I'm not up-to-date on javaspaces but with jms you can certainly have
multiple receivers on the same message queue, you can also have multiple
senders. The JMS spec does not specify any policy for how messages are
distributed between different receivers though.
As for message order, it is only guaranteed amongst messages sent to the
same queue from the same sender, that is if you receive two messages from
the same queue sent by the same sender they will arrive in the order sent
(except for some cases involving different priorities and the like).
Cheers,
David
> -----Original Message-----
> From: David Jencks [mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, August 22, 2001 12:48 PM
> To: [EMAIL PROTECTED]
> Subject: Re: [JBoss-dev] jbossmq & load balancing across vms
>
>
> I am not an expert.... Is this sharing of a message queue
> receiving end
> really spec compliant? How does it relate to
> order-of-messages guarantees?
> It seems to me this may be the conceptual difference between
> message queues
> and javaspaces..??
>
> david jencks
>
> On 2001.08.21 19:06:08 -0400 Jason Dillon wrote:
> > Hello again, I am running into a problem with the latest JBossMQ wrt
> > using
> > it to load balance across machines.
> >
> > I have one machine which acts as a message router, running
> JBossMQ. All
> > other machines use it for their JMSProvider. When I have
> more than one
> > MDB
> > attached to a single queue, and a user-thread adding
> messages over and
> > over,
> > it looks like only one of the MDB's will ever read any messages.
> >
> > I do not remember seeing this before. It looks like when I
> startup a new
> > MDB that 50% of the time it will take over and the others
> will remain
> > idle,
> > or it will simply never read any new messages.
> >
> > I have each of these MDB setup with:
> >
> > <MaximumSize>1</MaximumSize>
> > <MaxMessages>1</MaxMessages>
> >
> > Which could be causing problem... but honestly I don't
> really know what
> > these two setting actually do. I wanted to have these
> deployed MDB's to
> > only process one message at a time, which this seems to
> accomplish most
> > of
> > the time.
> >
> > Any ways, I am concerended about how JBossMQ is pushing
> messages over to
> > consumers. I mentioned before that if one producer added
> 1k messages to
> > a
> > queue, then one MDB was attached which would suck up all of
> the messages.
> > When a second MDB was attached it would not have anything
> todo. Hiram
> > mentioned something about this, but I am not really sure
> what the plans
> > were
> > to fix this.
> >
> > I would like to get this fixed soon, as I am fairly
> dependent on this
> > behavior.
> >
> > From my perspective, there are two major issues:
> >
> > 1) JBossMQ does not seem to trade off between consumers
> (ie. round-robin
> > or
> > whatever).
> >
> > 2) JBossMQ does not have any configurable limits on how
> messages are
> > pushed
> > from the server to clients/consumers.
> >
> > I understand why JBossMQ wants to push over bulk messages
> to consumers,
> > but
> > that is only really useful in some applications. In my
> case, I would
> > rather
> > that it pushed over smallers chunks (or even 1 msg at a
> time) to clients
> > so
> > that I could utilize the cluster of machines that I have to
> distribute
> > the
> > processing load.
> >
> > So, to the JBossMQ folks, does this sound like it would be easy to
> > implement? Do you have any suggestions on how it might be
> done (quick
> > fix
> > and full blown god JMS provider version)? I am willing to
> look into this
> > more, but I could use some pointers on which bits need to
> be tweaked.
> >
> > Any ideas?
> >
> > --jason
> >
> >
> > _______________________________________________
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> >
> >
>
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