The source code

    /*!
     * Ext JS Library 3.2.1
     * Copyright(c) 2006-2010 Ext JS, Inc.
     * licensing@extjs.com
     * http://www.extjs.com/license
     */
    /**
     * @class Ext.direct.RemotingProvider
     * @extends Ext.direct.JsonProvider
     *
     * The {@link Ext.direct.RemotingProvider RemotingProvider} exposes access to
     * server side methods on the client (a remote procedure call (RPC) type of
     * connection where the client can initiate a procedure on the server).
     *
     * This allows for code to be organized in a fashion that is maintainable,
     * while providing a clear path between client and server, something that is
     * not always apparent when using URLs.
     *
     * To accomplish this the server-side needs to describe what classes and methods
     * are available on the client-side. This configuration will typically be
     * outputted by the server-side Ext.Direct stack when the API description is built.
     */
    Ext.direct.RemotingProvider = Ext.extend(Ext.direct.JsonProvider, {
        /**
         * @cfg {Object} actions
         * Object literal defining the server side actions and methods. For example, if
         * the Provider is configured with:
         *
    "actions":{ // each property within the 'actions' object represents a server side Class
        "TestAction":[ // array of methods within each server side Class to be
        {              // stubbed out on client
            "name":"doEcho",
            "len":1
        },{
            "name":"multiply",// name of method
            "len":2           // The number of parameters that will be used to create an
                              // array of data to send to the server side function.
                              // Ensure the server sends back a Number, not a String.
        },{
            "name":"doForm",
            "formHandler":true, // direct the client to use specialized form handling method
            "len":1
        }]
    }
         *
         * Note that a Store is not required, a server method can be called at any time.
         * In the following example a client side handler is used to call the
         * server side method "multiply" in the server-side "TestAction" Class:
         *
    TestAction.multiply(
        2, 4, // pass two arguments to server, so specify len=2
        // callback function after the server is called
        // result: the result returned by the server
        //      e: Ext.Direct.RemotingEvent object
        function(result, e){
            var t = e.getTransaction();
            var action = t.action; // server side Class called
            var method = t.method; // server side method called
            if(e.status){
                var answer = Ext.encode(result); // 8

            }else{
                var msg = e.message; // failure message
            }
        }
    );
         *
         * In the example above, the server side "multiply" function will be passed two
         * arguments (2 and 4).  The "multiply" method should return the value 8 which will be
         * available as the result in the example above.
         */

        /**
         * @cfg {String/Object} namespace
         * Namespace for the Remoting Provider (defaults to the browser global scope of window).
         * Explicitly specify the namespace Object, or specify a String to have a
         * {@link Ext#namespace namespace created} implicitly.
         */

        /**
         * @cfg {String} url
         * Required. The url to connect to the {@link Ext.Direct} server-side router.
         */

        /**
         * @cfg {String} enableUrlEncode
         * Specify which param will hold the arguments for the method.
         * Defaults to 'data'.
         */

        /**
         * @cfg {Number/Boolean} enableBuffer
         * true or false to enable or disable combining of method
         * calls. If a number is specified this is the amount of time in milliseconds
         * to wait before sending a batched request (defaults to 10).
         *
    Calls which are received within the specified timeframe will be
         * concatenated together and sent in a single request, optimizing the
         * application by reducing the amount of round trips that have to be made
         * to the server.
         */
        enableBuffer: 10,

        /**
         * @cfg {Number} maxRetries
         * Number of times to re-attempt delivery on failure of a call. Defaults to 1.
         */
        maxRetries: 1,

        /**
         * @cfg {Number} timeout
         * The timeout to use for each request. Defaults to undefined.
         */
        timeout: undefined,

        constructor : function(config){
            Ext.direct.RemotingProvider.superclass.constructor.call(this, config);
            this.addEvents(
                /**
                 * @event beforecall
                 * Fires immediately before the client-side sends off the RPC call.
                 * By returning false from an event handler you can prevent the call from
                 * executing.
                 * @param {Ext.direct.RemotingProvider} provider
                 * @param {Ext.Direct.Transaction} transaction
                 */
                'beforecall',
                /**
                 * @event call
                 * Fires immediately after the request to the server-side is sent. This does
                 * NOT fire after the response has come back from the call.
                 * @param {Ext.direct.RemotingProvider} provider
                 * @param {Ext.Direct.Transaction} transaction
                 */
                'call'
            );
            this.namespace = (Ext.isString(this.namespace)) ? Ext.ns(this.namespace) : this.namespace || window;
            this.transactions = {};
            this.callBuffer = [];
        },

        // private
        initAPI : function(){
            var o = this.actions;
            for(var c in o){
                var cls = this.namespace[c] || (this.namespace[c] = {}),
                    ms = o[c];
                for(var i = 0, len = ms.length; i < len; i++){
                    var m = ms[i];
                    cls[m.name] = this.createMethod(c, m);
                }
            }
        },

        // inherited
        isConnected: function(){
            return !!this.connected;
        },

        connect: function(){
            if(this.url){
                this.initAPI();
                this.connected = true;
                this.fireEvent('connect', this);
            }else if(!this.url){
                throw 'Error initializing RemotingProvider, no url configured.';
            }
        },

        disconnect: function(){
            if(this.connected){
                this.connected = false;
                this.fireEvent('disconnect', this);
            }
        },

        onData: function(opt, success, xhr){
            if(success){
                var events = this.getEvents(xhr);
                for(var i = 0, len = events.length; i < len; i++){
                    var e = events[i],
                        t = this.getTransaction(e);
                    this.fireEvent('data', this, e);
                    if(t){
                        this.doCallback(t, e, true);
                        Ext.Direct.removeTransaction(t);
                    }
                }
            }else{
                var ts = [].concat(opt.ts);
                for(var i = 0, len = ts.length; i < len; i++){
                    var t = this.getTransaction(ts[i]);
                    if(t && t.retryCount < this.maxRetries){
                        t.retry();
                    }else{
                        var e = new Ext.Direct.ExceptionEvent({
                            data: e,
                            transaction: t,
                            code: Ext.Direct.exceptions.TRANSPORT,
                            message: 'Unable to connect to the server.',
                            xhr: xhr
                        });
                        this.fireEvent('data', this, e);
                        if(t){
                            this.doCallback(t, e, false);
                            Ext.Direct.removeTransaction(t);
                        }
                    }
                }
            }
        },

        getCallData: function(t){
            return {
                action: t.action,
                method: t.method,
                data: t.data,
                type: 'rpc',
                tid: t.tid
            };
        },

        doSend : function(data){
            var o = {
                url: this.url,
                callback: this.onData,
                scope: this,
                ts: data,
                timeout: this.timeout
            }, callData;

            if(Ext.isArray(data)){
                callData = [];
                for(var i = 0, len = data.length; i < len; i++){
                    callData.push(this.getCallData(data[i]));
                }
            }else{
                callData = this.getCallData(data);
            }

            if(this.enableUrlEncode){
                var params = {};
                params[Ext.isString(this.enableUrlEncode) ? this.enableUrlEncode : 'data'] = Ext.encode(callData);
                o.params = params;
            }else{
                o.jsonData = callData;
            }
            Ext.Ajax.request(o);
        },

        combineAndSend : function(){
            var len = this.callBuffer.length;
            if(len > 0){
                this.doSend(len == 1 ? this.callBuffer[0] : this.callBuffer);
                this.callBuffer = [];
            }
        },

        queueTransaction: function(t){
            if(t.form){
                this.processForm(t);
                return;
            }
            this.callBuffer.push(t);
            if(this.enableBuffer){
                if(!this.callTask){
                    this.callTask = new Ext.util.DelayedTask(this.combineAndSend, this);
                }
                this.callTask.delay(Ext.isNumber(this.enableBuffer) ? this.enableBuffer : 10);
            }else{
                this.combineAndSend();
            }
        },

        doCall : function(c, m, args){
            var data = null, hs = args[m.len], scope = args[m.len+1];

            if(m.len !== 0){
                data = args.slice(0, m.len);
            }

            var t = new Ext.Direct.Transaction({
                provider: this,
                args: args,
                action: c,
                method: m.name,
                data: data,
                cb: scope && Ext.isFunction(hs) ? hs.createDelegate(scope) : hs
            });

            if(this.fireEvent('beforecall', this, t) !== false){
                Ext.Direct.addTransaction(t);
                this.queueTransaction(t);
                this.fireEvent('call', this, t);
            }
        },

        doForm : function(c, m, form, callback, scope){
            var t = new Ext.Direct.Transaction({
                provider: this,
                action: c,
                method: m.name,
                args:[form, callback, scope],
                cb: scope && Ext.isFunction(callback) ? callback.createDelegate(scope) : callback,
                isForm: true
            });

            if(this.fireEvent('beforecall', this, t) !== false){
                Ext.Direct.addTransaction(t);
                var isUpload = String(form.getAttribute("enctype")).toLowerCase() == 'multipart/form-data',
                    params = {
                        extTID: t.tid,
                        extAction: c,
                        extMethod: m.name,
                        extType: 'rpc',
                        extUpload: String(isUpload)
                    };

                // change made from typeof callback check to callback.params
                // to support addl param passing in DirectSubmit EAC 6/2
                Ext.apply(t, {
                    form: Ext.getDom(form),
                    isUpload: isUpload,
                    params: callback && Ext.isObject(callback.params) ? Ext.apply(params, callback.params) : params
                });
                this.fireEvent('call', this, t);
                this.processForm(t);
            }
        },

        processForm: function(t){
            Ext.Ajax.request({
                url: this.url,
                params: t.params,
                callback: this.onData,
                scope: this,
                form: t.form,
                isUpload: t.isUpload,
                ts: t
            });
        },

        createMethod : function(c, m){
            var f;
            if(!m.formHandler){
                f = function(){
                    this.doCall(c, m, Array.prototype.slice.call(arguments, 0));
                }.createDelegate(this);
            }else{
                f = function(form, callback, scope){
                    this.doForm(c, m, form, callback, scope);
                }.createDelegate(this);
            }
            f.directCfg = {
                action: c,
                method: m
            };
            return f;
        },

        getTransaction: function(opt){
            return opt && opt.tid ? Ext.Direct.getTransaction(opt.tid) : null;
        },

        doCallback: function(t, e){
            var fn = e.status ? 'success' : 'failure';
            if(t && t.cb){
                var hs = t.cb,
                    result = Ext.isDefined(e.result) ? e.result : e.data;
                if(Ext.isFunction(hs)){
                    hs(result, e);
                } else{
                    Ext.callback(hs[fn], hs.scope, [result, e]);
                    Ext.callback(hs.callback, hs.scope, [result, e]);
                }
            }
        }
    });
    Ext.Direct.PROVIDERS['remoting'] = Ext.direct.RemotingProvider;