jquery.comet.js

(function($)
{
	var msgHandshake =
	{
		version: '1.0',
		minimumVersion: '0.9',
		channel: '/meta/handshake'
	};

	var oTransport = function()
	{
		this._bXD = 
			(($.comet._sUrl.substring(0,4) == 'http') && ($.comet._sUrl.substr(7,location.href.length).replace(/\/.*/, '') != location.host))
			?
			true
			:false;

		this.connectionType = (this._bXD) ? 'callback-polling' : 'long-polling';

		this.startup = function(oReturn)
		{
			if(this._comet._bConnected) return;
			this.tunnelInit();
		};

		this.tunnelInit = function()
		{
			var msgConnect = 
			{
				channel: '/meta/connect',
				clientId: $.comet.clientId, 
				id: String($.comet._nNextId++),
				connectionType: $.comet._oTransport.connectionType
			};

			this.openTunnel(msgConnect);
		};

		this.openTunnel = function(oMsg)
		{
			$.comet._bPolling = true;

			this._send($.comet._sUrl, oMsg, function(sReturn)
			{
				var oReturn = (typeof sReturn != "object") ? (eval('(' + sReturn + ')')) : sReturn;
				$.comet._bPolling = false;
				$.comet.deliver(oReturn);
				$.comet._oTransport.closeTunnel();
			});
		};

		this.closeTunnel = function()
		{
			if(!$.comet._bInitialized) return;

			if($.comet._advice)
			{
				if($.comet._advice.reconnect == 'none') return;

				if($.comet._advice.interval > 0)
				{
					setTimeout($.comet._oTransport._connect, $.comet._advice.interval);
				}
				else
				{
					$.comet._oTransport._connect();
				}
			}
			else
			{
				$.comet._oTransport._connect();
			}
		};

		this._connect = function()
		{
			if(!$.comet._bInitialized) return;

			if($.comet._bPolling) return;

			if($.comet._advice && $.comet._advice.reconnect == 'handshake')
			{
				$.comet._bConnected = false;
				$.comet.init($.comet._sUrl);
			}
			else if($.comet._bConnected)
			{
				var msgConnect = 
				{
					//jsonp: 'test',
					clientId: $.comet.clientId,
					id: String($.comet._nNextId++),
					channel: '/meta/connect',
					connectionType: $.comet._oTransport.connectionType
				};
				$.comet._oTransport.openTunnel(msgConnect);
			}
		};

		this._send = function(sUrl, oMsg, fCallback) {
			//default callback will check advice, deliver messages, and reconnect
			var fCallback = (fCallback) ? fCallback : function(sReturn)
			{
				var oReturn = (typeof sReturn != "object") ? (eval('(' + sReturn + ')')) : sReturn;

				$.comet.deliver(oReturn);

				if($.comet._advice)
				{
					if($.comet._advice.reconnect == 'none')
						return;

					if($.comet._advice.interval > 0)
					{
						setTimeout($.comet._oTransport._connect, $.comet._advice.interval);
					}
					else
					{
						$.comet._oTransport._connect();
					}
				}
				else
				{
					$.comet._oTransport._connect();
				}
			};

			//regular AJAX for same domain calls
			if((!this._bXD) && (this.connectionType == 'long-polling'))
			{
				this._pollRequest = $.ajax({
					url: sUrl,
					type: 'post',
					beforeSend: function(oXhr) { oXhr.setRequestHeader('Connection', 'Keep-Alive'); },
					data: { message: JSON.stringify(oMsg) },
					success: fCallback
				});
			}
			else // JSONP callback for cross domain
			{
				this._pollRequest = $.ajax({
					url: sUrl,
					dataType: 'jsonp',
					jsonp: 'jsonp',
					beforeSend: function(oXhr) { oXhr.setRequestHeader('Connection', 'Keep-Alive'); },
					data: 
					{ 
						message: JSON.stringify($.extend(oMsg,{connectionType: 'callback-polling' })) 
					},
					success: fCallback
				});
			}
		}
        };

	$.comet = new function()
	{
		this.CONNECTED = 'CONNECTED';
		this.CONNECTING = 'CONNECTING';
		this.DISCONNECTED = 'DISCONNECTED';
		this.DISCONNECTING = 'DISCONNECTING';

		this._aMessageQueue = [];
		this._aSubscriptions = [];
		this._aSubscriptionCallbacks = [];
		this._bInitialized = false;
		this._bConnected = false;
		this._nBatch = 0;
		this._nNextId = 0;
		// just define the transport, do not assign it yet.
		this._oTransport = ''; //oTransport;
		this._sUrl = '';

		this.supportedConectionTypes = [ 'long-polling', 'callback-polling' ];

		this.clientId = '';

		this._bTrigger = true; // this sends $.event.trigger(channel, data)

		this.init = function(sUrl)
		{
			this._sUrl = (sUrl) ? sUrl : '/cometd';

			this._oTransport = new oTransport();

			this._aMessageQueue = [];
			this._aSubscriptions = [];
			this._bInitialized = true;
			this.startBatch();

			var oMsg = $.extend(msgHandshake, {id: String(this._nNextId++)});

			this._oTransport._send(this._sUrl, oMsg, $.comet._finishInit);
		};

		this._finishInit = function(sReturn)
		{
			var oReturn = (typeof sReturn != "object") ? (eval('(' + sReturn + ')')[0]) : sReturn[0];

			if(oReturn.advice)
				$.comet._advice = oReturn.advice;

			var bSuccess = (oReturn.successful) ? oReturn.successful : false;
			// do version check

			if(bSuccess)
			{
				// pick transport ?
				// ......

				$.comet._oTransport._comet = $.comet;
				$.comet._oTransport.version = $.comet.version;

				$.comet.clientId = oReturn.clientId;
				$.comet._oTransport.startup(oReturn);
				$.comet.endBatch();
			}
		};

		this._sendMessage = function(oMsg)
		{
			if($.comet._nBatch <= 0)
			{
				if(oMsg.length > 0)
					for(var i in oMsg)
					{
						oMsg[i].clientId = String($.comet.clientId);
						oMsg[i].id = String($.comet._nNextId++);
					}
				else
				{
					oMsg.clientId = String($.comet.clientId);
					oMsg.id = String($.comet._nNextId++);
				}

				$.comet._oTransport._send($.comet._sUrl, oMsg);
			}
			else
			{
				$.comet._aMessageQueue.push(oMsg);
			}
		};


		this.startBatch = function() { this._nBatch++ };
		this.endBatch = function() {
			if(--this._nBatch <= 0)
			{
				this._nBatch = 0;
				if(this._aMessageQueue.length > 0)
				{
					this._sendMessage(this._aMessageQueue);
					this._aMessageQueue = [];
				}
			}
		};

		this.subscribe = function(sSubscription, fCallback)
		{
			// if this topic has not been subscribed to yet, send the message now
			if(!this._aSubscriptions[sSubscription])
			{
				this._aSubscriptions.push(sSubscription)

				if (fCallback) {
					this._aSubscriptionCallbacks[sSubscription] = fCallback;
				}

				this._sendMessage({ channel: '/meta/subscribe', subscription: sSubscription });
			}

			//$.event.add(window, sSubscription, fCallback);
		};

		this.unsubscribe = function(sSubscription) {
			$.comet._sendMessage({ channel: '/meta/unsubscribe', subscription: sSubscription });
		};

		this.publish = function(sChannel, oData)
		{
			$.comet._sendMessage({channel: sChannel, data: oData});
		};

		this.deliver = function(sReturn)
		{
			var oReturn = sReturn;//eval(sReturn);

			$(oReturn).each(function()
			{
					$.comet._deliver(this);
			});
		};

		this.disconnect = function()
		{
			$($.comet._aSubscriptions).each(function(i)
			{
				$.comet.unsubscribe($.comet._aSubscriptions[i]);
			});

			$.comet._sendMessage({channel:'/meta/disconnect'});

			$.comet._bInitialized = false;
		}

		this._deliver = function(oMsg,oData)
		{
			if(oMsg.advice)
			{
				$.comet._advice = oMsg.advice;
			}

			switch(oMsg.channel)
			{
				case '/meta/connect':
					if(oMsg.successful && !$.comet._bConnected)
					{
						$.comet._bConnected = $.comet._bInitialized;
						$.comet.endBatch();
					/*
					   $.comet._sendMessage(msgConnect);
					*/
					}
					else
					{}
						//$.comet._bConnected = false;
				break;

				// add in subscription handling stuff
				case '/meta/subscribe':
                                        if(!oMsg.successful)
                                        {
                                                $.comet._oTransport._cancelConnect();
                                                return;
                                        }
				break;

				case '/meta/unsubscribe':
                                        if(!oMsg.successful)
                                        {
                                                $.comet._oTransport._cancelConnect();
                                                return;
                                        }
				break;

			}

		if(oMsg.data)
		{
			if($.comet._bTrigger)
			{
				$.event.trigger(oMsg.channel, [oMsg]);
			}

			var cb = $.comet._aSubscriptionCallbacks[oMsg.channel];
			if (cb) {
				cb(oMsg);
			}
		}
	};
};

})(jQuery);