function createXMLHttpRequest()
{
  var httpRequest;

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

  return httpRequest;

} // createXMLHttpRequest()