public boolean registerMe(
     String token, UserInterface user, ClientReceptionInterface cri) { // throws RemoteException {
   if (alive_users.containsKey(token) && alive_users.get(token).equals(user)) {
     keepMeAlive(token);
     return true;
   } else {
     alive_users.put(token, user);
     alive_clients.put(token, new Date());
     alive_clients_to_push.put(token, cri);
     return EngineImpl.GetInstance().register(token, user.GetLastActive());
   }
 }