Nigel,
Thoughts inline below....
"John D. Ament" <john.d.ament_at_gmail.com> wrote on 02/08/2011 18:10:11:
> From: "John D. Ament" <john.d.ament_at_gmail.com>
> To: jsr343-experts_at_jms-spec.java.net
> Date: 02/08/2011 18:10
> Subject: [jms-spec users] [jsr343-experts] Re: Re: JMS over CDI or
> something else?
>
> Hi all,
>
> I wanted to bring this back up. I am wondering if we can discuss
> around this particular topic? I researched into the 3 open source
> JMS impls I know of, and of them 2 do not support sending messages
> created by another session/connection. Only OpenMQ supports that.
> Should it be supported across the board?
>
> John
> On Mon, Jul 11, 2011 at 8:06 AM, Nigel Deakin <nigel.deakin_at_oracle.com>
wrote:
> John,
>
>
> On 07/07/2011 20:07, John D. Ament wrote:
>
> 1. The event model is a direct integration between serializables and
> sending JMS messages. Obviously, the big
> limitation is that a created message needs to be bound to a specific
> JMS session. For right now, there is no way to
> guarantee that the JMS SEssion used to create a message fired is
> then actually sent via that session, CDI doesn't have a
> scope that confirms that.
> (snip)
>
> 2. The simplified APIs provided in Seam JMS are really just meant to
> supplement the fact that an injected
> MessageProducer is completely unusable as you need to guarantee that
> the JMS session injected for creating messages is
> the same one used to create your producer.
>
> I'm interested in your suggestion that you need to guarantee that
> the JMS session used for creating messages is the same one used to
> create your message producer. Where in the JMS spec or API do you
> think it says this?
I think most people interpret the spec to mean that the session that owns
the message producer must also be used to create the message to be sent.
The spec doesn't actually say that per se, but I think it is implied and
that implication is reinforced by all the examples I've seen.
It's also implied by articles such as
http://java.sun.com/developer/technicalArticles/Networking/messaging/ which
includes the following:
"Sessions are used to build message producers and message consumers, as
well as to build the messages themselves. "
>
> My own interpretation of the spec is that a MessageProducer must be
> able to send a javax.JMS.Message irrespective of how it was created.
> It might have been created using Session.createMessage(), or it may
> have been received by a MessageConsumer. It might even have been
> created by a foreign JMS provider (though the spec states that this
> might not be handled as efficiently as a provider's own
> implementation). Section 3.12 is worth reading.
>
> Anyone else have a view? Perhaps this is something we need to
> clarify, if it would make building frameworks easier.
You are correct that a MessageProducer might be sending a message received
by a MessageConsumer, as opposed to created locally, but for locally
created messages I think most people believe (rightly or not) that there is
a requirement for session affinity.
In fact, thinking about this further brings up another question, which is
why an application has to be connected to a messaging provider in order to
create a message. We obviously need the provider to supply a concrete (and
provider-specific) implementation of the Message interface, but the act of
creating a connection (and a session) involves far more than would seem to
be necessary to create a message object.
>
> Nigel