Capability Assertion

A "capability" or "capability interface" is a set of messages and mechanics that enables some functionality. For example, the Speaker capability defines events, directives, and use of the speaker MQTT topic.

A device must explicitly assert its support for each capability that it uses, including the always-required System capability.

• Getting Started
  • AIA Envelope
  • Topic Management
• publish Topic
  • Publish
• acknowledge Topic
  • Acknowledge

Getting Started

AIA Envelope

Asserting capabilities requires v1 of the AIA envelope.

Topic Management

To support capability assertion, the device must participate in the publish and acknowledge MQTT topics, which are nested under the capabilities topic.

publish Topic

Publish

The device must send the Publish message to inform AIA of which capability interfaces it supports.

The following principles determine when to send this message:

• The device may only send the Publish message immediately after receiving the Acknowledge message on the fromservice topic. If it is sent after any other message, AIA will reject it.
• After the first connection to AIA, the device must send the initial set of capabilities.
• If capabilities have changed, the device must re-establish a connection to AIA and send an updated set of capabilities.

Note: The Publish message must always include the full set of capabilities that the device supports. Partial updates will result in an error state or may be rejected.

Sample Message

{
  "header": {
    "name": "Publish",
    "messageId": "{{STRING}}"
  },
  "payload": {
    "capabilities": [
      {
        "type": "AisInterface",
        "interface": "{{STRING}}",
        "version": "{{STRING}}",
        "configurations": {
          ...
        }
      },
      ...
    ]
  }
}

Payload Parameters

acknowledge Topic

Acknowledge

AIA sends the Acknowledge message on the acknowledge topic in response to a Publish message on the publish topic.

Sample Message

{
  "header": {
    "name": "Acknowledge",
    "messageId": "{{STRING}}"
  },
  "payload": {
    "publishMessageId": "{{STRING}}",
    "code": "{{STRING}}",
    "description": "{{STRING}}"
  }
}

Payload Parameters