    /**
     * @class Ext.data.JsonP
     * @singleton
     * This class is used to create JSONP requests. JSONP is a mechanism that allows for making
     * requests for data cross domain. More information is available here:
     * http://en.wikipedia.org/wiki/JSONP
     */
    Ext.define('Ext.data.JsonP', {

        /* Begin Definitions */

        singleton: true,

        statics: {
            requestCount: 0,
            requests: {}
        },

        /* End Definitions */

        /**
         * @property timeout
         * @type Number
         * A default timeout for any JsonP requests. If the request has not completed in this time the
         * failure callback will be fired. The timeout is in ms. Defaults to <tt>30000</tt>.
         */
        timeout: 30000,

        /**
         * @property disableCaching
         * @type Boolean
         * True to add a unique cache-buster param to requests. Defaults to <tt>true</tt>.
         */
        disableCaching: true,

        /**
         * @property disableCachingParam
         * @type String
         * Change the parameter which is sent went disabling caching through a cache buster. Defaults to <tt>'_dc'</tt>.
         */
        disableCachingParam: '_dc',

        /**
         * @property callbackKey
         * @type String
         * Specifies the GET parameter that will be sent to the server containing the function name to be executed when
         * the request completes. Defaults to <tt>callback</tt>. Thus, a common request will be in the form of
         * url?callback=Ext.data.JsonP.callback1
         */
        callbackKey: 'callback',

        /**
         * Makes a JSONP request.
         * @param {Object} options An object which may contain the following properties. Note that options will
         * take priority over any defaults that are specified in the class.
         * <ul>
         * <li><b>url</b> : String <div class="sub-desc">The URL to request.</div></li>
         * <li><b>params</b> : Object (Optional)<div class="sub-desc">An object containing a series of
         * key value pairs that will be sent along with the request.</div></li>
         * <li><b>timeout</b> : Number (Optional) <div class="sub-desc">See {@link #timeout}</div></li>
         * <li><b>callbackKey</b> : String (Optional) <div class="sub-desc">See {@link #callbackKey}</div></li>
         * <li><b>callbackName</b> : String (Optional) <div class="sub-desc">The function name to use for this request.
         * By default this name will be auto-generated: Ext.data.JsonP.callback1, Ext.data.JsonP.callback2, etc.
         * Setting this option to "my_name" will force the function name to be Ext.data.JsonP.my_name.
         * Use this if you want deterministic behavior, but be careful - the callbackName should be different
         * in each JsonP request that you make.</div></li>
         * <li><b>disableCaching</b> : Boolean (Optional) <div class="sub-desc">See {@link #disableCaching}</div></li>
         * <li><b>disableCachingParam</b> : String (Optional) <div class="sub-desc">See {@link #disableCachingParam}</div></li>
         * <li><b>success</b> : Function (Optional) <div class="sub-desc">A function to execute if the request succeeds.</div></li>
         * <li><b>failure</b> : Function (Optional) <div class="sub-desc">A function to execute if the request fails.</div></li>
         * <li><b>callback</b> : Function (Optional) <div class="sub-desc">A function to execute when the request
         * completes, whether it is a success or failure.</div></li>
         * <li><b>scope</b> : Object (Optional)<div class="sub-desc">The scope in
         * which to execute the callbacks: The "this" object for the callback function. Defaults to the browser window.</div></li>
         * </ul>
         * @return {Object} request An object containing the request details.
         */
        request: function(options){
            options = Ext.apply({}, options);

            //<debug>
            if (!options.url) {
                Ext.Error.raise('A url must be specified for a JSONP request.');
            }
            //</debug>

            var me = this,
                disableCaching = Ext.isDefined(options.disableCaching) ? options.disableCaching : me.disableCaching,
                cacheParam = options.disableCachingParam || me.disableCachingParam,
                id = ++me.statics().requestCount,
                callbackName = options.callbackName || 'callback' + id,
                callbackKey = options.callbackKey || me.callbackKey,
                timeout = Ext.isDefined(options.timeout) ? options.timeout : me.timeout,
                params = Ext.apply({}, options.params),
                url = options.url,
                request,
                script;

            params[callbackKey] = 'Ext.data.JsonP.' + callbackName;
            if (disableCaching) {
                params[cacheParam] = new Date().getTime();
            }

            script = me.createScript(url, params);

            me.statics().requests[id] = request = {
                url: url,
                params: params,
                script: script,
                id: id,
                scope: options.scope,
                success: options.success,
                failure: options.failure,
                callback: options.callback,
                callbackName: callbackName
            };

            if (timeout > 0) {
                request.timeout = setTimeout(Ext.bind(me.handleTimeout, me, [request]), timeout);
            }

            me.setupErrorHandling(request);
            me[callbackName] = Ext.bind(me.handleResponse, me, [request], true);
            Ext.getHead().appendChild(script);
            return request;
        },

        /**
         * Abort a request. If the request parameter is not specified all open requests will
         * be aborted.
         * @param {Object/String} request (Optional) The request to abort
         */
        abort: function(request){
            var requests = this.statics().requests,
                key;

            if (request) {
                if (!request.id) {
                    request = requests[request];
                }
                this.abort(request);
            } else {
                for (key in requests) {
                    if (requests.hasOwnProperty(key)) {
                        this.abort(requests[key]);
                    }
                }
            }
        },

        /**
         * Sets up error handling for the script
         * @private
         * @param {Object} request The request
         */
        setupErrorHandling: function(request){
            request.script.onerror = Ext.bind(this.handleError, this, [request]);
        },

        /**
         * Handles any aborts when loading the script
         * @private
         * @param {Object} request The request
         */
        handleAbort: function(request){
            request.errorType = 'abort';
            this.handleResponse(null, request);
        },

        /**
         * Handles any script errors when loading the script
         * @private
         * @param {Object} request The request
         */
        handleError: function(request){
            request.errorType = 'error';
            this.handleResponse(null, request);
        },

        /**
         * Cleans up anu script handling errors
         * @private
         * @param {Object} request The request
         */
        cleanupErrorHandling: function(request){
            request.script.onerror = null;
        },

        /**
         * Handle any script timeouts
         * @private
         * @param {Object} request The request
         */
        handleTimeout: function(request){
            request.errorType = 'timeout';
            this.handleResponse(null, request);
        },

        /**
         * Handle a successful response
         * @private
         * @param {Object} result The result from the request
         * @param {Object} request The request
         */
        handleResponse: function(result, request){

            var success = true;

            if (request.timeout) {
                clearTimeout(request.timeout);
            }
            delete this[request.callbackName];
            delete this.statics()[request.id];
            this.cleanupErrorHandling(request);
            Ext.fly(request.script).remove();

            if (request.errorType) {
                success = false;
                Ext.callback(request.failure, request.scope, [request.errorType]);
            } else {
                Ext.callback(request.success, request.scope, [result]);
            }
            Ext.callback(request.callback, request.scope, [success, result, request.errorType]);
        },

        /**
         * Create the script tag
         * @private
         * @param {String} url The url of the request
         * @param {Object} params Any extra params to be sent
         */
        createScript: function(url, params) {
            var script = document.createElement('script');
            script.setAttribute("src", Ext.urlAppend(url, Ext.Object.toQueryString(params)));
            script.setAttribute("async", true);
            script.setAttribute("type", "text/javascript");
            return script;
        }
    });