    /*
     * Portions of this file are based on pieces of Yahoo User Interface Library
     * Copyright (c) 2007, Yahoo! Inc. All rights reserved.
     * YUI licensed under the BSD License:
     * http://developer.yahoo.net/yui/license.txt
     */
        Ext.lib.Ajax = function() {
    	    var activeX = ['MSXML2.XMLHTTP.3.0',
    			           'MSXML2.XMLHTTP',
    			           'Microsoft.XMLHTTP'];

    		// private
    		function setHeader(o) {
    	        var conn = o.conn,
    	        	prop;

    	        function setTheHeaders(conn, headers){
    		     	for (prop in headers) {
                        if (headers.hasOwnProperty(prop)) {
                            conn.setRequestHeader(prop, headers[prop]);
                        }
                    }
    	        }

                if (pub.defaultHeaders) {
    	            setTheHeaders(conn, pub.defaultHeaders);
                }

                if (pub.headers) {
    				setTheHeaders(conn, pub.headers);
                    pub.headers = null;
                }
            }

            // private
            function createExceptionObject(tId, callbackArg, isAbort) {
                return {
    	            tId : tId,
    	            status : isAbort ? -1 : 0,
    	            statusText : isAbort ? 'transaction aborted' : 'communication failure',
    	            argument : callbackArg
                };
            }

            // private
            function initHeader(label, value) {
    			(pub.headers = pub.headers || {})[label] = value;
            }

            // private
            function createResponseObject(o, callbackArg) {
                var headerObj = {},
                	headerStr,
                	conn = o.conn;

                try {
                    headerStr = o.conn.getAllResponseHeaders();
                    Ext.each(headerStr.split('\n'), function(v){
    	            	var t = v.split(':');
    	            	headerObj[t[0]] = t[1];
                    });
                } catch(e) {}

                return {
    		        tId : o.tId,
    	            status : conn.status,
    	            statusText : conn.statusText,
    	            getResponseHeader : headerObj,
    	            getAllResponseHeaders : headerStr,
    	            responseText : conn.responseText,
    	            responseXML : conn.responseXML,
    	            argument : callbackArg
            	};
            }

            // private
            function handleTransactionResponse(o, callback, isAbort) {
    	        var	status = o.conn.status,
    	        	httpStatus,
                	responseObject;

    			if (callback) {
    	            // Not sure the point of the try catch...?
    	            //try {
    		           	httpStatus = status || 13030;
    	            //} catch(e) {
    	            //    httpStatus = 13030;
    	            //}

    	            if (httpStatus >= 200 && httpStatus < 300) {
    	                responseObject = createResponseObject(o, callback.argument);
    	                if (callback.success) {
    		                callback.success.call(callback.scope, responseObject);
    	                }
    	            } else {
    					if ([12002, 12029, 12030, 12031, 12152, 13030].indexOf( httpStatus ) > -1) {
    		                responseObject = createExceptionObject(o.tId, callback.argument, (isAbort ? isAbort : false));
    	                    if (callback.failure) {
    		                    callback.failure.call(callback.scope, responseObject);
    	                    }
    	                } else {
    		                responseObject = createResponseObject(o, callback.argument);
    	                    if (callback.failure) {
    		                    callback.failure.call(callback.scope, responseObject);
    	                    }
    	                }
    	            }
    			}
                o = o.conn = responseObject = null;
            }

            // private
            function handleReadyState(o, callback){
    	    callback = callback || {};
                var conn = o.conn,
                	tId = o.tId,
                	poll = pub.poll,
    		cbTimeout = callback.timeout || null;

                if (cbTimeout) {
                    pub.timeout[tId] = setTimeout(function() {
                        pub.abort(o, callback, true);
                    }, cbTimeout);
                }

                poll[tId] = setInterval(
                    function() {
                        if (conn && conn.readyState == 4) {
                            clearInterval(poll[tId]);
                            poll[tId] = null;

                            if (cbTimeout) {
                                clearTimeout(pub.timeout[tId]);
                                pub.timeout[tId] = null;
                            }

                            handleTransactionResponse(o, callback);
                        }
                    },
                    pub.pollInterval);
            }

            // private
            function asyncRequest(method, uri, callback, postData) {
                var o = getConnectionObject() || null;

                if (o) {
                    o.conn.open(method, uri, true);

                    if (pub.useDefaultXhrHeader) {
                    	initHeader('X-Requested-With', pub.defaultXhrHeader);
                    }

                    if(postData && pub.useDefaultHeader && (!pub.headers || !pub.headers['Content-Type'])){
                        initHeader('Content-Type', pub.defaultPostHeader);
                    }

                    if (pub.defaultHeaders || pub.headers) {
                        setHeader(o);
                    }

                    handleReadyState(o, callback);
                    o.conn.send(postData || null);
                }
                return o;
            }

            // private
            function getConnectionObject() {
                var o;

                try {
                    if (o = createXhrObject(pub.transactionId)) {
                        pub.transactionId++;
                    }
                } catch(e) {
                } finally {
                    return o;
                }
            }

            // private
            function createXhrObject(transactionId) {
                var http;

                try {
                    http = new XMLHttpRequest();
                } catch(e) {
                    for (var i = 0; i < activeX.length; ++i) {
                        try {
                            http = new ActiveXObject(activeX[i]);
                            break;
                        } catch(e) {}
                    }
                } finally {
                    return {conn : http, tId : transactionId};
                }
            }

    	    var pub = {
    	        request : function(method, uri, cb, data, options) {
    			    if(options){
    			        var me = this,
    			        	xmlData = options.xmlData,
    			        	jsonData = options.jsonData;

    			        Ext.applyIf(me, options);

    		            if(xmlData || jsonData){
    			            initHeader('Content-Type', xmlData ? 'text/xml' : 'application/json');
    			            data = xmlData || Ext.encode(jsonData);
    			        }
    			    }
    			    return asyncRequest(method || options.method || "POST", uri, cb, data);
    	        },

    	        serializeForm : function(form) {
    		        var fElements = form.elements || (document.forms[form] || Ext.getDom(form)).elements,
    	            	hasSubmit = false,
    	            	encoder = encodeURIComponent,
    		        	element,
    	            	options,
    	            	name,
    	            	val,
    	            	data = '',
    	            	type;

    		        Ext.each(fElements, function(element) {
    	                name = element.name;
    					type = element.type;

    	                if (!element.disabled && name){
    		                if(/select-(one|multiple)/i.test(type)){
    				            Ext.each(element.options, function(opt) {
    					            if (opt.selected) {
    						            data += String.format("{0}={1}&",
    						            					 encoder(name),
    						            					  (opt.hasAttribute ? opt.hasAttribute('value') : opt.getAttribute('value') !== null) ? opt.value : opt.text);
                                    }
                                });
    		                } else if(!/file|undefined|reset|button/i.test(type)) {
    			                if(!(/radio|checkbox/i.test(type) && !element.checked) && !(type == 'submit' && hasSubmit)){

                                    data += encoder(name) + '=' + encoder(element.value) + '&';
                                    hasSubmit = /submit/i.test(type);
                                }
    		                }
    	                }
    	            });
    	            return data.substr(0, data.length - 1);
    	        },

    	        useDefaultHeader : true,
    	        defaultPostHeader : 'application/x-www-form-urlencoded; charset=UTF-8',
    	        useDefaultXhrHeader : true,
    	        defaultXhrHeader : 'XMLHttpRequest',
    	        poll : {},
    	        timeout : {},
    	        pollInterval : 50,
    	        transactionId : 0,

    //	This is never called - Is it worth exposing this?
    // 	        setProgId : function(id) {
    // 	            activeX.unshift(id);
    // 	        },

    //	This is never called - Is it worth exposing this?
    // 	        setDefaultPostHeader : function(b) {
    // 	            this.useDefaultHeader = b;
    // 	        },

    //	This is never called - Is it worth exposing this?
    // 	        setDefaultXhrHeader : function(b) {
    // 	            this.useDefaultXhrHeader = b;
    // 	        },

    //	This is never called - Is it worth exposing this?
    // 	        setPollingInterval : function(i) {
    // 	            if (typeof i == 'number' && isFinite(i)) {
    // 	                this.pollInterval = i;
    // 	            }
    // 	        },

    //	This is never called - Is it worth exposing this?
    // 	        resetDefaultHeaders : function() {
    // 	            this.defaultHeaders = null;
    // 	        },

    	        abort : function(o, callback, isTimeout) {
    		        var me = this,
    		        	tId = o.tId,
    		        	isAbort = false;

    	            if (me.isCallInProgress(o)) {
    	                o.conn.abort();
    	                clearInterval(me.poll[tId]);
    	               	me.poll[tId] = null;
    	                if (isTimeout) {
    	                    me.timeout[tId] = null;
    	                }

    	                handleTransactionResponse(o, callback, (isAbort = true));
    	            }
    	            return isAbort;
    	        },

    	        isCallInProgress : function(o) {
    	            return o.conn && !{1:1,4:4}[o.conn.readyState];
    	        }
    	    };
    	    return pub;
        }();