var timerid;

function keepmysession()
{ 
 xmlHttp=GetXmlHttpObject();
if (xmlHttp==null)
{
  return;
} 
var url="keepsession.php";
xmlHttp.onreadystatechange=stateChanged;
xmlHttp.open("GET",url,true);
xmlHttp.send(null);

 timderid = setTimeout("keepmysession()",600000);
}

function stateChanged() 
{ 
if (xmlHttp.readyState==4)
{ 

}
}

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;
}