/*
function AJAXInteraction(url, callback) {

    var req = init();
    req.onreadystatechange = processRequest;
        
    function init() {
      if (window.XMLHttpRequest) {
        return new XMLHttpRequest();
      } else if (window.ActiveXObject) {
        return new ActiveXObject("Microsoft.XMLHTTP");
      }
    }
    
    function processRequest () {
      // readyState of 4 signifies request is complete
      if (req.readyState == 4) {
	// status of 200 signifies sucessful HTTP call
        if (req.status == 200) {
          if (callback) callback(req.responseXML);
        }
      }
    }

    this.doGet = function() {
      // make a HTTP GET request to the URL asynchronously
      req.open("GET", url, true);
      req.send(null);
    }
}

function validateUserId() { 
    var target = document.getElementById("userid"); 
    var url = "validate?id=" + encodeURIComponent(target.value); 
    var ajax = new AJAXInteraction(url, validateCallback); 
    ajax.doGet(); 
}

function validateCallback(responseXML) {
  // see "The Callback Function" below for more details
}

function validateCallback(responseXML) {

   var msg = responseXML.
       getElementsByTagName("valid")[0].firstChild.nodeValue;

   if (msg == "false") {

       var mdiv = document.getElementById("userIdMessage");

       // set the style on the div to invalid

       mdiv.className = "bp_invalid";
       mdiv.innerHTML = "Invalid User Id";
       var submitBtn = document.getElementById("submit_btn");
       submitBtn.disabled = true;

    } else {

       var mdiv = document.getElementById("userIdMessage");

       // set the style on the div to valid

       mdiv.className = "bp_valid";
       mdiv.innerHTML = "Valid User Id";
       var submitBtn = document.getElementById("submit_btn");
       submitBtn.disabled = false;
    }  
}
*/