[OASIS Issue Tracker] (TOSCA-201) Harmonize Properties and Capabilities in Node Types

[OASIS Issues Tracker <workgroup_mailer@lists.oasis-open.org>]

    [ https://issues.oasis-open.org/browse/TOSCA-201?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=50274#comment-50274 ] 

Chris Lauwers commented on TOSCA-201:
-------------------------------------

Section 11 of the latest draft shows the following example:

node_templates:
  mysql:
    type: tosca.nodes.DBMS.MySQL
    properties:
      # omitted here for sake of brevity
    requirements:
      - host: 
          node: tosca.nodes.Compute
          target_filter:
            properties:
              - num_cpus: { in_range: [ 1, 4 ] }
              - mem_size: { greater_or_equal: 2 }
            capabilities:
              - os:
                  properties:
                    - architecture: x86_64
                    - type: linux
                    - distribution: ubuntu

In this example, we're specifying a requirement for a Ubuntu host using a capability, but we're specifying a requirement for 2G of memory using a property. My confusion is based on the fact that we seem to be using 2 different mechanisms to accomplish the same thing.

> Harmonize Properties and Capabilities in Node Types
> ---------------------------------------------------
>
>                 Key: TOSCA-201
>                 URL: https://issues.oasis-open.org/browse/TOSCA-201
>             Project: OASIS Topology and Orchestration Specification for Cloud Applications (TOSCA) TC
>          Issue Type: Improvement
>          Components: Profile-YAML
>            Reporter: Chris Lauwers
>            Priority: Minor
>
> It appears that both Properties and Capabilities are used to map Node Types to requirements without any clear distinction between the two mechanisms. Or, said a different way, both Properties and Capabilities are used to express the capabilities of node types. We should simplify things by harmonizing these two approaches and settle on one single way to express capabilities (e.g. by doing away with Properties on Node Types and only using Capabilities). 



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