function AjaxUpdateServer(userid, courseid, timecost)
{
	if (userid.length==0 || courseid == null)
	{ 
		document.getElementById("txtServerMsg").innerHTML="";
	return;
	}
		xmlHttp=GetXmlHttpObject();
	if (xmlHttp==null)
	{
		alert ("Your browser does not support AJAX!");
		return;
	} 
	var url="updateTime.php";
	url=url+"?userid="+userid;
	url=url+"&courseid="+courseid;
	url=url+"&t="+timecost;
	url=url+"&sid="+Math.random();
	xmlHttp.onreadystatechange=stateChanged;
	xmlHttp.open("GET",url,true);
	xmlHttp.send(null);
}

function GetXmlHttpObject()
{
	var xmlHttp=null;
	try
	{
		// Firefox, Opera 8.0+, Safari
		xmlHttp=new XMLHttpRequest();
	}
	catch (e)
	{
		// Internet Explorer
		try
		{
			xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
		}
		catch (e)
		{
			xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
		}
	}
	return xmlHttp;
}

function stateChanged() 
{ 
//	document.getElementById("txtServerMsg").innerHTML = "loi"
	if (xmlHttp.readyState==4)
	{ 	
		var timeRemain = xmlHttp.responseText;
		document.getElementById("timer").innerHTML = timeRemain;
		if (timeRemain == "0")
		{
			alert("Timed out");
			//ClosePopUpDiv();
			HideCenterDiv();
			//alert("View Course Window Close");
		}
		
	}
}