/**
                             * Provides a DataSource implementation which can be used to retrieve data via the IO Utility.
                             *
                             * @module datasource
                             * @submodule datasource-io
                             */
                            
                            /**
                             * IO subclass for the DataSource Utility.
                             * @class DataSource.IO
                             * @extends DataSource.Local
                             * @constructor
                             */
                            var DSIO = function() {
                                DSIO.superclass.constructor.apply(this, arguments);
                            };
                            
                            
                                /////////////////////////////////////////////////////////////////////////////
                                //
                                // DataSource.IO static properties
                                //
                                /////////////////////////////////////////////////////////////////////////////
                            Y.mix(DSIO, {
                                /**
                                 * Class name.
                                 *
                                 * @property NAME
                                 * @type String
                                 * @static
                                 * @final
                                 * @value "dataSourceIO"
                                 */
                                NAME: "dataSourceIO",
                            
                            
                                /////////////////////////////////////////////////////////////////////////////
                                //
                                // DataSource.IO Attributes
                                //
                                /////////////////////////////////////////////////////////////////////////////
                            
                                ATTRS: {
                                    /**
                                     * Pointer to IO Utility.
                                     *
                                     * @attribute io
                                     * @type Y.io
                                     * @default Y.io
                                     */
                                    io: {
                                        value: Y.io,
                                        cloneDefaultValue: false
                                    },
                            
                                    /**
                                     * Default IO Config.
                                     *
                                     * @attribute ioConfig
                                     * @type Object
                                     * @default null
                                     */
                                     ioConfig: {
                                        value: null
                                     }
                                }
                            });
                            
                            Y.extend(DSIO, Y.DataSource.Local, {
                                /**
                                * Internal init() handler.
                                *
                                * @method initializer
                                * @param config {Object} Config object.
                                * @private
                                */
                                initializer: function(config) {
                                    this._queue = {interval:null, conn:null, requests:[]};
                                },
                            
                                /**
                                * IO success callback.
                                *
                                * @method successHandler
                                * @param id {String} Transaction ID.
                                * @param response {String} Response.
                                * @param e {EventFacade} Event facade.
                                * @private
                                */
                                successHandler: function (id, response, e) {
                                    var defIOConfig = this.get("ioConfig"),
                                        payload = e.details[0];
                            
                                    delete Y.DataSource.Local.transactions[e.tId];
                            
                                    payload.data = response;
                                    this.fire("data", payload);
                            
                                    Y.log("Received IO data response for \"" + e.request + "\"", "info", "datasource-io");
                            
                                    if (defIOConfig && defIOConfig.on && defIOConfig.on.success) {
                                        defIOConfig.on.success.apply(defIOConfig.context || Y, arguments);
                                    }
                                },
                            
                                /**
                                * IO failure callback.
                                *
                                * @method failureHandler
                                * @param id {String} Transaction ID.
                                * @param response {String} Response.
                                * @param e {EventFacade} Event facade.
                                * @private
                                */
                                failureHandler: function (id, response, e) {
                                    var defIOConfig = this.get("ioConfig"),
                                        payload = e.details[0];
                            
                                    delete Y.DataSource.Local.transactions[e.tId];
                            
                                    payload.error = new Error("IO data failure");
                                    Y.log("IO data failure", "error", "datasource-io");
                            
                                    payload.data = response;
                                    this.fire("data", payload);
                            
                                    Y.log("Received IO data failure for \"" + e.request + "\"", "info", "datasource-io");
                            
                                    if (defIOConfig && defIOConfig.on && defIOConfig.on.failure) {
                                        defIOConfig.on.failure.apply(defIOConfig.context || Y, arguments);
                                    }
                                },
                            
                                /**
                                * @property _queue
                                * @description Object literal to manage asynchronous request/response
                                * cycles enabled if queue needs to be managed (asyncMode/ioConnMode):
                                * <dl>
                                *     <dt>interval {Number}</dt>
                                *         <dd>Interval ID of in-progress queue.</dd>
                                *     <dt>conn</dt>
                                *         <dd>In-progress connection identifier (if applicable).</dd>
                                *     <dt>requests {Object[]}</dt>
                                *         <dd>Array of queued request objects: {request:request, callback:callback}.</dd>
                                * </dl>
                                * @type Object
                                * @default {interval:null, conn:null, requests:[]}
                                * @private
                                */
                                _queue: null,
                            
                                /**
                                 * Passes query string to IO. Fires <code>response</code> event when
                                 * response is received asynchronously.
                                 *
                                 * @method _defRequestFn
                                 * @param e {EventFacade} Event Facade with the following properties:
                                 * <dl>
                                 * <dt>tId (Number)</dt> <dd>Unique transaction ID.</dd>
                                 * <dt>request (Object)</dt> <dd>The request.</dd>
                                 * <dt>callback (Object)</dt> <dd>The callback object with the following properties:
                                 *     <dl>
                                 *         <dt>success (Function)</dt> <dd>Success handler.</dd>
                                 *         <dt>failure (Function)</dt> <dd>Failure handler.</dd>
                                 *     </dl>
                                 * </dd>
                                 * <dt>cfg (Object)</dt> <dd>Configuration object.</dd>
                                 * </dl>
                                 * @protected
                                 */
                                _defRequestFn: function(e) {
                                    var uri = this.get("source"),
                                        io = this.get("io"),
                                        defIOConfig = this.get("ioConfig"),
                                        request = e.request,
                                        cfg = Y.merge(defIOConfig, e.cfg, {
                                            on: Y.merge(defIOConfig, {
                                                success: this.successHandler,
                                                failure: this.failureHandler
                                            }),
                                            context: this,
                                            "arguments": e
                                        });
                            
                                    // Support for POST transactions
                                    if(Y.Lang.isString(request)) {
                                        if(cfg.method && (cfg.method.toUpperCase() === "POST")) {
                                            cfg.data = cfg.data ? cfg.data+request : request;
                                        }
                                        else {
                                            uri += request;
                                        }
                                    }
                                    Y.DataSource.Local.transactions[e.tId] = io(uri, cfg);
                                    return e.tId;
                                }
                            });
                            
                            Y.DataSource.IO = DSIO;