The source code

    /**
     * @class Ext.data.DirectProxy
     * @extends Ext.data.DataProxy
     */
    Ext.data.DirectProxy = function(config){
        Ext.apply(this, config);
        if(typeof this.paramOrder == 'string'){
            this.paramOrder = this.paramOrder.split(/[\s,|]/);
        }
        Ext.data.DirectProxy.superclass.constructor.call(this, config);
    };

    Ext.extend(Ext.data.DirectProxy, Ext.data.DataProxy, {
        /**
         * @cfg {Array/String} paramOrder Defaults to <tt>undefined</tt>. A list of params to be executed
         * server side.  Specify the params in the order in which they must be executed on the server-side
         * as either (1) an Array of String values, or (2) a String of params delimited by either whitespace,
         * comma, or pipe. For example,
         * any of the following would be acceptable:<pre><code>
    paramOrder: ['param1','param2','param3']
    paramOrder: 'param1 param2 param3'
    paramOrder: 'param1,param2,param3'
    paramOrder: 'param1|param2|param'
         </code></pre>
         */
        paramOrder: undefined,

        /**
         * @cfg {Boolean} paramsAsHash
         * Send parameters as a collection of named arguments (defaults to <tt>true</tt>). Providing a
         * <tt>{@link #paramOrder}</tt> nullifies this configuration.
         */
        paramsAsHash: true,

        /**
         * @cfg {Function} directFn
         * Function to call when executing a request.  directFn is a simple alternative to defining the api configuration-parameter
         * for Store's which will not implement a full CRUD api.
         */
        directFn : undefined,

        /**
         * DirectProxy implementation of {@link Ext.data.DataProxy#doRequest}
         * @param {String} action The crud action type (create, read, update, destroy)
         * @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
         * <div class="sub-desc"><p>A function to be called after the request.
         * The <tt>callback</tt> is passed the following arguments:<ul>
         * <li><tt>r</tt> : Ext.data.Record[] The block of Ext.data.Records.</li>
         * <li><tt>options</tt>: Options object from the action request</li>
         * <li><tt>success</tt>: Boolean success indicator</li></ul></p></div>
         * @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.
         * @protected
         */
        doRequest : function(action, rs, params, reader, callback, scope, options) {
            var args = [],
                directFn = this.api[action] || this.directFn;

            switch (action) {
                case Ext.data.Api.actions.create:
                    args.push(params.jsonData);		// <-- create(Hash)
                    break;
                case Ext.data.Api.actions.read:
                    // If the method has no parameters, ignore the paramOrder/paramsAsHash.
                    if(directFn.directCfg.method.len > 0){
                        if(this.paramOrder){
                            for(var i = 0, len = this.paramOrder.length; i < len; i++){
                                args.push(params[this.paramOrder[i]]);
                            }
                        }else if(this.paramsAsHash){
                            args.push(params);
                        }
                    }
                    break;
                case Ext.data.Api.actions.update:
                    args.push(params.jsonData);        // <-- update(Hash/Hash[])
                    break;
                case Ext.data.Api.actions.destroy:
                    args.push(params.jsonData);        // <-- destroy(Int/Int[])
                    break;
            }

            var trans = {
                params : params || {},
                request: {
                    callback : callback,
                    scope : scope,
                    arg : options
                },
                reader: reader
            };

            args.push(this.createCallback(action, rs, trans), this);
            directFn.apply(window, args);
        },

        // private
        createCallback : function(action, rs, trans) {
            var me = this;
            return function(result, res) {
                if (!res.status) {
                    // @deprecated fire loadexception
                    if (action === Ext.data.Api.actions.read) {
                        me.fireEvent("loadexception", me, trans, res, null);
                    }
                    me.fireEvent('exception', me, 'remote', action, trans, res, null);
                    trans.request.callback.call(trans.request.scope, null, trans.request.arg, false);
                    return;
                }
                if (action === Ext.data.Api.actions.read) {
                    me.onRead(action, trans, result, res);
                } else {
                    me.onWrite(action, trans, result, res, rs);
                }
            };
        },

        /**
         * Callback for read actions
         * @param {String} action [Ext.data.Api.actions.create|read|update|destroy]
         * @param {Object} trans The request transaction object
         * @param {Object} result Data object picked out of the server-response.
         * @param {Object} res The server response
         * @protected
         */
        onRead : function(action, trans, result, res) {
            var records;
            try {
                records = trans.reader.readRecords(result);
            }
            catch (ex) {
                // @deprecated: Fire old loadexception for backwards-compat.
                this.fireEvent("loadexception", this, trans, res, ex);

                this.fireEvent('exception', this, 'response', action, trans, res, ex);
                trans.request.callback.call(trans.request.scope, null, trans.request.arg, false);
                return;
            }
            this.fireEvent("load", this, res, trans.request.arg);
            trans.request.callback.call(trans.request.scope, records, trans.request.arg, true);
        },
        /**
         * Callback for write actions
         * @param {String} action [{@link Ext.data.Api#actions create|read|update|destroy}]
         * @param {Object} trans The request transaction object
         * @param {Object} result Data object picked out of the server-response.
         * @param {Object} res The server response
         * @param {Ext.data.Record/Ext.data.Record[]} rs The Store resultset associated with the action.
         * @protected
         */
        onWrite : function(action, trans, result, res, rs) {
            var data = trans.reader.extractData(trans.reader.getRoot(result), false);
            var success = trans.reader.getSuccess(result);
            success = (success !== false);
            if (success){
                this.fireEvent("write", this, action, data, res, rs, trans.request.arg);
            }else{
                this.fireEvent('exception', this, 'remote', action, trans, result, rs);
            }
            trans.request.callback.call(trans.request.scope, data, res, success);
        }
    });