Clarification of Value-Only for Operation and Capability

[BirgitBoss]

What?

/submodels/{submodelIdentifier}/submodel-elements/{idShortPath}/$value:

For Operation and Capability there is no Value-Only serialization. However the idShortPath may point to a SubmodelElementList containing Operations or to a BasicEvent itself etc.

So in this case a error is returned? Or an empty object or list, resp.?

In the case a collection contains

myCollection: 
{ 
   "prop1": string, 
   "capability1": Capability,
   "operation1": Operation,
    "list": SubmodelElementList(typeofElements:Operation) 
}

then Value-Only of the collection is either

{
 "prop1": "value of prop1"
}

ignoring "capability1" and "operation1" and "list" or an error message is returned: "no Value-Only serialization possible". However, the latter would mean that there is no Value-Only serialization of a submodel containing Operations, Events or Capabilities.

Or (see https://github.com/admin-shell-io/aas-specs/issues/402)

{
 "prop1": "value of prop1"
 "list": []
}

ADDED: the idShortPath can direct link to an BasicEventElement or a Capability or an Operation: in this case it should be sufficient to throw an error.

[sebbader-sap]

We discussed the topic today in the task force call. It's clear that we have a critical gap here, however, we don't see that we will have a fix already for V3.0.2. Therefore, I am changing the milestone tag.

[sebbader-sap]

I think there are in total these four options:

1. throw an error
2. serialise these SMEs in a certain way, e.g., as an empty element
3. state that for these SMEs their normal serialisation shall be used
4. add specific ValueOnly elements for them.

[sebbader-sap]

As discussed in today's AAS Workstream:

• [ ] Define the error message/code for a GET .../submodel-elements/idShortOfaOperation/$value

[BirgitBoss]

Additionally define what happens for

• [ ] Define the error message/code for a GET .../submodel-elements/idShortOfaListOfOperationsOrCapabilities/$value