/**
  * get max period (from) in months (default: 2)
  * 
  * @return integer
  */
 protected function _getMaxPeriodFrom()
 {
     // if the client does support sync tokens and the plugin Tinebase_WebDav_Plugin_SyncToken is active
     if (Calendar_Convert_Event_VCalendar_Factory::supportsSyncToken($_SERVER['HTTP_USER_AGENT'])) {
         $result = Calendar_Config::getInstance()->get(Calendar_Config::MAX_FILTER_PERIOD_CALDAV_SYNCTOKEN, 100);
         if (Tinebase_Core::isLogLevel(Zend_Log::DEBUG)) {
             Tinebase_Core::getLogger()->debug(__METHOD__ . '::' . __LINE__ . ' SyncToken active: allow to filter for all calendar events => return ' . $result . ' months');
         }
         return $result;
     }
     return Calendar_Config::getInstance()->get(Calendar_Config::MAX_FILTER_PERIOD_CALDAV, 2);
 }
 /**
  * get max period (from) in months (default: 2)
  * 
  * @return integer
  */
 protected function _getMaxPeriodFrom()
 {
     //if the client does support sync tokens and the plugin Tinebase_WebDav_Plugin_SyncToken is active, allow to filter for all calendar events => return 100 years
     if (Calendar_Convert_Event_VCalendar_Factory::supportsSyncToken($_SERVER['HTTP_USER_AGENT'])) {
         return 100;
     }
     return Calendar_Config::getInstance()->get(Calendar_Config::MAX_FILTER_PERIOD_CALDAV, 2);
 }