// Keep session alive;
currRefresh=0;
maxRefresh=5;
newRefreshCon = setInterval('refreshSession()', 600000);
function refreshSession(){
  if(currRefresh<=maxRefresh){
    currRefresh++;
    sendAjax(refreshSession_callback,'POST', 'http://portal.nature.cz/inc/refresh.php', 'action=refresh',-1)
  }else{
    alert('Platnost aktuální relace vypršela. Prosím přihlašte se znovu');
    window.clearInterval(newRefreshCon);  
  }
}function refreshSession_callback(){null;}

function sendAjax (callback, method, url, content, jsTempNo, headers,sync) {
    
//     gEBIst('processBar').display = 'block';
    var xmlhttp = (window.XMLHttpRequest ? new XMLHttpRequest : (window.ActiveXObject ? new ActiveXObject("Microsoft.XMLHTTP") : false));
    var result = true;
    sync = sync?false:true;
    if (!xmlhttp) {
        return false;
    }
    xmlhttp.open(method, url, sync);
    xmlhttp.onreadystatechange = function() {
      if (xmlhttp.readyState == 4) {
        if(xmlhttp.status == 200 || xmlhttp.status==0){
          result = callback(xmlhttp, jsTempNo);
//           if(activeProcess < 1)gEBIst('processBar').display = 'none';
        }
        else alert("AJAX error: "+ xmlhttp.status +":"+ xmlhttp.statusText);
      }
    };
    if (headers) {
        for (var key in headers) {
            xmlhttp.setRequestHeader(key, headers[key]);
        }
    }
    xmlhttp.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
    xmlhttp.send(content);
    return result;
}