On Jul 27, 2013, at 12:12 PM, Caleb James DeLisle <calebdelisle(a)lavabit.com> wrote:
  XWiki uses a roll-your-own component manager similar
to OSGi but with much
 less functionality. The historical reason for this was because we used
 Plexus but as that project lost to more influential component systems such
 as OSGi and Guice, we were stuck with a bunch of components using the Plexus
 APIs. Breaking everything to move to a more popular DI system on the
 "would be nice" list. 
The real reason is that OSGi is too complex. We evaluated it instead of rolling our own
and we found it too complex.
See 
http://extensions.xwiki.org/xwiki/bin/view/Extension/Component+Module for details.
And no, moving to Guice wouldn't break XWiki. FTR we even have some unit tests proving
that XWiki components are Guice-compatible, see
https://github.com/xwiki/xwiki-commons/blob/master/xwiki-commons-core/xwiki…
Thanks
-Vincent