var reqXML;
    
function LoadXMLDoc(url){ 
  if (window.XMLHttpRequest){ //Mozilla, Firefox, Opera 8.01, Safari
    reqXML = new XMLHttpRequest(); 
    reqXML.onreadystatechange = BuildXMLResults; 
    reqXML.open("GET", url, true); 
    reqXML.send(null); 
  }
  else if(window.ActiveXObject){ //IE
    reqXML = new ActiveXObject("Microsoft.XMLHTTP"); 
    if (reqXML) { 
      reqXML.onreadystatechange = BuildXMLResults; 
      reqXML.open("GET", url, true); 
      reqXML.send(); 
    } 
  }
  else{ //Older Browsers
    alert("Your Browser does not support Ajax!");
  }
} 

function BuildXMLResults(){
  if(reqXML.readyState == 4){ //completed state
    if(reqXML.status == 200){ //We got a sucess page back
         
      //Check to verify the message from the server 
      if(reqXML.responseText.indexOf("Session Updated - Server Time:") === 0){
        window.status = reqXML.responseText; //display the message in the status bar
        SetTimer(); //restart timer
       }
      else{
        //display that that session expired
        alert("Your session appears to have expired. You may lose your current data.");
      }
    } 
    else{
      //display server code not be accessed
      alert("There was a problem retrieving the XML data:\n" + reqXML.statusText);
    }		
  }
}
      
function ConfirmUpdate(){
  //Extend automatically if window still open
    LoadXMLDoc('/bobexfr/javascript/AjaxSessionUpdate.jsp'); 
}      
      
var timerObj;
function SetTimer(){
  //How long before timeout (should be a few minutes before your server's timeout
  var dblMinutes = 25; //5 minutes before session timeout (30 min)
  //set timer to call function to confirm update 
  timerObj = setTimeout("ConfirmUpdate()",1000*60*dblMinutes);
}
      
//start the timer
SetTimer();