[p2-dev] External upgrades

[Daniel Jacobowitz <drow@xxxxxxxxx>]

I'm migrating our update infrastructure from EUM to p2.  I've hit a
lot of bumps - e.g. we used <site type="..."> in upgrade sites, which
p2 silently accepts and ignores - but I've got a sketch for everything
in the actual update process now.  But I have one issue further down
the road that I'm not sure how to approach.

We do our core product installation using an external tool, in this
case InstallAnywhere.  This drops our entire product, including
Eclipse, onto the system.  We also do in-place upgrades using
InstallAnywhere.  With EUM this worked fine; the old Eclipse is
removed, the configuration data and any user-installed plugins are
left behind, a new Eclipse is dropped in, and -clean is enough to
discover all the changes.  We even went from 3.3 to 3.4 this way
(with p2 removed).

Everything I've read about p2 suggests this isn't going to work.
It's going to find configuration data from the old Eclipse and not
start the right features.

The one thing I'm sure of, though, is that this is a perfectly
ordinary scenario.  We can't be alone in shipping Eclipse as part of a
larger product, where relying on Eclipse's update mechanism isn't
enough for the big picture.  Has anyone else addressed this problem?
Can you force p2 to regenerate its configuration from installed
bundles?

-- 
Daniel Jacobowitz
CodeSourcery