Introduction

In order to receive published messages, application must subscribe to a channel. The subscription API returns a Channel object which can  be used to add messaging callbacks. A callback is used by Backendless to deliver published messages to the client application.

Consider the following example, which demonstrates subscribing to a channel and adding a messaging callback:

final Channel channel = Backendless.Messaging.subscribe( "chat" );
AsyncCallback<String> callback = new AsyncCallback<String>()
    {
      @Override
      public void handleResponse( String chatMessage )
      {
        System.out.println( "got a message " + chatMessage );
      }

      @Override
      public void handleFault( BackendlessFault fault )
      {
        System.out.println( "got error " + fault );
      }
    };

channel.addMessageListener( callback );