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

Dear Chris, Calin and Arturo,
 
please find DÃnes questions below (he is not authorized to send mails to the TOSCA list).
 
Greetings,
 
GÃbor
 
 

From: "Nemeth, Denes (Nokia - HU/Budapest)" < denes.nemeth@nokia.com >
Date: 2020. May 18., Monday 14:02
To: " tosca@lists.oasis-open.org " < tosca@lists.oasis-open.org >
Cc: Arturo Martin De Nicolas < arturo.martin-de-nicolas@ericsson.com >
Subject: Re: [tosca] Use of properties defaults


 

Hello Chris and Calin and Arturo
 
I will try to attach a more concrete example that possibly includes all the corner cases to help the discussions.
Even after reading the 2.0 specs for me it is still not clear what is the exact intention.
 
Is it possible to define a default for a non-required property? (line in yellow).

 
If one property becomes required that had a default value, than is it used?

(lines in green)
 
Maybe if only the required properties shall have default values at all, than life would be simpler.
 
Cheers Denes
 
 
tosca_definitions_version: tosca_simple_yaml_1_0
node_types:
  my_type_1:
    properties:
      p0:
        type: string
        required: false
      p1:
        type: string
        required: false
       
default: d1
      p2:
        type: string
        required: true
        default: d2
      p3:
        type: string
        required: true
  my_type_2:
    derived_from: my_type_1
    properties:
      p 1 :
       
required: true
        default: d4
  my_type_3:
    derived_from: my_type_1
    properties:
     
p 1 :
         #required: true assumed even if not stated since true is the default for required
         description: dsad
topology_template:
  node_templates:
   node1:
     type: my_type_1
     properties:
       p0: a
       p1: b
       p2: c
       p3: d
   node2:
      type: my_type_1
      properties:
        # p0 does not have a value
       
# p1 does not have a value
        # p2 has value d2
        p3: d # this can not be ommited
  node3:
      type: my_type_2
      properties:
        # p0 does not have a value
       
# p1 has value d4
        # p2 has value d2
        p3: d # this can not be ommited
   node4:
      type: my_type_3
      properties:
        p0: a
       
# p1 has value d1
        # p2 has value d2
        p3: d
      
 

From: < tosca@lists.oasis-open.org > on behalf of Arturo Martin De Nicolas < arturo.martin-de-nicolas@ericsson.com >
Date: 2020. May 18., Monday 9:56
To: " tosca@lists.oasis-open.org " < tosca@lists.oasis-open.org >
Subject: [tosca] Use of properties defaults


 

Hello Chris and Calin,
 
The use of default values for properties in TOSCA is a recurrent topic of controversy in ETSI NFV SOL.
 
What has been stated in the TOSCA Language WG is that default values are only meaningful for properties that are defined as required = true e.g. in a node type definition.
 
A default value for a property that is defined as required = false in a node type definition is irrelevant and it will never be used: a node template either provides a property assignment for that property (in which case
the default value is overrriden) or it does not provide a property assignment (in which case the property is not used in this node template).
 
Unfortunately this is not explicitly written in the TOSCA spec. Furthermore, there is at least one example in 3.4.5.7 in TOSCA 2.0 with a default value for a property which has required = false. In TOSCA 1.3 there are
a few more examples but these are in the profile part.
 
Can we discuss this topic briefly tomorrow and add a clarification in TOSCA about the use of defaults?
 
Best regards,
Arturo