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   /*
    * Copyright 2012 The Netty Project
    *
    * The Netty Project 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:
    *
    *   https://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 io.netty.example.qotm;
  
  import io.netty.bootstrap.Bootstrap;
  import io.netty.buffer.Unpooled;
  import io.netty.channel.Channel;
  import io.netty.channel.ChannelOption;
  import io.netty.channel.EventLoopGroup;
  import io.netty.channel.nio.NioEventLoopGroup;
  import io.netty.channel.socket.DatagramPacket;
  import io.netty.channel.socket.nio.NioDatagramChannel;
  import io.netty.util.CharsetUtil;
  import io.netty.util.internal.SocketUtils;
  
  /**
   * A UDP broadcast client that asks for a quote of the moment (QOTM) to {@link QuoteOfTheMomentServer}.
   *
   * Inspired by <a href="https://docs.oracle.com/javase/tutorial/networking/datagrams/clientServer.html">the official
   * Java tutorial</a>.
   */
  public final class QuoteOfTheMomentClient {
  
      static final int PORT = Integer.parseInt(System.getProperty("port", "7686"));
  
      public static void main(String[] args) throws Exception {
  
          EventLoopGroup group = new NioEventLoopGroup();
          try {
              Bootstrap b = new Bootstrap();
              b.group(group)
               .channel(NioDatagramChannel.class)
               .option(ChannelOption.SO_BROADCAST, true)
               .handler(new QuoteOfTheMomentClientHandler());
  
              Channel ch = b.bind(0).sync().channel();
  
              // Broadcast the QOTM request to port 8080.
              ch.writeAndFlush(new DatagramPacket(
                      Unpooled.copiedBuffer("QOTM?", CharsetUtil.UTF_8),
                      SocketUtils.socketAddress("255.255.255.255", PORT))).sync();
  
              // QuoteOfTheMomentClientHandler will close the DatagramChannel when a
              // response is received.  If the channel is not closed within 5 seconds,
              // print an error message and quit.
              if (!ch.closeFuture().await(5000)) {
                  System.err.println("QOTM request timed out.");
              }
          } finally {
              group.shutdownGracefully();
          }
      }
  }