@Override
 public void sendError(String message) {
   if (socket.isConnected()) WebSocketHelper.sendError(socket, message);
 }
 @Override
 public void sendDone() {
   WebSocketHelper.sendData(socket, "done");
   if (socket.isConnected()) socket.close();
 }
 @Override
 public void sendOK() {
   WebSocketHelper.sendOk(socket);
 }