Allotted Resource TOSCA Model

Objective

The current implementation (Beijing) of Allotted Resources in TOSCA uses a property on the allotted resource that stores a providing service  identifier (metadata attribute) as a foreign key.  The proposal represents Allotted Resources in TOSCA using correct TOSCA syntax and semantics to define the mapping between allotted resources and their providing [infrastructure] services. 

Basics

Fundamentally, we are redefining an Allotted Resource to be any node type derived directly or indirectly from onap.nodes.Resource which has a requirement for a service with the capability to be an allotted resource provider.  

Allotted Resource Provider Capability 

Define a capability type, onap.nodes.AllottedResourceProvider, that “providing services” will have.  This is used to identify infrastructure services that can produce allotted resources. 

• Each providing service should declare this capability and populate the “valid_source_types” with the allotted resource node types it can produce.  Since “valid_source_types” is a list, providing services may produce multiple different allotted resources.  Given this is explicitly declared, the orchestrator can validate that a service exists to provide the allotted resource.
• Allotted resource concrete types will always map to a single providing service type.
• Allotted Resources declare a requirement for this capability.  Due to N:1 nature of allotted resources to providing services, the requirement can directly specify the providing service type (i.e., node filtering is not required).  This will be a “dangling” requirement, since the actual providing service instance will be chosen at run-time (by SNIRO/OOF)
• The existence of an AllottedResourceProvider requirement is sufficient to identify an allotted resource.  They do not need to be derived from some root “allotted_resource” type.

We also define a relationship type for the connection between allotted resources and their providing services.  This relationship must be defined on the requirement for an allotted resource provider (in the allotted resource node type).  At this time, there are no specific attributes defined for this relationship.

capability_types:
   onap.capabilities.AllottedResourceProvider:
      derived_from: tosca.capabilities.Root
      description:  Capability to produce allotted resources of the listed source types
      valid_source_types:  []
      properties:
         # TBD if any properties needed
      attributes:
         # TBD if any attributes needed

relationship_types:
   onap.relationships.AllottedBy:
      derived_from: tosca.relationships.DependsOn
      description:  Relates an allotted resource to its providing service (provider)