Enthuware

in the one of possible answers there is:

"The message will be received by the MDB listening on the destination queue once and only once of the DeliveryMode.PERSISTENT is used."
should be:
"The message will be received by the MDB listening on the destination queue once and only once if the DeliveryMode.PERSISTENT is used."

This has been updated.

thank you for your feedback!

The answer refers to a subscriber, which is the consumer in a pub/sub messaging model, but the question deals with sending messages to a queue, which applies in the point-to-point model. Is it ok to mix up the two here?

Also, the explanation refers to the "message retention policy" of a destination. Do I need to know how that works for the exam? (I don't see any mentions of this in the spec)

You are right, it should not be talking about subscriber in the option. As per section 4.5.17.1 of EJB 3.1 specification, queues are always durable. The option has been updated accordingly.

Regarding message retention policy, I would say it is better to read about it once rather than leave holes in your knowledge though you may not get any question on this in the exam.

thank you for your feedback!

I'm hoping you can clear up some confusion I have about this question.
In the mp.send(message, DeliveryMode.NON_PERSISTENT, 1, 30000); line of code, says that the "time-to-live" is 30,000 milliseconds (30 seconds) and the DeliveryMode is NON_PERSISTENT, so doesn't this mean that it will sit in memory for 30 seconds and then be dumped? So if the consumer does not come back up within that time frame won't the message be lost? Doesn't the consumer have to come back up within that time frame?

But according to the description provided in Oracle DeliveryMode Doc(http://docs.oracle.com/javaee/1.4/api/j ... PERSISTENT), As per my understanding as well as the usage of having persistent message delivery mode, the given answer may not correct.

No offense.

weera.zap wrote:

Code: Select all

Question is regarding, mp.send(message, DeliveryMode.NON_PERSISTENT, 1, 30000);
The answer is, 
The message will [b]not[/b] be missed even if the consumer is down for some time and comes back up later.

But according to the description provided in Oracle DeliveryMode Doc(http://docs.oracle.com/javaee/1.4/api/j ... PERSISTENT),

Code: Select all

public static final int NON_PERSISTENT

    This is the lowest-overhead delivery mode because it does not require that the message be logged to stable storage. The level of JMS provider failure that causes a NON_PERSISTENT message to be lost is not defined.

    [b]A JMS provider must deliver a NON_PERSISTENT message with an at-most-once guarantee. This means that it may lose the message, but it must not deliver it twice.[/b] 

As per my understanding as well as the usage of having persistent message delivery mode, the given answer may not correct.

No offense.

YOu are right and the given explanation also says the same thing. So I think this option has been mistakenly set as the right option instead of the first one.

This has now been fixed. Thank you for your feedback!

I'm using v3.22, Build: 20120505, and this still has not been fixed yet

Jofen wrote:I'm using v3.22, Build: 20120505, and this still has not been fixed yet

What you've quoted above is the version of ETS Viewer but you need to check the version of the question bank. The updated question bank has version 1.36. Here is the direct link: http://enthuware.com/downloads/ejbplusv6.ets

HTH,
Paul.