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1   /*
2    * Copyright 2012 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   https://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package io.netty.example.uptime;
17  
18  import io.netty.bootstrap.Bootstrap;
19  import io.netty.channel.ChannelFuture;
20  import io.netty.channel.ChannelFutureListener;
21  import io.netty.channel.ChannelInitializer;
22  import io.netty.channel.EventLoopGroup;
23  import io.netty.channel.MultiThreadIoEventLoopGroup;
24  import io.netty.channel.nio.NioIoHandler;
25  import io.netty.channel.socket.SocketChannel;
26  import io.netty.channel.socket.nio.NioSocketChannel;
27  import io.netty.handler.timeout.IdleStateHandler;
28  
29  
30  /**
31   * Connects to a server periodically to measure and print the uptime of the
32   * server.  This example demonstrates how to implement reliable reconnection
33   * mechanism in Netty.
34   */
35  public final class UptimeClient {
36  
37      static final String HOST = System.getProperty("host", "127.0.0.1");
38      static final int PORT = Integer.parseInt(System.getProperty("port", "8080"));
39      // Sleep 5 seconds before a reconnection attempt.
40      static final int RECONNECT_DELAY = Integer.parseInt(System.getProperty("reconnectDelay", "5"));
41      // Reconnect when the server sends nothing for 10 seconds.
42      private static final int READ_TIMEOUT = Integer.parseInt(System.getProperty("readTimeout", "10"));
43  
44      private static final UptimeClientHandler handler = new UptimeClientHandler();
45      private static final Bootstrap bs = new Bootstrap();
46  
47      public static void main(String[] args) throws Exception {
48          EventLoopGroup group = new MultiThreadIoEventLoopGroup(NioIoHandler.newFactory());
49          bs.group(group)
50                  .channel(NioSocketChannel.class)
51                  .remoteAddress(HOST, PORT)
52                  .handler(new ChannelInitializer<SocketChannel>() {
53                      @Override
54                      protected void initChannel(SocketChannel ch) throws Exception {
55                          ch.pipeline().addLast(new IdleStateHandler(READ_TIMEOUT, 0, 0), handler);
56                      }
57                  });
58          bs.connect();
59      }
60  
61      static void connect() {
62          bs.connect().addListener(new ChannelFutureListener() {
63              @Override
64              public void operationComplete(ChannelFuture future) throws Exception {
65                  if (future.cause() != null) {
66                      handler.startTime = -1;
67                      handler.println("Failed to connect: " + future.cause());
68                  }
69              }
70          });
71      }
72  }