code: // Licensed to the Software Freedom Conservancy (SFC) under one
  // or more contributor license agreements.  See the NOTICE file
  // distributed with this work for additional information
  // regarding copyright ownership.  The SFC licenses this file
  // to you under the Apache License, Version 2.0 (the
  // "License"); you may not use this file except in compliance
  // with the License.  You may obtain a copy of the License at
  //
  //   http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing,
  // software distributed under the License is distributed on an
  // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  // KIND, either express or implied.  See the License for the
  // specific language governing permissions and limitations
  // under the License.
  
  package org.openqa.selenium.netty.server;
  
  import io.netty.buffer.Unpooled;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.ChannelOutboundHandlerAdapter;
  import io.netty.channel.ChannelPromise;
  import io.netty.handler.codec.http.websocketx.BinaryWebSocketFrame;
  import io.netty.handler.codec.http.websocketx.CloseWebSocketFrame;
  import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
  import java.util.logging.Logger;
  import org.openqa.selenium.remote.http.BinaryMessage;
  import org.openqa.selenium.remote.http.CloseMessage;
  import org.openqa.selenium.remote.http.Message;
  import org.openqa.selenium.remote.http.TextMessage;
  
  class MessageOutboundConverter extends ChannelOutboundHandlerAdapter {
  
    private static final Logger LOG = Logger.getLogger(MessageOutboundConverter.class.getName());
  
    @Override
    public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise)
        throws Exception {
      if (!(msg instanceof Message)) {
        super.write(ctx, msg, promise);
        return;
      }
  
      Message seMessage = (Message) msg;
  
      if (seMessage instanceof CloseMessage) {
        ctx.writeAndFlush(new CloseWebSocketFrame(true, 0));
      } else if (seMessage instanceof BinaryMessage) {
        ctx.writeAndFlush(
            new BinaryWebSocketFrame(
                true, 0, Unpooled.copiedBuffer(((BinaryMessage) seMessage).data())));
      } else if (seMessage instanceof TextMessage) {
        ctx.writeAndFlush(new TextWebSocketFrame(true, 0, ((TextMessage) seMessage).text()));
      } else {
        LOG.warning(String.format("Unable to handle %s", msg));
        super.write(ctx, msg, promise);
      }
    }
  }
  