ActiveMQ dynamic queues

Hi,

With ActiveMQ, one can create a queue (or topic) on the fly, which is pretty cool. But I'm wondering if the queue can actually be created by a Consumer rather than a Producer.

Specifically, here's the issue I'm having. On application startup, I initialize a class that implements MessageListener and registers itself like this:

later on, a producer creates a queue also called "unique-subject" and places a message on it. What happens is the first time after I restart ActiveMQ, my MessageListener's onMessage() method is never called. However, when I subsequently run the application, onMessage() is in fact called (as long as I don't restart ActiveMQ).

This makes me think that the MessageListener is not being properly bound until the queue is created by a Producer. Is that how ActiveMQ actually behaves, or is this likely my error?

Thanks in advance.

Just calling the createQueue creates a queue dynamically.

http://activemq.apache.org/how-do-i-create-new-destinations.html

If it is not working for you someone from ActiveMQ forum may be able to help you.

You can check the detsinations created either using JMX or Active MQ API
http://activemq.apache.org/how-can-i-see-what-destinations-are-used.html

Thanks, Pradip. I basically just needed confirmation that my understanding about ActiveMQ was correct. There must be user-error (i.e. me) somewhere.

In case anyone else is having a similar issue, my problem seemed to stem from my not committing the Session after creating & adding the MessageListener. Once I added after

, my MessageListener immediately began receiving onMessage() notifications.

Thanks dave for letting us know the problem

Hi I was also trying to create a topic on the fly, but somehow it's giving following error.

"JNDI API lookup failed: javax.naming.NameNotFoundException: myTopic"

Here is my code.

import java.util.Properties;

import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.Destination;
import javax.jms.JMSException;
import javax.jms.MessageProducer;
import javax.jms.Session;
import javax.jms.TextMessage;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

public final class SimpleProducer {

private static final Log LOG = LogFactory.getLog(SimpleProducer.class);

private SimpleProducer() {
    //TODO Do nothing
  }

/**
   * @param args the destination name to send to and optionally, the number of messages to send
   */
  public static void main(String[] args) {
    Context jndiContext = null;
    ConnectionFactory connectionFactory = null;
    Connection connection = null;
    Session session = null;
    Destination destination = null;
    MessageProducer producer = null;
    String destinationName = null;
    final int numMsgs;

if ((args.length < 1) || (args.length > 2)) {
      LOG.info("Usage: java SimpleProducer <destination-name> [<number-of-messages>]");
      System.exit(1);
    }
    destinationName = args[0];
    LOG.info("Destination name is " + destinationName);
    if (args.length == 2) {
      numMsgs = (new Integer(args[1])).intValue();
    } else {
      numMsgs = 1;
    }
    Properties props = new Properties();
    props.setProperty(Context.INITIAL_CONTEXT_FACTORY,"org.apache.activemq.jndi.ActiveMQInitialContextFactory");
    props.setProperty(Context.PROVIDER_URL,"tcp://hostname:61616");
    /*
     * Create a JNDI API InitialContext object
     */
    try {
      jndiContext = new InitialContext(props);
    } catch (NamingException e) {
      LOG.info("Could not create JNDI API context: " + e.toString());
      System.exit(1);
    }

/*
     * Look up connection factory and destination.
     */
    try {
      connectionFactory = (ConnectionFactory) jndiContext.lookup("ConnectionFactory");
      destination = (Destination) jndiContext.lookup(destinationName);
    } catch (NamingException e) {
      LOG.info("JNDI API lookup failed: " + e);
      System.exit(1);
    }

/*
     * Create connection. Create session from connection; false means session is not transacted.
     * Create sender and text message. Send messages, varying text slightly. Send end-of-messages
     * message. Finally, close connection.
     */
    try {
      connection = connectionFactory.createConnection();
      session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
      producer = session.createProducer(destination);
      TextMessage message = session.createTextMessage();
      for (int i = 0; i < numMsgs; i++) {
        message.setText("This is message " + (i + 1));
        LOG.info("Sending message: " + message.getText());
        producer.send(message);
      }

/*
       * Send a non-text control message indicating end of messages.
       */
      producer.send(session.createMessage());
    } catch (JMSException e) {
      LOG.info("Exception occurred: " + e);
    } finally {
      if (connection != null) {
        try {
          connection.close();
        } catch (JMSException jmsException) {
          jmsException.printStackTrace();
        }
      }
    }
  }
}

Here is my jndi.properties file.

Can anybody explain what's wrong with this code? I am a newbie in JMS

FYI, I took this code from here