The whole MDB being designed as a push is that a push puts less strain on
the JMS provider. Messages can flow the the MDB with out the MDB having to
poll the server for messages.
Regards,
Hiram
>From: Jason Dillon <[EMAIL PROTECTED]>
>Reply-To: [EMAIL PROTECTED]
>To: <[EMAIL PROTECTED]>
>Subject: Re: [JBoss-dev] Improving MDB behavior in the presence of delivery
>failures
>Date: Fri, 17 Aug 2001 12:24:43 -0700 (PDT)
>
>MDB is not really a good solution for stuff like this. MDB is basically a
>push from the provider to a bean with out any insight as to the state of
>the
>application short of the available server sessions.
>
>A better approache would be a pull from the provider from the application
>layer which would simply hand off the message to a session bean which
>implementes MessageListener.
>
>The pulling thread could then use application specific logic to determine
>if
>it should pull off a message.
>
>I like the idea of a reject queue or something like that for MDB though.
>
>--jason
>
>
>On Thu, 16 Aug 2001, Scott M Stark wrote:
>
> > The mdb does not have to thrown an exception to cause this behavior. If
>it
> > interacts with another ejb that is transacted and that bean rolls the
> > transaction
> > back the msg will get redeliverd. I have a trivally test case that
>causes
> > the problem:
> >
> > public void onMessage(Message m)
> > {
> > try
> > {
> > IHome home = ...;
> > home.findByPrimaryKey(null);
> > }
> > catch(Throwable t)
> > {
> > }
> > }
> >
> > The tx will be rolled back by the failed findByPrimaryKey() call which
>will
> > cause the msg
> > to be redelivered and were spinning.
> >
> > ----- Original Message -----
> > From: "Hiram Chirino" <[EMAIL PROTECTED]>
> > To: <[EMAIL PROTECTED]>
> > Sent: Thursday, August 16, 2001 6:28 PM
> > Subject: Re: [JBoss-dev] Improving MDB behavior in the presence of
>delivery
> > failures
> >
> >
> > >
> > > Per spec the MDB should not be throwing any exceptions.. This would
>mean
> > > that it's thier responsibility to put the message to a 'rejected'
>queue.
> > >
> > > But I think that is the best solution would be to allow the MDB to be
> > > configured with the 'rejected' queue in it's deployment descriptor. I
> > know
> > > that not everybody will enclose thier MDB code in try { } catch
>(Throable
> > e)
> > > {}
> > >
> > >
> > > Regards,
> > > Hiarm
> > >
> > > >From: "Scott M Stark" <[EMAIL PROTECTED]>
> > > >Reply-To: [EMAIL PROTECTED]
> > > >To: <[EMAIL PROTECTED]>
> > > >Subject: [JBoss-dev] Improving MDB behavior in the presence of
>delivery
> > > >failures
> > > >Date: Thu, 16 Aug 2001 18:22:23 -0700
> > > >
> > > >Right now there are any number of ways to cause JBoss to spin in a
>tight
> > > >loop
> > > >trying to deliver a transacted msg to an mdb due to a problem with
>either
> > > >the msg or mdb code that either causes an exception thrown from
> > onMessage()
> > > >or the tx to be rolled back. A trivial example of the latter is to
>have
> > an
> > > >mdb
> > > >do a findByPrimaryKey() using a key from the msg that happens to be
>null.
> > > >
> > > >One solution would be to have the mdb container fail such msgs after
>so
> > > >many delivery attempts. On failure, the msg along with the exception
> > would
> > > >be placed into a error queue associated with the container. An admin
> > would
> > > >have to pull the msg off, fix any data problems and then place the
>msg
> > > >back onto the mdb queue/topic for redelivery.
> > > >
> > > >Are there any better ways to handle this?
> > > >
> > > >
> > > >
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> > >
> > >
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