/*
Copyright (c) 2009, Yahoo! Inc. All rights reserved.
Code licensed under the BSD License:
http://developer.yahoo.net/yui/license.txt
version: 2.7.0
*/
(function () {

var lang   = YAHOO.lang,
    util   = YAHOO.util,
    Ev     = util.Event;

/**
 * The DataSource utility provides a common configurable interface for widgets to
 * access a variety of data, from JavaScript arrays to online database servers.
 *
 * @module datasource
 * @requires yahoo, event
 * @optional json, get, connection 
 * @title DataSource Utility
 */

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

/**
 * Base class for the YUI DataSource utility.
 *
 * @namespace YAHOO.util
 * @class YAHOO.util.DataSourceBase
 * @constructor
 * @param oLiveData {HTMLElement}  Pointer to live data.
 * @param oConfigs {object} (optional) Object literal of configuration values.
 */
util.DataSourceBase = function(oLiveData, oConfigs) {
    if(oLiveData === null || oLiveData === undefined) {
        YAHOO.log("Could not instantiate DataSource due to invalid live database",
                "error", this.toString());
        return;
    }
    
    this.liveData = oLiveData;
    this._oQueue = {interval:null, conn:null, requests:[]};
    this.responseSchema = {};   

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

    // Initialize interval tracker
    this._aIntervals = [];

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

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

    /**
     * Fired when data is retrieved from the local cache.
     *
     * @event cacheResponseEvent
     * @param oArgs.request {Object} The request object.
     * @param oArgs.response {Object} The response object.
     * @param oArgs.callback {Object} The callback object.
     * @param oArgs.caller {Object} (deprecated) Use callback.scope.
     */
    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 {Object} The callback object.
     * @param oArgs.tId {Number} Transaction ID.     
     * @param oArgs.caller {Object} (deprecated) Use callback.scope.
     */
    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 {Object} The callback object.
     * @param oArgs.tId {Number} Transaction ID.     
     * @param oArgs.caller {Object} (deprecated) Use callback.scope.
     */
    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 {Object} The callback object.
     * @param oArgs.caller {Object} (deprecated) Use callback.scope.
     */
    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 {Object} The callback object.
     * @param oArgs.caller {Object} (deprecated) Use callback.scope.
     */
    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 {Object} The callback object.
     * @param oArgs.caller {Object} (deprecated) Use callback.scope.
     * @param oArgs.message {String} The error message.
     */
    this.createEvent("dataErrorEvent");

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

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

var DS = util.DataSourceBase;

lang.augmentObject(DS, {

/////////////////////////////////////////////////////////////////////////////
//
// DataSourceBase public constants
//
/////////////////////////////////////////////////////////////////////////////

/**
 * Type is unknown.
 *
 * @property TYPE_UNKNOWN
 * @type Number
 * @final
 * @default -1
 */
TYPE_UNKNOWN : -1,

/**
 * Type is a JavaScript Array.
 *
 * @property TYPE_JSARRAY
 * @type Number
 * @final
 * @default 0
 */
TYPE_JSARRAY : 0,

/**
 * Type is a JavaScript Function.
 *
 * @property TYPE_JSFUNCTION
 * @type Number
 * @final
 * @default 1
 */
TYPE_JSFUNCTION : 1,

/**
 * Type is hosted on a server via an XHR connection.
 *
 * @property TYPE_XHR
 * @type Number
 * @final
 * @default 2
 */
TYPE_XHR : 2,

/**
 * Type is JSON.
 *
 * @property TYPE_JSON
 * @type Number
 * @final
 * @default 3
 */
TYPE_JSON : 3,

/**
 * Type is XML.
 *
 * @property TYPE_XML
 * @type Number
 * @final
 * @default 4
 */
TYPE_XML : 4,

/**
 * Type is plain text.
 *
 * @property TYPE_TEXT
 * @type Number
 * @final
 * @default 5
 */
TYPE_TEXT : 5,

/**
 * Type is an HTML TABLE element. Data is parsed out of TR elements from all TBODY elements.
 *
 * @property TYPE_HTMLTABLE
 * @type Number
 * @final
 * @default 6
 */
TYPE_HTMLTABLE : 6,

/**
 * Type is hosted on a server via a dynamic script node.
 *
 * @property TYPE_SCRIPTNODE
 * @type Number
 * @final
 * @default 7
 */
TYPE_SCRIPTNODE : 7,

/**
 * Type is local.
 *
 * @property TYPE_LOCAL
 * @type Number
 * @final
 * @default 8
 */
TYPE_LOCAL : 8,

/**
 * Error message for invalid dataresponses.
 *
 * @property ERROR_DATAINVALID
 * @type String
 * @final
 * @default "Invalid data"
 */
ERROR_DATAINVALID : "Invalid data",

/**
 * Error message for null data responses.
 *
 * @property ERROR_DATANULL
 * @type String
 * @final
 * @default "Null data"
 */
ERROR_DATANULL : "Null data",

/////////////////////////////////////////////////////////////////////////////
//
// DataSourceBase private static properties
//
/////////////////////////////////////////////////////////////////////////////

/**
 * Internal class variable to index multiple DataSource instances.
 *
 * @property DataSourceBase._nIndex
 * @type Number
 * @private
 * @static
 */
_nIndex : 0,

/**
 * Internal class variable to assign unique transaction IDs.
 *
 * @property DataSourceBase._nTransactionId
 * @type Number
 * @private
 * @static
 */
_nTransactionId : 0,

/////////////////////////////////////////////////////////////////////////////
//
// DataSourceBase public static methods
//
/////////////////////////////////////////////////////////////////////////////

/**
 * Executes a configured callback.  For object literal callbacks, the third
 * param determines whether to execute the success handler or failure handler.
 *  
 * @method issueCallback
 * @param callback {Function|Object} the callback to execute
 * @param params {Array} params to be passed to the callback method
 * @param error {Boolean} whether an error occurred
 * @param scope {Object} the scope from which to execute the callback
 * (deprecated - use an object literal callback)
 * @static     
 */
issueCallback : function (callback,params,error,scope) {
    if (lang.isFunction(callback)) {
        callback.apply(scope, params);
    } else if (lang.isObject(callback)) {
        scope = callback.scope || scope || window;
        var callbackFunc = callback.success;
        if (error) {
            callbackFunc = callback.failure;
        }
        if (callbackFunc) {
            callbackFunc.apply(scope, params.concat([callback.argument]));
        }
    }
},

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

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

/**
 * Converts data to type Number.
 *
 * @method DataSourceBase.parseNumber
 * @param oData {String | Number | Boolean} Data to convert. Note, the following
 * values return as null: null, undefined, NaN, "". 
 * @return {Number} A number, or null.
 * @static
 */
parseNumber : function(oData) {
    if(!lang.isValue(oData) || (oData === "")) {
        return null;
    }

    //Convert to number
    var number = oData * 1;
    
    // Validate
    if(lang.isNumber(number)) {
        return number;
    }
    else {
        YAHOO.log("Could not convert data " + lang.dump(oData) + " to type Number", "warn", this.toString());
        return null;
    }
},
// Backward compatibility
convertNumber : function(oData) {
    YAHOO.log("The method YAHOO.util.DataSourceBase.convertNumber() has been" +
    " deprecated in favor of YAHOO.util.DataSourceBase.parseNumber()", "warn",
    this.toString());
    return DS.parseNumber(oData);
},

/**
 * Converts data to type Date.
 *
 * @method DataSourceBase.parseDate
 * @param oData {Date | String | Number} Data to convert.
 * @return {Date} A Date instance.
 * @static
 */
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 " + lang.dump(oData) + " to type Date", "warn", this.toString());
        return null;
    }
},
// Backward compatibility
convertDate : function(oData) {
    YAHOO.log("The method YAHOO.util.DataSourceBase.convertDate() has been" +
    " deprecated in favor of YAHOO.util.DataSourceBase.parseDate()", "warn",
    this.toString());
    return DS.parseDate(oData);
}

});

// Done in separate step so referenced functions are defined.
/**
 * Data parsing functions.
 * @property DataSource.Parser
 * @type Object
 * @static
 */
DS.Parser = {
    string   : DS.parseString,
    number   : DS.parseNumber,
    date     : DS.parseDate
};

// Prototype properties and methods
DS.prototype = {

/////////////////////////////////////////////////////////////////////////////
//
// DataSourceBase private properties
//
/////////////////////////////////////////////////////////////////////////////

/**
 * Name of DataSource instance.
 *
 * @property _sName
 * @type String
 * @private
 */
_sName : null,

/**
 * Local cache of data result object literals indexed chronologically.
 *
 * @property _aCache
 * @type Object[]
 * @private
 */
_aCache : null,

/**
 * Local queue of request connections, enabled if queue needs to be managed.
 *
 * @property _oQueue
 * @type Object
 * @private
 */
_oQueue : null,

/**
 * Array of polling interval IDs that have been enabled, needed to clear all intervals.
 *
 * @property _aIntervals
 * @type Array
 * @private
 */
_aIntervals : null,

/////////////////////////////////////////////////////////////////////////////
//
// DataSourceBase public properties
//
/////////////////////////////////////////////////////////////////////////////

/**
 * 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
 */
maxCacheEntries : 0,

 /**
 * Pointer to live database.
 *
 * @property liveData
 * @type Object
 */
liveData : null,

/**
 * Where the live data is held:
 * 
 * <dl>  
 *    <dt>TYPE_UNKNOWN</dt>
 *    <dt>TYPE_LOCAL</dt>
 *    <dt>TYPE_XHR</dt>
 *    <dt>TYPE_SCRIPTNODE</dt>
 *    <dt>TYPE_JSFUNCTION</dt>
 * </dl> 
 *  
 * @property dataType
 * @type Number
 * @default YAHOO.util.DataSourceBase.TYPE_UNKNOWN
 *
 */
dataType : DS.TYPE_UNKNOWN,

/**
 * Format of response:
 *  
 * <dl>  
 *    <dt>TYPE_UNKNOWN</dt>
 *    <dt>TYPE_JSARRAY</dt>
 *    <dt>TYPE_JSON</dt>
 *    <dt>TYPE_XML</dt>
 *    <dt>TYPE_TEXT</dt>
 *    <dt>TYPE_HTMLTABLE</dt> 
 * </dl> 
 *
 * @property responseType
 * @type Number
 * @default YAHOO.util.DataSourceBase.TYPE_UNKNOWN
 */
responseType : DS.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.DataSourceBase.parseDate}</dd>
 * <dt>metaFields</dt> <dd>Object literal of keys to include in the oParsedResponse.meta collection</dd>
 * <dt>metaNode</dt> <dd>Name of the node under which to search for meta information in XML response data</dd>
 * </dl>
 *
 * @property responseSchema
 * @type Object
 */
responseSchema : null,

/**
 * Additional arguments passed to the JSON parse routine.  The JSON string
 * is the assumed first argument (where applicable).  This property is not
 * set by default, but the parse methods will use it if present.
 *
 * @property parseJSONArgs
 * @type {MIXED|Array} If an Array, contents are used as individual arguments.
 *                     Otherwise, value is used as an additional argument.
 */
// property intentionally undefined
 
/////////////////////////////////////////////////////////////////////////////
//
// DataSourceBase public methods
//
/////////////////////////////////////////////////////////////////////////////

/**
 * Public accessor to the unique name of the DataSource instance.
 *
 * @method toString
 * @return {String} Unique name of the DataSource instance.
 */
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 {Object} Callback object.
 * @param oCaller {Object} (deprecated) Use callback object.
 * @return {Object} Cached response object or null.
 */
getCachedResponse : function(oRequest, oCallback, oCaller) {
    var aCache = this._aCache;

    // If cache is enabled...
    if(this.maxCacheEntries > 0) {        
        // Initialize local cache
        if(!aCache) {
            this._aCache = [];
            YAHOO.log("Cache initialized", "info", this.toString());
        }
        // Look in local cache
        else {
            var nCacheLength = aCache.length;
            if(nCacheLength > 0) {
                var oResponse = null;
                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)) {
                        // The cache returned a hit!
                        // Grab the cached response
                        oResponse = oCacheElem.response;
                        this.fireEvent("cacheResponseEvent", {request:oRequest,response:oResponse,callback:oCallback,caller:oCaller});
                        
                        // Refresh the position of the cache hit
                        if(i < nCacheLength-1) {
                            // Remove element from its original location
                            aCache.splice(i,1);
                            // Add as newest
                            this.addToCache(oRequest, oResponse);
                            YAHOO.log("Refreshed cache position of the response for \"" +  oRequest + "\"", "info", this.toString());
                        }
                        
                        // Add a cache flag
                        oResponse.cached = true;
                        break;
                    }
                }
                YAHOO.log("The cached response for \"" + lang.dump(oRequest) +
                        "\" is " + lang.dump(oResponse), "info", this.toString());
                return oResponse;
            }
        }
    }
    else if(aCache) {
        this._aCache = null;
        YAHOO.log("Cache destroyed", "info", this.toString());
    }
    return null;
},

/**
 * 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.
 */
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.
 */
addToCache : function(oRequest, oResponse) {
    var aCache = this._aCache;
    if(!aCache) {
        return;
    }

    // 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[aCache.length] = oCacheElem;
    this.fireEvent("responseCacheEvent", {request:oRequest,response:oResponse});
    YAHOO.log("Cached the response for \"" +  oRequest + "\"", "info", this.toString());
},

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

/**
 * Sets up a polling mechanism to send requests at set intervals and forward
 * responses to given callback.
 *
 * @method setInterval
 * @param nMsec {Number} Length of interval in milliseconds.
 * @param oRequest {Object} Request object.
 * @param oCallback {Function} Handler function to receive the response.
 * @param oCaller {Object} (deprecated) Use oCallback.scope.
 * @return {Number} Interval ID.
 */
setInterval : function(nMsec, oRequest, oCallback, oCaller) {
    if(lang.isNumber(nMsec) && (nMsec >= 0)) {
        YAHOO.log("Enabling polling to live data for \"" + oRequest + "\" at interval " + nMsec, "info", this.toString());
        var oSelf = this;
        var nId = setInterval(function() {
            oSelf.makeConnection(oRequest, oCallback, oCaller);
        }, nMsec);
        this._aIntervals.push(nId);
        return nId;
    }
    else {
        YAHOO.log("Could not enable polling to live data for \"" + oRequest + "\" at interval " + nMsec, "info", this.toString());
    }
},

/**
 * Disables polling mechanism associated with the given interval ID.
 *
 * @method clearInterval
 * @param nId {Number} Interval ID.
 */
clearInterval : function(nId) {
    // Remove from tracker if there
    var tracker = this._aIntervals || [];
    for(var i=tracker.length-1; i>-1; i--) {
        if(tracker[i] === nId) {
            tracker.splice(i,1);
            clearInterval(nId);
        }
    }
},

/**
 * Disables all known polling intervals.
 *
 * @method clearAllIntervals
 */
clearAllIntervals : function() {
    var tracker = this._aIntervals || [];
    for(var i=tracker.length-1; i>-1; i--) {
        clearInterval(tracker[i]);
    }
    tracker = [];
},

/**
 * First looks for cached response, then sends request to live data. The
 * following arguments are passed to the callback function:
 *     <dl>
 *     <dt><code>oRequest</code></dt>
 *     <dd>The same value that was passed in as the first argument to sendRequest.</dd>
 *     <dt><code>oParsedResponse</code></dt>
 *     <dd>An object literal containing the following properties:
 *         <dl>
 *         <dt><code>tId</code></dt>
 *         <dd>Unique transaction ID number.</dd>
 *         <dt><code>results</code></dt>
 *         <dd>Schema-parsed data results.</dd>
 *         <dt><code>error</code></dt>
 *         <dd>True in cases of data error.</dd>
 *         <dt><code>cached</code></dt>
 *         <dd>True when response is returned from DataSource cache.</dd> 
 *         <dt><code>meta</code></dt>
 *         <dd>Schema-parsed meta data.</dd>
 *         </dl>
 *     <dt><code>oPayload</code></dt>
 *     <dd>The same value as was passed in as <code>argument</code> in the oCallback object literal.</dd>
 *     </dl> 
 *
 * @method sendRequest
 * @param oRequest {Object} Request object.
 * @param oCallback {Object} An object literal with the following properties:
 *     <dl>
 *     <dt><code>success</code></dt>
 *     <dd>The function to call when the data is ready.</dd>
 *     <dt><code>failure</code></dt>
 *     <dd>The function to call upon a response failure condition.</dd>
 *     <dt><code>scope</code></dt>
 *     <dd>The object to serve as the scope for the success and failure handlers.</dd>
 *     <dt><code>argument</code></dt>
 *     <dd>Arbitrary data that will be passed back to the success and failure handlers.</dd>
 *     </dl> 
 * @param oCaller {Object} (deprecated) Use oCallback.scope.
 * @return {Number} Transaction ID, or null if response found in cache.
 */
sendRequest : function(oRequest, oCallback, oCaller) {
    // First look in cache
    var oCachedResponse = this.getCachedResponse(oRequest, oCallback, oCaller);
    if(oCachedResponse) {
        DS.issueCallback(oCallback,[oRequest,oCachedResponse],false,oCaller);
        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 default method generates a unique transaction ID and passes 
 * the live data reference directly to the  handleResponse function. This
 * method should be implemented by subclasses to achieve more complex behavior
 * or to access remote data.          
 *
 * @method makeConnection
 * @param oRequest {Object} Request object.
 * @param oCallback {Object} Callback object literal.
 * @param oCaller {Object} (deprecated) Use oCallback.scope.
 * @return {Number} Transaction ID.
 */
makeConnection : function(oRequest, oCallback, oCaller) {
    var tId = DS._nTransactionId++;
    this.fireEvent("requestEvent", {tId:tId, request:oRequest,callback:oCallback,caller:oCaller});

    /* accounts for the following cases:
    YAHOO.util.DataSourceBase.TYPE_UNKNOWN
    YAHOO.util.DataSourceBase.TYPE_JSARRAY
    YAHOO.util.DataSourceBase.TYPE_JSON
    YAHOO.util.DataSourceBase.TYPE_HTMLTABLE
    YAHOO.util.DataSourceBase.TYPE_XML
    YAHOO.util.DataSourceBase.TYPE_TEXT
    */
    var oRawResponse = this.liveData;
    
    this.handleResponse(oRequest, oRawResponse, oCallback, oCaller, tId);
    return tId;
},

/**
 * Receives raw data response and type converts to XML, JSON, etc as necessary.
 * Forwards oFullResponse to appropriate parsing function to get turned into
 * oParsedResponse. Calls doBeforeCallback() and adds oParsedResponse to 
 * the cache when appropriate before calling issueCallback().
 * 
 * The oParsedResponse object literal has the following properties:
 * <dl>
 *     <dd><dt>tId {Number}</dt> Unique transaction ID</dd>
 *     <dd><dt>results {Array}</dt> Array of parsed data results</dd>
 *     <dd><dt>meta {Object}</dt> Object literal of meta values</dd> 
 *     <dd><dt>error {Boolean}</dt> (optional) True if there was an error</dd>
 *     <dd><dt>cached {Boolean}</dt> (optional) True if response was cached</dd>
 * </dl>
 *
 * @method handleResponse
 * @param oRequest {Object} Request object
 * @param oRawResponse {Object} The raw response from the live database.
 * @param oCallback {Object} Callback object literal.
 * @param oCaller {Object} (deprecated) Use oCallback.scope.
 * @param tId {Number} Transaction ID.
 */
handleResponse : function(oRequest, oRawResponse, oCallback, oCaller, tId) {
    this.fireEvent("responseEvent", {tId:tId, request:oRequest, response:oRawResponse,
            callback:oCallback, caller:oCaller});
    YAHOO.log("Received live data response for \"" + oRequest + "\"", "info", this.toString());
    var xhr = (this.dataType == DS.TYPE_XHR) ? true : false;
    var oParsedResponse = null;
    var oFullResponse = oRawResponse;
    
    // Try to sniff data type if it has not been defined
    if(this.responseType === DS.TYPE_UNKNOWN) {
        var ctype = (oRawResponse && oRawResponse.getResponseHeader) ? oRawResponse.getResponseHeader["Content-Type"] : null;
        if(ctype) {
             // xml
            if(ctype.indexOf("text/xml") > -1) {
                this.responseType = DS.TYPE_XML;
            }
            else if(ctype.indexOf("application/json") > -1) { // json
                this.responseType = DS.TYPE_JSON;
            }
            else if(ctype.indexOf("text/plain") > -1) { // text
                this.responseType = DS.TYPE_TEXT;
            }
        }
        else {
            if(YAHOO.lang.isArray(oRawResponse)) { // array
                this.responseType = DS.TYPE_JSARRAY;
            }
             // xml
            else if(oRawResponse && oRawResponse.nodeType && oRawResponse.nodeType == 9) {
                this.responseType = DS.TYPE_XML;
            }
            else if(oRawResponse && oRawResponse.nodeName && (oRawResponse.nodeName.toLowerCase() == "table")) { // table
                this.responseType = DS.TYPE_HTMLTABLE;
            }    
            else if(YAHOO.lang.isObject(oRawResponse)) { // json
                this.responseType = DS.TYPE_JSON;
            }
            else if(YAHOO.lang.isString(oRawResponse)) { // text
                this.responseType = DS.TYPE_TEXT;
            }
        }
    }

    switch(this.responseType) {
        case DS.TYPE_JSARRAY:
            if(xhr && oRawResponse && oRawResponse.responseText) {
                oFullResponse = oRawResponse.responseText; 
            }
            try {
                // Convert to JS array if it's a string
                if(lang.isString(oFullResponse)) {
                    var parseArgs = [oFullResponse].concat(this.parseJSONArgs);
                    // Check for YUI JSON Util
                    if(lang.JSON) {
                        oFullResponse = lang.JSON.parse.apply(lang.JSON,parseArgs);
                    }
                    // Look for JSON parsers using an API similar to json2.js
                    else if(window.JSON && JSON.parse) {
                        oFullResponse = JSON.parse.apply(JSON,parseArgs);
                    }
                    // Look for JSON parsers using an API similar to json.js
                    else if(oFullResponse.parseJSON) {
                        oFullResponse = oFullResponse.parseJSON.apply(oFullResponse,parseArgs.slice(1));
                    }
                    // No JSON lib found so parse the string
                    else {
                        // Trim leading spaces
                        while (oFullResponse.length > 0 &&
                                (oFullResponse.charAt(0) != "{") &&
                                (oFullResponse.charAt(0) != "[")) {
                            oFullResponse = oFullResponse.substring(1, oFullResponse.length);
                        }

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

                            // Turn the string into an object literal...
                            // ...eval is necessary here
                            oFullResponse = eval("(" + oFullResponse + ")");

                        }
                    }
                }
            }
            catch(e1) {
            }
            oFullResponse = this.doBeforeParseData(oRequest, oFullResponse, oCallback);
            oParsedResponse = this.parseArrayData(oRequest, oFullResponse);
            break;
        case DS.TYPE_JSON:
            if(xhr && oRawResponse && oRawResponse.responseText) {
                oFullResponse = oRawResponse.responseText;
            }
            try {
                // Convert to JSON object if it's a string
                if(lang.isString(oFullResponse)) {
                    var parseArgs = [oFullResponse].concat(this.parseJSONArgs);
                    // Check for YUI JSON Util
                    if(lang.JSON) {
                        oFullResponse = lang.JSON.parse.apply(lang.JSON,parseArgs);
                    }
                    // Look for JSON parsers using an API similar to json2.js
                    else if(window.JSON && JSON.parse) {
                        oFullResponse = JSON.parse.apply(JSON,parseArgs);
                    }
                    // Look for JSON parsers using an API similar to json.js
                    else if(oFullResponse.parseJSON) {
                        oFullResponse = oFullResponse.parseJSON.apply(oFullResponse,parseArgs.slice(1));
                    }
                    // No JSON lib found so parse the string
                    else {
                        // Trim leading spaces
                        while (oFullResponse.length > 0 &&
                                (oFullResponse.charAt(0) != "{") &&
                                (oFullResponse.charAt(0) != "[")) {
                            oFullResponse = oFullResponse.substring(1, oFullResponse.length);
                        }
    
                        if(oFullResponse.length > 0) {
                            // Strip extraneous stuff at the end
                            var objEnd = Math.max(oFullResponse.lastIndexOf("]"),oFullResponse.lastIndexOf("}"));
                            oFullResponse = oFullResponse.substring(0,objEnd+1);
    
                            // Turn the string into an object literal...
                            // ...eval is necessary here
                            oFullResponse = eval("(" + oFullResponse + ")");
    
                        }
                    }
                }
            }
            catch(e) {
            }

            oFullResponse = this.doBeforeParseData(oRequest, oFullResponse, oCallback);
            oParsedResponse = this.parseJSONData(oRequest, oFullResponse);
            break;
        case DS.TYPE_HTMLTABLE:
            if(xhr && oRawResponse.responseText) {
                var el = document.createElement('div');
                el.innerHTML = oRawResponse.responseText;
                oFullResponse = el.getElementsByTagName('table')[0];
            }
            oFullResponse = this.doBeforeParseData(oRequest, oFullResponse, oCallback);
            oParsedResponse = this.parseHTMLTableData(oRequest, oFullResponse);
            break;
        case DS.TYPE_XML:
            if(xhr && oRawResponse.responseXML) {
                oFullResponse = oRawResponse.responseXML;
            }
            oFullResponse = this.doBeforeParseData(oRequest, oFullResponse, oCallback);
            oParsedResponse = this.parseXMLData(oRequest, oFullResponse);
            break;
        case DS.TYPE_TEXT:
            if(xhr && lang.isString(oRawResponse.responseText)) {
                oFullResponse = oRawResponse.responseText;
            }
            oFullResponse = this.doBeforeParseData(oRequest, oFullResponse, oCallback);
            oParsedResponse = this.parseTextData(oRequest, oFullResponse);
            break;
        default:
            oFullResponse = this.doBeforeParseData(oRequest, oFullResponse, oCallback);
            oParsedResponse = this.parseData(oRequest, oFullResponse);
            break;
    }


    // Clean up for consistent signature
    oParsedResponse = oParsedResponse || {};
    if(!oParsedResponse.results) {
        oParsedResponse.results = [];
    }
    if(!oParsedResponse.meta) {
        oParsedResponse.meta = {};
    }

    // Success
    if(oParsedResponse && !oParsedResponse.error) {
        // Last chance to touch the raw response or the parsed response
        oParsedResponse = this.doBeforeCallback(oRequest, oFullResponse, oParsedResponse, oCallback);
        this.fireEvent("responseParseEvent", {request:oRequest,
                response:oParsedResponse, callback:oCallback, caller:oCaller});
        // Cache the response
        this.addToCache(oRequest, oParsedResponse);
    }
    // Error
    else {
        // Be sure the error flag is on
        oParsedResponse.error = true;
        this.fireEvent("dataErrorEvent", {request:oRequest, response: oRawResponse, callback:oCallback, 
                caller:oCaller, message:DS.ERROR_DATANULL});
        YAHOO.log(DS.ERROR_DATANULL, "error", this.toString());
    }

    // Send the response back to the caller
    oParsedResponse.tId = tId;
    DS.issueCallback(oCallback,[oRequest,oParsedResponse],oParsedResponse.error,oCaller);
},

/**
 * Overridable method gives implementers access to the original full response
 * before the data gets parsed. Implementers should take care not to return an
 * unparsable or otherwise invalid response.
 *
 * @method doBeforeParseData
 * @param oRequest {Object} Request object.
 * @param oFullResponse {Object} The full response from the live database.
 * @param oCallback {Object} The callback object.  
 * @return {Object} Full response for parsing.
  
 */
doBeforeParseData : function(oRequest, oFullResponse, oCallback) {
    return oFullResponse;
},

/**
 * Overridable method gives implementers access to the original full 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 oFullResponse {Object} The full response from the live database.
 * @param oParsedResponse {Object} The parsed response to return to calling object.
 * @param oCallback {Object} The callback object. 
 * @return {Object} Parsed response object.
 */
doBeforeCallback : function(oRequest, oFullResponse, oParsedResponse, oCallback) {
    return oParsedResponse;
},

/**
 * Overridable method parses data of generic RESPONSE_TYPE into a response object.
 *
 * @method parseData
 * @param oRequest {Object} Request object.
 * @param oFullResponse {Object} The full Array from the live database.
 * @return {Object} Parsed response object with the following properties:<br>
 *     - results {Array} Array of parsed data results<br>
 *     - meta {Object} Object literal of meta values<br>
 *     - error {Boolean} (optional) True if there was an error<br>
 */
parseData : function(oRequest, oFullResponse) {
    if(lang.isValue(oFullResponse)) {
        var oParsedResponse = {results:oFullResponse,meta:{}};
        YAHOO.log("Parsed generic data is " +
                lang.dump(oParsedResponse), "info", this.toString());
        return oParsedResponse;

    }
    YAHOO.log("Generic data could not be parsed: " + lang.dump(oFullResponse), 
            "error", this.toString());
    return null;
},

/**
 * Overridable method parses Array data into a response object.
 *
 * @method parseArrayData
 * @param oRequest {Object} Request object.
 * @param oFullResponse {Object} The full Array from the live database.
 * @return {Object} Parsed response object with the following properties:<br>
 *     - results (Array) Array of parsed data results<br>
 *     - error (Boolean) True if there was an error
 */
parseArrayData : function(oRequest, oFullResponse) {
    if(lang.isArray(oFullResponse)) {
        var results = [],
            i, j,
            rec, field, data;
        
        // Parse for fields
        if(lang.isArray(this.responseSchema.fields)) {
            var fields = this.responseSchema.fields;
            for (i = fields.length - 1; i >= 0; --i) {
                if (typeof fields[i] !== 'object') {
                    fields[i] = { key : fields[i] };
                }
            }

            var parsers = {}, p;
            for (i = fields.length - 1; i >= 0; --i) {
                p = (typeof fields[i].parser === 'function' ?
                          fields[i].parser :
                          DS.Parser[fields[i].parser+'']) || fields[i].converter;
                if (p) {
                    parsers[fields[i].key] = p;
                }
            }

            var arrType = lang.isArray(oFullResponse[0]);
            for(i=oFullResponse.length-1; i>-1; i--) {
                var oResult = {};
                rec = oFullResponse[i];
                if (typeof rec === 'object') {
                    for(j=fields.length-1; j>-1; j--) {
                        field = fields[j];
                        data = arrType ? rec[j] : rec[field.key];

                        if (parsers[field.key]) {
                            data = parsers[field.key].call(this,data);
                        }

                        // Safety measure
                        if(data === undefined) {
                            data = null;
                        }

                        oResult[field.key] = data;
                    }
                }
                else if (lang.isString(rec)) {
                    for(j=fields.length-1; j>-1; j--) {
                        field = fields[j];
                        data = rec;

                        if (parsers[field.key]) {
                            data = parsers[field.key].call(this,data);
                        }

                        // Safety measure
                        if(data === undefined) {
                            data = null;
                        }

                        oResult[field.key] = data;
                    }                
                }
                results[i] = oResult;
            }    
        }
        // Return entire data set
        else {
            results = oFullResponse;
        }
        var oParsedResponse = {results:results};
        YAHOO.log("Parsed array data is " +
                lang.dump(oParsedResponse), "info", this.toString());
        return oParsedResponse;

    }
    YAHOO.log("Array data could not be parsed: " + lang.dump(oFullResponse), 
            "error", this.toString());
    return null;
},

/**
 * Overridable method parses plain text data into a response object.
 *
 * @method parseTextData
 * @param oRequest {Object} Request object.
 * @param oFullResponse {Object} The full text response from the live database.
 * @return {Object} Parsed response object with the following properties:<br>
 *     - results (Array) Array of parsed data results<br>
 *     - error (Boolean) True if there was an error
 */
parseTextData : function(oRequest, oFullResponse) {
    if(lang.isString(oFullResponse)) {
        if(lang.isString(this.responseSchema.recordDelim) &&
                lang.isString(this.responseSchema.fieldDelim)) {
            var oParsedResponse = {results:[]};
            var recDelim = this.responseSchema.recordDelim;
            var fieldDelim = this.responseSchema.fieldDelim;
            if(oFullResponse.length > 0) {
                // Delete the last line delimiter at the end of the data if it exists
                var newLength = oFullResponse.length-recDelim.length;
                if(oFullResponse.substr(newLength) == recDelim) {
                    oFullResponse = oFullResponse.substr(0, newLength);
                }
                if(oFullResponse.length > 0) {
                    // Split along record delimiter to get an array of strings
                    var recordsarray = oFullResponse.split(recDelim);
                    // Cycle through each record
                    for(var i = 0, len = recordsarray.length, recIdx = 0; i < len; ++i) {
                        var bError = false,
                            sRecord = recordsarray[i];
                        if (lang.isString(sRecord) && (sRecord.length > 0)) {
                            // Split each record along field delimiter to get data
                            var fielddataarray = recordsarray[i].split(fieldDelim);
                            var oResult = {};
                            
                            // Filter for fields data
                            if(lang.isArray(this.responseSchema.fields)) {
                                var fields = this.responseSchema.fields;
                                for(var j=fields.length-1; j>-1; j--) {
                                    try {
                                        // Remove quotation marks from edges, if applicable
                                        var data = fielddataarray[j];
                                        if (lang.isString(data)) {
                                            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 = (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());
                                            }
                                            var parser = (typeof field.parser === 'function') ?
                                                field.parser :
                                                DS.Parser[field.parser+''];
                                            if(parser) {
                                                data = parser.call(this, data);
                                            }
                                            // Safety measure
                                            if(data === undefined) {
                                                data = null;
                                            }
                                            oResult[key] = data;
                                        }
                                        else {
                                            bError = true;
                                        }
                                    }
                                    catch(e) {
                                        bError = true;
                                    }
                                }
                            }            
                            // No fields defined so pass along all data as an array
                            else {
                                oResult = fielddataarray;
                            }
                            if(!bError) {
                                oParsedResponse.results[recIdx++] = oResult;
                            }
                        }
                    }
                }
            }
            YAHOO.log("Parsed text data is " +
                    lang.dump(oParsedResponse), "info", this.toString());
            return oParsedResponse;
        }
    }
    YAHOO.log("Text data could not be parsed: " + lang.dump(oFullResponse), 
            "error", this.toString());
    return null;
            
},


/**
 * Overridable method parses XML data for one result into an object literal.
 *
 * @method parseXMLResult
 * @param result {XML} XML for one result.
 * @return {Object} Object literal of data for one result.
 */
parseXMLResult : function(result) {
    var oResult = {},
        schema = this.responseSchema;
        
    try {
        // Loop through each data field in each result using the schema
        for(var m = schema.fields.length-1; m >= 0 ; m--) {
            var field = schema.fields[m];
            var key = (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)) {
                    var item = xmlNode.item(0);
                    // For IE, then DOM...
                    data = (item) ? ((item.text) ? item.text : (item.textContent) ? item.textContent : null) : null;
                    // ...then fallback, but check for multiple child nodes
                    if(!data) {
                        var datapieces = [];
                        for(var j=0, len=item.childNodes.length; j<len; j++) {
                            if(item.childNodes[j].nodeValue) {
                                datapieces[datapieces.length] = item.childNodes[j].nodeValue;
                            }
                        }
                        if(datapieces.length > 0) {
                            data = datapieces.join("");
                        }
                    }
                }
            }
            // Safety net
            if(data === null) {
                   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());
            }
            var parser = (typeof field.parser === 'function') ?
                field.parser :
                DS.Parser[field.parser+''];
            if(parser) {
                data = parser.call(this, data);
            }
            // Safety measure
            if(data === undefined) {
                data = null;
            }
            oResult[key] = data;
        }
    }
    catch(e) {
        YAHOO.log("Error while parsing XML result: " + e.message);
    }

    return oResult;
},



/**
 * Overridable method parses XML data into a response object.
 *
 * @method parseXMLData
 * @param oRequest {Object} Request object.
 * @param oFullResponse {Object} The full XML response from the live database.
 * @return {Object} Parsed response object with the following properties<br>
 *     - results (Array) Array of parsed data results<br>
 *     - error (Boolean) True if there was an error
 */
parseXMLData : function(oRequest, oFullResponse) {
    var bError = false,
        schema = this.responseSchema,
        oParsedResponse = {meta:{}},
        xmlList = null,
        metaNode      = schema.metaNode,
        metaLocators  = schema.metaFields || {},
        i,k,loc,v;

    // In case oFullResponse is something funky
    try {
        xmlList = (schema.resultNode) ?
            oFullResponse.getElementsByTagName(schema.resultNode) :
            null;

        // Pull any meta identified
        metaNode = metaNode ? oFullResponse.getElementsByTagName(metaNode)[0] :
                   oFullResponse;

        if (metaNode) {
            for (k in metaLocators) {
                if (lang.hasOwnProperty(metaLocators, k)) {…