"In Fedora" or "For Fedora", or Library versions dependency management

[Fernando Nasser]

Hi folks,

We are preparing a set of JBoss AS 4.2.x RPMs _for_ Fedora.  I say 'for' 
because we have a huge (hundreds) dependency set and some of the things 
are not suitable for Fedora.  We've been working in reducing this set, 
solving problems but that will take a couple of years at least, and will 
probably be for an AS 5 version, never for the 4.2.x as there is no way 
to influence that upstream at this stage.

So we decided to have a separate repository that people can subscribe 
their systems too and install a jbossas 4.2.x RPM with the dependencies 
that are not on Fedora etc.

Another problem that is hitting us, and this is the main reason of this 
message, is that the versions of some packages that are in Fedora base 
are not compatible with ours stuff.  An App Server has to pass TCK 
certification and has too many component interactions end up requiring 
very specific versions of the libraries.  We are having to add some 
hacks to our package to work around that.  Some cases we can solve by 
upgrading the package in the next Fedora base, *IF* that dosen't break 
something else that depends on those libraries and is in Fedora already. 
  Some others we will keep bugging JBoss AS maintainers to upgrade in 
some new release.  Some we have a 'versioned' package that installs in 
parallel.  Other just can't be helped.

This problem of conflicts of dependency version requirements happens 
even between our products.  We have created a scoreboard with versions 
of the libraries we need so we could negotiate, among all projects, the 
versions we will be use in ALL products.  But it is not easy, there are 
cases which are very difficult to solve -- you either break one or the 
other, backporting is difficult etc.

My point is, the more packages we add to the Fedora base the worse it 
will be for us to agree on the versions of these.  So this would 
indicate that the "for Fedora", as opposed to "in Fedora" approach 
should be considered by all.

On the other hand, each of us having a different set of libraries in our 
own repositories will make it difficult for people wanting to install 
more than one.  A solution for this would be for us to foresee possible 
cases where interoperability is desired and work out the dependency 
problems just between those ISV products involved.

Another thing, even if we go to a "in Fedora" as the preferred method, 
we still can use the "for Fedora" approach as a intermediate state, 
before all dependencies needed by some product exist in Fedora.

One of our possible solutions to make our JBoss AS RPM set available is 
release it in JPackage.org.  They have mirrored repositories and there 
are distro specific repos, in addition to the generic repos, so our 
modifications for Fedora can be uploaded to their fedora-9 repo.

Of course, if we all decide to make things available from JPackage, the 
dependency conflict will move there.  But JPackage wants to have a 
'base' repo with additional (and optional) repos for some major 
components like App Servers, so one can decide if they want, for 
instance, JOnAS or JBoss, and get the appropriate dependencies.  This 
added to the yum priority plugin turns in a very flexible setup.


The above looks more like a brain dump, sorry.  I just came back from 
vacations and I am traveling for a meeting next week, so time is scarce.


Regards to all,
Fernando