On Apr 25, 2007, at 8:14 AM, ananner wrote:
I also have a requirement to limit a certain MDB to a maximum of one
instance, but I am a bit confused as to your response. Are you
saying that
I should put a pool size limit on the <outbound-resourceadapter> which
defines the Connection Factory that my MDB subscribes to?
The ResourceAdapter instance gets a BootstrapContext instance when
its started, and the BootstrapContext basically includes a thread
pool. So if you give it a thread pool with only one thread....
In geronimo you specify which thread pool to use with this part:
<workmanager>
<gbean-link>DefaultWorkManager</gbean-link>
</workmanager>
So you could include a thread pool:
<gbean name="SingleThreadPool"
class="org.apache.geronimo.pool.ThreadPool">
<attribute name="keepAliveTime">5000</attribute>
<attribute name="poolSize">1</attribute>
<attribute name="poolName"> SingleThreadPool </attribute>
</gbean>
and use it:
<workmanager>
<gbean-link>SingleWorkManager</gbean-link>
</workmanager>
This is a horrible solution because you have to set up a resource
adapter instance for each mdb that needs its size limited in this
way. Hopefully there's a way to restrict the mdb pool size that I
don't know about.
BTW, I recall hearing James Strachan talk about message groups. If
your requirements are that you get sets of messages that, within the
set, must be processed in order rather than all messages must be
processed in order you might be able to introduce some concurrency by
using message groups.
Hope this helps
david jencks
Thanks,
Aman
djencks wrote:
It might possibly work for activemq if you don't use any
transactions, but if you use transactions I would expect it to
completely break and give pretty random behavior. I don't think
there's any reason to expect it to work even without transactions.
I have trouble keeping all the places you can configure sizes
straight, but one way to limit the number of active mdbs is to give
the inbound resource adapter its own thread pool and limit that
size. I think there's a more direct way but don't recall what it is.
If the number of outbound connections is at least the number of mdbs
I would expect you wouldn't run into problems.
Maybe someone with more actual experience can give some more informed
advice.
thanks
david jencks
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