Unsubscribe durable subscribers with ActiveMQ

Question

I'm trying to UNSUBSCRIBE durable subscribers from TOPICS.

My app is a kind of social network : each user is a topic for other users. So, each time a user is doing something, his friends are notified. Of course, a subscriber may unsubscribe from a topic, wanting to receive notifications about a user no more.

Each time I'm trying to unsubscribe a subscriber from a topic, I've got an error telling me that : "javax.jms.JMSException: Durable consumer is in use"

Here are my 2 classes, the SENDER one and the RECEIVER one. Can someone tell me what I'm doing wrong ??

SENDER Class :

package com.citizenweb.classes;

import java.util.Date;
import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.Destination;
import javax.jms.JMSException;
import javax.jms.MessageFormatException;
import javax.jms.MessageProducer;
import javax.jms.Session;
import javax.jms.TextMessage;
import javax.jms.Topic;
import javax.jms.ObjectMessage;
import org.apache.activemq.ActiveMQConnection;
import org.apache.activemq.ActiveMQConnectionFactory;
import org.apache.activemq.ActiveMQSession;

import com.citizenweb.interfaces.PostIF;
import com.citizenweb.interfaces.UserIF;

public class Sender {

    private ActiveMQConnectionFactory factory = null;
    private ActiveMQConnection connection = null;
    private ActiveMQSession session = null;
    private Destination destination = null;
    private MessageProducer producer = null;

    public Sender() {
    }

    public void connect(){
        try{
            factory = new ActiveMQConnectionFactory(ActiveMQConnection.DEFAULT_BROKER_URL);
            // TODO Mécanisme de sécurité d'ActiveMQ à rétablir en production
            factory.setTrustAllPackages(true);
            connection = (ActiveMQConnection) factory.createConnection();
            connection.start();
            session = (ActiveMQSession) connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
        } catch (JMSException e){
            e.printStackTrace();
        }
    }

    public void sendPost(UserIF user,PostIF post) {
        if(session==null){connect();}
        try {
            destination = session.createTopic(user.toString());
            producer = session.createProducer(destination);
            ObjectMessage postMessage = session.createObjectMessage();
            postMessage.setObject(post);
            producer.send(postMessage);
            System.out.println("\n SENDER Object message sent");



        } catch (MessageFormatException e) {
            e.printStackTrace();
        } catch (JMSException e) {
            e.printStackTrace();
        }
    }

    public void sendInformation(UserIF user,String info){
        if(session==null){connect();}
        try {
            destination = session.createTopic(user.toString());
            producer = session.createProducer(destination);
            TextMessage infoMessage = session.createTextMessage();
            infoMessage.setText(info);
            producer.send(infoMessage);
            System.out.println("\n SENDER Information message sent");
        } catch (JMSException e) {
            e.printStackTrace();
        }
    }

    /**
     * @param args
     * @throws Exception
     */
    public static void main(String[] args) throws Exception {

        UserIF u1, u2, u3;
        String[] nom = new String[5];
        String[] prenom = new String[5];
        String[] login = new String[5];
        String[] password = new String[5];
        Date[] naiss = new Date[5];
        String[] mail = new String[5];
        for (int i = 0; i < 5; i++) {
            nom[i] = "nom_" + i;
            prenom[i] = "prenom_" + i;
            login[i] = "login_" + i;
            password[i] = "password_" + i;
            naiss[i] = new Date();
            mail[i] = "mail_" + i;
        }

        System.out.println("\n SENDER AFFECTATION DES NOMS");
        u1 = new User(nom[0], prenom[0], login[0], password[0], naiss[0], mail[0]);
        u2 = new User(nom[1], prenom[1], login[1], password[1], naiss[1], mail[1]);
        u3 = new User(nom[2], prenom[2], login[2], password[2], naiss[2], mail[2]);


        Sender sender = new Sender();

        sender.sendInformation(u1, "U1 notification");
        sender.sendInformation(u2, "U2 notification");
        sender.sendInformation(u3, "U3 notification");
        //PostIF post = new Post("Mon Post","Ceci est mon message",u1,u1,"Classe Sender",((User) u1).getIdUser(),0);
        //sender.sendPost(user, post);
        sender.session.close();
        sender.connection.close();

    }

}

RECEIVER Class :

package com.citizenweb.classes;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageConsumer;
import javax.jms.MessageListener;
import javax.jms.ObjectMessage;
import javax.jms.Session;
import javax.jms.TextMessage;
import javax.jms.Topic;

import org.apache.activemq.ActiveMQConnection;
import org.apache.activemq.ActiveMQConnectionFactory;
import org.apache.activemq.ActiveMQSession;
import org.apache.activemq.broker.region.Destination;
import com.citizenweb.interfaces.PostIF;
import com.citizenweb.interfaces.UserIF;
import com.citizenweb.classes.Post;

public class Receiver implements MessageListener, Serializable {

    private static final long serialVersionUID = 1L;
    private ActiveMQConnectionFactory factory = null;
    private ActiveMQConnection connection = null;
    private ActiveMQSession session = null;
    private Topic destination = null;
    private MessageConsumer consumer = null;

    UserIF userTopic = new User();
    UserIF userSubscriber = new User();
    List<Message> listeMsg = new ArrayList<Message>();

    public Receiver(UserIF subscriber) {
        this.userSubscriber = subscriber;
    }

    public void connect() {
        try {
            factory = new ActiveMQConnectionFactory(ActiveMQConnection.DEFAULT_BROKER_URL);
            // TODO Mécanisme de sécurité d'ActiveMQ à rétablir en production
            factory.setTrustAllPackages(true);
            connection = (ActiveMQConnection) factory.createConnection();
            // ClientID :
            // https://qnalist.com/questions/2068823/create-durable-topic-subscriber
            connection.setClientID(userSubscriber.toString());
            connection.start();
            session = (ActiveMQSession) connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
        } catch (JMSException e) {
            e.printStackTrace();
        }
    }

    public void receiveMessage(UserIF topic) {
        try {
            if (session == null) {
                connect();
            }
            destination = session.createTopic(topic.toString());
            String nomAbonnement = topic.toString() + "->" + userSubscriber.toString();
            //String nomAbonnement = userSubscriber.toString();
            consumer = session.createDurableSubscriber(destination, nomAbonnement);
            consumer.setMessageListener(this);
        } catch (JMSException e) {
            e.printStackTrace();
        }
    }

    public void unsubscribe(UserIF topic) {
        try {
            if (session == null) {
                connect();
            }
            System.out.println("\n RECEIVER Désinscription du topic " + topic.toString());
            //consumer.close();
            String nomAbonnement = topic.toString() + "->" + userSubscriber.toString();
            //String nomAbonnement = userSubscriber.toString();
            System.out.println("\n RECEIVER Abonnement à clore = " + nomAbonnement);
            session.unsubscribe(nomAbonnement);
            System.out.println("\n RECEIVER " + userSubscriber.toString() + " s'est désinscrit de " + nomAbonnement);
        } catch (JMSException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void onMessage(Message message) {
        System.out.println("\n RECEIVER OnMessage triggered for " + userSubscriber.toString());
        listeMsg.add(message);
        System.out.println("\n RECEIVER Nombre de messages reçus par " + userSubscriber + " = " + listeMsg.size());
        String classe = message.getClass().getSimpleName();
        System.out.println("\n RECEIVER Classe de message : " + classe);
        try {
            if (message instanceof TextMessage) {
                TextMessage text = (TextMessage) message;
                System.out.println("\n RECEIVER Information : " + text.getText());
            }
            if (message instanceof ObjectMessage) {
                System.out.println("\n RECEIVER ObjectMessage");
                ObjectMessage oMessage = (ObjectMessage) message;
                if (oMessage.getObject() instanceof PostIF) {
                    PostIF post = (PostIF) oMessage.getObject();
                    String s = ((Post) post).getCorpsMessage();
                    System.out.println("\n RECEIVER Post : " + s);
                }
            }
        } catch (JMSException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) throws JMSException {

        /*
         * EACH USER IS A TOPIC FOR OTHER USERS
         * WHATEVER A USER DOES RESULTS IN A NOTIFICATION TO SUBSCRIBERS
        */

        //CREATE USER
        UserIF u1, u2, u3;
        String[] nom = new String[5];
        String[] prenom = new String[5];
        String[] login = new String[5];
        String[] password = new String[5];
        Date[] naiss = new Date[5];
        String[] mail = new String[5];
        for (int i = 0; i < 5; i++) {
            nom[i] = "nom_" + i;
            prenom[i] = "prenom_" + i;
            login[i] = "login_" + i;
            password[i] = "password_" + i;
            naiss[i] = new Date();
            mail[i] = "mail_" + i;
        }

        u1 = new User(nom[0], prenom[0], login[0], password[0], naiss[0], mail[0]);
        u2 = new User(nom[1], prenom[1], login[1], password[1], naiss[1], mail[1]);
        u3 = new User(nom[2], prenom[2], login[2], password[2], naiss[2], mail[2]);

        /*
         * MAKE EACH USER A SUBSCRIBER
         */
        Receiver receiver1 = new Receiver(u1);
        Receiver receiver2 = new Receiver(u2);
        Receiver receiver3 = new Receiver(u3);

        /*
         * PUT A MESSAGE LISTENER FOR EACH USER
         */
        receiver1.receiveMessage(u2);
        receiver1.receiveMessage(u3);
        receiver2.receiveMessage(u1);
        receiver2.receiveMessage(u3);
        receiver3.receiveMessage(u1);
        receiver3.receiveMessage(u2);

        /*
         * CALL THE SENDER CLASS TO SEND MESSAGES
         */
        try {
            Sender.main(args);
        } catch (Exception e1) {
            e1.printStackTrace();
        }

        /*
         * A SLEEP TO HAVE ENOUGH TIME TO LOOK AT THE ACTIVEMQ CONSOLE
         * CAN BE REMOVE
         */
        try {
            Thread.sleep(10000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            return;
        }

        /*
         * UNSUBSCRIBE SUBSCRIBERS FROM TOPICS
         */
        receiver1.unsubscribe(u2);
        receiver1.unsubscribe(u3);
        receiver2.unsubscribe(u1);
        receiver2.unsubscribe(u3);
        receiver3.unsubscribe(u1);
        receiver3.unsubscribe(u2);
    }

}

score 2 · Answer 1 · edited Aug 09 '18 at 09:57

Each connection needs a unique ClientID : connection.setClientID("clientID");

My mistake was to misunderstand this unicity for a given client.

When a client subscribes to a Topic, there is one connection for this Topic. So, for a given client subscribed to 3 topics (for instance), 3 ClientID are needed because 3 connections are needed. A ClientID has to be unique because it identifies one connection of one client for one topic.

That's why I had so many JMSException telling that "Durable Consumer was In Use" when I wanted to end its subscription.

Tim Bish · Answer 2 · 2016-09-16T20:20:17.823

1

You can only unsubscribe a durable subscription if there is no active subscriber currently consuming from it. It looks like your code creates several subscriptions and does not stop the consumers so of course the unsubscribe will fail, if you close down the consumers and then do the unsubscribe you should get the result you are looking for.

An example of durable subscription unsubscribe is here.

edited Sep 16 '16 at 20:20

answered Sep 16 '16 at 13:01

Tim Bish

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Hi Tim and thanx for your help. When you say "You can only unsubscribe a durable subscription if there are no active subscriber currently consuming from it", you seem to talk about a **topic**. My problem is that **one topic** may have **many durable subscribers**. One of these subscribers may want to unsuscribe this topic, and there's no reason to stop the subscription of the other subscribers for the same topic I want to stop a subscription for a topic without killing the topic itself That's what I wanna do with the unsubscribe() method of my Receiver class Isn't it possible ? – Lovegiver Sep 16 '16 at 15:03
That's not what I said, read again carefully. A Topic subscription that is active cannot be unsubscribed, you need to close the consumer that is using the subscription you want to unsubscribe. – Tim Bish Sep 16 '16 at 16:12
OK Tim so if I do a session.unsubscribe(durableID) as shown in my code, this should stop the subscription for the given subscriber but only if I have done a consumer.close() before ? I've tried this a lot, but always got the same error message : durable consumer is in use What should I do more than this : 'consumer.close();' 'session.unsubscribe(nomAbonnement);' – Lovegiver Sep 16 '16 at 17:19
If I have 2 topics named "Topic A" & "TopicB", and 3 durable subscribers for each of these topics, "U1", "U2 and "U3", what should I do to stop the "U1" subscription for TopicA ? The session.unsubscribe(durableID) statement must specify the "durableID" which is a unique identifier for a subscriber and a subscription. If "U1" suscribed to 3 topics, the DurableID should be different for each. In my case, my DurableID is created this way : "Topic1->U1". User2 would have "Topic1->U2" fort the same topic and "Topic2->U2" for topic #2. What's wrong in my code ? – Lovegiver Sep 16 '16 at 17:56
Afraid I can't debug your code, the best thing to do is use the broker tooling such as the Web Console or JMX to validate that you have no active subscriber when you are doing the unsubscribe – Tim Bish Sep 16 '16 at 18:01

Unsubscribe durable subscribers with ActiveMQ

2 Answers2