Alexa.RTCSessionController Interface

Implement the Alexa.RTCSessionController interface in your Alexa skill for devices that are capable of real-time communication. By using the RTCSessionController interface in your skill, Alexa users can communicate remotely with their security cameras and other devices. For example, users can communicate with a visitor at their front door. For more details about security skills, see Smart Home Security Overview.

For the list of languages that the RTCSessionController interface supports, see List of Alexa Interfaces and Supported Languages.

To develop and test your Alexa skill, you can use the Smart Home debugger to see logs from your WebRTC sessions in real-time. For details, see Smart Home Debugger for WebRTC Skills.

Utterances

The Alexa.RTCSessionController interface uses the pre-built voice interaction model. Users can start conversations by using one of the following utterances:

Alexa, show me the front door camera
Alexa, answer the front door.
Alexa, talk to the front door.
Alexa, talk to the backyard camera.
Alexa, talk to the baby monitor.
Alexa, get the call going with the front door.
Alexa, please call front door.
Alexa, respond to the front door.
Alexa, speak to the front door.
Alexa, talk to my front door camera.
Alexa, talk to the person at the main door.

Users can end conversations by using one of the following utterances:

Alexa, go home.
Alexa, stop.

After the user says one of these utterances, Alexa sends a corresponding directive to your skill.

Discovery

You describe endpoints that support Alexa.RTCSessionController using the standard discovery mechanism described in Alexa.Discovery. In addition, identify if duplex is supported in the configuration of the Alexa.RTCSessionController capability.

Use CAMERA or DOORBELL for the display category. For the full list of display categories, see display categories.

In addition to the usual discovery response fields, for the RTCSessionController entry in the capabilities array, include a configuration object that contains the following fields.

Field Description Type
isFullDuplexAudioSupported True if the device supports 2-way (full duplex) communication. False if the device supports 1-way (half duplex) communication. The default is false. If your device doesn't support audio communication, set the value to false and include an `a=sendonly` attribute. Boolean

Discover response example

The following example shows a Discover.Response message for a security camera that supports the RTCSessionController, MediaMetadata, and EndpointHealth interfaces.

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{
  "event": {
    "header": {
      "namespace":"Alexa.Discovery",
      "name":"Discover.Response",
      "payloadVersion": "3",
      "messageId": "<message id>"
    },
    "payload":{
      "endpoints":[
        {
          "endpointId": "<unique ID of the endpoint>",
          "manufacturerName": "<the manufacturer name of the endpoint>",
          "description": "<a description that is shown in the Alexa app>",
          "friendlyName": "My front door camera",
          "displayCategories": ["CAMERA"],
          "cookie": {},
          "capabilities": [
            {
              "type": "AlexaInterface",
              "interface": "Alexa.RTCSessionController",
              "version": "3.1",
              "configuration": {
                "isFullDuplexAudioSupported": true
              }
            },
            {
              "type": "AlexaInterface",
              "interface": "Alexa.MediaMetadata",
              "version": "3",
              "proactivelyReported": true
            },
            {
              "type": "AlexaInterface",
              "interface": "Alexa.EndpointHealth",
              "version": "3",
              "properties": {
                "supported": [
                  {
                    "name":"connectivity"
                  }
                ],
                "proactivelyReported": true,
                "retrievable": true
              }
            },
            {
              "type": "AlexaInterface",
              "interface": "Alexa",
              "version": "3"
            }
          ]
        }
      ]
    }
  }
}

Directives

InitiateSessionWithOffer Directive

Support the InitiateSessionWithOffer directive so that users can initiate a real-time communication session with a front door device.

The following example shows a user utterance:

Alexa, talk to my front door camera

InitiateSessionWithOffer directive payload details

Field Description Type
sessionId The identifier of the session that wants to connect. A Version 4 UUID.
offer An SDP offer. String

InitiateSessionWithOffer directive example

The following example illustrates an InitiateSessionWithOffer directive that Alexa sends to your skill.

{
  "directive": {
    "header": {
      "namespace": "Alexa.RTCSessionController",
      "name": "InitiateSessionWithOffer",
      "messageId": "<message id>",
      "correlationToken": "<an opaque correlation token>",
      "payloadVersion": "3"
    },
    "endpoint": {
      "scope": {
        "type": "BearerToken",
        "token": "<an OAuth2 bearer token>"
      },
      "endpointId": "<endpoint id>",
      "cookie": {}
    },
    "payload": {
      "sessionId" : "<the session identifier>",
      "offer": {
        "format" : "SDP",
        "value" : "<an SDP offer value>"
      }
    }
  }
}

InitiateSessionWithOffer response event

If you handle a InitiateSessionWithOffer directive successfully, respond with an AnswerGeneratedForSession event. You can respond synchronously or asynchronously. If you respond asynchronously, include a correlation token and a scope with an authorization token.

AnswerGeneratedForSession response event payload details

Field Description Type
answer An SDP answer. String

AnswerGeneratedForSession response event example

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{
  "event": {
    "header": {
      "namespace": "Alexa.RTCSessionController",
      "name": "AnswerGeneratedForSession",
      "messageId": "<message id>",
      "correlationToken": "<an opaque correlation token>",
      "payloadVersion": "3"
    },
    "endpoint": {
      "scope": {
        "type": "BearerToken",
        "token": "<an OAuth2 bearer token>"
      },
      "endpointId": "<endpoint id>"
    },
    "payload": {
      "answer": {
        "format" : "SDP",
        "value" : "<an SDP answer value>"
      }
    }
  }
}

InitiateSessionWithOffer directive error handling

If you can't handle a InitiateSessionWithOffer directive successfully, respond with an Alexa.ErrorResponse event. If the customer needs to configure the camera, return the NOT_SUPPORTED_IN_CURRENT_MODE error type and include the currentDeviceMode field with a value of NOT_PROVISIONED.

SessionConnected Directive

The SessionConnected directive notifies you that your RTC session is connected.

SessionConnected directive payload details

Field Description Type
sessionId The identifier for the session from the original InitiateSessionWithOffer directive. A Version 4 UUID.

SessionConnected directive example

The following example illustrates a SessionConnected directive that Alexa sends to your skill.

{
  "directive": {
    "header": {
      "namespace": "Alexa.RTCSessionController",
      "name": "SessionConnected",
      "messageId": "<message id>",
      "correlationToken": "<an opaque correlation token>",
      "payloadVersion": "3"
    },
    "endpoint": {
      "scope": {
        "type": "BearerToken",
        "token": "<an OAuth2 bearer token>"
      },
      "endpointId": "<endpoint id>",
      "cookie": {}
    },
    "payload": {
      "sessionId" : "<the session identifier>"
    }
  }
}

SessionConnected response event

If you handle a SessionConnected directive successfully, respond with an SessionConnected event. You can respond synchronously or asynchronously. If you respond asynchronously, include a correlation token and a scope with an authorization token.

SessionConnected response event payload details

Field Description Type
sessionId The identifier for the session from the original InitiateSessionWithOffer directive. A Version 4 UUID.

SessionConnected response event example

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{
  "event": {
    "header": {
      "namespace": "Alexa.RTCSessionController",
      "name": "SessionConnected",
      "messageId": "<message id>",
      "correlationToken": "<an opaque correlation token>",
      "payloadVersion": "3"
    },
    "endpoint": {
      "scope": {
        "type": "BearerToken",
        "token": "<an OAuth2 bearer token>"
      },
      "endpointId": "<endpoint id>"
    },
    "payload": {
      "sessionId" : "<the session identifier>"
    }
  }
}

SessionConnected directive error handling

If you can't handle a SessionConnected directive successfully, respond with an Alexa.ErrorResponse event.

SessionDisconnected Directive

The SessionDisconnected directive notifies you that your RTC session is disconnected.

SessionDisconnected directive payload details

Field Description Type
sessionId The identifier for the session from the original InitiateSessionWithOffer directive. A Version 4 UUID.

SessionDisconnected directive example

The following example illustrates a SessionDisconnected directive that Alexa sends to your skill.

{
  "directive": {
    "header": {
      "namespace": "Alexa.RTCSessionController",
      "name": "SessionDisconnected",
      "messageId": "<message id>",
      "correlationToken": "<an opaque correlation token>",
      "payloadVersion": "3"
    },
    "endpoint": {
      "scope": {
        "type": "BearerToken",
        "token": "<an OAuth2 bearer token>"
      },
      "endpointId": "<endpoint id>",
      "cookie": {}
    },
    "payload": {
      "sessionId" : "<the session identifier>"
    }
  }
}

SessionDisconnected response event

If you handle a SessionDisconnected directive successfully, respond with an SessionDisconnected event. You can respond synchronously or asynchronously. If you respond asynchronously, include a correlation token and a scope with an authorization token.

SessionDisconnected response event payload details

Field Description Type
sessionId The identifier for the session from the original InitiateSessionWithOffer directive. A Version 4 UUID.

SessionDisconnected response event example

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{
  "event": {
    "header": {
      "namespace": "Alexa.RTCSessionController",
      "name": "SessionDisconnected",
      "messageId": "<message id>",
      "correlationToken": "<an opaque correlation token>",
      "payloadVersion": "3"
    },
    "endpoint": {
      "scope": {
        "type": "BearerToken",
        "token": "<an OAuth2 bearer token>"
      },
      "endpointId": "<endpoint id>"
    },
    "payload": {
      "sessionId" : "<the session identifier>"
    }
  }
}

SessionDisconnected directive error handling

If you can't handle a SessionDisconnected directive successfully, respond with an Alexa.ErrorResponse event.

State reporting

Alexa sends a ReportState directive to request information about the state of an endpoint. When Alexa sends a ReportState directive, you send a StateReport event in response. The response contains the current state of all of the retrievable properties in the context object. You identify your retrievable properties in your discovery response. For details about state reports, see Understand State and Change Reporting.

StateReport response event example

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{
  "event": {
    "header": {
      "namespace": "Alexa",
      "name": "StateReport",
      "messageId": "<message id>",
      "correlationToken": "<an opaque correlation token>",
      "payloadVersion": "3"
    },
    "endpoint": {
      "endpointId": "<endpoint id>"
    },
    "payload": {}
  },
  "context": {
    "properties": [
      {
        "namespace": "Alexa.EndpointHealth",
        "name": "connectivity",
        "value": {
          "value": "OK"
        },
        "timeOfSample": "2017-02-03T16:20:50.52Z",
        "uncertaintyInMilliseconds": 0
      }
    ]
  }
}

Change reporting

You send a ChangeReport event to proactively report changes in the state of an endpoint. You identify the properties that you proactively report in your discovery response. For details about change reports, see Understand State and Change Reporting.

ChangeReport event example

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{  
  "event": {
    "header": {
      "namespace": "Alexa",
      "name": "ChangeReport",
      "messageId": "<message id>",
      "payloadVersion": "3"
    },
    "endpoint": {
      "scope": {
        "type": "BearerToken",
        "token": "<an OAuth2 bearer token>"
      },
      "endpointId": "<endpoint id>"
    },
    "payload": {
      "change": {
        "cause": {
          "type": "PERIODIC_POLL"
        },
        "properties": [
          {
            "namespace": "Alexa.EndpointHealth",
            "name": "connectivity",
            "value": {
              "value": "UNREACHABLE"
            },
            "timeOfSample": "2017-02-03T16:20:50.52Z",
            "uncertaintyInMilliseconds": 0
          }
        ]
      }
    }
  },
  "context": {
    "properties": [
    ]
  }
}