/**
  * Sends the notification to all listener which are subscribed to the given
  * ref_id
  * 
  * @param ilNotificationConfig $notification
  * @param type $ref_id
  * @param type $processAsync 
  */
 private function toListeners(ilNotificationConfig $notification, $ref_id, $processAsync = false)
 {
     require_once 'Services/Notifications/classes/class.ilNotificationUserIterator.php';
     require_once 'Services/Notifications/classes/class.ilNotificationDatabaseHelper.php';
     if ($processAsync == false) {
         $users = ilNotificationDatabaseHandler::getUsersByListener($notification->getType(), $ref_id);
         self::toUsers($notification, $users, false);
         if ($notification->hasDisableAfterDeliverySet()) {
             ilNotificationDatabaseHandler::disableListeners($notification->getType(), $ref_id);
         }
     } else {
         ilNotificationDatabaseHandler::enqueueByListener($notification, $ref_id);
     }
 }