function makeHttpRequest(url, callback_function, return_xml)
{
  var http_request, response, i;

  var activex_ids = [
        'MSXML2.XMLHTTP.3.0',
        'MSXML2.XMLHTTP',
        'Microsoft.XMLHTTP'
  ];

  if (window.XMLHttpRequest) { // Mozilla, Safari, IE7+...
        http_request = new XMLHttpRequest();
        if (http_request.overrideMimeType) {
          http_request.overrideMimeType('text/xml');
        }
  } else if (window.ActiveXObject) { // IE6 and older
        for (i = 0; i < activex_ids.length; i++) {
          try {
                http_request = new ActiveXObject(activex_ids[i]);
          } catch (e) {}
        }
  }

  if (!http_request) {
        alert('Unfortunatelly your browser doesn\'t support this feature.');
        return false;
  }
  
  http_request.open('GET', url, true);

  http_request.onreadystatechange = function() {
        if (http_request.readyState != 4) {
                // not ready yet
                return;
        }
        if (http_request.status != 200) {
          // ready, but not OK
          alert('There was a problem with the request.(Code: ' + http_request.status + ')\n'+url);
          return;
        }
        if (return_xml) {
          response = http_request.responseXML;
        } else {
          response = http_request.responseText;
        }
        // invoke the callback
        if(callback_function != ""){
            callback_function(response);
        }
  };

  http_request.send(null);
}