Realtime updates via Server-Sent Events.

assets/js/application.js

@@ -11,12 +11,19 @@ $(document).ready(function() {
         status: status
       }),
 
+      events: new EventSource('/api/stream'),
+
       queue: new Queue('#queue', {
         queueSongs: queueSongs,
         status: status
       })
     };
 
+    mpdClient.events.onmessage = function(e) {
+      newStatus = JSON.parse(e.data);
+      status.attr(newStatus);
+    }
+
     status.bind('change', function(event, attr, how, newVal, oldVal) {
       if (attr == 'song') {
         mpdClient.queueSongs.updatePlaying(oldVal, newVal);

assets/js/controls/transport.js

@@ -13,10 +13,7 @@ var Transport = can.Control.extend({
     var self = this;
     can.ajax({
       url: '/api/control/' + command,
-      type: 'PUT',
-      success: function(status) {
-        self.updateStatus(status);
-      }
+      type: 'PUT'
     });
   },
 

models/mpd_connection.rb

@@ -1,6 +1,6 @@
 class MPDConnection
   def self.mpd
-    @mpd ||= MPD.new
+    @mpd ||= MPD.new('localhost', 6600, { callbacks: true })
     @mpd.connect unless @mpd.connected?
     @mpd
   end

mpd_client.rb

@@ -15,6 +15,8 @@ require './models/song'
 
 class MPDClient < Sinatra::Base
 
+  set server: 'thin', connections: []
+
   set :assets_precompile, %w(app.js app.css *.png *.jpg *.svg *.eot *.ttf *.woff)
   set :assets_prefix, 'assets'
   register Sinatra::AssetPipeline
@@ -25,21 +27,34 @@ class MPDClient < Sinatra::Base
     erb :index
   end
 
-  namespace '/api' do
+  def self.send_status
+    status = JSON MPDConnection.status
+    settings.connections.each { |out| out << "data: #{status}\n\n" }
+  end
 
-    before do
-      content_type 'application/json'
-    end
+  MPDConnection.mpd.on(:song) { |song| send_status }
+  MPDConnection.mpd.on(:state) { |state| send_status }
+
+  namespace '/api' do
 
     get '/status' do
       JSON MPDConnection.status
     end
 
+    get '/stream', provides: 'text/event-stream' do
+      stream :keep_open do |out|
+        settings.connections << out
+        out.callback { settings.connections.delete(out) }
+      end
+    end
+
     get '/albums' do
+      content_type 'application/json'
       JSON Album.all.map(&:to_h)
     end
 
     get '/artists/:artist' do
+      content_type 'application/json'
       JSON Album.by_artist(CGI.unescape(params[:artist])).sort.map(&:to_h)
     end
 
@@ -52,23 +67,25 @@ class MPDClient < Sinatra::Base
     #end
 
     get '/artists' do
+      content_type 'application/json'
       JSON Artist.all.map(&:to_h)
     end
 
     get '/queue' do
+      content_type 'application/json'
       JSON({ data: Song.queue.map(&:to_h) })
     end
 
     put '/control/:action' do
       if Control.controls.include?(params[:action].to_sym)
         Control.send(params[:action])
-        JSON MPDConnection.status
       else
         not_found
       end
     end
 
     put '/control/volume/:value' do
+      content_type 'application/json'
       Control.volume(params[:value])
     end