/**
  * Handle incoming control frames
  *
  * Sends Pong on Ping and closes the connection after a Close request.
  *
  * @param IWebSocketUser $user
  * @param WebSocketFrame $frame
  */
 protected function processControlFrame(WebSocketFrame $frame)
 {
     switch ($frame->getType()) {
         case WebSocketOpcode::CloseFrame:
             $frame = WebSocketFrame::create(WebSocketOpcode::CloseFrame);
             $this->sendFrame($frame);
             $this->_socket->disconnect();
             break;
         case WebSocketOpcode::PingFrame:
             $frame = WebSocketFrame::create(WebSocketOpcode::PongFrame);
             $this->sendFrame($frame);
             break;
     }
 }