content: /**
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF 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 example;
  
  import org.fusesource.hawtbuf.*;
  import org.fusesource.mqtt.client.*;
  
  /**
   * Uses an callback based interface to MQTT.  Callback based interfaces
   * are harder to use but are slightly more efficient.
   */
  class Listener {
  
      public static void main(String []args) throws Exception {
  
          String user = env("ACTIVEMQ_USER", "admin");
          String password = env("ACTIVEMQ_PASSWORD", "password");
          String host = env("ACTIVEMQ_HOST", "localhost");
          int port = Integer.parseInt(env("ACTIVEMQ_PORT", "1883"));
          final String destination = arg(args, 0, "/topic/event");
  
  
          MQTT mqtt = new MQTT();
          mqtt.setHost(host, port);
          mqtt.setUserName(user);
          mqtt.setPassword(password);
  
  
          final CallbackConnection connection = mqtt.callbackConnection();
          connection.listener(new org.fusesource.mqtt.client.Listener() {
              long count = 0;
              long start = System.currentTimeMillis();
  
              public void onConnected() {
              }
              public void onDisconnected() {
              }
              public void onFailure(Throwable value) {
                  value.printStackTrace();
                  System.exit(-2);
              }
              public void onPublish(UTF8Buffer topic, Buffer msg, Runnable ack) {
                  String body = msg.utf8().toString();
                  if( "SHUTDOWN".equals(body)) {
                      long diff = System.currentTimeMillis() - start;
                      System.out.println(String.format("Received %d in %.2f seconds", count, (1.0*diff/1000.0)));
                      connection.disconnect(new Callback<Void>() {
                          @Override
                          public void onSuccess(Void value) {
                              System.exit(0);
                          }
                          @Override
                          public void onFailure(Throwable value) {
                              value.printStackTrace();
                              System.exit(-2);
                          }
                      });
                  } else {
                      if( count == 0 ) {
                          start = System.currentTimeMillis();
                      }
                      if( count % 1000 == 0 ) {
                          System.out.println(String.format("Received %d messages.", count));
                      }
                      count ++;
                  }
                  ack.run();
              }
          });
          connection.connect(new Callback<Void>() {
              @Override
              public void onSuccess(Void value) {
                  Topic[] topics = {new Topic(destination, QoS.AT_LEAST_ONCE)};
                  connection.subscribe(topics, new Callback<byte[]>() {
                      public void onSuccess(byte[] qoses) {
                      }
                      public void onFailure(Throwable value) {
                          value.printStackTrace();
                          System.exit(-2);
                      }
                  });
              }
              @Override
              public void onFailure(Throwable value) {
                  value.printStackTrace();
                  System.exit(-2);
              }
          });
  
          // Wait forever..
          synchronized (Listener.class) {
              while(true)
                  Listener.class.wait();
          }
      }
  
      private static String env(String key, String defaultValue) {
          String rc = System.getenv(key);
          if( rc== null )
              return defaultValue;
          return rc;
      }
  
      private static String arg(String []args, int index, String defaultValue) {
          if( index < args.length )
              return args[index];
          else
              return defaultValue;
      }
  }