The source code

    /**
     * @class Ext.data.MemoryProxy
     * @extends Ext.data.DataProxy
     * An implementation of Ext.data.DataProxy that simply passes the data specified in its constructor
     * to the Reader when its load method is called.
     * @constructor
     * @param {Object} data The data object which the Reader uses to construct a block of Ext.data.Records.
     */
    Ext.data.MemoryProxy = function(data){
        // Must define a dummy api with "read" action to satisfy DataProxy#doRequest and Ext.data.Api#prepare *before* calling super
        var api = {};
        api[Ext.data.Api.actions.read] = true;
        Ext.data.MemoryProxy.superclass.constructor.call(this, {
            api: api
        });
        this.data = data;
    };

    Ext.extend(Ext.data.MemoryProxy, Ext.data.DataProxy, {
        /**
         * @event loadexception
         * Fires if an exception occurs in the Proxy during data loading. Note that this event is also relayed
         * through {@link Ext.data.Store}, so you can listen for it directly on any Store instance.
         * @param {Object} this
         * @param {Object} arg The callback's arg object passed to the {@link #load} function
         * @param {Object} null This parameter does not apply and will always be null for MemoryProxy
         * @param {Error} e The JavaScript Error object caught if the configured Reader could not read the data
         */

           /**
         * MemoryProxy implementation of DataProxy#doRequest
         * @param {String} action
         * @param {Ext.data.Record/Ext.data.Record[]} rs If action is load, rs will be null
         * @param {Object} params An object containing properties which are to be used as HTTP parameters
         * for the request to the remote server.
         * @param {Ext.data.DataReader} reader The Reader object which converts the data
         * object into a block of Ext.data.Records.
         * @param {Function} callback The function into which to pass the block of Ext.data.Records.
         * The function must be passed <ul>
         * <li>The Record block object</li>
         * <li>The "arg" argument from the load function</li>
         * <li>A boolean success indicator</li>
         * </ul>
         * @param {Object} scope The scope (<code>this</code> reference) in which the callback function is executed. Defaults to the browser window.
         * @param {Object} arg An optional argument which is passed to the callback as its second parameter.
         */
        doRequest : function(action, rs, params, reader, callback, scope, arg) {
            // No implementation for CRUD in MemoryProxy.  Assumes all actions are 'load'
            params = params || {};
            var result;
            try {
                result = reader.readRecords(this.data);
            }catch(e){
                // @deprecated loadexception
                this.fireEvent("loadexception", this, null, arg, e);

                this.fireEvent('exception', this, 'response', action, arg, null, e);
                callback.call(scope, null, arg, false);
                return;
            }
            callback.call(scope, result, arg, true);
        }
    });