Last-value queue

[diktatoren]

I'm trying to create a last-value queue, but am having trouble understanding how.

I've created a config like it says in the documentation:

hornetq-config.xml:

<address-setting match="coupon.client.numcorrect.#">
           <last-value-queue>true</last-value-queue>
</address-setting>

The queues themselves are created dynamically from within the code:

stompServer.createQueue("coupon.client.numcorrect." + userId, false);

/**
   * Creates a new queue if the specified queue doesn't exist
    * @param queueName
   */
  public void createQueue(String queueName, boolean persistent) throws HornetQException {
    ClientSession.QueueQuery result = session.queueQuery(new SimpleString(queueName));   

    if(!result.isExists())
      session.createQueue(queueName, queueName, persistent);
  }

The message is created like this:

/* (non-Javadoc)
   * @see eventmw.apps.couponmatcher.EventProcessor#processEvent(java.lang.Object)
   */
  @Override
  public void processEvent(NumCorrectEvent numCorrect) {
    System.out.println("numCorrect=" + numCorrect.getNumCorrect());
    try {
      ClientMessage clientMessage = stompServer.getClientSession().createMessage(true);
      clientMessage.getBodyBuffer().writeNullableSimpleString(new SimpleString(String.valueOf(numCorrect.getNumCorrect())));     
      stompServer.sendSimpleMessage("coupon.client.numcorrect."+numCorrect.getOwner(), clientMessage);
    } catch (Exception e) {
      e.printStackTrace();
    }
  }

The documented example uses TextMessage and setStringProperty, but I'm using ClientMessage and getBodyBuffer().writeNullableSimpleString. Is a last-value queue possible to achieve using this interface?

[jmesnil]

You don't use Last-value queue like you should.

See the doc http://hornetq.sourceforge.net/docs/hornetq-2.1.0.Final/user-manual/en/html/last-value-queues.html.

You must pass a string property value for the Last-Value property "_HQ_LVQ_NAME"

If you are using HornetQ Core API, you must use message.putStringProperty(String, String) to have it work. If you use the message body, HornetQ will not find the last-value queue property.

Tell me how it goes,

jeff

[diktatoren]

Hi Jeff,

I got it to work by assigning a value to the StringProperty marked as last value:

ClientMessage clientMessage = stompServer.getClientSession().createMessage(true);
clientMessage.putStringProperty("_HQ_LVQ_NAME", "ANTALLRETTE");
clientMessage.putStringProperty("ANTALLRETTE", String.valueOf(numCorrect.getNumCorrect()));

In order for the perl STOMP client to be able to access the content, I still have to put the same value in the message body, but it's a workaround I'm able to live with. Thanks again!

Pål