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/*
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* Ext JS Library 2.0.2
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* Copyright(c) 2006-2008, Ext JS, LLC.
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* licensing@extjs.com
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*
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* http://extjs.com/license
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*/
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/**
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* @class Ext.data.ScriptTagProxy
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* @extends Ext.data.DataProxy
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* An implementation of Ext.data.DataProxy that reads a data object from a URL which may be in a domain
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* other than the originating domain of the running page.<br>
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* <p>
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* <b>Note that if you are retrieving data from a page that is in a domain that is NOT the same as the originating domain
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* of the running page, you must use this class, rather than HttpProxy.</b><br>
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* <p>
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* The content passed back from a server resource requested by a ScriptTagProxy is executable JavaScript
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* source code that is used as the source inside a <script> tag.<br>
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* <p>
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* In order for the browser to process the returned data, the server must wrap the data object
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* with a call to a callback function, the name of which is passed as a parameter by the ScriptTagProxy.
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* Below is a Java example for a servlet which returns data for either a ScriptTagProxy, or an HttpProxy
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* depending on whether the callback name was passed:
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* <p>
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* <pre><code>
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boolean scriptTag = false;
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String cb = request.getParameter("callback");
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if (cb != null) {
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scriptTag = true;
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response.setContentType("text/javascript");
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} else {
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response.setContentType("application/x-json");
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}
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Writer out = response.getWriter();
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if (scriptTag) {
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out.write(cb + "(");
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}
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out.print(dataBlock.toJsonString());
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if (scriptTag) {
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out.write(");");
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}
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</code></pre>
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*
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* @constructor
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* @param {Object} config A configuration object.
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*/
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Ext.data.ScriptTagProxy = function(config){
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Ext.data.ScriptTagProxy.superclass.constructor.call(this);
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Ext.apply(this, config);
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this.head = document.getElementsByTagName("head")[0];
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};
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Ext.data.ScriptTagProxy.TRANS_ID = 1000;
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Ext.extend(Ext.data.ScriptTagProxy, Ext.data.DataProxy, {
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/**
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* @cfg {String} url The URL from which to request the data object.
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*/
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/**
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* @cfg {Number} timeout (Optional) The number of milliseconds to wait for a response. Defaults to 30 seconds.
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*/
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timeout : 30000,
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/**
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* @cfg {String} callbackParam (Optional) The name of the parameter to pass to the server which tells
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* the server the name of the callback function set up by the load call to process the returned data object.
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* Defaults to "callback".<p>The server-side processing must read this parameter value, and generate
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* javascript output which calls this named function passing the data object as its only parameter.
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*/
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callbackParam : "callback",
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/**
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* @cfg {Boolean} nocache (Optional) Defaults to true. Disable cacheing by adding a unique parameter
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* name to the request.
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*/
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nocache : true,
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/**
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* Load data from the configured URL, read the data object into
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* a block of Ext.data.Records using the passed Ext.data.DataReader implementation, and
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* process that block using the passed callback.
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* @param {Object} params An object containing properties which are to be used as HTTP parameters
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* for the request to the remote server.
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* @param {Ext.data.DataReader} reader The Reader object which converts the data
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* object into a block of Ext.data.Records.
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* @param {Function} callback The function into which to pass the block of Ext.data.Records.
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* The function must be passed <ul>
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* <li>The Record block object</li>
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* <li>The "arg" argument from the load function</li>
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* <li>A boolean success indicator</li>
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* </ul>
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* @param {Object} scope The scope in which to call the callback
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* @param {Object} arg An optional argument which is passed to the callback as its second parameter.
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*/
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load : function(params, reader, callback, scope, arg){
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if(this.fireEvent("beforeload", this, params) !== false){
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var p = Ext.urlEncode(Ext.apply(params, this.extraParams));
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var url = this.url;
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url += (url.indexOf("?") != -1 ? "&" : "?") + p;
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if(this.nocache){
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url += "&_dc=" + (new Date().getTime());
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}
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var transId = ++Ext.data.ScriptTagProxy.TRANS_ID;
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var trans = {
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id : transId,
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cb : "stcCallback"+transId,
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scriptId : "stcScript"+transId,
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params : params,
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arg : arg,
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url : url,
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callback : callback,
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scope : scope,
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reader : reader
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};
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var conn = this;
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window[trans.cb] = function(o){
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conn.handleResponse(o, trans);
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};
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url += String.format("&{0}={1}", this.callbackParam, trans.cb);
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if(this.autoAbort !== false){
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this.abort();
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}
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trans.timeoutId = this.handleFailure.defer(this.timeout, this, [trans]);
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var script = document.createElement("script");
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script.setAttribute("src", url);
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script.setAttribute("type", "text/javascript");
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script.setAttribute("id", trans.scriptId);
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this.head.appendChild(script);
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this.trans = trans;
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}else{
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callback.call(scope||this, null, arg, false);
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}
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},
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// private
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isLoading : function(){
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return this.trans ? true : false;
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},
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/**
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* Abort the current server request.
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*/
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abort : function(){
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if(this.isLoading()){
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this.destroyTrans(this.trans);
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}
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},
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// private
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destroyTrans : function(trans, isLoaded){
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this.head.removeChild(document.getElementById(trans.scriptId));
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clearTimeout(trans.timeoutId);
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if(isLoaded){
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window[trans.cb] = undefined;
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try{
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delete window[trans.cb];
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}catch(e){}
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}else{
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// if hasn't been loaded, wait for load to remove it to prevent script error
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window[trans.cb] = function(){
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window[trans.cb] = undefined;
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try{
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delete window[trans.cb];
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}catch(e){}
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};
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}
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},
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// private
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handleResponse : function(o, trans){
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this.trans = false;
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this.destroyTrans(trans, true);
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var result;
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try {
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result = trans.reader.readRecords(o);
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}catch(e){
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this.fireEvent("loadexception", this, o, trans.arg, e);
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trans.callback.call(trans.scope||window, null, trans.arg, false);
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return;
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}
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this.fireEvent("load", this, o, trans.arg);
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trans.callback.call(trans.scope||window, result, trans.arg, true);
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},
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// private
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handleFailure : function(trans){
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this.trans = false;
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this.destroyTrans(trans, false);
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this.fireEvent("loadexception", this, null, trans.arg);
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trans.callback.call(trans.scope||window, null, trans.arg, false);
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}
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});
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