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From "Juergen Weber" <webe...@gmail.com>
Subject Re: MDB - reading messages in transaction
Date Sat, 30 Aug 2008 08:08:48 GMT
On Fri, Aug 29, 2008 at 7:29 PM, David Jencks <david_jencks@yahoo.com> wrote:
>
> On Aug 29, 2008, at 9:59 AM, Juergen Weber wrote:
>
>>
>> Hi,
>>
>> can a Geronimo message driven bean read several messages in a transaction?
>> E.g. data might be split in several parts, one message for each part, and
>> the messages should not be removed from the queue until the MDB has
>> received
>> all parts and has acknowledged having read all parts?
>
> not directly.  No MDB can read more than one message in an invocation.
>
> You might possibly be able to have your mdb open a connection and listen for
> the rest of the mesages that go together but you'll have to do some extra
> configuration such as making sure all the messages are in a message group so
> they all go to the same mdb.  This would probably only work with ActiveMQ
> and very well might not work at all.
>
> You might be able to do something with a stateless session bean called from
> a controller that opens a connection and reads all the messages in a group.
>  I think this is more likely to work than an mdb.

But this would violate the J2EE spec, as an EJB would need to wait for
incoming messages which would quite certainly mean listen on a socket.

Seems like the scenario waiting for several messages is not covered by
the J2EE spec, is it?

Thanks,
Juergen

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