On 10/12/11 2:53 AM, Heiko Braun wrote:
On Oct 12, 2011, at 9:33 AM, Carlo de Wolf wrote:
> On 10/12/2011 09:10 AM, Heiko Braun wrote:
>>
>> Maybe this has been discussed elsewhere, but looking at the EJB
>> description I can see that expressions are allowed basically anywhere.
>> This is an example how is should _not_ be done. I.e. the
>> "default-mdb-instance-pool" is certainly not something you would like
>> to configure by external means, do you?
>
> I can easily counter this with: why not?
>
> Seriously I'm thinking of something like configuration items that are
> based on the system environment.
> This would have the bind.address make sense.
>
> A sliding one would be the default RA.
>
> It would make default-mdb-instance-pool a no-go, because that's an AS
> configuration item without any dependencies on system environment.
You seem to have answered the question yourself. Expressions are useful
when you need to configure certain aspects by external means or
depending on the environment.
It's the "need to configure certain aspects by external means" one that
can become pretty broad. Particularly in cloud cases where you may need
to build up a separate image just to have some variation in a config
file setting. That's pretty expensive.
That said, I would have no complaint about having these ejb3
"default-xxx" attributes not support expressions. They are references
from one bit of the model to another and without a solid use case that
ties back to the system environment I'm fine with not supporting
expressions for such things.
--
Brian Stansberry
Principal Software Engineer
JBoss by Red Hat