RE: [tosca] Groups - Refining Entity Definitions uploaded

[Arturo Martin De Nicolas <arturo.martin-de-nicolas@ericsson.com>]

Hello Chris,

 

Thanks for the good discussion paper.

 

One of the things mentioned as possible in the derivation is to “assign it a fixed value”:

 

Refining Property Definitions

TOSCA type entities can refine properties defined in one of their parent types by doing one or more of the following:

-          Adding a default value.

-          Adding (additional) constraints. The additional constraints must be narrower than the constraints specified in the original entity definition (i.e. it is not possible for property refinements to relax the constraints specified in the original entity definition).

-          Assigning a fixed value

-          Turning an optional property into a required property

-          Specifying entry_schema and/or key_schema for container types (i.e. lists and maps). If the original entity definition already includes an entry_schema or key_schema, then any such schemas specified in the refinement must derive from the equivalent schema in the original entity definition.

 

And in fact, we already have at least one example in the TOSCA Simple Profile of a type refinement in which this happens (10.1.4.2):

 

relationship_types:

 

  MyAttachesTo:

    derived_from: AttachesTo

    properties:

      location: /default_location

 

 

However, this is a property assignment in a node type definition. According to the grammar, node type definitions contain property definitions, but not assignments.

 

The way to achieve same result but complying with he grammar is with a constraint “equal”.

 

Do you agree that this is an inconsistency in the TOSCA Simple Profile?

 

Best regards,

Arturo

 

From: tosca@lists.oasis-open.org <tosca@lists.oasis-open.org> On Behalf Of Chris Lauwers
Sent: Tuesday, August 21, 2018 2:50 AM
To: tosca@lists.oasis-open.org
Subject: [tosca] Groups - Refining Entity Definitions uploaded

 

Document Name: Refining Entity Definitions

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Description
TOSCA allows template designers to refine entities defined in types.
However, these refinement mechanisms are not clearly spelled out in the
specification. In addition, there are inconsistencies in how different
types of entities can be refined. This document intends to more formally
define refinement functionality and suggest ways to eliminate
inconsistencies.
Download Latest Revision
Public Download Link

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Submitter: Chris Lauwers
Group: OASIS Topology and Orchestration Specification for Cloud Applications (TOSCA) TC
Folder: Working Documents
Date submitted: 2018-08-20 17:49:18
Revision: 1