It does not say... this is one of the grey-areas of the spec. Most
providers will round-robin over multipule recievers. It is really too bad
that this is not more concreate, as JMS would provide a nice mech. for
distributing over a large group of machines, and allow for ordering and
such.
I think that I will probably drop JMS for this as soon as I have time to
rearch. under a different distribution system (like JavaSpaces). JMS is too
ugly and too vendor specific. I will probably still keep it around for
async events from beans/to beans though. Just not as the backend for
distributing load.
--jason
On Tue, 21 Aug 2001, David Jencks wrote:
> 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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