var xmlhttp=null;

function AjaxResponseInit(url)
{
  xmlhttp=null;
  if (window.XMLHttpRequest) // code for IE7, Firefox, Opera, etc.
  {	
  	xmlhttp=new XMLHttpRequest();
  }
  else if (window.ActiveXObject) // code for IE6, IE5
  {	
  	xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
  
  if (xmlhttp!=null)
  {
  	xmlhttp.onreadystatechange=state_Change_response;
		xmlhttp.open("GET",url,true);
  	xmlhttp.send(null);
  }
  else
  {
  	alert("Your browser does not support XMLHTTP.");
  }
}

function state_Change_response()
{
	if (xmlhttp.readyState==4) // 4 = "loaded"
	{	
  	if (xmlhttp.status==200) // 200 = "OK"
    {
    	if (xmlhttp.responseText.substr(0,5) == "ERROR")
    	{
    		errorResponseReceived(xmlhttp.responseText);
    	}
    	else
    	{
    		responseReceived(xmlhttp.responseText);
    	}
    }
  	else
    {
    	errorResponseReceived("Problem retrieving data: " + xmlhttp.statusText);
    }
	}
}