source: Dev/trunk/src/client/dojox/socket.js

define("dojox/socket", ["dojo", "dojo/on", "dojo/Evented", "dojo/cookie", "dojo/_base/url"], function(dojo, on, Evented) {

var WebSocket = window.WebSocket;

function Socket(/*dojo.__XhrArgs*/ argsOrUrl){
        // summary:
        //              Provides a simple socket connection using WebSocket, or alternate
        //              communication mechanisms 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
        // description:
        //              Provides socket connections. This can be used with virtually any Comet protocol.
        // argsOrUrl:
        //              This uses the same arguments as the other I/O functions in Dojo, or a
        //              URL to connect to. The URL should be a relative URL in order to properly
        //              work with WebSockets (it can still be host relative, like //other-site.org/endpoint)
        // returns:
        //              An object that implements the WebSocket API
        // example:
        //              | dojo.require("dojox.socket");
        //              | var socket = dojox.socket({"url://comet-server/comet");
        //              | // we could also add auto-reconnect support
        //              | // now we can connect to standard HTML5 WebSocket-style events
        //              | dojo.connect(socket, "onmessage", function(event){
        //              |    var message = event.data;
        //              |    // do something with the message
        //              | });
        //              | // send something
        //              | socket.send("hi there");
        //              | whenDone(function(){
        //              |   socket.close();
        //              | });
        //              You can also use the Reconnect module:
        //              | dojo.require("dojox.socket");
        //              | dojo.require("dojox.socket.Reconnect");
        //              | var socket = dojox.socket({url:"/comet"});
        //              | // add auto-reconnect support
        //              | socket = dojox.socket.Reconnect(socket);
        if(typeof argsOrUrl == "string"){
                argsOrUrl = {url: argsOrUrl};
        }
        return WebSocket ? dojox.socket.WebSocket(argsOrUrl, true) : dojox.socket.LongPoll(argsOrUrl);
};
dojox.socket = Socket;

Socket.WebSocket = function(args, fallback){
        // summary:
        //              A wrapper for WebSocket, than handles standard args and relative URLs
        var ws = new WebSocket(new dojo._Url(document.baseURI.replace(/^http/i,'ws'), args.url));
        ws.on = function(type, listener){
                ws.addEventListener(type, listener, true);
        };
        var opened;
        dojo.connect(ws, "onopen", function(event){
                opened = true;
        });
        dojo.connect(ws, "onclose", function(event){
                if(opened){
                        return;
                }
                if(fallback){
                        Socket.replace(ws, dojox.socket.LongPoll(args), true);
                }
        });
        return ws;
};
Socket.replace = function(socket, newSocket, listenForOpen){
        // make the original socket a proxy for the new socket
        socket.send = dojo.hitch(newSocket, "send");
        socket.close = dojo.hitch(newSocket, "close");
        if(listenForOpen){
                proxyEvent("open");
        }
        // redirect the events as well
        dojo.forEach(["message", "close", "error"], proxyEvent);
        function proxyEvent(type){
                (newSocket.addEventListener || newSocket.on).call(newSocket, type, function(event){
                        on.emit(socket, event.type, event);
                }, true);
        }
};
Socket.LongPoll = function(/*dojo.__XhrArgs*/ args){
        // summary:
        //              Provides a simple long-poll based comet-style socket/connection to a server and returns an
        //              object implementing the WebSocket interface:
        //              http://dev.w3.org/html5/websockets/#websocket
        // args:
        //              This uses the same arguments as the other I/O functions in Dojo, with this addition:
        //      args.interval:
        //              Indicates the amount of time (in milliseconds) after a response was received
        //              before another request is made. By default, a request is made immediately
        //              after getting a response. The interval can be increased to reduce load on the
        //              server or to do simple time-based polling where the server always responds
        //              immediately.
        //      args.transport:
        //              Provide an alternate transport like dojo.io.script.get
        // returns:
        //              An object that implements the WebSocket API
        // example:
        //              | dojo.require("dojox.socket.LongPoll");
        //              | var socket = dojox.socket.LongPoll({url:"/comet"});
        //              or:
        //              | dojo.require("dojox.socket.LongPoll");
        //              | dojox.socket.LongPoll.add();
        //              | var socket = dojox.socket({url:"/comet"});

var cancelled = false,
                first = true,
                timeoutId,
                connections = [];

        // create the socket object
        var socket = {
                send: function(data){
                        // summary:
                        //              Send some data using XHR or provided transport
                        var sendArgs = dojo.delegate(args);
                        sendArgs.rawBody = data;
                        clearTimeout(timeoutId);
                        var deferred = first ? (first = false) || socket.firstRequest(sendArgs) :
                                socket.transport(sendArgs);
                        connections.push(deferred);
                        deferred.then(function(response){
                                // got a response
                                socket.readyState = 1;
                                // remove the current connection
                                connections.splice(dojo.indexOf(connections, deferred), 1);
                                // reconnect to listen for the next message if there are no active connections,
                                // we queue it up in case one of the onmessage handlers has a message to send
                                if(!connections.length){
                                        timeoutId = setTimeout(connect, args.interval);
                                }
                                if(response){
                                        // now send the message along to listeners
                                        fire("message", {data: response}, deferred);
                                }
                        }, function(error){
                                connections.splice(dojo.indexOf(connections, deferred), 1);
                                // an error occurred, fire the appropriate event listeners
                                if(!cancelled){
                                        fire("error", {error:error}, deferred);
                                        if(!connections.length){
                                                socket.readyState = 3;
                                                fire("close", {wasClean:false}, deferred);
                                        }
                                }
                        });
                        return deferred;
                },
                close: function(){
                        // summary:
                        //              Close the connection
                        socket.readyState = 2;
                        cancelled = true;
                        for(var i = 0; i < connections.length; i++){
                                connections[i].cancel();
                        }
                        socket.readyState = 3;
                        fire("close", {wasClean:true});
                },
                transport: args.transport || dojo.xhrPost,
                args: args,
                url: args.url,
                readyState: 0,
                CONNECTING: 0,
                OPEN: 1,
                CLOSING: 2,
                CLOSED: 3,
                on: Evented.prototype.on,
                firstRequest: function(args){
                        // summary:
                        //              This allows for special handling for the first request. This is useful for
                        //              providing information to disambiguate between the first request and
                        //              subsequent long-poll requests so the server can properly setup a
                        //              connection on the first connection or reject a request for an expired
                        //              connection if the request is not expecting to be the first for a connection.
                        //              This method can be overriden. The default behavior is to include a Pragma
                        //              header with a value of "start-long-poll"
                        var headers = (args.headers || (args.headers = {}));
                        headers.Pragma = "start-long-poll";
                        try{
                                return this.transport(args);
                        }finally{
                                // cleanup the header so it is not used on subsequent requests
                                delete headers.Pragma;
                        }
                }
        };
        function connect(){
                if(socket.readyState == 0){
                        // we fire the open event now because we really don't know when the "socket"
                        // is truly open, and this gives us a to do a send() and get it included in the
                        // HTTP request
                        fire("open",{});
                }
                // make the long-poll connection, to wait for response from the server
                if(!connections.length){
                        socket.send();
                }
        }
        function fire(type, object, deferred){
                if(socket["on" + type]){
                        object.ioArgs = deferred && deferred.ioArgs;
                        object.type = type;
                        on.emit(socket, type, object);
                }
        }
        // provide an alias for Dojo's connect method
        socket.connect = socket.on;
        // do the initial connection
        setTimeout(connect);
        return socket;
};
return Socket;
});