ws_events_dispatcher.js

/* Ismael Celis 2010
Simplified WebSocket events dispatcher (no channels, no users)

// conn is an instance of WebSocket
var socket = new ServerEventDispatcher(conn);

// bind to server events
socket.bind('some_event', function(data){
  alert(data.name + ' says: ' + data.message)
});

// broadcast events to all connected users
socket.trigger( 'some_event', {name: 'ismael', message : 'Hello world'} );
*/

var ServerEventDispatcher = function(conn){
  var callbacks = {};
  
  this.bind = function(event_name, callback){
    callbacks[event_name] = callbacks[event_name] || [];
    callbacks[event_name].push(callback);
    return this;// chainable
  };
  
  this.trigger = function(event_name, data){
    var payload = JSON.stringify([event_name, data]);
    conn.send( payload ); // <= send JSON data to socket server
    return this;
  };
  
  // dispatch to the right handlers
  conn.onmessage = function(evt){
    var data = JSON.parse(evt.data),
        event_name = data[0], 
        message = data[1];
    dispatch(event_name, message);
  };
  
  conn.onclose = function(){dispatch('close',null);}
  conn.onopen = function(){dispatch('open',null);}
  
  var dispatch = function(event_name, message){
    var chain = callbacks[event_name];
    if(typeof chain == 'undefined') return; // no callbacks for this event
    for(var i = 0; i < chain.length; i++){
      chain[i]( message );
    }
  }
};