var ping_interval = 9*60;
var ping_url = "/scripts/content/sessionping.aspx";
var ping_request = false;

function pingURL(url)
{ if(window.XMLHttpRequest)
    ping_request = new XMLHttpRequest();
  else if(window.ActiveXObject)
    ping_request = new ActiveXObject("Microsoft.XMLHTTP");

  //alert(url);
  if(ping_request)
  { ping_request.onreadystatechange = function() {}; //alert(ping_request.readyState); };
    ping_request.open("GET", url, true);
    ping_request.send("");
  }
}

function pingSession()
{ // alert("ping");  
  pingURL(ping_url);
  setTimeout("pingSession()", ping_interval*1000);
}

function pingInit()
{ // alert("init");
  setTimeout("pingSession()", ping_interval*1000);
}