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AVS Plugin

Version: 1.0

Status: ⚫⚪⚪

AVS plugin for Thunder framework.

Table of Contents

Introduction

Scope

This document describes purpose and functionality of the AVS plugin. It includes detailed specification about its configuration, methods provided and notifications sent.

Case Sensitivity

All identifiers of the interfaces described in this document are case-sensitive. Thus, unless stated otherwise, all keywords, entities, properties, relations and actions should be treated as such.

Acronyms, Abbreviations and Terms

The table below provides and overview of acronyms used in this document and their definitions.

Acronym Description
API Application Programming Interface
HTTP Hypertext Transfer Protocol
JSON JavaScript Object Notation; a data interchange format
JSON-RPC A remote procedure call protocol encoded in JSON

The table below provides and overview of terms and abbreviations used in this document and their definitions.

Term Description
callsign The name given to an instance of a plugin. One plugin can be instantiated multiple times, but each instance the instance name, callsign, must be unique.

References

Ref ID Description
HTTP HTTP specification
JSON-RPC JSON-RPC 2.0 specification
JSON JSON specification
Thunder Thunder API Reference

Description

The Alexa Voice Service Headless Client serves as a personal assistant.

The plugin is designed to be loaded and executed within the Thunder framework. For more information about the framework refer to [Thunder].

Configuration

The table below lists configuration options of the plugin.

Name Type M/O Description
callsign string mandatory Plugin instance name (default: AVS)
classname string mandatory Class name: AVS
locator string mandatory Library name: libThunderAVS.so
startmode string mandatory Determines in which state the plugin should be moved to at startup of the framework
configuration object optional ...
configuration.alexaclientconfig string mandatory The path to the AlexaClientSDKConfig.json (e.g /usr/share/Thunder/AVS/AlexaClientSDKConfig.json)
configuration?.smartscreenconfig string optional The path to the SmartScreenSDKConfig.json (e.g /usr/share/Thunder/AVS/SmartScreenSDKConfig.json). This config will be used only when SmartScreen functionality is enabled
configuration?.kwdmodelspath string optional Path to the Keyword Detection models (e.g /usr/share/Thunder/AVS/models). The path mus contain the localeToModels.json file
configuration?.loglevel string optional Capitalized log level of the AVS components. Possible values: NONE, CRITICAL, ERROR, WARN, INFO. Debug log levels start from DEBUG0 up to DEBUG0
configuration.audiosource string mandatory The callsign of the plugin that provides the voice audio input or PORTAUDIO, when the portaudio library should be used. (e.g BluetoothRemoteControll, PORTAUDIO)
configuration?.enablesmartscreen boolean optional Enable the SmartScreen support in the runtime. The SmartScreen functionality must be compiled in
configuration?.enablekwd boolean optional Enable the Keyword Detection engine in the runtime. The KWD functionality must be compiled in

Interfaces

This plugin implements the following interfaces:

  • IAVSController (IAVSClient.h) (version 1.0.0) (uncompliant-collapsed format)

    This interface uses legacy lowercase naming convention. With the next major release the naming convention will change to camelCase.

Methods

The following methods are provided by the AVS plugin:

Built-in methods:

Method Description
versions Retrieves a list of JSON-RPC interfaces offered by this service
exists Checks if a JSON-RPC method or property exists
register Registers for an asynchronous JSON-RPC notification
unregister Unregisters from an asynchronous JSON-RPC notification

AVSController interface methods:

Method Description
mute Mutes the audio output of AVS
record Starts or stops the voice recording, skipping keyword detection

versions method

Retrieves a list of JSON-RPC interfaces offered by this service.

Parameters

This method takes no parameters.

Result

Name Type M/O Description
result array mandatory A list ofsinterfaces with their version numbers
Array length must be at most 255 elements.
result[#] object mandatory ...
result[#].name string mandatory Name of the interface
result[#].major integer mandatory Major part of version number
result[#].minor integer mandatory Minor part of version number
result[#].patch integer mandatory Patch part of version version number

Example

Request

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "AVS.1.versions"
}

Response

{
  "jsonrpc": "2.0",
  "id": 42,
  "result": [
    {
      "name": "JMyInterface",
      "major": 1,
      "minor": 0,
      "patch": 0
    }
  ]
}

exists method

Checks if a JSON-RPC method or property exists.

Description

This method will return True for the following methods/properties: versions, exists, register, unregister, mute, record.

Parameters

Name Type M/O Description
params object mandatory ...
params.method string mandatory Name of the method or property to look up

Result

Name Type M/O Description
result boolean mandatory Denotes if the method exists or not

Example

Request

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "AVS.1.exists",
  "params": {
    "method": "methodName"
  }
}

Response

{
  "jsonrpc": "2.0",
  "id": 42,
  "result": false
}

register method

Registers for an asynchronous JSON-RPC notification.

Description

This method supports the following event names: dialoguestatechange.

Parameters

Name Type M/O Description
params object mandatory ...
params.event string mandatory Name of the notification to register for
params.id string mandatory Client identifier

Result

Name Type M/O Description
result null mandatory Always null

Errors

Message Description
ERROR_FAILED_REGISTERED Failed to register for the notification (e.g. already registered)

Example

Request

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "AVS.1.register",
  "params": {
    "event": "eventName",
    "id": "myapp"
  }
}

Response

{
  "jsonrpc": "2.0",
  "id": 42,
  "result": null
}

unregister method

Unregisters from an asynchronous JSON-RPC notification.

Description

This method supports the following event names: dialoguestatechange.

Parameters

Name Type M/O Description
params object mandatory ...
params.event string mandatory Name of the notification to register for
params.id string mandatory Client identifier

Result

Name Type M/O Description
result null mandatory Always null

Errors

Message Description
ERROR_FAILED_UNREGISTERED Failed to unregister from the notification (e.g. not yet registered)

Example

Request

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "AVS.1.unregister",
  "params": {
    "event": "eventName",
    "id": "myapp"
  }
}

Response

{
  "jsonrpc": "2.0",
  "id": 42,
  "result": null
}

mute method

Mutes the audio output of AVS.

Parameters

Name Type M/O Description
params boolean mandatory ...

Result

Name Type M/O Description
result null mandatory Always null

Errors

Message Description
ERROR_GENERAL when there is a fatal error or authorisation is not possible

Example

Request

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "AVS.1.mute",
  "params": false
}

Response

{
  "jsonrpc": "2.0",
  "id": 42,
  "result": null
}

record method

Starts or stops the voice recording, skipping keyword detection.

Parameters

Name Type M/O Description
params boolean mandatory ...

Result

Name Type M/O Description
result null mandatory Always null

Errors

Message Description
ERROR_GENERAL when there is a fatal error or authorisation is not possible

Example

Request

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "AVS.1.record",
  "params": false
}

Response

{
  "jsonrpc": "2.0",
  "id": 42,
  "result": null
}

Notifications

Notifications are autonomous events triggered by the internals of the implementation and broadcasted via JSON-RPC to all registered observers. Refer to [Thunder] for information on how to register for a notification.

The following events are provided by the AVS plugin:

AVSController interface events:

Notification Description
dialoguestatechange Notifies about dialogue state changes

dialoguestatechange notification

Notifies about dialogue state changes.

Notification Parameters

Name Type M/O Description
params string mandatory The new state (must be one of the following: Expecting, Idle, Listening, Speaking, Thinking)

Example

Registration

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "AVS.1.register",
  "params": {
    "event": "dialoguestatechange",
    "id": "myid"
  }
}

Notification

{
  "jsonrpc": "2.0",
  "method": "myid.dialoguestatechange",
  "params": "SPEAKING"
}

The client ID parameter is passed within the notification designator, i.e. <client-id>.dialoguestatechange.