[cross-project-issues-dev] Orbit and WTP are not greedy, how about you?

[David M Williams <david_williams@xxxxxxxxxx>]

I wanted to give some advance warning that I have upgraded the Orbit and
WTP build so it produces repositories where the run-time optional bundles
are specified as non-greedy. This will take effect for M5, in particular,
for Orbit, the for-M5 Orbit build of
http://download.eclipse.org/tools/orbit/downloads/drops/S20120120232307/

See bug 247099 [1] and the p2 Publisher wiki [2] for some history and
details on this issue of greedy vs. non-greedy requirements.

In short, p2 assumes greedy='true' if it is not specified and in the past
the publisher did not specify it, so there have been many cases in the past
where users and adopters get things installed that they did not want or
need. Plus, it would depend on which repo was "pointed to" or what was
available in that repo at the time of the install, making things a little
indeterminate. Rather than change the way p2 works (which would have had
compatibility issues) it was decided to change the way the p2 publisher
works.

Most of the time, this change will be nothing but goodness, but I'm giving
this notice since it does have the potential to "break" something ... or,
at least, not work as expected.

Potentially it could effect builds, if you use p2 to fetch Orbit pre-reqs
and if you really required some optional thing, but did not specify it
explicitly, getting it "by accident" before, due to a bundle having it as
an optional dependencies.

The more likely impact would be in distribution packages or user installs
which might have the same issue, of wanting something they got before "by
accident" but would not now be installed, unless explicitly specified in a
feature.

The fix, if any required, in most cases will be to add some missing
optional item to a feature; sometimes it would be an existing feature, but
often might be a new feature, in order to let users or adopters decide if
they want that optional thing or not.

If you do encounter an issue where this change effects your project,
especially in a negative way, I would appreciate a note in bug 368999 so we
understand unanticipated impacts.

How about your repo?

I mean this as a rhetorical question, for now, but encourage everyone to
move to this type of repository for Juno (not for Indigo SR2) where
"optional at runtime" is not "greedily installed". If we have a mix of some
specifying them as greedy and some not, I suspect the resulting builds,
package distributions, and common repository will be indeterminate when we
aggregate. And indeterminate is bad. We'll discuss this more for M6 as we
gain experience with M5.

Thanks everyone,

[1] https://bugs.eclipse.org/bugs/show_bug.cgi?id=247099
[2] http://wiki.eclipse.org/Equinox/p2/Publisher
[3] https://bugs.eclipse.org/bugs/show_bug.cgi?id=368999