From time to time, I am changing/cleaning up the "node
types" that the
repository uses while in development.
This may mean if you are playing with it you will need to blow away your
repo and let it create it (not bothering with migrations as I am still
cleaning it up).
I don't expect there to be many changes once it is finished. JCR lends
itself to pretty generic hierarchies, and it is resilient to additions of
properties etc.
As a happy co-incidence. the "CND" format used by Jackrabbit looks like
becoming the standard for "JCR2" (JSR-283 I think?) content repos - which
means it will be even easier to migrate between different vendors for the
database/rules repository.
Michael.