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WebSockets API Reference

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Volumio edited this page Sep 5, 2015 · 40 revisions

Introduction

The most used API transport in Volumio2 is its Websockets API as it allows almost real time communication with multiple clients. Volumio's WebUI gets and sends data (almost) exclusively via WS. Volumio's WS layer is powered by Socket.io.

Scenarios

Websocket communication in Volumio is identifiable in the most basic server/client architecture. The Server is Volumio itself (aka the host where Volumio is running), the client can be one or more WebUIs or other consumers (Apps and so on). In some cases, Volumio hosts can also act as client, to communicate with other hosts on the same network.

Events

Socket.io allows to invoke events triggered by other events, emit and receive communications (on its most basic implementation). As an example, defining which event should be invoked on a client connection looks like:

self.libSocketIO.on('connection', function (connWebSocket) {
  // use connWebSocket here
});

This way, we can define what event should be triggered when a particular message is received:

connWebSocket.on('bringmepizza', function () {
  givehimpizza();
});

Events Documentation

Basic Playback Commands

Play: play Pause: pause Stop: stop Previous: previous Next: next Seek seek N (N is the time in seconds that the playback will keep)

Get Player State

GetState

Reply:

{"status":play,
"position":0,
"title":Macaco,
"artist":Paolo Conte,
"album":Paolo Conte,
"albumart":http://img2-ak.lst.fm/i/u/300x300/1b82dd5e54554209bf2326ffb76f6814.png,
"seek":25390,
"duration":146,
"samplerate":44100,
"bitdepth":16,
"channels":2,
"volume":100,
"mute":false,
"service":mpd}

Where

  • status is the status of the player
  • position is the position in the play queue of current playing track (if any)
  • title is the item's title
  • artist is the item's artist
  • album is the item's album
  • albumart the URL of AlbumArt (via last.fm APIs)
  • seek is the item's current elapsed time
  • duration is the item's duration, if any
  • samplerate current samplerate
  • bitdepth bitdepth
  • channels mono or stereo
  • volume current Volume
  • mute if true, Volumio is muted
  • service current playback service (mpd, spop...)

Set the Volume

volume VolumeInteger

Where VolumeInteger is a numeric (0-100) volume level

To mute/unmute

volume mute
volume unmute

When Volume is already muted, sending another "mute" emit will result in Volume being unmuted

Browse Music Library

browseLibrary objBrowseParameters

Where objBrowseParameters are the parameters we want to dig into. This returns the desired level in the music library along with navigation and pagination informations.

{
  navigation: {
    prev: {
      uri: ''
    },
    list: [
      {service: 'mpd', type: 'song',  title: 'track a', artist: 'artist a', album: 'album', icon: 'music' uri: 'uri'},
      {type: 'folder',  title: 'folder a', icon: 'folder-open-o' uri: 'uri'},
      {type: 'folder',  title: 'folder b', image: '//ip/image' uri: 'uri2'},
      {type: 'playlist',  title: 'playlist', icon: 'bars' uri: 'uri4'}
    ]
  }
}

The browsable items can be;

  • Track
  • Folder (can also be a category)
  • Playlist

Their parameters are:

  • Type: track, folder, category
  • Title: If this is a song: title, if folder or category is their name.
  • Artist and Album: used only if the type is song
  • Icon or image: Select the icon to display (naming of Font-Awesome ) , or image (URL served by Volumio Backend or external service)
  • Uri: Uri

Get Music Library Available filters

getBrowseFilters

This returns available filters (browse by)

{name:'Genres by Name', index: 'index:Genres by Name'},
{name:'Artists by Name', index: 'index:Artists by Name'},
{name:'Albums by Name', index: 'index:Albums by Name'},
{name:'Albums by Artist', index: 'index:Albums by Artist'},
{name:'Tracks by Name', index: 'index:Tracks by Name'}

Get Music Sources (TO BE IMPLEMENTED)

getBrowseSources

This returns a list of available Music Sources

{name:'USB', uri: 'usb'},
{name:'NAS', uri: 'nas'},
{name:'Web Radio', uri: 'web-radio'},
{name:'Spotify', uri: 'spotify'}

Get Current Play Queue

GetQueue

The queue is a json object:

[ { uri: 'NAS/Flac/Paolo Conte - 1984 - Paolo Conte [1995 Reissue]/10 - Macaco.flac',
    service: 'mpd',
    name: 'Macaco',
    artist: 'Paolo Conte',
    album: 'Paolo Conte',
    type: 'track',
    tracknumber: '0',
    albumart: 'http://img2-ak.lst.fm/i/u/300x300/1b82dd5e54554209bf2326ffb76f6814.png' },
  { uri: 'NAS/Flac/Paolo Conte - 1984 - Paolo Conte [1995 Reissue]/01 - Sparring Partner.flac',
    service: 'mpd',
    name: 'Sparring partner',
    artist: 'Paolo Conte',
    album: 'Paolo Conte',
    type: 'track',
    tracknumber: '1',
    albumart: 'http://img2-ak.lst.fm/i/u/300x300/1b82dd5e54554209bf2326ffb76f6814.png' }]

Remove Item from queue

removeFromQueue N

where N is the track number in the queue, 0 for the first, 9 for the tenth and so on

Add Item to Queue

addToQueue {'uri:uri'}

where uri is the uri of the item we want to add

Playlist handling

createPlaylist
deletePlaylist
addToPlaylist
removeFromPlaylist 
playPlaylist
enqueue

createPlaylist

This method creates a new playlist

Input:

   {
    "name":"myplaylist"
   }

Output:

   {
    "success":true|false
    "reason":"failure details"
   }

The reason field is set only if success is false

deletePlaylist

This method deletes a playlist

Input:

   {
    "name":"myplaylist"
   }

Output:

   {
    "success":true|false
    "reason":"failure details"
   }

The reason field is set only if success is false

addToPlaylist

This method adds a song to an existing playlist

Input:

   {
    "name":"my playlist",
    "uri":"USB/..."
   }

Output:

   {
    "success":true|false
    "reason":"failure details"
   }

The reason field is set only if success is false

removeFromPlaylist

This method removes all occurrences of a song from an existing playlist

Input:

   {
    "name":"my playlist",
    "uri":"USB/..."
   }

Output:

   {
    "success":true|false
    "reason":"failure details"
   }

The reason field is set only if success is false

playPlaylist

This method clears the queue, adds the playlist and play

Input:

   {
    "name":"my playlist"
   }

Output:

   {
    "success":true|false
    "reason":"failure details"
   }

The reason field is set only if success is false

enqueue

This method enqueue all songs of a playlist

Input:

   {
    "name":"my playlist"
   }

Output:

   {
    "success":true|false
    "reason":"failure details"
   }

The reason field is set only if success is false

CallMethod on Plugin

Each method of a plugin can be execute through a websocket call. As of now there's no ACL or any security feature but thi s will change in the future. To execute a method the following socket.io command shall be issued:

callMethod

The payload shall be a json with the following structure:

   {
    "endpoint":"category/name",
    "method":"methodName",
    "data": {}
   }

where:

  • endpoint is a string used to target the plugin. Its structure is a linux path like string containing the plugin category, a slash and the plugin name. An example: endpoint:'music_service/spop'.
  • method is a string containing the name of the method to be executed.
  • data is a complex value (can be a string or a Json) and is passed as is to the method.

IMPORTANT: There should be no "-" in this call, due to FE parsing method (it converts / to -). So plugins and functions should not contain "-".

Once the method returns, the result is pushed back to the client with the event 'pushMethod'.

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