function XMLHttpObj(url, parameters, method, backfunc)
{
  var xmlhttp = getXMLHTTP(); 
  if(xmlhttp == null)
     alert("your browser does not suport ajax");
  else
  {
     connect(url, parameters, method, backfunc);
  }

  function connect(url, parameters, method, backfunc)
  {
       xmlhttp.onreadystatechange = function()
       {
          if(xmlhttp.readyState == 4)
               backfunc(xmlhttp.responseText);
       }
     method = method.toUpperCase();
     if(method == "GET")
     {       
        xmlhttp.open("GET", url + "?" + parameters, true);
        xmlhttp.send(null);
     }
     else
     {
       xmlhttp.open("POST", url, true);
       xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
       xmlhttp.setRequestHeader("Content-length", parameters.length);
       xmlhttp.setRequestHeader("Connection", "close");
       xmlhttp.send(parameters);

     }
  }
 
     function getXMLHTTP()
     {
       if (window.XMLHttpRequest)
       {
          // code for IE7+, Firefox, Chrome, Opera, Safari
          return xmlhttp=new XMLHttpRequest();
        }
        else if (window.ActiveXObject)
        {
          // code for IE6, IE5
           return xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
        }
        else
        {
            return null;
        }
      }
}

function getSelectedValue(id)
 {
            var ele = document.getElementById(id);
            var index = ele.selectedIndex;
            return ele[index].value;
 }
 

function resetOptionList(id, message)
 {
             var selectBox = document.getElementById(id);
             if(selectBox.options.length >0)
                  selectBox.options.length =0;
             var opt = new Option(message, "");
             selectBox.options.add(opt);
 }