Alexa.PowerController Interface 3.0
The Alexa.PowerController capability interface comprises the mechanics related to control and reporting on the power state of an endpoint.
It defines reportable state properties and uses the centralized Alexa interface for state reporting.
You can think of Alexa.PowerController as a pre-built, named instance of the Alexa.ToggleController, which is one of the AVS generic controllers.
Dependencies
An endpoint for which support for Alexa.PowerController 3.0 is asserted must also have Alexa 3.0 or higher implemented on its behalf.
A device maintaining an HTTP/2 connection that implements the Alexa.PowerController 3.0 capability on its own behalf or on behalf of other connected endpoints must also implement support for Alexa.Discovery 3.0 or higher.
Capability assertion
To use the Alexa.PowerController capability, it must be asserted in the capabilities
list of a Discover.Response
or AddOrUpdateReport
event in the Alexa.Discovery interface.
The device maintaining the HTTP/2 connection may implement the Alexa.PowerController capability both on its own behalf as an endpoint and on behalf of other endpoints. The device must assert support for the Alexa.PowerController capability and its dependencies in the capabilities
list for each endpoint that leverages it.
Sample Object
{ "type": "AlexaInterface", "interface": "Alexa.PowerController", "version": "3", "properties": { "supported": [ { "name": "powerState" } ], "proactivelyReported": {{BOOLEAN}}, "retrievable": {{BOOLEAN}} } }, { "type": "AlexaInterface", "interface": "Alexa", "version": "3" }
Object Parameters
Parameter | Description | Type |
---|---|---|
properties. proactivelyReported |
Whether changes in values of the reportable state properties for this capability on this endpoint can be reported by the device through the ChangeReport event. |
boolean |
properties. retrievable |
Whether the values of the reportable state properties for this capability on this endpoint will be reported by the device through the StateReport event in response the ReportState directive. |
boolean |
Reportable state properties
powerState
Alexa.PowerController 3.0 defines the powerState
property, an instance of the PowerState
property schema.
Sample Object
{ "namespace": "Alexa.PowerController", "name": "powerState", "value": "{{STRING}}", "timeOfSample": "{{STRING}}", "uncertaintyInMilliseconds": {{LONG}} }
Object Parameters
Parameter | Description | Type |
---|---|---|
value |
The value of the powerState property.Accepted Values: ON , OFF
|
string |
timeOfSample | The UTC timestamp corresponding to when the property value was recorded, in ISO 8601 YYYY-MM-DDThh:mm:ssZ format. |
string |
uncertaintyInMilliseconds | The number of milliseconds that have elapsed since the property value was last confirmed. For example, if the device sampled the property value from the endpoint 60 seconds ago, the uncertaintyInMilliseconds would be 60000 . |
long |
Directives
TurnOn
AVS will send the TurnOn
directive to instruct the device to send a "turn on" signal to the specified endpoint.
The device must send the Response
event in the Alexa namespace in response. The DeferredResponse
event is not supported as an alternative to sending an immediate Response
event.
If the TurnOn
directive can't run, the device should send the ErrorResponse
event instead.
Sample Message
{ "directive": { "header": { "namespace": "Alexa.PowerController", "name": "TurnOn", "payloadVersion": "3", "messageId": "{{STRING}}", "correlationToken": "{{STRING}}" }, "endpoint": { "endpointId": "{{STRING}}" } "payload": { } } }
Message Parameters
Parameter | Description | Type |
---|---|---|
directive. header. messageId |
A universally unique identifier (UUID) generated to the RFC 4122 specification. | string |
directive. header. correlationToken |
An opaque token that must be included in any events responding to this directive. | string |
directive. endpoint. endpointId |
The identifier of the endpoint for which the state is being set. | string |
Note: The payload
is an empty object.
TurnOff
AVS will send the TurnOff
directive to instruct the device to send a "turn off" signal to the specified endpoint.
The device must send the Response
event in the Alexa namespace in response. The DeferredResponse
event is not supported as an alternative to sending an immediate Response
event.
If the TurnOff
directive can't run, the device should send the ErrorResponse
event instead.
Sample Message
{ "directive": { "header": { "namespace": "Alexa.PowerController", "name": "TurnOff", "payloadVersion": "3", "messageId": "{{STRING}}", "correlationToken": "{{STRING}}" }, "endpoint": { "endpointId": "{{STRING}}" } "payload": { } } }
Message Parameters
Parameter | Description | Type |
---|---|---|
directive. header. messageId |
A universally unique identifier (UUID) generated to the RFC 4122 specification. | string |
directive. header. correlationToken |
An opaque token that must be included in any events responding to this directive. | string |
directive. endpoint. endpointId |
The identifier of the endpoint for which the state is being set. | string |
Note: The payload
is an empty object.
Events
Alexa.PowerController does not define any events within its namespace. Interactions involving power control leverage the centralized state change and reporting mechanisms defined in the Alexa interface:
- Responses to Alexa.PowerController directives use the
Response
andErrorResponse
events. - Changes to Alexa.PowerController's reportable state properties detected by the device use the
ChangeReport
event. - The device must use the
StateReport
event to respond to the cloud's interrogation of Alexa.PowerController's reportable state properties' values via theReportState
directive.
Additional resources
The Alexa.PowerController 3.0 capability has its origins in the Alexa Smart Home Skills API. It is now available directly to AVS devices with an HTTP/2 connection, without requiring an AWS Lambda or maintaining a separate cloud service. The following resources provide additional context and examples:
Last updated: Jan 22, 2021