groups section allows for grouping one or more node templates within a TOSCA Service Template and for assigning special attributes like policies to the group.

5.2.6.2.5.1     Grammar

The grammar of the groups section is as follows:

groups:

  <group_defn_1>

  ...

  <group_defn_n>

5.2.6.2.5.2     Example

The following example shows the definition of three Compute nodes in the node_templates section of a service_template as well as the grouping of two of the Compute nodes in a group server_group_1.

node_templates:

  server1:

    type: tosca.nodes.Compute

    # more details ...

 

  server2:

    type: tosca.nodes.Compute

    # more details ...

 

  server3:

    type: tosca.nodes.Compute

    # more details ...

 

groups:

  # server2 and server3 are part of the same group

  server_group_1:

    type: tosca.groups.Root

    members: [ server2, server3 ]

5.2.6.2.6 policies

The policies section allows for declaring policies that can be applied to entities in the service template.

5.2.6.2.6.1     Grammar

The grammar of the policies section is as follows:

policies:

  - <policy_defn_1>

  - ...

  - <policy_defn_n>

5.2.6.2.6.2     Example

The following example shows the definition of a placement policy.

policies:

  - my_placement_policy:

      type: mycompany.mytypes.policy.placement

5.2.6.2.7 substitution_mapping
5.2.6.2.7.1     requirement_mapping

The grammar of a requirement_mapping is as follows:

<requirement_name>: [ <node_template_name>, <node_template_requirement_name> ]

The multi-line grammar is as follows :

<requirement_name>:

  mapping: [ <node_template_name>, <node_template_capability_name> ]

  properties:

    <property_name>: <property_value>

·         requirement_name: represents the name of the requirement as it appears in the Node Type definition for the Node Type (name) that is declared as the value for on the substitution_mappings’ “node_type” key.

·         node_template_name: represents a valid name of a Node Template definition (within the same service_template declaration as the substitution_mapping is declared).

·         node_template_requirement_name: represents a valid name of a requirement definition within the <node_template_name> declared in this mapping.

5.2.6.2.7.2     Example

The following example shows the definition of a placement policy.

service_template:

 

inputs:

   cpus:

     type: integer

     validation: { $less_than: [ $value, 2 ] } # OR use “defaults” key

 

substitution_mappings:

    node_type: MyService

    properties:  # Do not care if running or matching (e.g., Compute node)

      # get from outside?  Get from contsraint?

      num_cpus: cpus # Implied “PUSH”

      # get from some node in the topology…

      num_cpus: [ <node>, <cap>, <property> ]

      # 1) Running

      architecture:

        # a) Explicit

        value: { $get_property: [some_service, architecture] }

        # b) implicit

        value: [ some_service, <req | cap name>, <property name> architecture ]

        default: “amd”

        # c) INPUT mapping?

        ???

      # 2) Catalog (Matching)

      architecture:

         contraints: equals: “x86”

 

    capabilities:

      bar: [ some_service, bar ]

    requirements:

      foo: [ some_service, foo ]

 

  node_templates:

    some_service:

      type: MyService

      properties:

        rate: 100

      capabilities:

        bar:

          ...

      requirements:

        - foo:

            ...

 

 

5.3 Nodes and Relationships

5.3.1 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 and attributes, the capabilities and requirements of the node as well as its supported interfaces and the artifacts it uses.

5.3.1.1 Keynames

The Node Type is a TOSCA type entity and has the common keynames listed in Section 4.2.5.2 Common keynames in type definitions. In addition, the Node Type has the following recognized keynames:

Keyname

Mandatory

Type

Description

properties

no

map of

property definitions

An optional map of property definitions for the Node Type.

attributes

no

map of

attribute definitions

An optional map of attribute definitions for the Node Type.

capabilities

no

map of

capability definitions

An optional map of capability definitions for the Node Type.

requirements

no

list of

requirement definitions

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

5.3.1.2 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>

  properties:

    <property_definitions>

  attributes:

    <attribute_definitions>

  capabilities:

    <capability_definitions>

  requirements:

    - <requirement_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 mandatory 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.

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

·         requirement_definitions: represents the optional list of requirement 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

5.3.1.3 Derivation rules

During Node Type derivation the keyname definitions follow these rules:

·         properties: existing property definitions may be refined; new property definitions may be added.

·         attributes: existing attribute definitions may be refined; new attribute definitions may be added.

·         capabilities: existing capability definitions may be refined; new capability definitions may be added.

·         requirements: existing requirement definitions may be refined; new requirement definitions may be added.

·         interfaces: existing interface definitions may be refined; new interface definitions may be added.

·         artifacts: existing artifact definitions (identified by their symbolic name) may be redefined; new artifact definitions may be added.

      note that an artifact is created for a specific purpose and corresponds to a specific file (with e.g. a path name and checksum); if it cannot meet its purpose in a derived type then a new artifact should be defined and used.

      thus, if an artifact defined in a parent node type does not correspond anymore with the needs in the child node type, its definition may be completely redefined; thus, an existing artifact definition is not refined, but completely overwritten.

5.3.1.4 Additional Requirements

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

5.3.1.5 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

      validation:

        $and:

          - { $min_length: [ $value, 6 ] }

          - { $max_length: [ $value, 10 ] }

  attributes:

    my_app_port:

      type: integer

      description: application port number

  requirements:

    - some_database:

        capability: EndPoint.Database

        node: Database   

        relationship: ConnectsTo

5.3.2 Node Template

A Node Template specifies the occurrence of a manageable component as part of an application’s topology model which is defined in a TOSCA Service Template.  A Node Template is an instance of a specified Node Type and can provide customized properties, relationships, or interfaces that complement and change the defaults provided by its Node Type.

5.3.2.1 Keynames

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

Keyname

Mandatory

Type

Description

type

yes

string

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

description

no

string

An optional description for the Node Template.

metadata

no

map of string

Defines a section used to declare additional metadata information.

directives

no

list of string

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

properties

no

map of

property assignments

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

attributes

no

map of

attribute assignments

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

requirements

no

list of

requirement assignments

An optional list of requirement assignments for the Node Template.

capabilities

no

map of

capability assignments

An optional map of capability assignments for the Node Template.

interfaces

no

map of

interface assignments

An optional map of interface assignments for the Node Template.

artifacts

no

map of

artifact definitions

 

An optional map of artifact definitions for the Node Template.

node_filter

no

node filter

The optional filter definition that TOSCA orchestrators will use to select the correct target node. 

copy

no

string

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

5.3.2.2 Grammar

<node_template_name>:

  type: <node_type_name>

  description: <node_template_description>

  directives: [<directives>]

  metadata:

    <map of string>

  properties:

    <property_assignments>

  attributes:

    <attribute_assignments>

  requirements:

    - <requirement_assignments>

  capabilities:

    <capability_assignments>

  interfaces:

    <interface_assignments>

  artifacts:

    <artifact_definitions>

  node_filter:

    <node_filter_definition>

  copy: <source_node_template_name>

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

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

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

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

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

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

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

·         requirement_assignments: represents the optional list of requirement assignments for the Node Template for requirement definitions provided in its declared Node Type.

·         capability_assignments: represents the optional map of capability assignments for the Node Template for capability definitions provided in its declared Node Type.

·         interface_assignments: represents the optional map of interface assignments for the Node Template interface definitions provided in its declared Node Type.

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

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

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

5.3.2.3 Additional requirements

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

5.3.2.4 Example

node_templates:

  mysql:

    type: tosca.nodes.DBMS.MySQL

    properties:

      root_password: { $get_input: my_mysql_rootpw }

      port: { $get_input: my_mysql_port }

    requirements:

      - host: db_server

    interfaces:

      Standard:

        operations:

          configure: scripts/my_own_configure.sh

 

5.3.3 Relationship Type

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

5.3.3.1 Keynames

The Relationship Type is a TOSCA type entity and has the common keynames listed in Section 4.2.5.2 Common keynames in type definitions. In addition, the Relationship Type has the following recognized keynames:

Keyname

Mandatory

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 supported by the Relationship Type.

valid_capability_types

 

no

list of string

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

valid_target_node_types

no

list of string

An optional list of one or more names of Node Types that are valid targets for this relationship. If undefined, all Node Types are valid targets.

valid_source_node_types

no

list of string

An optional list of one or more names of Node Types that are valid sources for this relationship. If undefined, all Node Types are valid sources.

5.3.3.2 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_capability_types: [ <capability_type_names> ]

  valid_target_node_types: [ <target_node_type_names> ]

  valid_source_node_types: [ <source_node_type_names> ]

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

·         relationship_type_name: represents the mandatory 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 interface definitions supported by the Relationship Type.

·         capability_type_names: represents the optional list of valid target Capability Types for the relationship; if undefined, the valid target types are not restricted at all (i.e., all Capability Types are valid).

·         target_node_type_names: represents the optional list of valid target Node Types for the relationship; if undefined, the valid types are not restricted at all (i.e., all Node Types are valid).

·         source_node_type_names: represents the optional list of valid source Node Types for the relationship; if undefined, the valid types are not restricted at all (i.e., all Node Types are valid).

5.3.3.3 Derivation rules

During Relationship Type derivation the keyname definitions follow these rules:

·         properties: existing property definitions may be refined; new property definitions may be added.

·         attributes: existing attribute definitions may be refined; new attribute definitions may be added.

·         interfaces: existing interface definitions may be refined; new interface definitions may be added.

·         valid_capability_types: if valid_capability_types is defined in the parent type, each element in this list must either be in the parent type list or derived from an element in the parent type list; if valid_target_types is not defined in the parent type then no restrictions are applied.

·         valid_target_node_types: same derivation rules as for valid_capability_types

·         valid_source_node_types: same derivation rules as for valid_capability_types

5.3.3.4 Examples

mycompanytypes.myrelationships.AppDependency:

  derived_from: tosca.relationships.DependsOn

  valid_capability_types: [ mycompanytypes.mycapabilities.SomeAppCapability ]

 

5.3.4 Relationship Template

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

Relations between Node Templates can be defined either using Relationship Templates or Requirements and Capability definitions within Node Types. Use of Relationship Templates decouples relationship definitions from Node Type definitions, allowing Node Type definitions to be more “generic” for use in a wider set of service templates which have varying relation definition requirements. The Relationship Templates are local within a service template and so have a limited scope. Requirements and Capabilities defined in Node Types have a wider scope, exposed within any service template which contains a Node Template of the Node Type.

Note that using the relationship templates is underspecified currently and can be used only as a further template for relationships in requirements definition. This topic needs further work.

5.3.4.1 Keynames

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

Keyname

Mandatory

Type

Description

type

yes

string

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

description

no

string

An optional description for the Relationship Template.

metadata

no

map of string

Defines a section used to declare additional metadata information.

properties

no

map of

property assignments

An optional map of property assignments for the Relationship Template.

attributes

no

map of

attribute assignments

An optional map of attribute assignments for the Relationship Template.

interfaces

no

map of

interface assignments

An optional map of interface assignments for the relationship template.

copy

no

string

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

5.3.4.2 Grammar

<relationship_template_name>:

  type: <relationship_type_name>

  description: <relationship_type_description>

  metadata:

    <map of string>

  properties:

    <property_assignments>

  attributes:

    <attribute_assignments>

  interfaces:

    <interface_assignments>

  copy:

    <source_relationship_template_name>

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

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

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

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

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

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

·         interface_assignments: represents the optional map of interface assignments for the Relationship Template for interface definitions provided by its declared Relationship Type.

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

5.3.4.3 Additional requirements

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

5.3.4.4 Example

relationship_templates:

  storage_attachment:

    type: AttachesTo

    properties:

      location: /my_mount_point

 

5.3.5 Capabilities and Requirements

5.3.5.1 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.

5.3.5.1.1 Keynames

The Capability Type is a TOSCA type entity and has the common keynames listed in Section 4.2.5.2 Common keynames in type definitions. In addition, the Capability Type has the following recognized keynames:

Keyname

Mandatory

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_node_types

no

list of 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. If undefined, all Node Types are valid sources.

valid_relationship_types

no

list of string

An optional list of one or more valid names of Relationship Types that are supported as valid types of any relationship established to the declared Capability Type. If undefined, all Relationship Types are valid.

5.3.5.1.2 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_node_types: [ <node_type_names> ]

  valid_relationship_types: [ <relationship_type_names> ]

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

·         capability_type_name: represents the mandatory 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 Capability Type.

·         property_definitions: represents the optional map of property definitions for the Capability Type.

·         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 a capability of this Capability Type; if undefined, the valid source types are not restricted at all (i.e. all Node Types are valid).

·         relationship_type_names: represents the optional list of one or more names of Relationship Types that the Capability Type supports as valid types for a successful relationship to be established to a capability of this Capability Type; if undefined, the valid types are not restricted at all (i.e. all Relationship Types are valid).

5.3.5.1.3 Derivation rules

During Capability Type derivation the keyname definitions follow these rules:

·         properties: existing property definitions may be refined; new property definitions may be added.

·         attributes: existing attribute definitions may be refined; new attribute definitions may be added.

·         valid_source_node_types: if valid_source_types is defined in the parent type, each element in this list must either be in the parent type list or derived from an element in the parent type list; if valid_source_types is not defined in the parent type then no restrictions are applied.

·         valid_relationship_types: same derivations rules as for valid_source_node_types.

 

5.3.5.1.4 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

 

5.3.5.2 Capability definition

A Capability definition defines a typed set of data that a node can expose and is used to describe a relevant feature of the component described by the node. A Capability is defined part of a Node Type definition and may be refined during Node Type derivation.

5.3.5.2.1 Keynames

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

Keyname

Mandatory

Type

Description

type

yes

string

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

description

no

string

The optional description of the Capability definition.

properties

no

map of

property refinements

An optional map of property refinements for the Capability definition. The referred properties must have been defined in the Capability Type definition referred by the type keyword. New properties may not be added.

attributes

no

map of

attribute refinements

An optional map of attribute refinements for the Capability definition. The referred attributes must have been defined in the Capability Type definition referred by the type keyword. New attributes may not be added.

valid_source_node_types

no

list of 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. If undefined, all node types are valid sources.

If valid_source_node_types is defined in the Capability Type, each element in this list must either be or derived from an element in the list defined in the type.

valid_relationship_types

no

list of string

An optional list of one or more valid names of Relationship Types that are supported as valid types of any relationship established to the declared Capability Type. If undefined, all Relationship Types are valid.

If valid_relationship_types is defined in the Capability Type, each element in this list must either be or derived from an element in the list defined in the type.

5.3.5.2.2 Grammar

Capability definitions have one of the following grammars:

5.3.5.2.2.1     Short notation

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

<capability_definition_name>: <capability_type>

5.3.5.2.2.2     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_refinements>

  attributes:

    <attribute_refinements>

  valid_source_node_types: [ <node_type_names> ]

  valid_relationship_types: [ <relationship_type_names> ]

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

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

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

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

·         property_refinements: represents the optional map of property definitions refinements for properties already defined in the capability type; new properties may not be added.

·         attribute_refinements: represents the optional map of attribute definitions refinements for attributes already defined in the capability type; new attributes may not be added.

·         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 said capability

·         if valid_source_node_types is defined in the capability type, each element in this list MUST either be in that list or derived from an element in that list; if valid_source_types is not defined in the capability type then no restrictions are applied.

·         relationship_type_names: represents the optional list of one or more names of relationship types that the capability definition supports as valid type for a successful relationship to be established to said capability

·         if valid_relationship_types is defined in the capability type, each element in this list MUST either be in that list or derived from an element in that list; if valid_source_types is not defined in the capability type then no restrictions are applied.

 

5.3.5.2.3 Refinement rules

A capability definition within a node type uses the following definition refinement rules when the containing node type is derived:

·         type: must be derived from (or the same as) the type in the capability definition in the parent node type definition.

·         description: a new definition is unrestricted and will overwrite the one inherited from the capability definition in the parent node type definition.

·         properties: not applicable to the definitions in the parent node type but to the definitions in the capability type referred by the type keyname (see grammar above for the rules).

·         attributes: not applicable to the definitions in the parent node type but to the definitions in the capability type referred by the type keyname (see grammar above for the rules).

·         valid_source_node_types: not applicable to the definitions in the parent node type but to the definitions in the capability type referred by the type keyname (see grammar above for the rules).

·         valid_relationship_types: not applicable to the definitions in the parent node type but to the definitions in the capability type referred by the type keyname (see grammar above for the rules).

 

5.3.5.2.4 Examples

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

5.3.5.2.4.1     Simple notation example

# Simple notation, no properties need to be refined

some_capability: mytypes.mycapabilities.MyCapabilityTypeName

5.3.5.2.4.2     Full notation example

# Full notation, refining properties

some_capability:

  type: mytypes.mycapabilities.MyCapabilityTypeName

  properties:

    limit:

      default: 100

5.3.5.2.5 Additional requirements

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

5.3.5.2.6 Note

·         The occurrences keyname is deprecated in TOSCA 2.0. By default, the number of “occurrences” is UNBOUNDED, i.e. any number of relationships can be created with a certain capability as a target. To constrain the creation of a relationship to a target capability, the new “allocation” keyname is used within a requirement assignment.

 

5.3.5.3 Capability assignment

A capability assignment allows node template authors to assign values to properties and attributes for a capability definition that is part of the node templates’ respective type definition, and also to set the capability occurrences.

5.3.5.3.1 Keynames

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

Keyname

Mandatory

Type

Description

properties

no

map of

property assignments

An optional map of property assignments for the Capability definition.

attributes

no

map of

attribute assignments

An optional map of attribute assignments for the Capability definition.

directives

no

 

default: [internal, external]

list of string

 

valid string values:

“internal”,

“external”

Describes if the fulfillment of this capability assignment should use relationships with source nodes created within this template (“internal”) or should use source nodes created outside this template as available to the TOSCA environment ("external”) or if it should use a combination of the above. If so, the order of the strings in the list defines which scope should be attempted first. If no scope is defined, the default value is [internal, external]. If no directives are defined, the default value is left to the particular implementation.

 

5.3.5.3.2 Grammar

Capability assignments have one of the following grammars:

<capability_definition_name>:

  properties:

    <property_assignments>

  attributes:

    <attribute_assignments>

  directives: <directives_list>

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

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

·         property_assignments: represents the optional map of property assignments that provide values for properties defined in the Capability definition.

·         attribute_assignments: represents the optional map of attribute assignments that provide values for attributes defined in the Capability definition.

·         directives_list: represents the optional list of strings that defines directives for this capability:

·         valid values for the strings:

·         “internal” – relationships to this capability can be created from source nodes created within this template.

·         “external” – relationships to this capability can be created from source nodes created outside this template as available to the TOSCA environment.

·         the order of the strings in the list defines which scope should be attempted first when fulfilling the assignment.

·         If no directives are defined, the default value is left to the particular implementation.

 

5.3.5.3.3 Example

The following example shows a capability assignment:

5.3.5.3.3.1     Notation example

node_templates:

  some_node_template:

    capabilities:

      some_capability:

        properties:

          limit: 100

5.3.5.3.4 Note

·         The occurrences keyname is deprecated in TOSCA 2.0. By default, the number of “occurrences” is UNBOUNDED, i.e. any number of relationships can be created with a certain capability as a target. To constrain the creation of a relationship to a target capability, the new “allocation” keyname is used within a requirement assignment.

 

5.3.5.4 Requirement Type

Requirement types are not defined in TOSCA. TOSCA seeks to simplify the modeling by not declaring specific Requirement Types with nodes declaring their features sets using TOSCA Capability Types. So, it suffices that capabilities are advertised a-priory by Capability Types, while requirement definitions can be directly created during Node Type design.

 

5.3.5.5 Requirement definition

The Requirement definition describes a requirement (dependency) of a TOSCA node which needs to be fulfilled by a matching Capability definition declared by another TOSCA node. A Requirement is defined as part of a Node Type definition and may be refined during Node Type derivation.

5.3.5.5.1 Keynames

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

Keyname

Mandatory

Type

Description

description

no

string

The optional description of the Requirement definition.

capability

yes

string

The mandatory keyname used to provide either the:

·         symbolic name of a Capability definition within a target Node Type that can fulfill the requirement.

·         name of a Capability Type that the TOSCA orchestrator will use to select a type-compatible target node to fulfill the requirement at runtime.

node

conditional

string

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

If a symbolic name of a Capability definition has been used for the capability keyname, then the node keyname is mandatory.

relationship

conditional

string

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

The relationship definition is mandatory either in the requirement definition of in the requirement assignment.

node_filter

no

node filter

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

count_range

no

range of integer

The optional minimum required and maximum allowed number of relationships created by the requirement. If this key is not specified, the implied default of [0, UNBOUNDED] will be used.

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

5.3.5.5.1.1     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 parameters may need to be passed to the relationship (perhaps for configuration). In these cases, additional grammar is provided so that the requirement definition may declare interface refinements (e.g. changing the implementation definition or declaring additional parameter definitions to be used as inputs/outputs). 

Keyname

Mandatory

Type

Description

type

yes

string

The optional keyname used to provide the name of the Relationship Type as part of the relationship keyname definition.

interfaces

no

map of interface refinements

The optional keyname used to reference declared interface definitions on the corresponding Relationship Type for refinement.

5.3.5.5.2 Grammar

Requirement definitions have one of the following grammars:

5.3.5.5.2.1     Simple grammar (Capability Type only)

<requirement_definition_name>: <capability_type_name>

5.3.5.5.2.2     Extended grammar (with Node and Relationship Types)

<requirement_definition_name>:

  description: <requirement_description>

  capability: <capability_symbolic_name> | <capability_type_name>

  node: <node_type_name>

  relationship: <relationship_type_name>

  node_filter: <node_filter_definition>

  count_range: [ <min_count>, <max_count> ]

5.3.5.5.2.3     Extended grammar for declaring Parameter Definitions on the relationship’s Interfaces

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

<requirement_definition_name>:

  # Other keynames omitted for brevity

  relationship:

    type: <relationship_type_name>

    interfaces: <interface_refinements>

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

·         requirement_definition_name: represents the mandatory symbolic name of the requirement definition as a string.

·         requirement_description: represents the optional description of the requirement definition.

·         capability_symbolic_name: represents the mandatory symbolic name of the Capability definition within the target Node Type.

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

·         node_type_name: represents the name of a Node Type that contains either the Capability Type or the Capability definition the requirement can be fulfilled by; the node_type_name is mandatory if the capability_symbolic_name was used, and is optional if the capability_type_name was used.

·         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).

·         node_filter_definition: represents the optional node filter TOSCA orchestrators will use to fulfill the requirement when selecting a target node, or to verify that the specified node template fulfills the requirement (if a node template was specified during requirement assignment).

·         min_count, max_count: represents the optional range between a minimum required and maximum allowed count of the requirement

·         this range constrains how many relationships from this requirement towards target capabilities (in target nodes) are created, and that number MUST be within the range specified here.

·         by default (i.e. if count_range is undefined here), a requirement shall form exactly one relationship ( [1, 1] i.e. allowed at least one, and at most one).

·         interface_refinements: represents refinements for one or more already declared interface definitions in the Relationship Type (as declared on the type keyname)

·         allowing for the declaration of new parameter definitions for these interfaces or for specific operation or notification definitions of these interfaces or for the change of the description or implementation definitions.

5.3.5.5.3 Refinement rules

A requirement definition within a node type uses the following definition refinement rules when the containing node type is derived:

·         description: a new definition is unrestricted and will overwrite the one inherited from the requirement definition in the parent node type definition.

·         capability: the type of the capability must be derived from (or the same as) the capability type in the requirement definition in the parent node type definition.

·         if the capability was specified using the symbolic name of a capability definition in the target node type, then the capability keyname definition MUST remain unchanged in any subsequent refinements or during assignment.

·         node: must be derived from (or the same as) the node type in the requirement definition in the parent node type definition; if node is not defined in the parent type then no restrictions are applied;

·         the node type specified by the node keyname must also contain a capability definition that fulfills the requirement set via the capability keyname above.

·         relationship: must be derived from (or the same as) the relationship type in the requirement definition in the parent node type definition; if relationship is not defined in the parent type then no restrictions are applied.

·         node_filter: a new definition is unrestricted and will be considered in addition (i.e. logical and) to the node_filter definition in the parent node type definition; further refinements may add further node filters.

·         count_range: the new range MUST be within the range defined in the requirement definition in the parent node type definition.

5.3.5.5.4 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 count_range keyname is not present, then a default declaration as follows will be assumed: 

count_range: [0, UNBOUNDED]

5.3.5.5.5 Notes

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

5.3.5.5.6 Requirement definition is a tuple with a filter

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

4.     Node Type (mandatory/optional)

5.     Relationship Type (optional)

6.     Capability definition or Capability Type (mandatory)

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 Capability definition or Capability Type on the target node is provided using the capability keyname. Note that if a Capability definition is used, the Node Type definition is mandatory (as it refers to a Capability definition in that Node Type).

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. Also, if a Node Template was specified during requirement assignment it allows TOSCA orchestrators to verify that the specified node template fulfills the requirement.

 

5.3.5.6 Requirement assignment

A Requirement assignment allows Node Template authors to provide assignments for the corresponding Requirement definition (i.e. having the same symbolic name) in the Node Type definition.

A Requirement assignment provides either names of Node Templates or selection criteria for TOSCA orchestrators to find matching TOSCA nodes that are used to fulfill the requirement’s declared Capability Type and/or Node Type. A Requirement assignment also provides either names of Relationship Templates (to use) or the name of Relationship Types (to create relationships) for relating the source node (containing the Requirement) to the target node (containing the Capability).

Note that several Requirement assignments in the Node Template definition can have the same symbolic name, each referring to different counts of the Requirement definition. To how many counts a particular assignment allows is set via the count_range keyname. Nevertheless, the sum of the count values for all of the Requirement assignments with the same symbolic name MUST be within the range of count_range specified by the corresponding Requirement definition.

5.3.5.6.1 Keynames

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

Keyname

Mandatory

Type

Description

capability

no

string

The optional keyname used to provide either the:

·         symbolic name of a Capability definition within a target node that can fulfill the requirement.

·         name of a Capability Type that the TOSCA orchestrator will use to select a type-compatible target node to fulfill the requirement at runtime.

node

no

string

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

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

·         name of a Node Type that the TOSCA orchestrator will use to select a type-compatible target node to fulfill the requirement at runtime.

relationship

conditional

string

The conditional keyname used to provide either the:

·         name of a Relationship Template to use to relate this node to the target node when fulfilling the requirement.

·         name of a Relationship Type that the TOSCA orchestrator will use to create a relationship to relate this node to the target node when fulfilling the requirement.

·         Details of a Relationship Type and its property and interface assignments that the TOSCA orchestrator will use to create a relationship to relate this node to the target node when fulfilling the requirement.

The relationship definition is mandatory either in the requirement definition of in the requirement assignment.

allocation

no

allocation block

The optional keyname that allows the inclusion of an allocation block. The allocation block contains a map of property assignments that semantically represent “allocations” from the property with the same name in the target capability.

·         The allocation acts as a “capacity filter” for the target capability in the target node. When the requirement is resolved, a capability in a node is a valid target for the requirement relationship if for each property of the target capability, the sum of all existing allocations plus the current allocation is less_or_equal to the property value.

 

node_filter

no

node filter

The optional filter definition that TOSCA orchestrators will use to select a type-compatible target node that can fulfill the requirement at runtime.

count

no

non-negative integer

An optional keyname that sets the cardinality of the requirement assignment, that is how many relationships to be established from this requirement assignment specification.

If not defined, the assumed count for an assignment is 1.

Note that there can be multiple requirement assignments for a requirement with a specific symbolic name.

·         The sum of all count values of assignments for a requirement with a specific symbolic name must be within the count_range defined in the requirement definition.

·         Moreover, the sum of all count values of non-optional assignments for a requirement with a specific symbolic name must also be within the count_range defined in the requirement definition.

directives

no

 

 

list of string

 

valid string values:

“internal”,

“external”

Describes if the fulfillment of this requirement assignment should use relationships with target nodes created within this template (“internal”) or should use target nodes created outside this template as available to the TOSCA environment ("external”) or if it should use a combination of the above. If so, the order of the strings in the list defines which directive should be attempted first. If no directives are defined, the default value is left to the particular implementation.

optional

no

 

default:

false

boolean

Describes if the fulfillment of this requirement assignment is optional (true) or not (false).

If not specified, the requirement assignment must be fulfilled, i.e. the default value is false.

Note also, that non-optional requirements have precedence, thus during a service deployment, the optional requirements for all nodes should be resolved only after the non-optional requirements for all nodes have been resolved.

The following is the list of recognized keynames for a TOSCA requirement assignment’s relationship keyname which is used when property assignments or interface assignments (for e.g. changing the implementation keyname or declare additional parameter definitions to be used as inputs/outputs) need to be provided: 

Keyname

Mandatory

Type

Description

type

no

string

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

properties

no

map of

property assignments

An optional keyname providing property assignments for the relationship.

interfaces

no

map of

interface assignments

The optional keyname providing Interface assignments for the corresponding Interface definitions in the Relationship Type.

5.3.5.6.2 Grammar

Requirement assignments have one of the following grammars:

5.3.5.6.2.1     Short notation:

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

<requirement_name>: <node_template_name>

5.3.5.6.2.2     Extended notation:

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

<requirement_name>:

  capability: <capability_symbolic_name> | <capability_type_name>

  node: <node_template_name> | <node_type_name>

  relationship: <relationship_template_name> | <relationship_type_name>

  node_filter: <node_filter_definition>

  count: <count_value>

  directives: <directives_list>

  optional: <is_optional>

5.3.5.6.2.3     Extended grammar with Property Assignments and Interface Assignments for the relationship

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

<requirement_name>:

  # Other keynames omitted for brevity

  relationship:

    type: <relationship_template_name> | <relationship_type_name>

    properties: <property_assignments>

    interfaces: <interface_assignments>

5.3.5.6.2.4     Extended grammar with capacity allocation

The following additional multi-line grammar is provided for capacity allocation in the target capability. The property assignments under the allocation keyname represent “allocations” from the property with the same name in the target capability.

·         The sum of all the allocations for all requirements assignments for a property in a target capability cannot exceed the value of that property.

·         This means that during the deployment time of a certain service template – as a certain requirement assignment is resolved – a capability in a node is a valid target if

·         for each property of the target capability

·         the sum of all existing allocations plus the current allocation is less_or_equal to the property value

·         Of course, allocations can be defined only for integer, float, or scalar property types.

<requirement_name>:

  # Other keynames omitted for brevity

  allocation:

    properties: <allocation_property_assignments>

 

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

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

·         capability_symbolic_name: represents the optional name of the Capability definition within the target Node Type or Node Template;

·         if the capability in the Requirement definition was specified using the symbolic name of a capability definition in a target node type, then the capability keyname definition

·         MUST remain unchanged in any subsequent refinements or during assignment.

·         if the capability in the Requirement definition was specified using the name of a Capability Type, then the Capability definition referred here by the capability_symbolic_name must be of a type that is the same as or derived from the said Capability Type in the Requirement definition.

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

·         may not be used if the capability in the Requirement definition was specified using the symbolic name of a capability definition in a target node type.

·         otherwise the capability_type_name must be of a type that is the same as or derived from the type defined by the capability keyname in the Requirement definition.

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

·         in addition, the Node Type of the Node Template must be of a type that is the same as or derived from the type defined by the node keyname (if the node keyname is defined) in the Requirement definition,

·         in addition, the Node Template must fulfill the node filter requirements of the node_filter (if a node_filter is defined) in the Requirement definition.

·         node_type_name: represents the optional name of a Node Type that contains the capability this Requirement will be fulfilled by;

·         in addition, the node_type_name must be of a type that is the same as or derived from the type defined by the node keyname (if the node keyname is defined) in the Requirement definition.

·         relationship_template_name: represents the optional name of a Relationship Template to be used when relating the Requirement to the Capability in the target node.

·         in addition, the Relationship Type of the Relationship Template must be of a type that is the same as or derived from the type defined by the relationship keyname (if the relationship keyname is defined) in the Requirement definition.

·         relationship_type_name: represents the optional name of a Relationship Type that is compatible with the Capability Type in the target node; the TOSCA orchestrator will create a relationship of the  Relationship Type when relating the Requirement to the Capability in the target node.

·         in addition, the relationship_type_name must be of a type that is the same as or derived from the type defined by the relationship keyname (if the relationship keyname is defined) in the Requirement definition.

·         property_assignments: within the relationship declaration, it represents the optional map of property assignments for the declared relationship.

·         interface_assignments: represents the optional map of interface assignments for the declared relationship used to provide parameter assignments on inputs and outputs of interfaces, operations and notifications or changing the implementation definition.

·         allocation_property_assignments: within the allocation declaration, it represents the optional map of property assignments that semantically represent “allocations” from the property with the same name in the target capability. Syntactically their form is the same as for a normal property assignments.

·         The allocation acts as a “capacity filter” for the target capability in the target node. When the requirement is resolved, a capability in a node is a valid target for the requirement relationship if for each property of the target capability, the sum of all existing allocations plus the current allocation is less_or_equal to the property value.

·         Intuitively, the sum of “allocations” from all the incoming relationships for a certain capability property cannot exceed the value of the property.

·         If the “allocation” refers (via its name) to a property that does not exist in a capability, then that capability cannot be a valid target.

·         Of course, allocations can be defined only for integer, float, or scalar property types.

·         node_filter_definition: represents the optional node filter TOSCA orchestrators will use to fulfill the requirement for selecting a target node; if a node template was specified during requirement assignment, the TOSCA orchestrator verifies that the specified node template fulfills the node filter.

·         this node_filter does not replace the node_filter definition in the Requirement definition, it is applied in addition to that.

·         count_value: represents the optional cardinality of this requirement assignment, that is how many relationships are to be established from this requirement assignment specification.

·         If count is not defined, the assumed count_value for an assignment is 1.

·         Note that there can be multiple requirement assignments for a requirement with a specific symbolic name.

·         The sum of all count values of assignments for a requirement with a specific symbolic name must be within the count_range defined in the requirement definition.

·         Moreover, the sum of all count values of non-optional assignments for a requirement with a specific symbolic name must also be within the count_range defined in the requirement definition.

·         directives: represents the optional list of strings that defines directives for this requirement assignment:

·         valid values for the strings:

·         “internal” – relationship created by this requirement assignment use target nodes created within this template.

·         “external” – relationship created by this requirement assignment use target nodes created outside this template as available to the TOSCA environment.

·         the order of the strings in the list defines which directive should be attempted first when fulfilling the assignment.

·         If no directives are defined, the default value is left to the particular implementation.

·         is_optional: represents the optional boolean value specifying if this requirement assignment is optional or not.

·         If is_optional is false, the assignment MUST be fulfilled.

·         If is_optional is true, the assignment SHOULD be fulfilled, but if not possible the service deployment is still considered valid.

·         The default value for is_optional is false.

5.3.5.6.3 Notes

·         If no explicit requirement assignment for a requirement with symbolic name is defined, a default requirement assignment with keynames: capability, node, relationship, node_filter having the same values as in the requirement definition in the corresponding node type is assumed.

·         Additionally, the count_value is assumed to be equal to the min_count value of the requirement definition in the corresponding node type.

·         For all explicit requirement assignments with the same symbolic name:

·         the sum of the count_value must be within the count_range specified in the corresponding requirement definition.

·         the sum of the count_value for all non-optional requirements assignments must be within the count_range specified in the corresponding requirement definition.

·         Non-optional requirements have precedence, thus during a service deployment, the optional requirements for all nodes should be resolved only after the non-optional requirements for all nodes have been resolved.

5.3.5.6.4 Examples

Examples of uses for the extended requirement assignment grammar include:

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

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

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

·         The need to specify the number of counts the requirement assigns (when greater than 1).

5.3.5.6.4.1     Example 1 – Hosting requirement on a Node Type

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

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

node_templates:

  my_application_node_template:

    type: tosca.nodes.WebApplication

    ...

    requirements:

      - host:

          node: tosca.nodes.WebServer

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

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

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

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

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

my_application_node_template:

  requirements:

    - database:

        node: my_database

        capability: Endpoint.Database

        relationship: my.types.CustomDbConnection

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

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

node_templates:

  mysql:

   type: tosca.nodes.DBMS.MySQL

    properties:

      # omitted here for brevity

    requirements:

      - host:

          node: tosca.nodes.Compute

          node_filter:

            capabilities:

              - host:

                  properties:

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

                    - mem_size: { greater_or_equal: 512 MB }

              - os:

                  properties:

                    - architecture: { equal: x86_64 }

                    - type: { equal: linux }

                    - distribution: { equal: ubuntu }

              - mytypes.capabilities.compute.encryption:

                  properties:

                    - algorithm: { equal: aes }

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

5.3.5.6.4.4     Example 4 - Requirement assignment for definition with count_range: [2,2]

This example shows how the assignments can look if the Requirement definition has the count_range different from the default [1,1]. In this case the redundant_database requirement has count_range: [2,2]. The Requirement definition is not presented here for brevity. In the Requirement assignment we use the short notation. Note that the count keyname for each assignment is not declared (i.e. the default value of 1 is used) and that the sum of the count values of both assignments is 2 which is in the range of [2,2] as specified in the Requirement definition.

# Example of a (redundant_database) requirement that is fulfilled by

# two node templates named “database1” and “database1

my_critical_application_node_template:

  requirements:

    - redundant_database: database1

    - redundant_database: database2

5.3.5.6.4.5     Example 5 - Requirement assignment for definition with capacity allocation

This example shows how the assignment can look if the requirement is assuming a “capacity allocation” on the properties of the target capability (in this case a capability of type “tosca.capabilities.Compute”). When this requirement is resolved, a node is a valid target and a relationship is created only if both the capacity allocations for num_cpu and mem_size are fulfilled, that is the sum of the capacity allocations from all established relationships + current allocation is less or equal to the value of each respective property in the target capability.

So assuming that num_cpu property in the target capability of a candidate node has value 4 and the sum of capacity allocations of the other resolved requirements to that capability for num_cpu is 1 then then there is enough “remaining capacity” (4 – 1 = 3) to fulfill the current allocation (2), and a relationship to that node is established. Another node with num_cpu with value 2 could not be a valid target since 1 (existing) + 2 (current) = 3, and that is larger than the property value which is 2. Of course, similar calculations must be done for the mem_size allocation.

# Example of a (redundant_database) requirement that is fulfilled by

# two node templates named “database1” and “database1

my_critical_application_node_template:

  requirements:

    - host:

        node: tosca.nodes.Compute

        allocation:

          properties:

            num_cpu: 2

            mem_size: 128 MB

 

5.3.5.7 Node Filter definition

5.3.5.7.1 Grammar

Node filters are defines using condition clauses as shown in the following grammar:

node_filter: <condition_clause>

In the above grammar, the condition_clause represents a Boolean expression that will be used to select (filter) TOSCA nodes that are valid candidates for fulfilling the requirement that defines the node filter. TOSCA orchestrators use node filters are follows:

·         Orchestrators select an initial set of target node candidates based on the target capability type and/or the target node type specified in the requirement definition.

·         A node in this initial set is a valid target node candidate if—when that node is used as the target node for the requirement—the node filter condition clause evaluates to True.

·         Note that the context within which the node filter must be evaluated is the relationship that is established to the target node as a result of fulfilling the requirement. Specifically, this means that the SELF keyword in any TOSCA Path expressions refer to that relationship.

5.3.5.7.2 Example

The following example is a filter that will be used to select a Compute node based upon the values of its defined capabilities. Specifically, this filter will select Compute nodes that support 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:

          $and:

            - $in_range:

              - $get_property: [ SELF, CAPABILITY, num_cpus ]

              - [ 1, 4 ]

            - $greater_or_equal:

              - $get_property: [ SELF, CAPABILITY, mem_size ]

              - 512 MB

 

5.3.6 Interfaces

5.3.6.1 Interface Type

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

5.3.6.1.1 Keynames

The Interface Type is a TOSCA type entity and has the common keynames listed in Section 4.2.5.2 Common keynames in type definitions. In addition, the Interface Type has the following recognized keynames:

Keyname

Mandatory

Type

Description

inputs

no

map of parameter definitions

The optional map of input parameter definitions available to all operations defined for this interface.

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.

5.3.6.1.2 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:

    <parameter_definitions>

  operations:

    <operation_definitions>

  notifications:

    <Error! Reference source not found.Error! Reference source not found.notification_definitions>

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

·         interface_type_name: represents the mandatory 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 for the Interface Type.

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

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

·         notification_definitions: represents the optional map of one or more notification definitions.

5.3.6.1.3 Derivation rules

During Interface Type derivation the keyname definitions follow these rules:

·         inputs: existing parameter definitions may be refined; new parameter definitions may be added.

·         operations: existing operation definitions may be refined; new operation definitions may be added.

·         notifications: existing notification definitions may be refined; new notification definitions may be added.

5.3.6.1.4 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

5.3.6.1.5 Additional Requirements

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

 

5.3.6.2 Interface definition

An Interface definition defines an interface (containing operations and notifications definitions) that can be associated with (i.e. defined within) a Node or Relationship Type definition (including Interface definitions in Requirements definitions). An Interface definition may be refined in subsequent Node or Relationship Type derivations.

5.3.6.2.1 Keynames

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

Keyname

Mandatory

Type

Description

type

yes

string

The mandatory name of the Interface Type this interface definition is based upon.

description

no

string

The optional description for this interface definition.

inputs

no

map of

parameter definitions and refinements

The optional map of input parameter refinements and new input parameter definitions available to all operations defined for this interface (the input parameters to be refined have been defined in the Interface Type definition).

operations

no

map of operation refinements

The optional map of operations refinements for this interface. The referred operations must have been defined in the Interface Type definition.

notifications

no

map of notification refinements

The optional map of notifications refinements for this interface. The referred operations must have been defined in the Interface Type definition.

5.3.6.2.2 Grammar

Interface definitions in Node or Relationship Type definitions have the following grammar:

<interface_definition_name>:

  type: <interface_type_name>

  description: <interface_description>

  inputs:

    <parameter_definitions_and_refinements>

  operations:

    <operation_refinements>

  notifications:

    <Error! Reference source not found.Error! Reference source not found.notification_refinements>

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

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

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

·         interface_description: represents the optional description string for the interface.

·         parameter_definitions_and_refinements: represents the optional map of input parameters which the TOSCA orchestrator will make available (i.e. pass) to all defined operations. This means these parameters and their values will be accessible to the implementation artifacts (e.g., scripts) associated to each operation during their execution

·         the map represents a mix of parameter refinements (for parameters already defined in the Interface Type) and new parameter definitions.

·         with the new parameter definitions, we can flexibly add new parameters when changing the implementation of operations and notifications during refinements or assignments.

·         operation_refinements: represents the optional map of operation definition refinements for this interface; the referred operations must have been previously defined in the Interface Type.

·         notification_refinements: represents the optional map of notification definition refinements for this interface; the referred notifications must have been previously defined in the Interface Type.

5.3.6.2.3 Refinement rules

An interface definition within a node or relationship type (including interface definitions in requirements definitions) uses the following definition refinement rules when the containing entity type is derived:

·         type: must be derived from (or the same as) the type in the interface definition in the parent entity type definition.

·         description: a new definition is unrestricted and will overwrite the one inherited from the interface definition in the parent entity type definition.

 

·         inputs: not applicable to the definitions in the parent entity type but to the definitions in the interface type referred by the type keyname (see grammar above for the rules).

·         operations: not applicable to the definitions in the parent entity type but to the definitions in the interface type referred by the type keyname (see grammar above for the rules).

·         notifications: not applicable to the definitions in the parent entity type but to the definitions in the interface type referred by the type keyname (see grammar above for the rules).

 

5.3.6.3 Interface assignment

An Interface assignment is used to specify assignments for the inputs, operations and notifications defined in the Interface. Interface assignments may be used within a Node or Relationship Template definition (including when Interface assignments are referenced as part of a Requirement assignment in a Node Template).

5.3.6.3.1 Keynames

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

Keyname

Mandatory

Type

Description

inputs

no

map of parameter value assignments

The optional map of input parameter assignments. Template authors MAY provide parameter assignments for interface inputs that are not defined in their corresponding Interface Type.

operations

no

map of operation assignments

The optional map of operations assignments specified for this interface.

notifications

no

map of notification assignments

The optional map of notifications assignments specified for this interface.

5.3.6.3.2 Grammar

Interface assignments have the following grammar:

<interface_definition_name>:

  inputs:

    <parameter_value_assignments>

  operations:

    <operation_assignments>

  notifications:

    <notification_assignments>

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

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

·         parameter_value_assignments: represents the optional map of parameter value assignments for passing input parameter values to all interface operations

·         template authors MAY provide new parameter assignments for interface inputs that are not defined in the Interface definition.

·         operation_assignments: represents the optional map of operation assignments for operations defined in the Interface definition.

·         notification_assignments: represents the optional map of notification assignments for notifications defined in the Interface definition.

 

5.3.6.4 Operation definition

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

A new operation definition may be declared only inside interface type definitions (this is the only place where new operations can be defined). In interface type, node type, or relationship type definitions (including operation definitions as part of a requirement definition) we may further refine operations already defined in an interface type.

An operation definition or refinement inside an interface type definition may not contain an operation implementation definition and it may not contain an attribute mapping as part of its output definition (as both these keynames are node/relationship specific).

5.3.6.4.1 Keynames

The following is the list of recognized keynames for a TOSCA operation definition (including definition refinement)

Keyname

Mandatory

Type

Description

description

no

string

The optional description string for the associated operation.

implementation

no

operation implementation definition

The optional definition of the operation implementation. May not be used in an interface type definition (i.e. where an operation is initially defined), but only during refinements.

inputs

no

map of

parameter definitions

The optional map of parameter definitions for operation input values.

outputs

no

map of

parameter definitions

The optional map of parameter definitions for operation output values.

Only as part of node and relationship type definitions, the output definitions may include mappings onto attributes of the node or relationship type that contains the definition.

5.3.6.4.2 Grammar

Operation definitions have the following grammar:

5.3.6.4.2.1     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>: <operation_implementation_definition>

5.3.6.4.2.2     Extended notation

The following multi-line grammar may be used when additional information about the operation is needed:

<operation_name>:

   description: <operation_description>

   implementation: <operation_implementation_definition>

   inputs:

     <parameter_definitions>

   outputs:

     <parameter_definitions>

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

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

·         operation_description: represents the optional description string for the operation.

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

·         parameter_definitions: represents the optional map of parameter definitions which the TOSCA orchestrator will make available as inputs to or receive as outputs from the corresponding implementation artifact during its execution.

5.3.6.4.3 Refinement rules

An operation definition within an interface, node, or relationship type (including interface definitions in requirements definitions) uses the following refinement rules when the containing entity type is derived:

·         description: a new definition is unrestricted and will overwrite the one inherited from the operation definition in the parent entity type definition.

·         implementation: a new definition is unrestricted and will overwrite the one inherited from the operation definition in the parent entity type definition.

·         inputs: parameter definitions inherited from the parent entity type may be refined; new parameter definitions may be added.

·         outputs: parameter definitions inherited from the parent entity type may be refined; new parameter definitions may be added.

5.3.6.4.4 Additional requirements

·         The definition of implementation is not allowed in interface type definitions (as a node or node type context is missing at that point). Thus, it can be part only of an operation refinement and not of the original operation definition.

·         The default refinement behavior for implementations SHALL be overwrite. That is, implementation definitions in a derived type overwrite any defined in its parent type.

·         Defining a fixed value for an input parameter (as part of its definition) may only use a parameter_value_expression that is meaningful in the scope of the context. For example, within the context of an Interface Type definition functions such as get_propery or get_attribute cannot be used. Within the context of Node or Relationship Type definitions, these functions may only reference properties and attributes accessible starting from SELF (i.e. accessing a node by symbolic name is not meaningful).

·         Defining attribute mapping as part of the output parameter definition is not allowed in interface type definitions (i.e. as part of operation definitions). It is allowed only in node and relationship type definitions (as part of operation refinements) and has to be meaningful in the scope of the context (e.g. SELF).

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

5.3.6.4.5 Examples
5.3.6.4.5.1     Single-line example

interfaces:

  Standard:

    start: scripts/start_server.sh

5.3.6.4.5.2     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

5.3.6.4.5.3     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

 

5.3.6.5 Operation assignment

An operation assignment may be used to assign values for input parameters, specify attribute mappings for output parameters, and define/redefine the implementation definition of an already defined operation in the interface definition. An operation assignment may be used inside interface assignments inside node template or relationship template definitions (this includes when operation assignments are part of a requirement assignment in a node template).

An operation assignment may add or change the implementation and description definition of the operation. Assigning a value to an input parameter that had a fixed value specified during operation definition or refinement is not allowed. Providing an attribute mapping for an output parameter that was mapped during an operation refinement is also not allowed.

Note also that in the operation assignment we can use inputs and outputs that have not been previously defined in the operation definition. This is equivalent to an ad-hoc definition of a parameter, where the type is inferred from the assigned value (for input parameters) or from the attribute to map to (for output parameters).

5.3.6.5.1 Keynames

The following is the list of recognized keynames for an operation assignment:

Keyname

Mandatory

Type

Description

implementation

no

operation implementation definition

The optional definition of the operation implementation. Overrides implementation provided at operation definition.

inputs

no

map of parameter value assignments

The optional map of parameter value assignments for assigning values to operation inputs.

outputs

no

map of parameter

mapping assignments

The optional map of parameter mapping assignments that specify how operation outputs are mapped onto attributes of the node or relationship that contains the operation definition.

5.3.6.5.2 Grammar

Operation assignments have the following grammar:

5.3.6.5.2.1     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>: <operation_implementation_definition>

5.3.6.5.2.2     Extended notation

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

<operation_name>:

   implementation: <operation_implementation_definition>

   inputs:

     <parameter_value_assignments>

   outputs:

     <parameter_mapping_assignments>

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

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

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

·         the implementation declared here overrides the implementation provided at operation definition.

·         parameter_value_assignments: represents the optional map of parameter value assignments for passing input parameter values to operations.

·         assignments for operation inputs that are not defined in the operation definition may be provided

·         parameter_mapping_assignments: represents the optional map of parameter mapping assignments that consists of named output values returned by operation implementations (i.e. artifacts) and associated attributes into which this output value must be stored

·         assignments for operation outputs that are not defined in the operation definition may be provided.

5.3.6.5.3 Additional requirements

·         The behavior for implementation of operations SHALL be override. That is, implementation definitions assigned in an operation assignment override any defined in the operation definition.

·         Template authors MAY provide parameter assignments for operation inputs that are not defined in the operation definition.

·         Template authors MAY provide attribute mappings for operation outputs that are not defined in the operation definition.

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

5.3.6.5.4 Examples

TBD

 

5.3.6.6 Notification definition

A notification definition defines an asynchronous notification or incoming message that can be associated with an interface. The notification is a way for an external event to be transmitted to the TOSCA orchestrator. Values can be sent with a notification as notification outputs and we can map them to node/relationship attributes similarly 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. As opposed to an operation definition, a notification definition does not include an inputs keyname since notifications are not invoked from the orchestrator.

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 (using the <interface_name>.<notification_name> notation) itself identifies the event type that is generated and can be textually used when defining the associated triggers.

A notification definition may be used only inside interface type definitions (this is the only place where new notifications can be defined). Inside interface type, node type, or relationship type definitions (including notifications definitions as part of a requirement definition) we may further refine a notification already defined in the interface type.

A notification definition or refinement inside an interface type definition may not contain a notification implementation definition and it may not contain an attribute mapping as part of its output definition (as both these keynames are node/relationship specific).

5.3.6.6.1 Keynames

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

Keyname

Mandatory

Type

Description

description

no

string

The optional description string for the associated notification.

implementation

no

notification implementation definition

The optional definition of the notification implementation.

outputs

no

map of parameter definitions

The optional map of parameter definitions that specify notification output values.

Only as part of node and relationship type definitions, the output definitions may include their mappings onto attributes of the node type or relationship type that contains the definition.

5.3.6.6.2 Grammar

Notification definitions have the following grammar:

5.3.6.6.2.1     Short notation

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

<notification_name>: <notification_implementation_definition>

5.3.6.6.2.2     Extended notation

The following multi-line grammar may be used when additional information about the notification is needed:

<notification_name>:

  description: <notification_description>

  implementation: <notification_implementation_definition>

  outputs:

    <parameter_definitions>

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

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

·         notification_description: represents the optional description string for the notification.

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

·         parameter_definitions: represents the optional map of parameter definitions for parameters that the orchestrator will receive as outputs from the corresponding implementation artifact during its execution.

5.3.6.6.3 Refinement rules

A notification definition within an interface, node, or relationship type (including interface definitions in requirements definitions) uses the following refinement rules when the containing entity type is derived:

·         description: a new definition is unrestricted and will overwrite the one inherited from the notification definition in the parent entity type definition.

·         implementation: a new definition is unrestricted and will overwrite the one inherited from the notification definition in the parent entity type definition.

·         outputs: parameter definitions inherited from the parent entity type may be refined; new parameter definitions may be added.

5.3.6.6.4 Additional requirements

·         The definition of implementation is not allowed in interface type definitions (as a node or node type context is missing at that point). Thus, it can be part only of a notification refinement and not of the original notification definition.

·         The default sub-classing (i.e. refinement) behavior for implementations of notifications SHALL be overwrite.  That is, implementation artifacts definitions in a derived type overwrite any defined in its parent type.

·         Defining attribute mapping as part of the output parameter definition is not allowed in interface type definitions (i.e. as part of operation definitions). It is allowed only in node and relationship type definitions (as part of operation refinements).

·         Defining a mapping in an output parameter definition may use an attribute target that is meaningful in the scope of the context. Within the context of Node or Relationship Type definitions these functions may only reference attributes starting from the same node (i.e. SELF).

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

5.3.6.6.5 Examples

TBD

 

5.3.6.7 Notification assignment

A notification assignment may be used to specify attribute mappings for output parameters and to define/redefine the implementation definition and description definition of an already defined notification in the interface definition. A notification assignment may be used inside interface assignments inside node or relationship template definitions (this includes when notification assignments are part of a requirement assignment in a node template).

Providing an attribute mapping for an output parameter that was mapped during a previous refinement is not allowed. Note also that in the notification assignment we can use outputs that have not been previously defined in the operation definition. This is equivalent to an ad-hoc definition of an output parameter, where the type is inferred from the attribute to map to.

5.3.6.7.1 Keynames

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

Keyname

Mandatory

Type

Description

implementation

no

notification implementation definition

The optional definition of the notification implementation. Overrides implementation provided at notification definition.

outputs

no

map of parameter

mapping assignments

The optional map of parameter mapping assignments that specify how notification outputs values are mapped onto attributes of the node or relationship type that contains the notification definition.

5.3.6.7.2 Grammar

Notification assignments have the following grammar:

5.3.6.7.2.1     Short notation

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

<notification_name>: <notification_implementation_definition>

5.3.6.7.2.2     Extended notation

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

<notification_name>:

  implementation: <notification_implementation_definition>

  outputs:

    <parameter_mapping_assignments>

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

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

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

·         the implementation declared here overrides the implementation provided at notification definition.

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

·         assignments for notification outputs that are not defined in the operation definition may be provided.

5.3.6.7.3 Additional requirements

·         The behavior for implementation of notifications SHALL be override. That is, implementation definitions assigned in a notification assignment override any defined in the notification definition.

·         Template authors MAY provide attribute mappings for notification outputs that are not defined in the corresponding notification definition.

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

5.3.6.7.4 Examples

TBD

 

5.3.6.8 Operation and notification 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.

A notification implementation definition specifies one or more artifacts to be used by the orchestrator to subscribe and receive a particular notification (i.e. the artifact implements the notification).

The operation implementation definition and the notification implementation definition share the same keynames and grammar, with the exception of the timeout keyname that has no meaning in the context of a notification implementation definition and should not be used in such.

5.3.6.8.1 Keynames

The following is the list of recognized keynames for an operation implementation definition or a notification implementation definition:

Keyname

Mandatory

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. Has no meaning and should not be used within a notification implementation definition.

5.3.6.8.2 Grammar

Operation implementation definitions and notification implementation definitions have the following grammar:

5.3.6.8.2.1     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 an 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.

5.3.6.8.2.2     Short notation for use with multiple artifacts

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>

  timeout: 60

5.3.6.8.2.3     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>

  timeout: 100

5.3.6.8.2.4     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>

  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.

 

5.3.7 Artifacts

5.3.7.1 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.

5.3.7.1.1 Keynames

The Artifact Type is a TOSCA type entity and has the common keynames listed in Section 4.2.5.2 Common keynames in type definitions. In addition, the Artifact Type has the following recognized keynames:

Keyname

Mandatory

Type

Description

mime_type

no

string

The optional mime type property for the Artifact Type.

file_ext

no

list of string

The optional file extension property for the Artifact Type.

properties

no

map of

property definitions

An optional map of property definitions for the Artifact Type.

5.3.7.1.2 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.

5.3.7.1.3 Derivation rules

During Artifact Type derivation the keyname definitions follow these rules:

·         mime_type: a new definition is unrestricted and will overwrite the one inherited from the parent type.

·         file_ext: a new definition is unrestricted and will overwrite the one inherited from the parent type.

·         properties: existing property definitions may be refined; new property definitions may be added.

5.3.7.1.4 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

5.3.7.1.5 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

5.3.7.1.6 Notes

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

·         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.

·         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.

 

5.3.7.2 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.

5.3.7.2.1 Keynames

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

Keyname

Mandatory

Type

Description

type

yes

string

The mandatory artifact type for the artifact definition.

file

yes

string

The mandatory 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

string

The optional description for the artifact definition.

deploy_path

no

string

The file path the associated file will be deployed on 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.

5.3.7.2.2 Grammar

Artifact definitions have one of the following grammars:

5.3.7.2.2.1     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>

5.3.7.2.2.2     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 mandatory symbolic name of the artifact as a string.

·         artifact_description: represents the optional description for the artifact.

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

·         artifact_file_URI: represents the mandatory 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 will 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

5.3.7.2.3 Refinement rules

Artifact definitions represent specific external entities. If a certain artifact definition cannot be reused as is, then it may be completely redefined.

·         If an artifact is redefined, the symbolic name from the definition in the parent node type is reused, but no keyname definitions are inherited from the definition in the parent node type, and the new definition completely overwrites the definition in the parent.

·         If the artifact is not redefined the complete definition is inherited from the parent node type.

5.3.7.2.4 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

 

5.4 Properties, Attributes, and Parameters

This section presents handling data in TOSCA via properties, attributes, and parameters.

The type of the values they contain can be divided into built-in primitive types, special types that are extensions of the primitive types, and collection types, as well as user-defined refinements of these and complex data types that can themselves be defined in TOSCA profiles and the TOSCA file.

Values can also be evaluated from expressions based on TOSCA functions. [See XXX]

The following table summarizes the built-in types. All of these type names are reserved and cannot be used for custom data types. Note, however, that it is possible to derive a custom data type from a primitive type in order to add validation clauses.

Primitive Types: (section 4.4.1)

·         string

·         integer

·         float

·         boolean

·         bytes

·         nil

Special Types: (section 4.4.2)

·         range

·         timestamp

·         scalar-unit.size

·         scalar-unit.time

·         scalar-unit.frequency

·         scalar-unit.bitrate

Collection Types: (section 4.4.3)

·         list

·         map

Notes that were originally in the metadata section:

Important notes:

YAML map keys can be any value, not just strings. TOSCA metadata grammar allows that full YAML expressiveness and does not add additional restrictions beyond requiring correct YAM syntax.

YAML does not specify the bit width of integers and floats but suggests that 32 bits should be acceptable.

Users should be careful about the difference between parsing floats and integers. If they explicitly want a float, they should add ".0".

Users should be careful with version strings being parsed as floats. E.g., "3.2" is a float but "3.2.1" is a string,

 

5.4.1 Primitive Types

The TOSCA primitive types have been specified to allow for the broadest possible support for implementations.

Guiding principles:

1.     Because TOSCA files are written in YAML they must support all the literal primitives in YAML. However, it is important to also allow for consistency of representation of external data, e.g. service template inputs and outputs, property and attribute values stored in a database, etc.

2.     Adherence to 64-bit precision to ensure portability of numeric data.

3.     TOSCA parsers shall not automatically convert between primitive types. Thus, care should be taken to use the correct YAML notation for that type. Details will be provided below.

5.4.1.1 string

An array of Unicode runes. (For storing an arbitrary array of bytes see the “bytes” type, below.)

Because we adhere to 64-bit precision, the minimum length of strings is 0 and the maximum length of strings is 4,294,967,295.

TOSCA does not specify a character encoding. For example, a string could be encoded as UTF-8 or UTF-16. The exact encoding used depends on the implementation.

Be aware that YAML parsers will attempt to parse unquoted character sequences as other types (booleans, integers, floats, etc.) before falling back to the !!string type. For example, the unquoted sequence “0.1” would be interpreted as a YAML !!float. Likewise, the unquoted sequence “nan” would become the !!float value of not-a-number. However, in TOSCA a string value must be specified in YAML as a !!string.

A TOSCA parser shall not attempt to convert other primitive types to strings if a string type is required. This requirement is necessary for ensuring portability, because there is no single, standard representation for the other types, e.g. scientific notations for decimals, the words “true” vs. “True” for booleans, etc. In YAML users should thus add quotation marks around literal strings that YAML would otherwise interpret as other types.

This following example would be invalid if there were no quotation marks around “0.1”:

node_types:

  Node:

  properties:

    name:

    type: string

 

service_template:

  node_templates:

    node:

      type: Node

      properties:

        name: "0.1"

 

5.4.1.1.1 Notes:

1.     There are various ways to specify literal !!string data in YAML for handling indentation, newlines, as well as convenient support for line folding for multiline strings. All may be used in TOSCA. A TOSCA parser shall not modify the YAML string in any way, e.g. no trimming of whitespace or newlines. [YAML 1.2 chapter 6]

2.     The TOSCA functions “concat”, “join”, “token”, “length”, “min_length”, “max_length”, and “pattern” are all Unicode-aware. Specifically, the length of a string is a count of its runes, not the length of the byte array, which may differ according to the encoding. [See XXX]

3.     The TOSCA functions that check for equality, “equal” and “valid_values”, should work regardless of the Unicode encoding. For example, comparing two strings that are “!”, one of which is in UTF-8 and is encoded as “0x21”, the other which is in UTF-16 and is encoded as “0x0021”, would result in equality.  For simplicity, implementations may standardize on a single encoding, e.g., UTF-8, and convert all other encodings to it. [See XXX]

4.     Relatedly, although in YAML 1.2 a !!string is already defined as a Unicode sequence [YAML 1.2 section 10.1.1.3], this sequence can be variously encoded according to the character set and encoding of the YAML stream [YAML 1.2 chapter 5]. The consequence is that a TOSCA string specified in literal YAML may inherit the encoding of the YAML document. Again, implementations may prefer to convert all strings to a single encoding.

5.     TOSCA strings cannot be the null value but can be empty strings (a string with length zero). [See “nil”, below]

6.     YAML is a streaming format, but TOSCA strings are explicitly not streams and thus do have a size limit. Thus, TOSCA implementations should check against the size limit.

[Tal’s comment: for functions we should specify their exact behavior for various primitive types. Some won’t work on all types, e.g. “length” should not work on integers.]

5.4.1.2 integer

A 64-bit signed integer.

For simplicity, TOSCA does not have integers of other bit widths, nor does it have an unsigned integer type. However, it is possible to enforce most of these variations using data type validation clauses [see XXX].

For example, this would be a custom data type for unsigned 16-bit integers:

data_types:

  UInt16:

    derived_from: integer

    validation: { $in_range: [ $value, [ 0, 0xFFFF ] ] }

5.4.1.2.1 Notes

YAML allows for the standard decimal notation as well as hexadecimal and octal notations [YAML 1.2 example 2.19]. In the above example we indeed used the hexadecimal notation.

7.     The JSON schema for YAML 1.2 [YAML 1.2 chapter 10.2] allows for compatibility with JSON, such that YAML would be a superset of JSON. However, note that the JSON format does not distinguish between integers and floats, and thus many JSON implementations use floats instead of integers.

8.     TOSCA does not specify the endianness of integers and indeed makes no requirements for data representation.

5.4.1.3 float

A 64-bit (double-precision) floating-point number [IEEE 754], including the standard values for negative infinity, positive infinity, and not-a-number.

Be aware that YAML parsers will parse numbers with a decimal point as !!float even if they could be represented as !!int, and likewise numbers without a decimal point would always be parsed as !!int.

A TOSCA parser shall not attempt to convert a YAML !!int to a float. This requirement is necessary for avoiding rounding errors and ensuring portability. Users should thus add a “.0” suffix to literal integers that must be floats. Note that this even includes zero, i.e. users must specify “0” for a zero integer and “0.0” for a zero float.

This following example would be invalid if there were no “.0” suffix added to “10”:

node_types:

  Node:

    properties:

      velocity:

        type: float

 

service_template:

  node_templates:

    node:

      type: Node

      properties:

        velocity: 10.0

5.4.1.3.1 Notes

1.     In addition to decimal, YAML also allows for specifying floats using scientific notation as well as special unquoted words for negative infinity, positive infinity, and not-a-number [YAML 1.2 example 2.20].

2.     TOSCA does not specify how to convert to other precisions nor to other formats, e.g. Bfloat16 and TensorFloat-32.

3.     TOSCA does not specify the endianness of floats and indeed makes no requirements for data representation.

5.4.1.4 boolean

A single bit.

Note that in YAML literal booleans can be only either the unquoted all-lowercase words “true” or “false”.

A TOSCA parser shall not attempt to convert these values, nor variations such as “yes” or “True”, as quoted strings to booleans, nor shall it attempt to convert integer values (such as 1 and 0) to booleans. This requirement is necessary for ensuring portability as well as clarity.

5.4.1.5 bytes

An array of arbitrary bytes. Because we adhere to 64-bit precision, the minimum length of bytes is 0 and the maximum length of bytes is 4,294,967,295.

To specify literal bytes in YAML you must use a Base64-encoded !!string [RFC 2045 section 6.8]. There exist many free tools to help you convert arbitrary data to Base64.

Example:

node_types:

  Node:

    properties:

      preamble:

        type: bytes

 

service_template:

  node_templates:

    node:

      type: Node

        properties:

          preamble: "\

R0lGODlhDAAMAIQAAP//9/X17unp5WZmZgAAAOfn515eXvPz7Y6OjuDg4J+fn5\

OTk6enp56enmlpaWNjY6Ojo4SEhP/++f/++f/++f/++f/++f/++f/++f/++f/+\

+f/++f/++f/++f/++f/++SH+Dk1hZGUgd2l0aCBHSU1QACwAAAAADAAMAAAFLC\

AgjoEwnuNAFOhpEMTRiggcz4BNJHrv/zCFcLiwMWYNG84BwwEeECcgggoBADs="

 

5.4.1.5.1 Notes

1.     There is no standard way to represent literal bytes in YAML 1.2. Though some YAML implementations may support the !!binary type working draft, to ensure portability TOSCA implementations shall not accept this YAML type.

2.     The TOSCA functions “length”, “min_length”, and “max_length” work differently for the bytes type vs. the string type. For the latter the length is the count of Unicode runes, not the count of bytes.

3.     TOSCA bytes values cannot be the null value but can be empty arrays (a bytes value with length zero). [See “nil”, below]

5.4.1.6 nil

The nil type always has the same singleton value. No other type can have this value.

This value is provided literally in YAML via the unquoted all-lowercase word “null”.

Example:

node_types:

  Node:

    properties:

      nothing:

        type: nil

        required: true

 

service_template:

  node_templates:

    node:

      type: Node

      properties:

        nothing: null

 

Note that a nil-typed value is distinct from an unassigned value. For consistency TOSCA requires you to assign nil values even though their value is obvious. Thus, the above example would be invalid if we did not specify the null value for the property at the node template.

Following is a valid example of not assigning a value:

node_types:

  Node:

    properties:

      nothing:

        type: nil

        required: false

 

service_template:

  node_templates:

    node:

      type: Node

5.4.2 Special Types

5.4.2.1 TOSCA version

A TOSCA version string.

TOSCA supports the concept of “reuse” of type definitions, as well as template definitions which could be versioned 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.

5.4.2.1.1 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 mandatory integer value greater than or equal to 0 (zero)

·         minor_version: is a mandatory 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.

5.4.2.1.2 Version Comparison

·         When specifying a version string that contains just a major and a minor version number, the version string must be enclosed in quotes to prevent the YAML parser from treating the version as a floating point value.

·         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 branches derived from the same code.

5.4.2.1.3 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

5.4.2.1.4 Notes

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

5.4.2.1.5 Additional Requirements

·         A version value of zero (i.e., ‘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.

5.4.2.2 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.

5.4.2.2.1 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 mandatory integer value that denotes the lower boundary of the range.

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

5.4.2.2.2 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.

5.4.2.2.3 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 ]

5.4.2.3 TOSCA timestamp type

A local instant in time containing two elements: the local notation plus the time zone offset.

TOSCA timestamps are represented as strings following [RFC 3339], which in turn uses a simplified profile of [ISO 8601]. TOSCA adds an exception to RFC 3339: though RFC 3339 supports timestamps with unknown local offsets, represented as the "-0" timezone, TOSCA does not support this feature and will treat the unknown time zone as UTC. There are two reasons for this exception: the first is that many systems do not support this distinction and TOSCA aims for interoperability, and the second is that timestamps with unknown time zones cannot be converted to UTC, making it impossible to apply comparison functions. If this feature is required, it can be supported via a custom data type (see XXX).

5.4.2.3.1 Notes

·         It is strongly recommended that all literal YAML timestamps be enclosed in quotation marks to ensure that they are parsed as strings. Otherwise, some YAML parsers might interpret them as the YAML !!timestamp type, which is rejected by TOSCA (see below).

·         The TOSCA functions "equal", "greater_than", "greater_or_equal", "less_than", and "less_or_equal" all use the universal instant, i.e. as the local instant is converted to UTC by applying the timezone offset.

·         Some YAML implementations may support the !!timestamp type working draft, but to ensure portability TOSCA implementations shall not accept this YAML type. Also note that the YAML !!timestamp supports a relaxed notation with whitespace, which does not conform to RFC 3339.

·         RFC 3339 is based on the Gregorian calendar, including leap years and leap seconds, and is thus explicitly culturally biased. It cannot be used for non-Gregorian locales. Other calendar representations can be supported via custom data types (see XXX).

·         Time zone information is expressed and stored numerically as an offset from UTC, thus daylight savings and other local changes are not included.

·         TOSCA does not specify a canonical representation for timestamps. The only requirement is that representations adhere to RFC 3339.

5.4.2.4 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.

5.4.2.4.1 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 mandatory scalar value.

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

5.4.2.4.2 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 validation 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:

      storage_size: in_range [ 4 GB, 20 GB ]

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

5.4.2.4.3 Concrete Types

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.

5.4.2.4.4 scalar-unit.size
5.4.2.4.4.1     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)

5.4.2.4.4.2     Examples

# Storage size in Gigabytes

properties:

  storage_size: 10 GB

5.4.2.4.4.3     Notes

·         The unit values recognized by TOSCA 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’ is 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 will be based upon individual provider capabilities.

5.4.2.4.5 scalar-unit.time
5.4.2.4.5.1     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

5.4.2.4.5.2     Examples

# Response time in milliseconds

properties:

  respone_time: 10 ms

5.4.2.4.5.3     Notes

·         The unit values recognized by TOSCA 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: 

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

      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

5.4.2.4.6 scalar-unit.frequency
5.4.2.4.6.1     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.

5.4.2.4.6.2     Examples

# Processor raw clock rate

properties:

  clock_rate: 2.4 GHz

5.4.2.4.6.3     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/

5.4.2.4.7 scalar-unit.bitrate
5.4.2.4.7.1     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

5.4.2.4.7.2     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

5.4.3 Collection Types

5.4.3.1 TOSCA list type

The list type allows for specifying multiple values for a 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 must be of the same type. The type (for simple entries) or schema (for complex entries) is defined by the mandatory entry_schema attribute of the respective property definition, attribute definitions, or input or output parameter definitions. Schema definitions can be arbitrarily complex (they may themselves define a list).

5.4.3.1.1 Grammar

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

5.4.3.1.1.1      Square bracket notation

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

5.4.3.1.1.2     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.

5.4.3.1.2 Declaration Examples
5.4.3.1.2.1     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 an additional validation clause):

<some_entity>:

  ...

  properties: 

    listen_ports:

      type: list

      entry_schema:

        description: listen port entry (simple integer type)

        type: integer

        validation: { $max_length: [ $value, 128 ] }

5.4.3.1.2.2     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

5.4.3.1.3 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.

5.4.3.1.3.1     Square bracket notation

listen_ports: [ 80, 8080 ]

5.4.3.1.3.2     Bulleted list notation

listen_ports:

  - 80

  - 8080

5.4.3.2 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.

5.4.3.2.1 Grammar

TOSCA maps are normal YAML dictionaries with following grammar:

5.4.3.2.1.1     Single-line grammar

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

5.4.3.2.1.2     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 mandatory key for an entry in the map

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

5.4.3.2.2 Declaration Examples
5.4.3.2.2.1     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 an additional validation clause):

<some_entity>:

  ...

  properties: 

    emails:

      type: map

      entry_schema:

        description: basic email address

        type: string

        validation: { $max_length: [ $value, 128 ] }

5.4.3.2.2.2     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

5.4.3.2.3 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.

5.4.3.2.3.1     Single-line notation

# notation option for shorter maps

user_name_to_id_map: { user1: 1001, user2: 1002 }

5.4.3.2.3.2     Multi-line notation

# notation for longer maps

user_name_to_id_map:

  user1: 1001

  user2: 1002

5.4.4 Data Type

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

5.4.4.1 Keynames

The Data Type is a TOSCA type entity and has the common keynames listed in Section 4.2.5.2 Common keynames in type definitions. In addition, the Data Type has the following recognized keynames:

Keyname

Mandatory

Type

Description

validation

no

validation clause

The optional validation clause that must evaluate to True for values of this Data Type to be valid.

properties

no

map of property definitions

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

key_schema

conditional (default: string)

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. If not specified, the key_schema defaults to string. For data types that do not derive from the TOSCA map data type, the key_schema is not allowed.

entry_schema

conditional

schema definition

For data types that derive from the TOSCA map or list data types, the mandatory schema definition for the entries in properties of this data type. For data types that do not derive from the TOSCA list or map data type, the entry_schema is not allowed.

5.4.4.2 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>

  validation: <validation_clause>

  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 mandatory 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 primitive type or data type this new data type derives from.

·         validation_clause: represents the optional validation clause that must evaluate to True for values of this data type to be valid.

·         property_definitions: represents the optional map of one or more property definitions that provide the schema for the data type

      property_definitions may not be added to data types derived_from TOSCA primitive types.

·         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), it represents the optional schema definition for the keys used to identify entry 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), it represents the mandatory schema definition for the entries in properties of this type.

5.4.4.3 Derivation rules

During Data Type derivation the keyname definitions follow these rules:

·         validation: a new validation clause may be defined; this validation clause does not replace the validation clause defined in the parent type but is considered in addition to it.

·         properties: existing property definitions may be refined; new property definitions may be added.

·         key_schema: the key_schema definition may be refined according to schema refinement rules.

·         entry_schema: the entry_schema definition may be refined according to schema refinement rules.

5.4.4.4 Additional Requirements

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

·         Any validation 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.

·         Property definitions may not be added to data types derived from TOSCA primitive types.

5.4.4.5 Examples

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

5.4.4.5.1 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

5.4.4.5.2 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

      validation: { $max_length: [ $value, 128 ] }

5.4.5 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.

If the schema definition specifies a map key, the type of the key schema must be derived originally from the string type (which basically ensures that the schema type is a string with additional validation clauses). As there is little need for complex keys this caters to more straight-forward and clear specifications. If the key schema is not defined it is assumed to be string by default.

Schema definitions appear in data type definitions when derived_from a map or list type or in parameter, property, or attribute definitions of a map or list type.

5.4.5.1 Keynames

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

Keyname

Mandatory

Type

Description

type

yes

string

The mandatory data type for the key or entry.

If this schema definition is for a map key, then the referred type must be derived originally from string.

description

no

string

The optional description for the schema.

validation

no

validation clauses\

The optional validation clause that must evaluate to True for the property.

key_schema

no (default: string)

schema definition

When the schema itself is of type map, the optional schema definition that is used to specify the type of the keys of that map’s entries (if key_schema is not defined it is assumed to be “string” by default). For other schema types, the key_schema must not be defined.

entry_schema

conditional

schema definition

When the schema itself is of type map or list, the schema definition is mandatory and is used to specify the type of the entries in that map or list. For other schema types, the entry_schema must not be defined.

5.4.5.2 Grammar

5.4.5.2.1 Short notation

The following single-line grammar may be used when only the schema type needs to be declared:

<schema_definition>: <schema_type>

5.4.5.2.2 Extended Notation

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

<schema_definition>:

  type: <schema_type>

  description: <schema_description>

  validation: <schema_validation_clause>

  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_type: represents the mandatory type name for entries of the specified schema

      if this schema definition is for a map key, then the schema_type must be derived originally from string.

·         schema_description: represents the optional description of the schema definition

·         schema_validation_clause: represents the optional validation clause for entries of the specified schema.

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

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

5.4.5.3 Refinement rules

A schema definition uses the following definition refinement rules when the containing entity type is derived:

·         type: must be derived from (or the same as) the type in the schema definition in the parent entity type definition.

·         description: a new definition is unrestricted and will overwrite the one inherited from the schema definition in the parent entity type definition.

·         validation: a new definition is unrestricted; this validation clause does not replace the validation clause defined in the schema definition in the parent entity type but is considered in addition to it.

·         key_schema: may be refined (recursively) according to schema refinement rules.

·         entry_schema: may be refined (recursively) according to schema refinement rules.

5.4.6 Validation clause definition

A validation clause that must evaluate to True if the value for the entity it references is considered valid.

5.4.6.1 Grammar

Validation clauses have the following grammar:

validation: < validation_clause>

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

·         validation_clause: represents a Boolean expression that must evaluate to True in order for values to be valid. Any Boolean expression can be used with any function with any degree of nesting.

5.4.6.2 The $value Function

The Boolean expression used as a validation clause must have a mechanism for referencing the value to which the expression applies. A special-purpose function is introduced for this purpose. This function is named $value and refers to the value used for the data type or the parameter definition that contains the validation clause.

5.4.6.3 Examples

The following shows an example of validation clauses used in data type definitions:

data_types:

 

  # Full function syntax for the $value function

  Count1:

    derived_from: integer

    validation: { $greater_or_equal: [ { $value: [] }, 0 ] }

 

  # Simple function syntax for the $value function

  Count2:

    derived_from: integer

    validation: { $greater_or_equal: [ $value, 0 ] }

 

  # Full function syntax with arguments

  FrequencyRange:

    properties:

      low:

        type: scalar-unit.frequency

      high:

        type: scalar-unit.frequency

    validation:

      $greater_or_equal: [ { $value: [ high ] }, { $value: [ low ] } ]

 

The following shows an example of validation clauses used in property definitions:

node_types:

 

  Scalable:

    properties:

      minimum_instances:

        type: integer

        validation: { $greater_or_equal: [ $value,  0 ] }  # positive integer

      maximum_instances:

        type: integer

        validation:

          $greater_or_equal:

            - $value

            - $get_property: [ SELF, minimum_instances ]

      default_instances:

        type: integer

        validation:

          $and:

            - $greater_or_equal:

              - $value

              - $get_property: [ SELF, minimum_instances ]

            - $less_or_equal:

              - $value

              - $get_property: [ SELF, maximum_instances ]

        required: false

 

5.4.7 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.

5.4.7.1 Attribute and Property reflection

The actual state of the entity, at any point in its lifecycle once instantiated, is reflected by an attribute.  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). If an attribute is reflected from a property, its initial value is the value of the reflected property.

5.4.7.2 Keynames

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

Keyname

Mandatory

Type

Description

type

yes

string

The mandatory data type for the property.

description

no

string

The optional description for the property.

required

No (default: true)

 

boolean

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

default

no

<must match property type>

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

The default keyname SHALL NOT be defined when property is not required (i.e. the value of the required keyname is false).

value

no

<see below>

An optional key that may provide a fixed value to be used. A property that has a fixed value provided (as part of a definition or refinement) cannot be subject to a further refinement or assignment. That is, a fixed value cannot be changed.

status

No (default: supported)

 

string

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

validation

no

validation clause

The optional validation clause for the property.

key_schema

conditional (default: string)

schema definition

The schema definition for the keys used to identify entries in properties of type TOSCA map (or types that derive from map). If not specified, the key_schema defaults to string. For properties of type other than map, the key_schema is not allowed.

entry_schema

conditional

schema definition

The schema definition for the entries in properties of TOSCA collection types such as list, map, or types that derive from list or map) If the property type is a collection type, the entry schema is mandatory. For other types, the entry_schema is not allowed.

external-schema

no

string

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

Defines a section used to declare additional metadata information.

5.4.7.3 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.

5.4.7.4 Grammar

Property definitions have the following grammar:

<property_name>:

  type: <property_type>

  description: <property_description>

  required: <property_required>

  default: <default_value>

  value: <property_value> | { <property_value_expression> }

  status: <status_value>

  validation: <validation_clause>

  key_schema: <key_schema_definition>

  entry_schema: <entry_schema_definition>

  metadata:

    <metadata_map>

The following single-line grammar is supported when only a fixed value or fixed value expression needs to be provided to a property:

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

This single-line grammar is equivalent to the following:

<property_name>:

    value: <property_value> | { <property_value_expression> }

Note that the short form can be used only during a refinement (i.e. the property has been previously defined).

 

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

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

·         property_description: represents the optional description of the property.

·         property_type: represents the mandatory 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 is used as a default value if a value is not provided by another means (via the fixed_value definition or via property assignment);

      the default_value shall not be defined for properties that are not required (i.e. property_required is “false”) as they will stay undefined.

·         <property_value> | { <property_value_expression> }: contains a type-compatible value or value expression that may be defined during property definition or refinement to set and fix the value definition of the property

      note that a value definition cannot be changed; once defined, the property cannot be further refined or assigned. Thus, value definitions should be avoided in data_type definitions.

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

·         validation_clause: represents the optional Boolean expression that must evaluate to true for a value of this property to be valid.

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

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

·         metadata_map: represents the optional map of string.

5.4.7.5 Refinement rules

A property definition within data, capability, node, relationship, group, policy, and artifact types (including capability definitions in node types) matching the name of a property in the derived entity type uses the following refinement rules to combine the two property definitions together:

·         type: must be derived from (or the same as) the type in the property definition in the parent entity type definition.

·         description: a new definition is unrestricted and will overwrite the one inherited from the property definition in the parent entity type definition.

·         required: if defined to “false” in the property definition parent entity type it may be redefined to “true”; note that if undefined it is automatically considered as being defined to “true”.

·         default: a new definition is unrestricted and will overwrite the one inherited from the property definition in the parent entity type definition (note that the definition of a default value is only allowed if the required keyname is (re)defined as “true”).

·         value: if undefined in the property definition in the parent entity type, it may be defined to any type-compatible value; once defined, the property cannot be further refined or assigned.

·         status: a new definition is unrestricted and will overwrite the one inherited from the property definition in the parent entity type definition.

·         validation: a new definition is unrestricted; this validation clause does not replace the validation clause defined in the property definition in the parent entity type but is considered in addition to it.

·         key_schema: if defined in the property definition in the parent entity type it may be refined according to schema refinement rules.

·         entry_schema: if defined in the property definition in the parent entity type it may be refined according to schema refinement rules.

·         metadata: a new definition is unrestricted and will overwrite the one inherited from the property definition in the parent entity type definition.

5.4.7.6 Additional Requirements

·         Implementations of TOSCA 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.

·         If a key_schema or entry_schema keyname is provided, its value (string) MUST represent a valid schema definition that matches the property type (i.e. the property type as defined by the type keyword must be the same as or derived originally from map (for key_schema) or map or list (for entry_schema).

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

5.4.7.7 Examples

The following represents an example of a property definition with a validation clause:

properties:

  num_cpus:

    type: integer

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

    default: 1

    required: true

    validation; { $valid_values: [ $value, [ 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

 

5.4.8 Property assignment

This section defines the grammar for assigning values to properties within TOSCA templates.

5.4.8.1 Keynames

The TOSCA property assignment has no keynames.

5.4.8.2 Grammar

Property assignments have the following grammar:

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

·         property_name: represents the name of a property that will 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 property.  Property values may be provided as the result of the evaluation of an expression or a function.

5.4.8.3 Additional Requirements

·         Properties that have a (fixed) value defined during their definition or during a subsequent refinement may not be assigned (as their value is already set).

·         If a required property has no value defined or assigned, its default value is assigned

·         A non-required property that is not assigned it stays undefined, thus the default keyname is irrelevant for a non-required property.

5.4.9 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.

5.4.9.1 Attribute and Property reflection

The actual state of the entity, at any point in its lifecycle once instantiated, is reflected by an attribute.  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). If an attribute is reflected from a property, its initial value is the value of the reflected property.

5.4.9.2 Keynames

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

Keyname

Mandatory

Type

Description

type

yes

string

The mandatory data type for the attribute.

description