Alexa.RTCSessionController Interface 3

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. For the definitions of the message properties, see Alexa Interface Message and Property Reference.

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": "Unique identifier, preferably a version 4 UUID"
    },
    "payload":{
      "endpoints":[
        {
          "endpointId": "Unique ID of the endpoint",
          "manufacturerName": "Manufacturer of the endpoint",
          "description": "Description to be shown in the Alexa app",
          "friendlyName": "My front door camera",
          "displayCategories": ["CAMERA"],
          "cookie": {},
          "capabilities": [
            {
              "type": "AlexaInterface",
              "interface": "Alexa.RTCSessionController",
              "version": "3",
              "configuration": {
                "isFullDuplexAudioSupported": true
              }
            },
            {
              "type": "AlexaInterface",
              "interface": "Alexa.MediaMetadata",
              "version": "3",
              "proactivelyReported": true
            },
            {
              "type": "AlexaInterface",
              "interface": "Alexa.EndpointHealth",
              "version": "3.2",
              "properties": {
                "supported": [
                  {
                    "name":"connectivity"
                  }
                ],
                "proactivelyReported": true,
                "retrievable": true
              }
            },
            {
              "type": "AlexaInterface",
              "interface": "Alexa",
              "version": "3"
            }
          ]
        }
      ]
    }
  }
}

Directives and events

The Alexa.RTCSessionController interface defines the following directives and events.

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 example

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

{
  "directive": {
    "header": {
      "namespace": "Alexa.RTCSessionController",
      "name": "InitiateSessionWithOffer",
      "messageId": "Unique version 4 UUID",
      "correlationToken": "Opaque correlation token",
      "payloadVersion": "3"
    },
    "endpoint": {
      "scope": {
        "type": "BearerToken",
        "token": "OAuth2.0 bearer token"
      },
      "endpointId": "Endpoint ID",
      "cookie": {}
    },
    "payload": {
      "sessionId" : "Session identifier",
      "offer": {
        "format" : "SDP",
        "value" : "an SDP offer value"
      }
    }
  }
}

InitiateSessionWithOffer directive payload

Field Description Type
sessionId Identifies the session that wants to connect. Version 4 UUID.
offer SDP offer. String

InitiateSessionWithOffer response

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 event example

The following example shows an AnswerGeneratedForSession event.

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{
  "event": {
    "header": {
      "namespace": "Alexa.RTCSessionController",
      "name": "AnswerGeneratedForSession",
      "messageId": "Unique identifier, preferably a version 4 UUID",
      "correlationToken": "Opaque correlation token that matches the request",
      "payloadVersion": "3"
    },
    "endpoint": {
      "scope": {
        "type": "BearerToken",
        "token": "OAuth2.0 bearer token"
      },
      "endpointId": "Endpoint ID"
    },
    "payload": {
      "answer": {
        "format" : "SDP",
        "value" : "an SDP answer value"
      }
    }
  }
}

AnswerGeneratedForSession event payload

Field Description Type
answer An SDP answer. String

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 example

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

{
  "directive": {
    "header": {
      "namespace": "Alexa.RTCSessionController",
      "name": "SessionConnected",
      "messageId": "Unique version 4 UUID",
      "correlationToken": "Opaque correlation token",
      "payloadVersion": "3"
    },
    "endpoint": {
      "scope": {
        "type": "BearerToken",
        "token": "OAuth2.0 bearer token"
      },
      "endpointId": "Endpoint ID",
      "cookie": {}
    },
    "payload": {
      "sessionId" : "Session identifier"
    }
  }
}

SessionConnected directive payload

Field Description Type
sessionId Identifies the session from the original InitiateSessionWithOffer directive. Version 4 UUID

SessionConnected response

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 event example

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{
  "event": {
    "header": {
      "namespace": "Alexa.RTCSessionController",
      "name": "SessionConnected",
      "messageId": "Unique identifier, preferably a version 4 UUID",
      "correlationToken": "Opaque correlation token that matches the request",
      "payloadVersion": "3"
    },
    "endpoint": {
      "scope": {
        "type": "BearerToken",
        "token": "OAuth2.0 bearer token"
      },
      "endpointId": "Endpoint ID"
    },
    "payload": {
      "sessionId" : "Session identifier"
    }
  }
}

SessionConnected event payload

Field Description Type
sessionId Identifies the session from the original InitiateSessionWithOffer directive. Version 4 UUID

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 example

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

{
  "directive": {
    "header": {
      "namespace": "Alexa.RTCSessionController",
      "name": "SessionDisconnected",
      "messageId": "Unique version 4 UUID",
      "correlationToken": "Opaque correlation token",
      "payloadVersion": "3"
    },
    "endpoint": {
      "scope": {
        "type": "BearerToken",
        "token": "OAuth2.0 bearer token"
      },
      "endpointId": "Endpoint ID",
      "cookie": {}
    },
    "payload": {
      "sessionId" : "Session identifier"
    }
  }
}

SessionDisconnected directive payload

Field Description Type
sessionId Identifies the session from the original InitiateSessionWithOffer directive. Version 4 UUID

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 event example

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{
  "event": {
    "header": {
      "namespace": "Alexa.RTCSessionController",
      "name": "SessionDisconnected",
      "messageId": "Unique identifier, preferably a version 4 UUID",
      "correlationToken": "Opaque correlation token that matches the request",
      "payloadVersion": "3"
    },
    "endpoint": {
      "scope": {
        "type": "BearerToken",
        "token": "OAuth2.0 bearer token"
      },
      "endpointId": "Endpoint ID"
    },
    "payload": {
      "sessionId" : "Session identifier"
    }
  }
}

SessionDisconnected event payload

Field Description Type
sessionId Identifies the session from the original InitiateSessionWithOffer directive. Version 4 UUID

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 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 example

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{
  "event": {
    "header": {
      "namespace": "Alexa",
      "name": "StateReport",
      "messageId": "Unique identifier, preferably a version 4 UUID",
      "correlationToken": "Opaque correlation token that matches the request",
      "payloadVersion": "3"
    },
    "endpoint": {
      "scope": {
        "type": "BearerToken",
        "token": "OAuth2.0 bearer token"
      },
      "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 report changes proactively 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": "Unique identifier, preferably a version 4 UUID",
      "payloadVersion": "3"
    },
    "endpoint": {
      "scope": {
        "type": "BearerToken",
        "token": "OAuth2.0 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": [
    ]
  }
}