function callAjax(url, pageElement, callMessage, errorMessage) {
    document.getElementById(pageElement).innerHTML = callMessage;
    try {
    req = new XMLHttpRequest(); /* e.g. Firefox */
    } catch(e) {
      try {
      req = new ActiveXObject("Msxml2.XMLHTTP");  /* some versions IE */
      } catch (e) {
        try {
        req = new ActiveXObject("Microsoft.XMLHTTP");  /* some versions IE */
        } catch (E) {
         req = false;
        }
      }
    }
    req.onreadystatechange = function() {responseAjax(pageElement, errorMessage);};
    req.open("GET",url,true);
    req.send(null);
 }

function responseAjax(pageElement, errorMessage) {
  var output = '';
  if(req.readyState == 4) {
     if(req.status == 200) {
        output = req.responseText;
        document.getElementById(pageElement).innerHTML = output;
        } else {
        document.getElementById(pageElement).innerHTML = errorMessage+"\n"+output;
        }
     }
 }