///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

//using XMLHttpRequest Object

function AJAX()

{	

	this.xmlHttp = null;

	this.lpfnStateChangeCallBack = null;

	this.lpfnPrevSendCallBack = null;

	this.lpfnFinishCallBack = null;

	this.responseText = "";

	this.responseXML = "";

	this.lastError = "";

		

	this.lpfnInProgress = 0;

	AJAX.prototype.nCounter = 0;

	AJAX.prototype.ptrThis = this;

	

	//callback params

	this.callbackParams = null;

	

	//initialize xmlHttp object

	this._initialize = function()

	{		

		try

		{

			this.xmlHttp = new XMLHttpRequest();

		}

		catch(e)

		{

			try{

				this.xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");	//require IE6.0 or newer

			}catch(e)

			{

				this.lastError = e.message;

			}			

		}

		return this.xmlHttp!=null;

	}

	

	//get readystate

	this.getReadyState = function()

	{

		if(!this.xmlHttp)

			return -1;

		return this.xmlHttp.readyState;

	}

	

	//get status

	this.getStatusCode = function()

	{

		if(!this.xmlHttp)

			return -1;

		if(this.xmlHttp.readyState==4)

			return this.xmlHttp.status;

		return -1;

	}

	

	//send request

	this.send = function(method, url, params, lpfnStateChangeCallBack, lpfnPrevSendCallBack, lpfnFinishCallBack, lpfnInProgress)

	{

		this.nCounter = 0;

		

		if(!this.xmlHttp)

			return false;

		

		if(this.xmlHttp.readyState!=0 && this.xmlHttp.readyState!=4)//not initialized or busy

			return false;

		if(this.xmlHttp.readyState!=4)

			this.xmlHttp.abort();

	

		this.lpfnStateChangeCallBack = lpfnStateChangeCallBack;

		this.lpfnPrevSendCallBack = lpfnPrevSendCallBack;

		this.lpfnFinishCallBack = lpfnFinishCallBack;		

		this.lpfnInProgress = lpfnInProgress;

		

		if(this.lpfnPrevSendCallBack)

		{

			this.lpfnPrevSendCallBack();

		}

			

		try

		{

			//start timer proc

			setTimeout("AJAX.prototype._lpfninprogress()", 0);

			//open

			this.xmlHttp.open(method, url);

			if(method.toLowerCase()=="post")

				this.xmlHttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");

			this.xmlHttp.onreadystatechange = lpfnStateChangeCallBack ? lpfnStateChangeCallBack : onReadyStateChangeRoutine;			

			this.xmlHttp.send(params);

		}

		catch(e)

		{

			this.lastError = e.message;

			//alert("Error connect to server. System message: " + e.message);

			if(lpfnFinishCallBack)

				lpfnFinishCallBack();

		}

	}//end send

	

	//timer function

	AJAX.prototype._lpfninprogress = function()

	{

		pthis = AJAX.prototype.ptrThis;

		++pthis.nCounter

		

		if(pthis.xmlHttp.readyState==4 || pthis.nCounter>60)

		{

			if(pthis.nCounter>60){

				alert("Sorry, server not responding. Press F5 to reload this page.");

				document.location = document.location.href;

			}

			pthis.nCounter = 0;

			return;

		}

		

		if(pthis.lpfnInProgress)

			pthis.lpfnInProgress(pthis.nCounter);

		setTimeout("AJAX.prototype._lpfninprogress()", 1000)

	}//end timer

	

	//initialize AJAX object

	this._initialize();

}//end class



//onreadystatechange callback

function onReadyStateChangeRoutine()

{		

	if(!Ajax.xmlHttp)

	{

		return;

	}

	if(Ajax.xmlHttp.readyState == 4)

	{

		try

		{	

			if(Ajax.xmlHttp.status == 200)

			{			

				Ajax.responseText = getResponseText(Ajax.xmlHttp.responseText);

				Ajax.responseXML = Ajax.xmlHttp.responseXML;

				var ret = Ajax.responseText;

				if(ret.indexOf("-ERROR_CONNECT")==0)

				{

					alert("Server is too busy. Please try later. Thanks!"); 

					document.location = "";

					return;

				}

				

				if(Ajax.lpfnFinishCallBack)

				{

					Ajax.lpfnFinishCallBack();

				}

			}

		}catch(e)

		{

			Ajax.lastError = e.message;

		}		

	}

}//end onReadyStateChange



function getResponseText(str)

{

	var len1 = String("<response>").length;

	var len2 = String("</response>").length;

	

	var istart = str.indexOf("<response>");

	var iend = str.indexOf("</response>");

	str = str.substr(istart + len1, iend - istart - len1);

	return str;

	//return str.replace(/&amp;/g, "&");

}



///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

//create and initialize GLOBAL Ajax object

var Ajax = new AJAX();

//End Initializing

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////