Question: Should invokeaction always respond with an ActionStatus object

[benfrancis]

Currently a synchronous invokeaction response contains an output member whereas an asynchronous invokeaction response contains a status member with an ActionStatus object.

I think @hspaay would prefer that invokeaction always responds with an ActionStatus object, so I have opened this issue to discuss that in case anyone else agrees.

[benfrancis]

Personally I prefer keeping the simpler payload format for synchronous invokeaction response because it is far neater in the simple case of a synchronous action where the request contains an input member and the response contains an output member:

Request:

{
  "thingID": "https://mythingserver.com/things/mylamp1",
  "messageID": "ff29aac5-062a-4583-9044-be2d45d6ad57",
  "messageType": "request",
  "operation": "invokeaction",
  "name": "fade",
  "input": {
    "level": 100,
    "duration": 5
  },
  "correlationID": "50d5f441-cb07-4513-80b4-cd062cddc1e0"
}

Response:

{
  "thingID": "https://mythingserver.com/things/mylamp1",
  "messageID": "e47c3727-d68b-4284-a2cc-5883d8fa43a4",
  "messageType": "response",
  "operation": "invokeaction",
  "name": "fade",
  "output": true,
  "timestamp": "2025-09-03T18:14:55.541Z",
  "correlationID": "50d5f441-cb07-4513-80b4-cd062cddc1e0"
}

The current intepretation of synchronous actions in the specification is that synchronous actions are not queryable or cancellable, and therefore there is no need for them to be assigned an actionID or state, and there is no need for timeRequested or timeEnded because the timeRequested is the time the request was sent and the timeEnded is the time the response is received (reflected in the timestamp member of the response).

However, depending on the outcome of issue #98 it may be reasonable to revisit that.