socket.js

dojo.provide("dojo.socket");

dojo.socket = function(/*dojo.__XhrArgs*/ argsOrUrl){
	// summary:
	//		Provides a simple socket connection using WebSocket or long-polling based 
	// 		communication in legacy browsers for comet-style communication. This is based
	//		on the WebSocket API and returns an object that implements the WebSocket interface:
	//		http://dev.w3.org/html5/websockets/#websocket
	//	argsOrUrl:
	//		This uses the same arguments as the other I/O functions in Dojo, or a 
	// 		URL to connect to. Several additional properties are supported:
	//	argsOrUrl.transport:
	//		Provide an alternate transport like dojo.io.script.get
	// argsOrUrl.reconnectTime
	//		Will attempt to reconnect after a closed connection after a given amount of time
	//		Specify -1 to prevent reconnection
	// returns:
	// 		An object that implements the WebSocket API
	// example:
	//		| var socket = dojo.socket({url:"/comet"});
	//		| dojo.connect(socket, "onmessage", function(event){
	//		|    var message = event.data;
	//		|    // do something with the message
	//		| });
	//		| whenDone(function(){
	//		|   socket.close();
	//		| });
	if(typeof argsOrUrl == "string"){
		argsOrUrl = {url: argsOrUrl};
	}
	var deferred, socket, reconnectTime = argsOrUrl.reconnectTime || 10000;
	function connect(){
		if(typeof WebSocket == "undefined" || argsOrUrl.noWebSocket){
			socket = {
				send: function(data){
					(argsOrUrl.transport ?
						argsOrUrl.transport(argsOrUrl) :
						dojo.xhr(argsOrUrl.method || "POST", args)).then(null, onError);
				},
				close: function(){
					reconnectTime = -1;
					deferred.cancel();
				}
			};
			deferred = argsOrUrl.transport ?
				argsOrUrl.transport(argsOrUrl) :
				dojo.xhr(argsOrUrl.method || "POST", args);
			deferred.then(function(response){
				connect();
				setTimeout(function(){
					if(socket.onmessage){
						socket.onmessage({
							name: "message",
							data: response,
							ioArgs: deferred.ioArgs
						});
					}
				});
			}, onError);
			return socket;
		}
		var ws = new WebSocket(argsOrUrl.url);
		if(reconnectTime > -1){
			ws.addEventListener("close", onClose);
		}
		return ws;
	}
	function onError(error){
		setTimeout(function(){
			if(socket.onerror){
				socket.onerror({
					name: "error",
					error: error,
					ioArgs: deferred.ioArgs
				});
			}
		});
		onClose({
			name: "close",
			wasClean: false,
			ioArgs: deferred.ioArgs
		});
	}
	function onClose(event){
		if(reconnectTime > -1){
			setTimeout(connect, reconnectTime);
		}else{
			setTimeout(function(){
				if(socket && socket.onclose){
					socket.onclose(event);
				}
			});
		}
	}
};