var userAgent = { };
userAgent.isAJAX  = (createXMLHttpRequest()?true:false);
userAgent.isMozilla  = (navigator.userAgent.match(/\bGecko\b/));
userAgent.isOpera  = (navigator.userAgent.match(/\bOpera\b/));
userAgent.isInternetExplorer  =(navigator.userAgent.match(/\bMSIE\b/) && !userAgent.isOpera);

function createXMLHttpRequest() {
  var xmlReq = false;
  // branch for native XMLHttpRequest object
  if(window.XMLHttpRequest) {
    try {
      xmlReq = new XMLHttpRequest();
    } catch(e) {
      xmlReq = false;
    }
  // branch for IE/Windows ActiveX version
  } else if(window.ActiveXObject) {
    try {
      xmlReq = new  ActiveXObject("Msxml2.XMLHTTP");
    } catch(e) {
      try {
        xmlReq = new  ActiveXObject("Microsoft.XMLHTTP");
      } catch(e) {
        xmlReq = false;
      }
    }
  }
  return xmlReq;
}

function callServer(method, url, data, dataType, func, arg) {
  if (!method) method='GET';
  if (data && !dataType)  dataType='application/x-www-form-urlencoded';
  var xmlReq = createXMLHttpRequest();
  if(xmlReq) {
    xmlReq.onreadystatechange = function() {
      // only if xmlReq shows "loaded"
      if (xmlReq.readyState ==  4 ) {
        func(arg, xmlReq.responseText,  xmlReq.responseXML,
             xmlReq.status, xmlReq.statusText);
      }
    }
    xmlReq.open(method, url, true);
    if (userAgent.isMozilla) dataType=dataType+';charset=utf-8';
    xmlReq.setRequestHeader('Content-Type',  String(dataType));
    xmlReq.send(data);
    return false;
  }
  return true;
}