Use condition syntax in node filters and capability filters

[lauwers]

I have a need to define more complex requirement fulfillment logic than what can be expressed using node and capability filters. I believe the existing condition syntax could be used for this purpose. The following example shows how condition syntax could express anti-collocation behavior:

tosca_definitions_version: tosca_2_0

capability_types:
  Host:
    description: for hosting software components

relationship_types:
  HostedOn:
    description: relationship to hosting container

node_types:

  Host:
    properties:
      uuid:
        type: string
    capabilities:
      host:
        type: Host

  SoftwareComponent:
    requirements:
      - host:
          capability: Host
          relationship: HostedOn

service_template:

  node_templates:

    host1:
      type: Host
      properties:
        uuid: host.1
      
    host2:
      type: Host
      properties:
        uuid: host.2
      
    host3:
      type: Host
      properties:
        uuid: host.3
      
    software1:
      type: SoftwareComponent
      requirements:
        - host:
            node: Host

    software2:
      type: SoftwareComponent
      requirements:
        - host:
            node: Host
            filter:
              - not:
                  [TARGET, uuid] : { equal: [software1, RELATIONSHIP, host, TARGET, uuid ] }

[lauwers]

My apologies, but I believe I have an error in the filter clause in the above example. I think the condition in the filter needs a get_property function to work correctly, as follows:

tosca_definitions_version: tosca_2_0

capability_types:
  Host:
    description: for hosting software components

relationship_types:
  HostedOn:
    description: relationship to hosting container

node_types:

  Host:
    properties:
      uuid:
        type: string
    capabilities:
      host:
        type: Host

  SoftwareComponent:
    requirements:
      - host:
          capability: Host
          relationship: HostedOn

service_template:

  node_templates:

    host1:
      type: Host
      properties:
        uuid: host.1
      
    host2:
      type: Host
      properties:
        uuid: host.2
      
    host3:
      type: Host
      properties:
        uuid: host.3
      
    software1:
      type: SoftwareComponent
      requirements:
        - host:
            node: Host

    software2:
      type: SoftwareComponent
      requirements:
        - host:
            node: Host
            filter:
              - not:
                  [TARGET, uuid] : { equal:  { get_property: [software1, RELATIONSHIP, host, TARGET, uuid ] } }

[lauwers]

Node filters now use boolean expressions as documented in https://docs.oasis-open.org/tosca/TOSCA/v2.0/csd05/TOSCA-v2.0-csd05.html#_Toc125468604. Using this syntax, the example above would look as follows:

tosca_definitions_version: tosca_2_0

capability_types:
  Host: {}

relationship_types:
  HostedOn: {}

node_types:
  Host:
    properties:
      uuid:
        type: string
    capabilities:
      host:
        type: Host

  SoftwareComponent:
    requirements:
      - host:
          capability: Host
          relationship: HostedOn
          count_range: [1, 1]

service_template:
  node_templates:

    host1:
      type: Host
      properties:
        uuid: host.1
      
    host2:
      type: Host
      properties:
        uuid: host.2
      
    host3:
      type: Host
      properties:
        uuid: host.3
      
    software1:
      type: SoftwareComponent
      requirements:
        - host:
            node: Host

    software2:
      type: SoftwareComponent
      requirements:
        - host:
            node: Host
            node_filter:
              $not:
                $equal:
                  - $get_property: [SELF, TARGET, uuid]
                  - $get_property: [software1, RELATIONSHIP, host, TARGET, uuid] 

Of course, the example itself is a bit convoluted, since anti-collocation behavior should be specified instead using a declarative policy as suggested in Issue #141