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.AsciiBuffer;
  import org.fusesource.hawtbuf.Buffer;
  import org.fusesource.hawtbuf.UTF8Buffer;
  import org.fusesource.mqtt.client.Future;
  import org.fusesource.mqtt.client.FutureConnection;
  import org.fusesource.mqtt.client.MQTT;
  import org.fusesource.mqtt.client.QoS;
  
  import java.util.LinkedList;
  
  /**
   * Uses a Future based API to MQTT.
   */
  class Publisher {
  
      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");
  
          int messages = 10000;
          int size = 256;
  
          String DATA = "abcdefghijklmnopqrstuvwxyz";
          String body = "";
          for( int i=0; i < size; i ++) {
              body += DATA.charAt(i%DATA.length());
          }
         Buffer msg = new AsciiBuffer(body);
  
          MQTT mqtt = new MQTT();
          mqtt.setHost(host, port);
          mqtt.setUserName(user);
          mqtt.setPassword(password);
  
          FutureConnection connection = mqtt.futureConnection();
          connection.connect().await();
  
          final LinkedList<Future<Void>> queue = new LinkedList<Future<Void>>();
          UTF8Buffer topic = new UTF8Buffer(destination);
          for( int i=1; i <= messages; i ++) {
  
              // Send the publish without waiting for it to complete. This allows us
              // to send multiple message without blocking..
              queue.add(connection.publish(topic, msg, QoS.AT_LEAST_ONCE, false));
  
              // Eventually we start waiting for old publish futures to complete
              // so that we don't create a large in memory buffer of outgoing message.s
              if( queue.size() >= 1000 ) {
                  queue.removeFirst().await();
              }
  
              if( i % 1000 == 0 ) {
                  System.out.println(String.format("Sent %d messages.", i));
              }
          }
  
          queue.add(connection.publish(topic, new AsciiBuffer("SHUTDOWN"), QoS.AT_LEAST_ONCE, false));
          while( !queue.isEmpty() ) {
              queue.removeFirst().await();
          }
  
          connection.disconnect().await();
  
          System.exit(0);
      }
  
      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;
      }
  
  }