function makeHttpRequest(url, callback_function, return_xml) 
{ 
   var http_request = false; 

   if (window.XMLHttpRequest) { // Mozilla, Safari,... 
       http_request = new XMLHttpRequest(); 
       if (http_request.overrideMimeType) { 
           http_request.overrideMimeType('text/xml'); 
       } 
   } else if (window.ActiveXObject) { // IE 
       try { 
           http_request = new ActiveXObject("Msxml2.XMLHTTP"); 
       } catch (e) { 
           try { 
               http_request = new ActiveXObject("Microsoft.XMLHTTP"); 
           } catch (e) {} 
       } 
   } 

   if (!http_request) { 
       alert('Unfortunatelly you browser doesn\'t support this feature.'); 
       return false; 
   } 
   http_request.onreadystatechange = function() { 
       if (http_request.readyState == 4) { 
           if (http_request.status == 200) { 
               if (return_xml) { 
                   eval(callback_function + '(http_request.responseXML)'); 
               } else { 
                   eval(callback_function + '(http_request.responseText)'); 
               } 
           } else { 
               alert('There was a problem with the request.(Code: ' + http_request.status + ')'); 
           } 
       } 
   } 
   http_request.open('GET', url, true); 
   http_request.send(null); 
}