The source code

    /**
     * @class Ext.data.XmlReader
     * @extends Ext.data.DataReader
     * <p>Data reader class to create an Array of {@link Ext.data.Record} objects from an XML document
     * based on mappings in a provided {@link Ext.data.Record} constructor.</p>
     * <p><b>Note</b>: that in order for the browser to parse a returned XML document, the Content-Type
     * header in the HTTP response must be set to "text/xml" or "application/xml".</p>
     * <p>Example code:</p>
     * <pre><code>
    var Employee = Ext.data.Record.create([
       {name: 'name', mapping: 'name'},     // "mapping" property not needed if it is the same as "name"
       {name: 'occupation'}                 // This field will use "occupation" as the mapping.
    ]);
    var myReader = new Ext.data.XmlReader({
       totalProperty: "results", // The element which contains the total dataset size (optional)
       record: "row",           // The repeated element which contains row information
       idProperty: "id"         // The element within the row that provides an ID for the record (optional)
       messageProperty: "msg"   // The element within the response that provides a user-feedback message (optional)
    }, Employee);
    </code></pre>
     * <p>
     * This would consume an XML file like this:
     * <pre><code>
    &lt;?xml version="1.0" encoding="UTF-8"?>
    &lt;dataset>
     &lt;results>2&lt;/results>
     &lt;row>
       &lt;id>1&lt;/id>
       &lt;name>Bill&lt;/name>
       &lt;occupation>Gardener&lt;/occupation>
     &lt;/row>
     &lt;row>
       &lt;id>2&lt;/id>
       &lt;name>Ben&lt;/name>
       &lt;occupation>Horticulturalist&lt;/occupation>
     &lt;/row>
    &lt;/dataset>
    </code></pre>
     * @cfg {String} totalProperty The DomQuery path from which to retrieve the total number of records
     * in the dataset. This is only needed if the whole dataset is not passed in one go, but is being
     * paged from the remote server.
     * @cfg {String} record The DomQuery path to the repeated element which contains record information.
     * @cfg {String} successProperty The DomQuery path to the success attribute used by forms.
     * @cfg {String} idPath The DomQuery path relative from the record element to the element that contains
     * a record identifier value.
     * @constructor
     * Create a new XmlReader.
     * @param {Object} meta Metadata configuration options
     * @param {Object} recordType Either an Array of field definition objects as passed to
     * {@link Ext.data.Record#create}, or a Record constructor object created using {@link Ext.data.Record#create}.
     */
    Ext.data.XmlReader = function(meta, recordType){
        meta = meta || {};

        // backwards compat, convert idPath or id / success
        Ext.applyIf(meta, {
            idProperty: meta.idProperty || meta.idPath || meta.id,
            successProperty: meta.successProperty || meta.success
        });

        Ext.data.XmlReader.superclass.constructor.call(this, meta, recordType || meta.fields);
    };
    Ext.extend(Ext.data.XmlReader, Ext.data.DataReader, {
        /**
         * This method is only used by a DataProxy which has retrieved data from a remote server.
         * @param {Object} response The XHR object which contains the parsed XML document.  The response is expected
         * to contain a property called <tt>responseXML</tt> which refers to an XML document object.
         * @return {Object} records A data block which is used by an {@link Ext.data.Store} as
         * a cache of Ext.data.Records.
         */
        read : function(response){
            var doc = response.responseXML;
            if(!doc) {
                throw {message: "XmlReader.read: XML Document not available"};
            }
            return this.readRecords(doc);
        },

        /**
         * Create a data block containing Ext.data.Records from an XML document.
         * @param {Object} doc A parsed XML document.
         * @return {Object} records A data block which is used by an {@link Ext.data.Store} as
         * a cache of Ext.data.Records.
         */
        readRecords : function(doc){
            /**
             * After any data loads/reads, the raw XML Document is available for further custom processing.
             * @type XMLDocument
             */
            this.xmlData = doc;

            var root    = doc.documentElement || doc,
                q       = Ext.DomQuery,
                totalRecords = 0,
                success = true;

            if(this.meta.totalProperty){
                totalRecords = this.getTotal(root, 0);
            }
            if(this.meta.successProperty){
                success = this.getSuccess(root);
            }

            var records = this.extractData(q.select(this.meta.record, root), true); // <-- true to return Ext.data.Record[]

            // TODO return Ext.data.Response instance.  @see #readResponse
            return {
                success : success,
                records : records,
                totalRecords : totalRecords || records.length
            };
        },

        /**
         * Decode an XML response from server.
         * @param {String} action [{@link Ext.data.Api#actions} create|read|update|destroy]
         * @param {Object} response HTTP Response object from browser.
         * @return {Ext.data.Response} An instance of {@link Ext.data.Response}
         */
        readResponse : function(action, response) {
            var q = Ext.DomQuery,
                doc = response.responseXML,
                root = doc.documentElement || doc;

            // create general Response instance.
            var res = new Ext.data.Response({
                action: action,
                success : this.getSuccess(root),
                message: this.getMessage(root),
                data: this.extractData(q.select(this.meta.record, root) || q.select(this.meta.root, root), false),
                raw: doc
            });

            if (Ext.isEmpty(res.success)) {
                throw new Ext.data.DataReader.Error('successProperty-response', this.meta.successProperty);
            }

            // Create actions from a response having status 200 must return pk
            if (action === Ext.data.Api.actions.create) {
                var def = Ext.isDefined(res.data);
                if (def && Ext.isEmpty(res.data)) {
                    throw new Ext.data.JsonReader.Error('root-empty', this.meta.root);
                }
                else if (!def) {
                    throw new Ext.data.JsonReader.Error('root-undefined-response', this.meta.root);
                }
            }
            return res;
        },

        getSuccess : function() {
            return true;
        },

        /**
         * build response-data extractor functions.
         * @private
         * @ignore
         */
        buildExtractors : function() {
            if(this.ef){
                return;
            }
            var s       = this.meta,
                Record  = this.recordType,
                f       = Record.prototype.fields,
                fi      = f.items,
                fl      = f.length;

            if(s.totalProperty) {
                this.getTotal = this.createAccessor(s.totalProperty);
            }
            if(s.successProperty) {
                this.getSuccess = this.createAccessor(s.successProperty);
            }
            if (s.messageProperty) {
                this.getMessage = this.createAccessor(s.messageProperty);
            }
            this.getRoot = function(res) {
                return (!Ext.isEmpty(res[this.meta.record])) ? res[this.meta.record] : res[this.meta.root];
            };
            if (s.idPath || s.idProperty) {
                var g = this.createAccessor(s.idPath || s.idProperty);
                this.getId = function(rec) {
                    var id = g(rec) || rec.id;
                    return (id === undefined || id === '') ? null : id;
                };
            } else {
                this.getId = function(){return null;};
            }
            var ef = [];
            for(var i = 0; i < fl; i++){
                f = fi[i];
                var map = (f.mapping !== undefined && f.mapping !== null) ? f.mapping : f.name;
                ef.push(this.createAccessor(map));
            }
            this.ef = ef;
        },

        /**
         * Creates a function to return some particular key of data from a response.
         * @param {String} key
         * @return {Function}
         * @private
         * @ignore
         */
        createAccessor : function(){
            var q = Ext.DomQuery;
            return function(key) {
                if (Ext.isFunction(key)) {
                    return key;
                }
                switch(key) {
                    case this.meta.totalProperty:
                        return function(root, def){
                            return q.selectNumber(key, root, def);
                        };
                        break;
                    case this.meta.successProperty:
                        return function(root, def) {
                            var sv = q.selectValue(key, root, true);
                            var success = sv !== false && sv !== 'false';
                            return success;
                        };
                        break;
                    default:
                        return function(root, def) {
                            return q.selectValue(key, root, def);
                        };
                        break;
                }
            };
        }(),

        /**
         * extracts values and type-casts a row of data from server, extracted by #extractData
         * @param {Hash} data
         * @param {Ext.data.Field[]} items
         * @param {Number} len
         * @private
         * @ignore
         */
        extractValues : function(data, items, len) {
            var f, values = {};
            for(var j = 0; j < len; j++){
                f = items[j];
                var v = this.ef[j](data);
                values[f.name] = f.convert((v !== undefined) ? v : f.defaultValue, data);
            }
            return values;
        }
    });