This document discusses using the Moquette broker and Eclipse Paho client library to implement MQTT messaging in Java. It provides code examples for setting up a Moquette broker configured to run on port 1883, creating an MQTT client in Java using Eclipse Paho to publish messages to a broker, and using a message interceptor class to log published messages on the broker side. The full code example runs a Moquette broker instance and demonstrates an MQTT client publishing and receiving a message through the broker.

1. Micha Kops
http://www.hascode.com/2016/06/playing-around-with-mqtt-and-java-with-moquette-and-eclipse-paho/
MQTT for Java
Client and Broker examples using Moquette and
Apache Paho

2. Micha Kops
http://www.hascode.com/2016/06/playing-around-with-mqtt-and-java-with-moquette-and-eclipse-paho/
Dependencies
<dependency>
<groupId>io.moquette</groupId>
<artifactId>moquette-broker</artifactId>
<version>0.8</version>
</dependency>
<dependency>
<groupId>org.eclipse.paho</groupId>
<artifactId>org.eclipse.paho.client.mqttv3</artifactId>
<version>1.0.2</version>
</dependency>

3. Micha Kops
http://www.hascode.com/2016/06/playing-around-with-mqtt-and-java-with-moquette-and-eclipse-paho/
Moquette Configuration
port 1883
host 0.0.0.0
allow_anonymous true
File moquette.conf

4. Micha Kops
http://www.hascode.com/2016/06/playing-around-with-mqtt-and-java-with-moquette-and-eclipse-paho/
Message Interceptor
class PublisherListener extends AbstractInterceptHandler {
@Override
public void onPublish(InterceptPublishMessage message) {
System.out.println("moquette mqtt broker message intercepted, topic: " +
message.getTopicName()
+ ", content: " + new String(message.getPayload().array()));
}
}

5. Micha Kops
http://www.hascode.com/2016/06/playing-around-with-mqtt-and-java-with-moquette-and-eclipse-paho/
Shutdown hook
final IConfig classPathConfig = new ClasspathConfig();
final Server mqttBroker = new Server();
final List<? extends InterceptHandler> userHandlers = Arrays.asList(new
PublisherListener());
mqttBroker.startServer(classPathConfig, userHandlers);
System.out.println("moquette mqtt broker started, press ctrl-c to shutdown..");
Runtime.getRuntime().addShutdownHook(new Thread() {
@Override
public void run() {
System.out.println("stopping moquette mqtt broker..");
mqttBroker.stopServer();
System.out.println("moquette mqtt broker stopped");
}
});

6. Micha Kops
http://www.hascode.com/2016/06/playing-around-with-mqtt-and-java-with-moquette-and-eclipse-paho/
Eclipse Paho MQTT Client
String topic = "news";
String content = "Visit www.hascode.com! :D";
int qos = 2;
String broker = "tcp://0.0.0.0:1883";
String clientId = "paho-java-client";
try {
MqttClient sampleClient = new MqttClient(broker, clientId, new MemoryPersistence());
MqttConnectOptions connOpts = new MqttConnectOptions();
connOpts.setCleanSession(true);
System.out.println("paho-client connecting to broker: " + broker);
sampleClient.connect(connOpts);
System.out.println("paho-client connected to broker");
System.out.println("paho-client publishing message: " + content);
MqttMessage message = new MqttMessage(content.getBytes());
message.setQos(qos);
sampleClient.publish(topic, message);
System.out.println("paho-client message published");
sampleClient.disconnect();
System.out.println("paho-client disconnected");
} catch (MqttException me) {}

7. Micha Kops
http://www.hascode.com/2016/06/playing-around-with-mqtt-and-java-with-moquette-and-eclipse-paho/
Running Example
final IConfig classPathConfig = new ClasspathConfig();
final Server mqttBroker = new Server();
final List<? extends InterceptHandler> userHandlers = Arrays.asList(new PublisherListener());
mqttBroker.startServer(classPathConfig, userHandlers);
Runtime.getRuntime().addShutdownHook(new Thread() {
@Override
public void run() {
mqttBroker.stopServer();
}
});
String topic = "news";
String content = "Visit www.hascode.com! :D";
int qos = 2;
String broker = "tcp://0.0.0.0:1883";
String clientId = "paho-java-client";
MqttClient sampleClient = new MqttClient(broker, clientId, new MemoryPersistence());
MqttConnectOptions connOpts = new MqttConnectOptions();
connOpts.setCleanSession(true);
sampleClient.connect(connOpts);
MqttMessage message = new MqttMessage(content.getBytes());
message.setQos(qos);
sampleClient.publish(topic, message);
sampleClient.disconnect();

8. Micha Kops
http://www.hascode.com/2016/06/playing-around-with-mqtt-and-java-with-moquette-and-eclipse-paho/
Running the Example
$ mvn exec:java -Dexec.mainClass=com.hascode.tutorial.mqtt.Main
[INFO] Scanning for projects...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building mqtt-java-tutorial 1.0.0
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- exec-maven-plugin:1.3.1:java (default-cli) @ mqtt-java-tutorial ---
moquette mqtt broker started, press ctrl-c to shutdown..
paho-client connecting to broker: tcp://0.0.0.0:1883
paho-client connected to broker
paho-client publishing message: Visit www.hascode.com! :D
moquette mqtt broker message intercepted, topic: news, content: Visit www.hascode.com! :D
paho-client message published
paho-client disconnected
^Cstopping moquette mqtt broker..
moquette mqtt broker stopped

9. Micha Kops
http://www.hascode.com/2016/06/playing-around-with-mqtt-and-java-with-moquette-and-eclipse-paho/
Resources
● Sources:
https://bitbucket.org/hascode/mqtt-java-tutorial
● Tutorial:
http://www.hascode.com/2016/06/playing-around-wi
● MQTT Website: http://mqtt.org/
● Eclipse Paho:
https://eclipse.org/paho/clients/java/
● Moquette: http://andsel.github.io/moquette/

10. Micha Kops
http://www.hascode.com/2016/06/playing-around-with-mqtt-and-java-with-moquette-and-eclipse-paho/
Le Fin
Thanks for your audience!