# Yahoo! UI Library

### AutoComplete Widget 2.3.1

Yahoo! UI Library > autocomplete > DataSource.js (source view)

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    /**
     * The DataSource utility provides a common configurable interface for widgets
     * to access a variety of data, from JavaScript arrays to online servers over
     * XHR.
     *
     * @namespace YAHOO.util
     * @module datasource
     * @requires yahoo, event
     * @optional connection
     * @title DataSource Utility
     * @beta
     */

    /****************************************************************************/
    /****************************************************************************/
    /****************************************************************************/

    /**
     * The DataSource class defines and manages a live set of data for widgets to
     * interact with. Examples of live databases include in-memory
     * local data such as a JavaScript array, a JavaScript function, or JSON, or
     * remote data such as data retrieved through an XHR connection.
     *
     * @class DataSource
     * @uses YAHOO.util.EventProvider
     * @constructor
     * @param oLiveData {Object} Pointer to live database.
     * @param oConfigs {Object} (optional) Object literal of configuration values.
     */
    YAHOO.util.DataSource = function(oLiveData, oConfigs) {
        // Set any config params passed in to override defaults
        if(oConfigs && (oConfigs.constructor == Object)) {
            for(var sConfig in oConfigs) {
                if(sConfig) {
                    this[sConfig] = oConfigs[sConfig];
                }
            }
        }

        if(!oLiveData) {
            YAHOO.log("Could not instantiate DataSource due to invalid live database",
                    "error", this.toString());
            return;
        }

        if(oLiveData.nodeType && oLiveData.nodeType == 9) {
            this.dataType = YAHOO.util.DataSource.TYPE_XML;
        }
        else if(YAHOO.lang.isArray(oLiveData)) {
            this.dataType = YAHOO.util.DataSource.TYPE_JSARRAY;
        }
        else if(YAHOO.lang.isString(oLiveData)) {
            this.dataType = YAHOO.util.DataSource.TYPE_XHR;
        }
        else if(YAHOO.lang.isFunction(oLiveData)) {
            this.dataType = YAHOO.util.DataSource.TYPE_JSFUNCTION;
        }
        else if(oLiveData.nodeName && (oLiveData.nodeName.toLowerCase() == "table")) {
            this.dataType = YAHOO.util.DataSource.TYPE_HTMLTABLE;
        }
        else if(YAHOO.lang.isObject(oLiveData)) {
            this.dataType = YAHOO.util.DataSource.TYPE_JSON;
        }
        else {
            this.dataType = YAHOO.util.DataSource.TYPE_UNKNOWN;
        }

        this.liveData = oLiveData;
        this._oQueue = {interval:null, conn:null, requests:[]};

        // Validate and initialize public configs
        var maxCacheEntries = this.maxCacheEntries;
        if(!YAHOO.lang.isNumber(maxCacheEntries) || (maxCacheEntries < 0)) {
            maxCacheEntries = 0;
        }

        // Initialize local cache
        if(maxCacheEntries > 0 && !this._aCache) {
            this._aCache = [];
            YAHOO.log("Cache initialized", "info", this.toString());
        }

        this._sName = "DataSource instance" + YAHOO.util.DataSource._nIndex;
        YAHOO.util.DataSource._nIndex++;
        YAHOO.log("DataSource initialized", "info", this.toString());

        /////////////////////////////////////////////////////////////////////////////
        //
        // Custom Events
        //
        /////////////////////////////////////////////////////////////////////////////

        /**
         * Fired when a request is made to the local cache.
         *
         * @event cacheRequestEvent
         * @param oArgs.request {Object} The request object.
         * @param oArgs.callback {Function} The callback function.
         * @param oArgs.caller {Object} The parent object of the callback function.
         */
        this.createEvent("cacheRequestEvent");

        /**
         * Fired when data is retrieved from the local cache.
         *
         * @event getCachedResponseEvent
         * @param oArgs.request {Object} The request object.
         * @param oArgs.response {Object} The response object.
         * @param oArgs.callback {Function} The callback function.
         * @param oArgs.caller {Object} The parent object of the callback function.
         * @param oArgs.tId {Number} Transaction ID.
         */
        this.createEvent("cacheResponseEvent");

        /**
         * Fired when a request is sent to the live data source.
         *
         * @event requestEvent
         * @param oArgs.request {Object} The request object.
         * @param oArgs.callback {Function} The callback function.
         * @param oArgs.caller {Object} The parent object of the callback function.
         */
        this.createEvent("requestEvent");

        /**
         * Fired when live data source sends response.
         *
         * @event responseEvent
         * @param oArgs.request {Object} The request object.
         * @param oArgs.response {Object} The raw response object.
         * @param oArgs.callback {Function} The callback function.
         * @param oArgs.caller {Object} The parent object of the callback function.
         */
        this.createEvent("responseEvent");

        /**
         * Fired when response is parsed.
         *
         * @event responseParseEvent
         * @param oArgs.request {Object} The request object.
         * @param oArgs.response {Object} The parsed response object.
         * @param oArgs.callback {Function} The callback function.
         * @param oArgs.caller {Object} The parent object of the callback function.
         */
        this.createEvent("responseParseEvent");

        /**
         * Fired when response is cached.
         *
         * @event responseCacheEvent
         * @param oArgs.request {Object} The request object.
         * @param oArgs.response {Object} The parsed response object.
         * @param oArgs.callback {Function} The callback function.
         * @param oArgs.caller {Object} The parent object of the callback function.
         */
        this.createEvent("responseCacheEvent");
        /**
         * Fired when an error is encountered with the live data source.
         *
         * @event dataErrorEvent
         * @param oArgs.request {Object} The request object.
         * @param oArgs.callback {Function} The callback function.
         * @param oArgs.caller {Object} The parent object of the callback function.
         * @param oArgs.message {String} The error message.
         */
        this.createEvent("dataErrorEvent");

        /**
         * Fired when the local cache is flushed.
         *
         * @event cacheFlushEvent
         */
        this.createEvent("cacheFlushEvent");
    };

    YAHOO.augment(YAHOO.util.DataSource, YAHOO.util.EventProvider);

    /////////////////////////////////////////////////////////////////////////////
    //
    // Public constants
    //
    /////////////////////////////////////////////////////////////////////////////

    /**
     * Type is unknown.
     *
     * @property TYPE_UNKNOWN
     * @type Number
     * @final
     * @default -1
     */
    YAHOO.util.DataSource.TYPE_UNKNOWN = -1;

    /**
     * Type is a JavaScript Array.
     *
     * @property TYPE_JSARRAY
     * @type Number
     * @final
     * @default 0
     */
    YAHOO.util.DataSource.TYPE_JSARRAY = 0;

    /**
     * Type is a JavaScript Function.
     *
     * @property TYPE_JSFUNCTION
     * @type Number
     * @final
     * @default 1
     */
    YAHOO.util.DataSource.TYPE_JSFUNCTION = 1;

    /**
     * Type is hosted on a server via an XHR connection.
     *
     * @property TYPE_XHR
     * @type Number
     * @final
     * @default 2
     */
    YAHOO.util.DataSource.TYPE_XHR = 2;

    /**
     * Type is JSON.
     *
     * @property TYPE_JSON
     * @type Number
     * @final
     * @default 3
     */
    YAHOO.util.DataSource.TYPE_JSON = 3;

    /**
     * Type is XML.
     *
     * @property TYPE_XML
     * @type Number
     * @final
     * @default 4
     */
    YAHOO.util.DataSource.TYPE_XML = 4;

    /**
     * Type is plain text.
     *
     * @property TYPE_TEXT
     * @type Number
     * @final
     * @default 5
     */
    YAHOO.util.DataSource.TYPE_TEXT = 5;

    /**
     * Type is an HTML TABLE element.
     *
     * @property TYPE_HTMLTABLE
     * @type Number
     * @final
     * @default 6
     */
    YAHOO.util.DataSource.TYPE_HTMLTABLE = 6;

    /**
     * Error message for invalid dataresponses.
     *
     * @property ERROR_DATAINVALID
     * @type String
     * @final
     * @default "Invalid data"
     */
    YAHOO.util.DataSource.ERROR_DATAINVALID = "Invalid data";

    /**
     * Error message for null data responses.
     *
     * @property ERROR_DATANULL
     * @type String
     * @final
     * @default "Null data"
     */
    YAHOO.util.DataSource.ERROR_DATANULL = "Null data";

    /////////////////////////////////////////////////////////////////////////////
    //
    // Private variables
    //
    /////////////////////////////////////////////////////////////////////////////

    /**
     * Internal class variable to index multiple DataSource instances.
     *
     * @property DataSource._nIndex
     * @type Number
     * @private
     * @static
     */
    YAHOO.util.DataSource._nIndex = 0;

    /**
     * Internal class variable to assign unique transaction IDs.
     *
     * @property DataSource._nTransactionId
     * @type Number
     * @private
     * @static
     */
    YAHOO.util.DataSource._nTransactionId = 0;

    /**
     * Name of DataSource instance.
     *
     * @property _sName
     * @type String
     * @private
     */
    YAHOO.util.DataSource.prototype._sName = null;

    /**
     * Local cache of data result object literals indexed chronologically.
     *
     * @property _aCache
     * @type Object[]
     * @private
     */
    YAHOO.util.DataSource.prototype._aCache = null;

    /**
     * Local queue of request connections, enabled if queue needs to be managed.
     *
     * @property _oQueue
     * @type Object
     * @private
     */
    YAHOO.util.DataSource.prototype._oQueue = null;

    /////////////////////////////////////////////////////////////////////////////
    //
    // Private methods
    //
    /////////////////////////////////////////////////////////////////////////////

    /////////////////////////////////////////////////////////////////////////////
    //
    // Public member variables
    //
    /////////////////////////////////////////////////////////////////////////////

    /**
     * Max size of the local cache.  Set to 0 to turn off caching.  Caching is
     * useful to reduce the number of server connections.  Recommended only for data
     * sources that return comprehensive results for queries or when stale data is
     * not an issue.
     *
     * @property maxCacheEntries
     * @type Number
     * @default 0
     */
    YAHOO.util.DataSource.prototype.maxCacheEntries = 0;

     /**
     * Pointer to live database.
     *
     * @property liveData
     * @type Object
     */
    YAHOO.util.DataSource.prototype.liveData = null;

    /**
     * Where the live data is held.
     *
     * @property dataType
     * @type Number
     * @default YAHOO.util.DataSource.TYPE_UNKNOWN
     *
     */
    YAHOO.util.DataSource.prototype.dataType = YAHOO.util.DataSource.TYPE_UNKNOWN;

    /**
     * Format of response.
     *
     * @property responseType
     * @type Number
     * @default YAHOO.util.DataSource.TYPE_UNKNOWN
     */
    YAHOO.util.DataSource.prototype.responseType = YAHOO.util.DataSource.TYPE_UNKNOWN;

    /**
     * Response schema object literal takes a combination of the following properties:
     *
     * <dl>
     * <dt>resultsList</dt> <dd>Pointer to array of tabular data</dd>
     * <dt>resultNode</dt> <dd>Pointer to node name of row data (XML data only)</dd>
     * <dt>recordDelim</dt> <dd>Record delimiter (text data only)</dd>
     * <dt>fieldDelim</dt> <dd>Field delimiter (text data only)</dd>
     * <dt>fields</dt> <dd>Array of field names (aka keys), or array of object literals
     * such as: {key:"fieldname",parser:YAHOO.util.DataSource.parseDate}</dd>
     * </dl>
     *
     * @property responseSchema
     * @type Object
     */
    YAHOO.util.DataSource.prototype.responseSchema = null;

     /**
     * Alias to YUI Connection Manager. Allows implementers to specify their own
     * subclasses of the YUI Connection Manager utility.
     *
     * @property connMgr
     * @type Object
     * @default YAHOO.util.Connect
     */
    YAHOO.util.DataSource.prototype.connMgr = null;

     /**
     * If data is accessed over XHR via Connection Manager, this setting defines
     * request/response management in the following manner:
     * <dl>
     *     <dt>queueRequests</dt>
     *     <dd>If a request is already in progress, wait until response is returned
     *     before sending the next request.</dd>
     *
     *     <dt>cancelStaleRequests</dt>
     *     <dd>If a request is already in progress, cancel it before sending the next
     *     request.</dd>
     *
     *     <dt>ignoreStaleResponses</dt>
     *     <dd>Send all requests, but handle only the response for the most recently
     *     sent request.</dd>
     *
     *     <dt>allowAll</dt>
     *     <dd>Send all requests and handle all responses.</dd>
     *
     * </dl>
     *
     * @property connXhrMode
     * @type String
     * @default "allowAll"
     */
    YAHOO.util.DataSource.prototype.connXhrMode = "allowAll";

     /**
     * If data is accessed over XHR via Connection Manager, true if data should be
     * sent via POST, otherwise data will be sent via GET.
     *
     * @property connMethodPost
     * @type Boolean
     * @default false
     */
    YAHOO.util.DataSource.prototype.connMethodPost = false;

     /**
     * If data is accessed over XHR via Connection Manager, the connection timeout
     * defines how many  milliseconds the XHR connection will wait for a server
     * response. Any non-zero value will enable the Connection utility's
     * Auto-Abort feature.
     *
     * @property connTimeout
     * @type Number
     * @default 0
     */
    YAHOO.util.DataSource.prototype.connTimeout = 0;

    /////////////////////////////////////////////////////////////////////////////
    //
    // Public static methods
    //
    /////////////////////////////////////////////////////////////////////////////

    /**
     * Converts data to type String.
     *
     * @method DataSource.parseString
     * @param oData {String | Number | Boolean | Date | Array | Object} Data to parse.
     * The special values null and undefined will return null.
     * @return {Number} A string, or null.
     * @static
     */
    YAHOO.util.DataSource.parseString = function(oData) {
        // Special case null and undefined
        if(!YAHOO.lang.isValue(oData)) {
            return null;
        }

        //Convert to string
        var string = oData + "";

        // Validate
        if(YAHOO.lang.isString(string)) {
            return string;
        }
        else {
            YAHOO.log("Could not convert data " + YAHOO.lang.dump(oData) + " to type String", "warn", this.toString());
            return null;
        }
    };

    /**
     * Converts data to type Number.
     *
     * @method DataSource.parseNumber
     * @param oData {String | Number | Boolean | Null} Data to convert. Beware, null
     * returns as 0.
     * @return {Number} A number, or null if NaN.
     * @static
     */
    YAHOO.util.DataSource.parseNumber = function(oData) {
        //Convert to number
        var number = oData * 1;

        // Validate
        if(YAHOO.lang.isNumber(number)) {
            return number;
        }
        else {
            YAHOO.log("Could not convert data " + YAHOO.lang.dump(oData) + " to type Number", "warn", this.toString());
            return null;
        }
    };
    // Backward compatibility
    YAHOO.util.DataSource.convertNumber = function(oData) {
        YAHOO.log("The method YAHOO.util.DataSource.convertNumber() has been" +
        " deprecated in favor of YAHOO.util.DataSource.parseNumber()", "warn",
        this.toString());
        return YAHOO.util.DataSource.parseNumber(oData);
    };

    /**
     * Converts data to type Date.
     *
     * @method DataSource.parseDate
     * @param oData {Date | String | Number} Data to convert.
     * @return {Date} A Date instance.
     * @static
     */
    YAHOO.util.DataSource.parseDate = function(oData) {
        var date = null;

        //Convert to date
        if(!(oData instanceof Date)) {
            date = new Date(oData);
        }
        else {
            return oData;
        }

        // Validate
        if(date instanceof Date) {
            return date;
        }
        else {
            YAHOO.log("Could not convert data " + YAHOO.lang.dump(oData) + " to type Date", "warn", this.toString());
            return null;
        }
    };
    // Backward compatibility
    YAHOO.util.DataSource.convertDate = function(oData) {
        YAHOO.log("The method YAHOO.util.DataSource.convertDate() has been" +
        " deprecated in favor of YAHOO.util.DataSource.parseDate()", "warn",
        this.toString());
        return YAHOO.util.DataSource.parseDate(oData);
    };

    /////////////////////////////////////////////////////////////////////////////
    //
    // Public methods
    //
    /////////////////////////////////////////////////////////////////////////////

    /**
     * Public accessor to the unique name of the DataSource instance.
     *
     * @method toString
     * @return {String} Unique name of the DataSource instance.
     */
    YAHOO.util.DataSource.prototype.toString = function() {
        return this._sName;
    };

    /**
     * Overridable method passes request to cache and returns cached response if any,
     * refreshing the hit in the cache as the newest item. Returns null if there is
     * no cache hit.
     *
     * @method getCachedResponse
     * @param oRequest {Object} Request object.
     * @param oCallback {Function} Handler function to receive the response.
     * @param oCaller {Object} The Calling object that is making the request.
     * @return {Object} Cached response object or null.
     */
    YAHOO.util.DataSource.prototype.getCachedResponse = function(oRequest, oCallback, oCaller) {
        var aCache = this._aCache;
        var nCacheLength = (aCache) ? aCache.length : 0;
        var oResponse = null;

        // If cache is enabled...
        if((this.maxCacheEntries > 0) && aCache && (nCacheLength > 0)) {
            this.fireEvent("cacheRequestEvent", {request:oRequest,callback:oCallback,caller:oCaller});

            // Loop through each cached element
            for(var i = nCacheLength-1; i >= 0; i--) {
                var oCacheElem = aCache[i];

                // Defer cache hit logic to a public overridable method
                if(this.isCacheHit(oRequest,oCacheElem.request)) {
                    // Grab the cached response
                    oResponse = oCacheElem.response;
                    // The cache returned a hit!
                    // Remove element from its original location
                    aCache.splice(i,1);
                    // Add as newest
                    this.addToCache(oRequest, oResponse);
                    this.fireEvent("cacheResponseEvent", {request:oRequest,response:oResponse,callback:oCallback,caller:oCaller});
                    break;
                }
            }
        }
        YAHOO.log("The cached response for \"" + YAHOO.lang.dump(oRequest) +
                "\" is " + YAHOO.lang.dump(oResponse), "info", this.toString());
        return oResponse;
    };

    /**
     * Default overridable method matches given request to given cached request.
     * Returns true if is a hit, returns false otherwise.  Implementers should
     * override this method to customize the cache-matching algorithm.
     *
     * @method isCacheHit
     * @param oRequest {Object} Request object.
     * @param oCachedRequest {Object} Cached request object.
     * @return {Boolean} True if given request matches cached request, false otherwise.
     */
    YAHOO.util.DataSource.prototype.isCacheHit = function(oRequest, oCachedRequest) {
        return (oRequest === oCachedRequest);
    };

    /**
     * Adds a new item to the cache. If cache is full, evicts the stalest item
     * before adding the new item.
     *
     * @method addToCache
     * @param oRequest {Object} Request object.
     * @param oResponse {Object} Response object to cache.
     */
    YAHOO.util.DataSource.prototype.addToCache = function(oRequest, oResponse) {
        var aCache = this._aCache;
        if(!aCache) {
            return;
        }

        //TODO: check for duplicate entries

        // If the cache is full, make room by removing stalest element (index=0)
        while(aCache.length >= this.maxCacheEntries) {
            aCache.shift();
        }

        // Add to cache in the newest position, at the end of the array
        var oCacheElem = {request:oRequest,response:oResponse};
        aCache.push(oCacheElem);
        this.fireEvent("responseCacheEvent", {request:oRequest,response:oResponse});
        YAHOO.log("Cached the response for \"" +  oRequest + "\"", "info", this.toString());
    };

    /**
     * Flushes cache.
     *
     * @method flushCache
     */
    YAHOO.util.DataSource.prototype.flushCache = function() {
        if(this._aCache) {
            this._aCache = [];
            this.fireEvent("cacheFlushEvent");
            YAHOO.log("Flushed the cache", "info", this.toString());
        }
    };

    /**
     * First looks for cached response, then sends request to live data.
     *
     * @method sendRequest
     * @param oRequest {Object} Request object.
     * @param oCallback {Function} Handler function to receive the response.
     * @param oCaller {Object} The Calling object that is making the request.
     * @return {Number} Transaction ID, or null if response found in cache.
     */
    YAHOO.util.DataSource.prototype.sendRequest = function(oRequest, oCallback, oCaller) {
        // First look in cache
        var oCachedResponse = this.getCachedResponse(oRequest, oCallback, oCaller);
        if(oCachedResponse) {
            oCallback.call(oCaller, oRequest, oCachedResponse);
            return null;
        }

        // Not in cache, so forward request to live data
        YAHOO.log("Making connection to live data for \"" + oRequest + "\"", "info", this.toString());
        return this.makeConnection(oRequest, oCallback, oCaller);
    };

    /**
     * Overridable method provides default functionality to make a connection to
     * live data in order to send request. The response coming back is then
     * forwarded to the handleResponse function. This method should be customized
     * to achieve more complex implementations.
     *
     * @method makeConnection
     * @param oRequest {Object} Request object.
     * @param oCallback {Function} Handler function to receive the response.
     * @param oCaller {Object} The Calling object that is making the request.
     * @return {Number} Transaction ID.
     */
    YAHOO.util.DataSource.prototype.makeConnection = function(oRequest, oCallback, oCaller) {
        this.fireEvent("requestEvent", {request:oRequest,callback:oCallback,caller:oCaller});
        var oRawResponse = null;
        var tId = YAHOO.util.DataSource._nTransactionId++;

        // How to make the connection depends on the type of data
        switch(this.dataType) {
            // If the live data is a JavaScript Function
            // pass the request in as a parameter and
            // forward the return value to the handler
            case YAHOO.util.DataSource.TYPE_JSFUNCTION:
                oRawResponse = this.liveData(oRequest);
                this.handleResponse(oRequest, oRawResponse, oCallback, oCaller, tId);
                break;
            // If the live data is over Connection Manager
            // set up the callback object and
            // pass the request in as a URL query and
            // forward the response to the handler
            case YAHOO.util.DataSource.TYPE_XHR:
                var oSelf = this;
                var oConnMgr = this.connMgr || YAHOO.util.Connect;
                var oQueue = this._oQueue;

                /**
                 * Define Connection Manager success handler
                 *
                 * @method _xhrSuccess
                 * @param oResponse {Object} HTTPXMLRequest object
                 * @private
                 */
                var _xhrSuccess = function(oResponse) {
                    // If response ID does not match last made request ID,
                    // silently fail and wait for the next response
                    if(oResponse && (this.connXhrMode == "ignoreStaleResponses") &&
                            (oResponse.tId != oQueue.conn.tId)) {
                        YAHOO.log("Ignored stale response", "warn", this.toString());
                        return null;
                    }
                    // Error if no response
                    else if(!oResponse) {
                        this.fireEvent("dataErrorEvent", {request:oRequest,
                                callback:oCallback, caller:oCaller,
                                message:YAHOO.util.DataSource.ERROR_DATANULL});
                        YAHOO.log(YAHOO.util.DataSource.ERROR_DATANULL, "error", this.toString());

                        // Send error response back to the caller with the error flag on
                        oCallback.call(oCaller, oRequest, oResponse, true);

                        return null;
                    }
                    // Forward to handler
                    else {
                        this.handleResponse(oRequest, oResponse, oCallback, oCaller, tId);
                    }
                };

                /**
                 * Define Connection Manager failure handler
                 *
                 * @method _xhrFailure
                 * @param oResponse {Object} HTTPXMLRequest object
                 * @private
                 */
                var _xhrFailure = function(oResponse) {
                    this.fireEvent("dataErrorEvent", {request:oRequest,
                            callback:oCallback, caller:oCaller,
                            message:YAHOO.util.DataSource.ERROR_DATAINVALID});
                    YAHOO.log(YAHOO.util.DataSource.ERROR_DATAINVALID + ": " +
                            oResponse.statusText, "error", this.toString());

                    // Backward compatibility
                    if((this.liveData.lastIndexOf("?") !== this.liveData.length-1) &&
                        (oRequest.indexOf("?") !== 0)){
                            YAHOO.log("DataSources using XHR no longer supply a \"?\"" +
                            " between the host and query parameters" +
                            " -- please check that the request URL is correct", "warn", this.toString());
                    }

                    // Send failure response back to the caller with the error flag on
                    oCallback.call(oCaller, oRequest, oResponse, true);
                    return null;
                };

                /**
                 * Define Connection Manager callback object
                 *
                 * @property _xhrCallback
                 * @param oResponse {Object} HTTPXMLRequest object
                 * @private
                 */
                 var _xhrCallback = {
                    success:_xhrSuccess,
                    failure:_xhrFailure,
                    scope: this
                };

                // Apply Connection Manager timeout
                if(YAHOO.lang.isNumber(this.connTimeout)) {
                    _xhrCallback.timeout = this.connTimeout;
                }

                // Cancel stale requests
                if(this.connXhrMode == "cancelStaleRequests") {
                        // Look in queue for stale requests
                        if(oQueue.conn) {
                            if(oConnMgr.abort) {
                                oConnMgr.abort(oQueue.conn);
                                oQueue.conn = null;
                                YAHOO.log("Canceled stale request", "warn", this.toString());
                            }
                            else {
                                YAHOO.log("Could not find Connection Manager abort() function", "error", this.toString());
                            }
                        }
                }

                // Get ready to send the request URL
                if(oConnMgr && oConnMgr.asyncRequest) {
                    var sLiveData = this.liveData;
                    var isPost = this.connMethodPost;
                    var sMethod = (isPost) ? "POST" : "GET";
                    var sUri = (isPost) ? sLiveData : sLiveData+oRequest;
                    var sRequest = (isPost) ? oRequest : null;

                    // Send the request right away
                    if(this.connXhrMode != "queueRequests") {
                        oQueue.conn = oConnMgr.asyncRequest(sMethod, sUri, _xhrCallback, sRequest);
                    }
                    // Queue up then send the request
                    else {
                        // Found a request already in progress
                        if(oQueue.conn) {
                            // Add request to queue
                            oQueue.requests.push({request:oRequest, callback:_xhrCallback});

                            // Interval needs to be started
                            if(!oQueue.interval) {
                                oQueue.interval = setInterval(function() {
                                    // Connection is in progress
                                    if(oConnMgr.isCallInProgress(oQueue.conn)) {
                                        return;
                                    }
                                    else {
                                        // Send next request
                                        if(oQueue.requests.length > 0) {
                                            sUri = (isPost) ? sLiveData : sLiveData+oQueue.requests[0].request;
                                            sRequest = (isPost) ? oQueue.requests[0].request : null;
                                            oQueue.conn = oConnMgr.asyncRequest(sMethod, sUri, oQueue.requests[0].callback, sRequest);

                                            // Remove request from queue
                                            oQueue.requests.shift();
                                        }
                                        // No more requests
                                        else {
                                            clearInterval(oQueue.interval);
                                            oQueue.interval = null;
                                        }
                                    }
                                }, 50);
                            }
                        }
                        // Nothing is in progress
                        else {
                            oQueue.conn = oConnMgr.asyncRequest(sMethod, sUri, _xhrCallback, sRequest);
                        }
                    }
                }
                else {
                    YAHOO.log("Could not find Connection Manager asyncRequest() function", "error", this.toString());
                    // Send null response back to the caller with the error flag on
                    oCallback.call(oCaller, oRequest, null, true);
                }

                break;
            // Simply forward the entire data object to the handler
            default:
                /* accounts for the following cases:
                YAHOO.util.DataSource.TYPE_UNKNOWN:
                YAHOO.util.DataSource.TYPE_JSARRAY:
                YAHOO.util.DataSource.TYPE_JSON:
                YAHOO.util.DataSource.TYPE_HTMLTABLE:
                YAHOO.util.DataSource.TYPE_XML:
                */
                oRawResponse = this.liveData;
                this.handleResponse(oRequest, oRawResponse, oCallback, oCaller, tId);
                break;
        }
        return tId;
    };

    /**
     * Handles raw data response from live data source. Sends a parsed response object
     * to the callback function in this format:
     *
     * fnCallback(oRequest, oParsedResponse)
     *
     * where the oParsedResponse object literal with the following properties:
     * <ul>
     *     <li>tId {Number} Unique transaction ID</li>
     *     <li>results {Array} Array of parsed data results</li>
     *     <li>error {Boolean} True if there was an error</li>
     * </ul>
     *
     * @method handleResponse
     * @param oRequest {Object} Request object
     * @param oRawResponse {Object} The raw response from the live database.
     * @param oCallback {Function} Handler function to receive the response.
     * @param oCaller {Object} The calling object that is making the request.
     * @param tId {Number} Transaction ID.
     */
    YAHOO.util.DataSource.prototype.handleResponse = function(oRequest, oRawResponse, oCallback, oCaller, tId) {
        this.fireEvent("responseEvent", {request:oRequest, response:oRawResponse,
                callback:oCallback, caller:oCaller, tId: tId});
        YAHOO.log("Received live data response for \"" + oRequest + "\"", "info", this.toString());
        var xhr = (this.dataType == YAHOO.util.DataSource.TYPE_XHR) ? true : false;
        var oParsedResponse = null;
        var bError = false;

        // Access to the raw response before it gets parsed
        oRawResponse = this.doBeforeParseData(oRequest, oRawResponse);

        switch(this.responseType) {
            case YAHOO.util.DataSource.TYPE_JSARRAY:
                if(xhr && oRawResponse.responseText) {
                    oRawResponse = oRawResponse.responseText;
                }
                oParsedResponse = this.parseArrayData(oRequest, oRawResponse);
                break;
            case YAHOO.util.DataSource.TYPE_JSON:
                if(xhr && oRawResponse.responseText) {
                    oRawResponse = oRawResponse.responseText;
                }
                oParsedResponse = this.parseJSONData(oRequest, oRawResponse);
                break;
            case YAHOO.util.DataSource.TYPE_HTMLTABLE:
                if(xhr && oRawResponse.responseText) {
                    oRawResponse = oRawResponse.responseText;
                }
                oParsedResponse = this.parseHTMLTableData(oRequest, oRawResponse);
                break;
            case YAHOO.util.DataSource.TYPE_XML:
                if(xhr && oRawResponse.responseXML) {
                    oRawResponse = oRawResponse.responseXML;
                }
                oParsedResponse = this.parseXMLData(oRequest, oRawResponse);
                break;
            case YAHOO.util.DataSource.TYPE_TEXT:
                if(xhr && oRawResponse.responseText) {
                    oRawResponse = oRawResponse.responseText;
                }
                oParsedResponse = this.parseTextData(oRequest, oRawResponse);
                break;
            default:
                //var contentType = oRawResponse.getResponseHeader["Content-Type"];
                YAHOO.log("Could not parse data for request \"" + oRequest +
                        "\" due to unknown response type", "error", this.toString());
                break;
        }

        if(oParsedResponse) {
            // Last chance to touch the raw response or the parsed response
            oParsedResponse.tId = tId;
            oParsedResponse = this.doBeforeCallback(oRequest, oRawResponse, oParsedResponse);
            this.fireEvent("responseParseEvent", {request:oRequest,
                    response:oParsedResponse, callback:oCallback, caller:oCaller});
            // Cache the response
            this.addToCache(oRequest, oParsedResponse);
        }
        else {
            this.fireEvent("dataErrorEvent", {request:oRequest, callback:oCallback,
                    caller:oCaller, message:YAHOO.util.DataSource.ERROR_DATANULL});
            YAHOO.log(YAHOO.util.DataSource.ERROR_DATANULL, "error", this.toString());

            // Send response back to the caller with the error flag on
            oParsedResponse = {error:true};
        }

        // Send the response back to the caller
        oCallback.call(oCaller, oRequest, oParsedResponse);
    };

    /**
     * Overridable method gives implementers access to the original raw response
     * before the data gets parsed. Implementers should take care not to return an
     * unparsable or otherwise invalid raw response.
     *
     * @method doBeforeParseData
     * @param oRequest {Object} Request object.
     * @param oRawResponse {Object} The raw response from the live database.
     * @return {Object} Raw response for parsing.
     */
    YAHOO.util.DataSource.prototype.doBeforeParseData = function(oRequest, oRawResponse) {
        return oRawResponse;
    };

    /**
     * Overridable method gives implementers access to the original raw response and
     * the parsed response (parsed against the given schema) before the data
     * is added to the cache (if applicable) and then sent back to callback function.
     * This is your chance to access the raw response and/or populate the parsed
     * response with any custom data.
     *
     * @method doBeforeCallback
     * @param oRequest {Object} Request object.
     * @param oRawResponse {Object} The raw response from the live database.
     * @param oParsedResponse {Object} The parsed response to return to calling object.
     * @return {Object} Parsed response object.
     */
    YAHOO.util.DataSource.prototype.doBeforeCallback = function(oRequest, oRawResponse, oParsedResponse) {
        return oParsedResponse;
    };

    /**
     * Overridable method parses raw array data into a response object.
     *
     * @method parseArrayData
     * @param oRequest {Object} Request object.
     * @param oRawResponse {Object} The raw response from the live database.
     * @return {Object} Parsed response object.
     */
    YAHOO.util.DataSource.prototype.parseArrayData = function(oRequest, oRawResponse) {
        if(YAHOO.lang.isArray(oRawResponse) && YAHOO.lang.isArray(this.responseSchema.fields)) {
            var oParsedResponse = {results:[]};
            var fields = this.responseSchema.fields;
            for(var i=oRawResponse.length-1; i>-1; i--) {
                var oResult = {};
                for(var j=fields.length-1; j>-1; j--) {
                    var field = fields[j];
                    var key = (YAHOO.lang.isValue(field.key)) ? field.key : field;
                    var data = (YAHOO.lang.isValue(oRawResponse[i][j])) ? oRawResponse[i][j] : oRawResponse[i][key];
                    // Backward compatibility
                    if(!field.parser && field.converter) {
                        field.parser = field.converter;
                        YAHOO.log("The field property converter has been deprecated" +
                                " in favor of parser", "warn", this.toString());
                    }
                    if(field.parser) {
                        data = field.parser.call(this, data);
                    }
                    // Safety measure
                    if(data === undefined) {
                        data = null;
                    }
                    oResult[key] = data;
                }
                oParsedResponse.results.unshift(oResult);
            }
            YAHOO.log("Parsed array data is " +
                    YAHOO.lang.dump(oParsedResponse), "info", this.toString());
            return oParsedResponse;
        }
        else {
            YAHOO.log("Array data could not be parsed: " +
                    YAHOO.lang.dump(oRawResponse), "error", this.toString());
            return null;
        }
    };

    /**
     * Overridable method parses raw plain text data into a response object.
     *
     * @method parseTextData
     * @param oRequest {Object} Request object.
     * @param oRawResponse {Object} The raw response from the live database.
     * @return {Object} Parsed response object.
     */
    YAHOO.util.DataSource.prototype.parseTextData = function(oRequest, oRawResponse) {
        var oParsedResponse = {};
        if(YAHOO.lang.isString(oRawResponse) &&
                YAHOO.lang.isArray(this.responseSchema.fields) &&
                YAHOO.lang.isString(this.responseSchema.recordDelim) &&
                YAHOO.lang.isString(this.responseSchema.fieldDelim)) {
            oParsedResponse.results = [];
            var recDelim = this.responseSchema.recordDelim;
            var fieldDelim = this.responseSchema.fieldDelim;
            var fields = this.responseSchema.fields;
            if(oRawResponse.length > 0) {
                // Delete the last line delimiter at the end of the data if it exists
                var newLength = oRawResponse.length-recDelim.length;
                if(oRawResponse.substr(newLength) == recDelim) {
                    oRawResponse = oRawResponse.substr(0, newLength);
                }
                // Split along record delimiter to get an array of strings
                var recordsarray = oRawResponse.split(recDelim);
                // Cycle through each record, except the first which contains header info
                for(var i = recordsarray.length-1; i>-1; i--) {
                    var oResult = {};
                    for(var j=fields.length-1; j>-1; j--) {
                        // Split along field delimter to get each data value
                        var fielddataarray = recordsarray[i].split(fieldDelim);

                        // Remove quotation marks from edges, if applicable
                        var data = fielddataarray[j];
                        if(data.charAt(0) == "\"") {
                            data = data.substr(1);
                        }
                        if(data.charAt(data.length-1) == "\"") {
                            data = data.substr(0,data.length-1);
                        }
                        var field = fields[j];
                        var key = (YAHOO.lang.isValue(field.key)) ? field.key : field;
                        // Backward compatibility
                        if(!field.parser && field.converter) {
                            field.parser = field.converter;
                            YAHOO.log("The field property converter has been deprecated" +
                                    " in favor of parser", "warn", this.toString());
                        }
                        if(field.parser) {
                            data = field.parser.call(this, data);
                        }
                        // Safety measure
                        if(data === undefined) {
                            data = null;
                        }
                        oResult[key] = data;
                    }
                    oParsedResponse.results.unshift(oResult);
                }
            }
            YAHOO.log("Parsed text data is " +
                    YAHOO.lang.dump(oParsedResponse), "info", this.toString());
        }
        else {
            YAHOO.log("Text data could not be parsed: " +
                    YAHOO.lang.dump(oRawResponse), "error", this.toString());
            oParsedResponse.error = true;
        }
        return oParsedResponse;
    };

    /**
     * Overridable method parses raw XML data into a response object.
     *
     * @method parseXMLData
     * @param oRequest {Object} Request object.
     * @param oRawResponse {Object} The raw response from the live database.
     * @return {Object} Parsed response object.
     */
    YAHOO.util.DataSource.prototype.parseXMLData = function(oRequest, oRawResponse) {
            var bError = false;
            var oParsedResponse = {};
            var xmlList = (this.responseSchema.resultNode) ?
                    oRawResponse.getElementsByTagName(this.responseSchema.resultNode) :
                    null;
            if(!xmlList || !YAHOO.lang.isArray(this.responseSchema.fields)) {
                bError = true;
            }
            // Loop through each result
            else {
                oParsedResponse.results = [];
                for(var k = xmlList.length-1; k >= 0 ; k--) {
                    var result = xmlList.item(k);
                    var oResult = {};
                    // Loop through each data field in each result using the schema
                    for(var m = this.responseSchema.fields.length-1; m >= 0 ; m--) {
                        var field = this.responseSchema.fields[m];
                        var key = (YAHOO.lang.isValue(field.key)) ? field.key : field;
                        var data = null;
                        // Values may be held in an attribute...
                        var xmlAttr = result.attributes.getNamedItem(key);
                        if(xmlAttr) {
                            data = xmlAttr.value;
                        }
                        // ...or in a node
                        else {
                            var xmlNode = result.getElementsByTagName(key);
                            if(xmlNode && xmlNode.item(0) && xmlNode.item(0).firstChild) {
                                data = xmlNode.item(0).firstChild.nodeValue;
                            }
                            else {
                                   data = "";
                            }
                        }
                        // Backward compatibility
                        if(!field.parser && field.converter) {
                            field.parser = field.converter;
                            YAHOO.log("The field property converter has been deprecated" +
                                    " in favor of parser", "warn", this.toString());
                        }
                        if(field.parser) {
                            data = field.parser.call(this, data);
                        }
                        // Safety measure
                        if(data === undefined) {
                            data = null;
                        }
                        oResult[key] = data;
                    }
                    // Capture each array of values into an array of results
                    oParsedResponse.results.unshift(oResult);
                }
            }
            if(bError) {
                YAHOO.log("XML data could not be parsed: " +
                        YAHOO.lang.dump(oRawResponse), "error", this.toString());
                oParsedResponse.error = true;
            }
            else {
                YAHOO.log("Parsed XML data is " +
                        YAHOO.lang.dump(oParsedResponse), "info", this.toString());
            }
            return oParsedResponse;
    };

    /**
     * Overridable method parses raw JSON data into a response object.
     *
     * @method parseJSONData
     * @param oRequest {Object} Request object.
     * @param oRawResponse {Object} The raw response from the live database.
     * @return {Object} Parsed response object.
     */
    YAHOO.util.DataSource.prototype.parseJSONData = function(oRequest, oRawResponse) {
        var oParsedResponse = {};
        if(oRawResponse && YAHOO.lang.isArray(this.responseSchema.fields)) {
            var fields = this.responseSchema.fields;
            var bError = false;
            oParsedResponse.results = [];
            var jsonObj,jsonList;

            // Parse JSON object out if it's a string
            if(YAHOO.lang.isString(oRawResponse)) {
                // Check for latest JSON lib but divert KHTML clients
                var isNotMac = (navigator.userAgent.toLowerCase().indexOf('khtml')== -1);
                if(oRawResponse.parseJSON && isNotMac) {
                    // Use the new JSON utility if available
                    jsonObj = oRawResponse.parseJSON();
                    if(!jsonObj) {
                        bError = true;
                    }
                }
                // Check for older JSON lib but divert KHTML clients
                else if(window.JSON && JSON.parse && isNotMac) {
                    // Use the JSON utility if available
                    jsonObj = JSON.parse(oRawResponse);
                    if(!jsonObj) {
                        bError = true;
                    }
                }
                // No JSON lib found so parse the string
                else {
                    try {
                        // Trim leading spaces
                        while (oRawResponse.length > 0 &&
                                (oRawResponse.charAt(0) != "{") &&
                                (oRawResponse.charAt(0) != "[")) {
                            oRawResponse = oRawResponse.substring(1, oRawResponse.length);
                        }

                        if(oRawResponse.length > 0) {
                            // Strip extraneous stuff at the end
                            var objEnd = Math.max(oRawResponse.lastIndexOf("]"),oRawResponse.lastIndexOf("}"));
                            oRawResponse = oRawResponse.substring(0,objEnd+1);

                            // Turn the string into an object literal...
                            // ...eval is necessary here
                            jsonObj = eval("(" + oRawResponse + ")");
                            if(!jsonObj) {
                                bError = true;
                            }

                        }
                        else {
                            jsonObj = null;
                            bError = true;
                        }
                    }
                    catch(e) {
                        bError = true;
                   }
                }
            }
            // Response must already be a JSON object
            else if(oRawResponse.constructor == Object) {
                jsonObj = oRawResponse;
            }
            // Not a string or an object
            else {
                bError = true;
            }
            // Now that we have a JSON object, parse a jsonList out of it
            if(jsonObj && jsonObj.constructor == Object) {
                try {
                    // eval is necessary here since schema can be of unknown depth
                    jsonList = eval("jsonObj." + this.responseSchema.resultsList);
                }
                catch(e) {
                    bError = true;
                }
            }

            if(bError || !jsonList) {
                YAHOO.log("JSON data could not be parsed: " +
                        YAHOO.lang.dump(oRawResponse), "error", this.toString());
                oParsedResponse.error = true;
            }
            if(jsonList && !YAHOO.lang.isArray(jsonList)) {
                jsonList = [jsonList];
            }
            else if(!jsonList) {
                jsonList = [];
            }

            // Loop through the array of all responses...
            for(var i = jsonList.length-1; i >= 0 ; i--) {
                var oResult = {};
                var jsonResult = jsonList[i];
                // ...and loop through each data field value of each response
                for(var j = fields.length-1; j >= 0 ; j--) {
                    var field = fields[j];
                    var key = (YAHOO.lang.isValue(field.key)) ? field.key : field;
                    // ...and capture data into an array mapped according to the schema...
                    // eval is necessary here since schema can be of unknown depth
                    var data = eval("jsonResult." + key);
                    //YAHOO.log("data: " + i + " value:" +j+" = "+dataFieldValue,"debug",this.toString());

                    // Backward compatibility
                    if(!field.parser && field.converter) {
                        field.parser = field.converter;
                        YAHOO.log("The field property converter has been deprecated" +
                                " in favor of parser", "warn", this.toString());
                    }
                    if(field.parser) {
                        data = field.parser.call(this, data);
                    }
                    // Safety measure
                    if(data === undefined) {
                        data = null;
                    }
                    oResult[key] = data;
                }
                // Capture the array of data field values in an array of results
                oParsedResponse.results.unshift(oResult);
            }
            YAHOO.log("Parsed JSON data is " +
                    YAHOO.lang.dump(oParsedResponse), "info", this.toString());
        }
        else {
            YAHOO.log("JSON data could not be parsed: " +
                    YAHOO.lang.dump(oRawResponse), "error", this.toString());
            oParsedResponse.error = true;
        }
        return oParsedResponse;
    };

    /**
     * Overridable method parses raw HTML TABLE element data into a response object.
     *
     * @method parseHTMLTableData
     * @param oRequest {Object} Request object.
     * @param oRawResponse {Object} The raw response from the live database.
     * @return {Object} Parsed response object.
     */
    YAHOO.util.DataSource.prototype.parseHTMLTableData = function(oRequest, oRawResponse) {
            var bError = false;
            var elTable = oRawResponse;
            var fields = this.responseSchema.fields;
            var oParsedResponse = {};
            oParsedResponse.results = [];

            // Iterate through each TBODY
            for(var i=0; i<elTable.tBodies.length; i++) {
                var elTbody = elTable.tBodies[i];

                // Iterate through each TR
                for(var j=elTbody.rows.length-1; j>-1; j--) {
                    var elRow = elTbody.rows[j];
                    var oResult = {};

                    for(var k=fields.length-1; k>-1; k--) {
                        var field = fields[k];
                        var key = (YAHOO.lang.isValue(field.key)) ? field.key : field;
                        var data = elRow.cells[k].innerHTML;

                        // Backward compatibility
                        if(!field.parser && field.converter) {
                            field.parser = field.converter;
                            YAHOO.log("The field property converter has been deprecated" +
                                    " in favor of parser", "warn", this.toString());
                        }
                        if(field.parser) {
                            data = field.parser.call(this, data);
                        }
                        // Safety measure
                        if(data === undefined) {
                            data = null;
                        }
                        oResult[key] = data;
                    }
                    oParsedResponse.results.unshift(oResult);
                }
            }

            if(bError) {
                YAHOO.log("HTML TABLE data could not be parsed: " +
                        YAHOO.lang.dump(oRawResponse), "error", this.toString());
                oParsedResponse.error = true;
            }
            else {
                YAHOO.log("Parsed HTML TABLE data is " +
                        YAHOO.lang.dump(oParsedResponse), "info", this.toString());
            }
            return oParsedResponse;
    };

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