One OSGI compliant JTA implementation which works well with spring exists: wouldn't it be possible to integrate Atomikos in Gemini-JPA (or Gemini-Tx) in order to support JTA XA transaction in JPA?
Or making a bridge in order to integrate these both worlds.
Unfortunately, i'm neither an Atomikos expert nor a Gemini-JPA source code explorer, it was just a suggestion.
If you find some more competent lead dev I would be glad to help.
I will try to view how both are coded, and if it they're easy to mix, but I can't promise any result.
From what I recall of the OSGi transaction spec it wouldn't actually be very hard to add the OSGi support for Atomikos. It's just the time factor of creating a project to do it in...
You wouldn't need to do the JPA part. I would do that