public void sendMessageToClient(AbstractMessage message) {
   try {
     Container.logger().debug(">>> " + message);
     Buffer b1 = encoder.enc(message);
     sendMessageToClient(b1);
   } catch (Throwable e) {
     Container.logger().error(e.getMessage(), e);
   }
 }
 @Override
 public void onError(Throwable e) {
   String clientInfo = getClientInfo();
   Container.logger().error(clientInfo + ", " + e.getMessage(), e);
   //        if(e instanceof CorruptedFrameException) {
   closeConnection();
   //        }
 }
 @Override
 public void onToken(byte[] token, boolean timeout) throws Exception {
   try {
     Buffer buffer = Buffer.buffer(token);
     AbstractMessage message = decoder.dec(buffer);
     onMessageFromClient(message);
   } catch (Throwable ex) {
     String clientInfo = getClientInfo();
     Container.logger().error(clientInfo + ", Bad error in processing the message", ex);
     closeConnection();
   }
 }
  private void onMessageFromClient(AbstractMessage msg) throws Exception {
    Container.logger().debug("<<< " + msg);
    switch (msg.getMessageType()) {
      case CONNECT:
        ConnectMessage connect = (ConnectMessage) msg;
        ConnAckMessage connAck = new ConnAckMessage();
        if (session == null) {
          session = new MQTTSession(vertx, config);
          session.setPublishMessageHandler(this::sendMessageToClient);
          session.setKeepaliveErrorHandler(
              clientID -> {
                String cinfo = clientID;
                if (session != null) {
                  cinfo = session.getClientInfo();
                }
                Container.logger()
                    .info("keep alive exausted! closing connection for client[" + cinfo + "] ...");
                closeConnection();
              });
          connAck.setSessionPresent(false);
        } else {
          Container.logger().warn("Session alredy allocated ...");
          /*
          The Server MUST process a second CONNECT Packet sent from a Client as a protocol violation and disconnect the Client
           */
          //                    connAck.setSessionPresent(true);// TODO implement cleanSession=false
          closeConnection();
          break;
        }
        session.handleConnectMessage(
            connect,
            authenticated -> {
              if (authenticated) {
                connAck.setReturnCode(ConnAckMessage.CONNECTION_ACCEPTED);
                sendMessageToClient(connAck);
              } else {
                Container.logger()
                    .error(
                        "Authentication failed! clientID= "
                            + connect.getClientID()
                            + " username="******"type of message not known: " + msg.getClass().getSimpleName());
        break;
    }

    // TODO: forward mqtt message to backup server

  }