Accessing nested properties

[Paul Jordan <paul.m.jordan@outlook.com>]

I recently came across a sytax restriction. Not sure if the TC have 
already discussed this.

Consider the valid syntax:


node_types

ÂÂÂ <node_name>:

ÂÂÂ derived from: <node_type_name>

ÂÂÂ requirements:

ÂÂÂ -ÂÂÂ <requirement_name>

ÂÂÂ ÂÂÂ capability: <capability_type_name>

ÂÂÂ ÂÂÂ relationship:

ÂÂÂ ÂÂÂ ÂÂÂ type: <relationship_type_name>

ÂÂÂ ÂÂÂ ÂÂÂ interfaces:

ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ <interface_name>:

ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ operations:

ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ <operation_name>

ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ inputs:

ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ <parameter_name>

ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ type: <datatype_name>

ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ value: ( get_property: [ SOURCE, 
.... ] }


Now, note that the capability referenced by <capability_type_name> may 
have properties. However according to V2.0 draft Section 4.4.2 there 
does not seem to be a valid syntax to reference the capability property 
from within the get_property clause.

There seems to be a need for a general purpose syntax to permit 
selection of a single parameter value from a valid TOSCA template of 
arbitrary depth and complexity; something like JSONPath or the less well 
supported YAMLPath.

Regards

Paul Jordan