[jboss-as7-dev] OSGi subsystem dependencies

[Jason T. Greene]

This was talked about briefly on the pull request list, but no 
resolution was made.

The issue is that JBAS-8585 and JBAS-8599 both add module dependencies 
from some of the core subsystems on to the osgi subsystem (naming and 
transactions). In addition we already have a module dependency from 
domain to osgi.  So for all intents and purposes, we are moving towards 
AS7 having osgi as a required base level component. Before progressing 
much further in this direction we should evaluate whether this is the 
right thing to do, and how this solution compares to alternative 
approaches. I can think of three approaches right off the bat.

1. Continue as is, osgi is a core required component
    Pros: OSGi subsystem module is simpler, no additional subsystems or 
modules needed
    Cons: AS7 must always have OSGi binaries no matter the configuration

2. Change the osgi subsystem to use optional dependencies on all of the 
subsystems it maps.
    Pros: No additional subsystems are needed
          AS7 no longer requires OSGi binaries
    Cons: osgi subsystem code will need to do a lot of conditional 
checking for handling different subsystems being available

3. Create an osgi subsystem per subsystem it wraps (e.g. osgi-naming, 
osgi-transactions, etc)
     Pros: OSGi subsystem code is simpler
           AS7 no longer requires OSGi binaries
     Cons: More subsystems are introduced, almost one per functional
           subsystem.

Let the debate begin :)

-- 
Jason T. Greene
JBoss, a division of Red Hat