RabbitMQ MQTT Adapter and Paho MQTT client - rabbitmq

Question

I’m using RabbitMQ MQTT Adapter and Paho MQTT client.
RabbitMQ version: {rabbitmq_mqtt,"RabbitMQ MQTT Adapter","3.2.1"}
Paho MQTT client version:
<dependency>
<groupId>org.eclipse.paho</groupId>
<artifactId>org.eclipse.paho.client.mqttv3</artifactId>
<version>RELEASE</version>
</dependency>
Please see code inline.
I’m trying to understand if, the subscriber queue can be durable without expiration time. And If the messages can be durable also.
As I understood from RabbitMQ documentation, each time a subscriber subscribes to a topic
RabbitMQ will create a queue with this naming convention:
mqtt-subscription-<ClientName>qos<ClientQOS>
This queue has an expiration time, how can I create a queue without an expiration time? Can I change this queue expiration time to infinite?
As for now each time I run this command: “service rabbitmq-server restart”
The messages in the queue get deleted.
How can I prevent this? Is there a way I can keep the messages in the queue after restart?
In RabbitMQ management UI, I can see under “Publish message” -> “Delivery mode:” which can be “2-persistent”.
If I use management UI to publish messages with Delivery mode = 2-persistent. The messages will be in the queue after service restart.
How can I achieve the same using Paho MQTT Client?
// Heavily based on RabbitMQ MQTT adapter test case code!
// first, import the RabbitMQ Java client
// and the Paho MQTT client classes, plus any other
// requirements
import com.rabbitmq.client.*;
import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
import org.eclipse.paho.client.mqttv3.MqttCallback;
import org.eclipse.paho.client.mqttv3.MqttClient;
import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
import org.eclipse.paho.client.mqttv3.MqttDeliveryToken;
import org.eclipse.paho.client.mqttv3.MqttException;
import org.eclipse.paho.client.mqttv3.MqttMessage;
import org.eclipse.paho.client.mqttv3.MqttTopic;
import org.eclipse.paho.client.mqttv3.internal.NetworkModule;
import org.eclipse.paho.client.mqttv3.internal.TCPNetworkModule;
// import org.eclipse.paho.client.mqttv3.internal.trace.Trace;
import org.eclipse.paho.client.mqttv3.internal.wire.MqttOutputStream;
import org.eclipse.paho.client.mqttv3.internal.wire.MqttPublish;
import javax.net.SocketFactory;
import java.io.IOException;
import java.net.InetAddress;
import java.net.Socket;
import java.util.*;
/***
* MQTT v3.1 tests
* TODO: synchronise access to variables
*/
public class MqttTestClean implements MqttCallback {
// setup some variables which define where the MQTT broker is
private final String host = "0.0.0.0";
private final int port = 1883;
private final String brokerUrl = "tcp://" + host + ":" + port;
private String clientId;
private String clientId3;
private MqttClient client;
private MqttClient client3;
private MqttConnectOptions conOpt;
private ArrayList<MqttMessage> receivedMessages;
// specify a message payload - doesn't matter what this says, but since MQTT expects a byte array
// we convert it from string to byte array here
private final byte[] payload = "This payload was published on MQTT and read using AMQP.".getBytes();
// specify the topic to be used
private final String topic = "topic/proxy/1.0.0/Report/*";
private int testDelay = 2000;
private long lastReceipt;
private boolean expectConnectionFailure;
private ConnectionFactory connectionFactory;
private Connection conn;
private Channel ch;
// override 10s limit
private class MyConnOpts extends MqttConnectOptions {
private int keepAliveInterval = 60;
#Override
public void setKeepAliveInterval(int keepAliveInterval) {
this.keepAliveInterval = keepAliveInterval;
}
#Override
public int getKeepAliveInterval() {
return keepAliveInterval;
}
}
public void setUpMqtt() throws MqttException {
clientId = getClass().getSimpleName() + ((int) (10000*Math.random()));
client = new MqttClient(brokerUrl, clientId);
conOpt = new MyConnOpts();
setConOpts(conOpt);
receivedMessages = new ArrayList<MqttMessage>();
expectConnectionFailure = false;
}
public void tearDownMqtt() throws MqttException {
try {
client.disconnect();
} catch (Exception _) {}
}
private void setUpAmqp() throws Exception {
connectionFactory = new ConnectionFactory();
connectionFactory.setHost(host);
conn = connectionFactory.newConnection();
ch = conn.createChannel();
}
private void tearDownAmqp() throws IOException {
conn.close();
}
private void setConOpts(MqttConnectOptions conOpts) {
conOpts.setCleanSession(true);
conOpts.setKeepAliveInterval(60);
}
private void publish(MqttClient client, String topicName, int qos, byte[] payload) throws MqttException {
MqttTopic topic = client.getTopic(topicName);
MqttMessage message = new MqttMessage(payload);
message.setQos(qos);
MqttDeliveryToken token = topic.publish(message);
token.waitForCompletion();
}
public void connectionLost(Throwable cause) {
if (!expectConnectionFailure)
System.out.println("Connection unexpectedly lost");
}
public void messageArrived(String topic, MqttMessage message) throws Exception {
lastReceipt = System.currentTimeMillis();
System.out.println("-------------------------------------------------");
System.out.println("------------------" + lastReceipt + "-------------------------------");
System.out.println("------------------" + message.toString() + "-------------------------------");
receivedMessages.add(message);
}
public void deliveryComplete(IMqttDeliveryToken token) {
}
public void run() {
try {
setUpMqtt(); // initialise the MQTT connection
setUpAmqp(); // initialise the AMQP connection
connect();
//String queue = ch.queueDeclare().getQueue();
// String queue = ch.queueDeclare("mqtt-subscription-Snabel-3qos1", true, false, false, null).getQueue();
//ch.queueBind(queue, "amq.topic", "sci-topic.sc.proxy_1393.1.0.0.ApReport.*"/*topic*/);
client.connect(conOpt);
publish(client, "topic/proxy/1.0.0/Report/123456789",1, payload); // publish the MQTT message
client.disconnect();
Thread.sleep(testDelay);
tearDownAmqp(); // cleanup AMQP resources
tearDownMqtt(); // cleanup MQTT resources*/
disConnect();
} catch (Exception mqe) {
mqe.printStackTrace();
}
}
private void connect() throws Exception {
clientId3 = "Test-3";
client3 = new MqttClient(brokerUrl, clientId3);
MqttConnectOptions connOpts = new MqttConnectOptions();
connOpts.setCleanSession(false);
client3.connect(connOpts);
client3.setCallback(this);
client3.subscribe(topic);
if(!client3.isConnected()){
System.out.println("Not Connected");
return;
}
System.out.println("Connected");
}
private void disConnect() throws Exception {
try {
client3.disconnect();
} catch (Exception _) {}
}
public static void main(String[] args) {
MqttTest mqt = new MqttTest();
mqt.run();
}
}

Answer 1

This was a RabbitMQ bug:
http://rabbitmq.1065348.n5.nabble.com/MQTT-plugin-message-delivery-mode-td32925.html
It was fixed in:
http://www.rabbitmq.com/release-notes/README-3.2.4.txt