[jboss-as7-dev] Web UI: Profile & host sections mutable?

[Brian Stansberry]

On 2/14/11 11:14 AM, David M. Lloyd wrote:
> On 02/14/2011 11:03 AM, Heiko Braun wrote:
>>
>> On Feb 14, 2011, at 5:54 PM, David M. Lloyd wrote:
>>
>>>    I think we should strive to modify our
>>> subsystem/extension architecture such that there are no inter-subsystem
>>> dependencies.
>>
>>
>> Sorry, I had to read your email a second time. Do you really think this will be possible?
>> A typical shared subsystem is the the TransactionManager. How can JCA be left out
>> in a custom profile without including this one?
>
> The way we've solved this in other subsystems is by introducing optional
> dependencies at the service level.  For example if the transaction
> subsystem is configured with an ORB present, we configure JTS, otherwise
> we do not; if OSGi and Txn are both present, then OSGi exposes the Txn
> service.
>
> I'm not 100% certain we can extend this technique to all cases, but I
> think we should at least try to.  JCA for example would obviously be
> quite crippled without JTA.  So I do not have an answer to that case;
> maybe it suffices to print a warning message in this case.  We should at
> least explore it before we throw out the idea though.

Let's assume for the sake of argument that we want to expose dependency 
info via the management interface. I see here hard dependencies (e.g. 
presumably JCA and JTA) and optional. Extensions could register these 
dependencies when they initialize. It opens up a can of worms though, as 
we'd need a proper language to describe the dependencies.

Thinking out loud here, could we use the module dependency information 
for this?  Nah, that would just say, e.g. that JCA needs the JTA APIs, 
but says nothing about the impl.

-- 
Brian Stansberry
Principal Software Engineer
JBoss by Red Hat