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From "Niall Pemberton" <niall.pember...@gmail.com>
Subject Re: Support for OSGi
Date Fri, 01 Feb 2008 15:19:37 GMT
On Feb 1, 2008 1:19 PM, Oberhuber, Martin
<Martin.Oberhuber@windriver.com> wrote:
> Hello Niall / Stuart,
>
> thanks for your answers. It looks like the usage patterns
> of OSGi in the Apache and Eclipse communities are just
> a bit different: Apache focuses on packages whereas Eclipse
> focuses on Bundle granularity for Re-use.
>
> That's why we don't explicitly import all exported packages
> at Eclipse -- we're using Require-Bundle instead of
> Import-Package throughout our system, mostly due to the way
> Eclipse Plugins have been workign in the past. For details,
> see also
>
> http://dev.eclipse.org/mhonarc/lists/orbit-dev/msg00627.html
>
> What does that mean in practice?
>
> 1.) Looks like we Eclipse folk will need to continue writing
>     our own OSGi Manifests for some time since the
>     "Require-Bundle" vs. "Import-Package" patterns do not
>     mix too well.

It would have been good to meet everyone's needs but from the link you
posted and what Peter and Stuart have said in this thread then that
doesn't seem possible and from my limited perspective it seems clear
that we (in Commons) should follow whats considerd good OSGi practice
rather than those of eclipse.

Niall

> 2.) Whenever somebody converts an auto-generated OSGi Manifest
>     into a manually maintained one, it's worth thinking about
>     a) What packages are really API and thus worth being
>        exported, versus what packages are considered internal
>        hidden implementation;
>     b) What packages are expected to be potentially split
>        across multiple bundles, or would always reside inside
>        the same bundle.
>
> Or am I missing something?
>
> Thanks,
> --
> Martin Oberhuber, Senior Member of Technical Staff, Wind River
> Target Management Project Lead, DSDP PMC Member
> http://www.eclipse.org/dsdp/tm
>
>
>
> > -----Original Message-----
> > From: mcculls@gmail.com [mailto:mcculls@gmail.com] On Behalf
> > Of Stuart McCulloch
> > Sent: Donnerstag, 31. Jänner 2008 16:53
> > To: dev@felix.apache.org
> > Cc: Jakarta Commons Developers List; Orbit Developer discussion
> > Subject: Re: Support for OSGi
> >
>
> > On 31/01/2008, Oberhuber, Martin
> > <Martin.Oberhuber@windriver.com> wrote:
> > >
> > > Hello Niall,
> > >
> > > it would be interesting for Eclipse consumers as
> > > well to get Apache bundles with Meta-info already
> > > applied.
> > >
> > > Currently, the Meta-info is mostly added manually
> > > as part of the Eclipse Orbit project.
> > >
> > > I have had a brief look at your auto-generated
> > > MANIFEST for commons net, and found a few issues:
> > >
> > >
> > http://people.apache.org/~niallp/commons-osgi/commons-net-1.5.
> > 0-SNAPSHOT
> > > -MANIFEST.MF
> > >
> > > 1. Import-Package: examples;version="1.5.0.SNAPSHOT"
> > >    this is just wrong. The commons net deliverable
> > >    jar should not import examples.
> >
> >
> > I assume there's an examples package somewhere (or something
> > pulls in the
> > examples package)
> > You can explicitly ask Bnd to remove/ignore this import by
> > using !examples
> > in the Import-Package
> > if you know that you won't actually need it during runtime (ie. it's
> > dead/unused code)
> >
> > eg:   <Import-Package>!examples,*</Import-Package>
> >
> > 2. Import-Package: org.apache.commons.net.smtp
> > >    this is also wrong though less destructive.
> > >    commons.net.smtp is really exported and not imported.
> >
> >
> > Actually this is correct - it's good practice to import your
> > exports as it
> > ensures a consistent class
> > space and avoids problems when upgrading bundles. Otherwise
> > you *will* run
> > into casting issues.
> >
> > 3. Export-Package:
> > >
> > org.apache.commons.net.smtp;uses:="org.apache.commons.net.io,o
> > rg.apache.
> > > commons.net"
> > >    It's useless to add a "uses" directive for
> > >    packages that are in the same bundle. At
> > >    Eclipse-Orbit, we've found problems with "uses"
> > >    and decided to no longer use it.
> >
> >
> > As Peter says, he's recently updated Bnd to give users more
> > control over
> > "uses" and improved
> > the default generation. BTW, there is a good reason for the
> > "uses" clause as
> > explained by Glyn:
> >
> >
> > http://underlap.blogspot.com/2007/10/osgi-type-safety-and-uses
> > -directive.html
> >
> > I haven't seen any problem with "uses" on Felix, but I guess
> > Equinox could
> > always add an option
> > to ignore it - as there are likely to be other bundles out
> > there that have
> > "uses" in their manifest.
> >
> > I guess that these should perhaps really be bug
> > > reports against the Bnd utility which autogenerated
> > > the Manifest; Tool: Bnd-0.0.227.
> >
> >
> > The elimination of "uses" is really a new feature, and the imports of
> > exports is not a bug - the
> > only bug (as such) is the appearance of the "examples"
> > package, but I'd need
> > to see the final
> > jar to understand why Bnd detected it (ie. it may be a
> > justified import
> > based on the content)
> >
> > But for me, it also shows that in the current stage
> > > it looks like the OSGi manifest still needs to be
> > > written by hand and not auto-generated.
> >
> >
> > From experience I'd argue it's the other way round - OSGi
> > manifests should
> > be auto-generated.
> > But, as with any tool, you should verify it yourself and add
> > any customized
> > attributes and minor
> > adjustments.
> >
> > Otherwise you'll have to manually keep the manifest in step
> > with your code,
> > and it's amazingly
> > easy to miss imports when they're buried inside the code,
> > which is why such
> > tools are needed.
> >
> > The other benefit of auto-generation is you can do it
> > dynamically - for
> > example, at OPS4J we
> > have a deployment tool that lets you load third-party jars which
> > automatically get turned into
> > OSGi bundles. This really helps with rapid prototyping (great
> > if you have a
> > legacy jar, but don't
> > know the code well enough to craft an OSGi manifest yourself)
> >
> > Anyways, if there is a plan to make a downloadable
> > > release of any commons packages with OSGi info
> > > added, I'd like to know.
> > >
> > > Thanks,
> > > --
> > > Martin Oberhuber, Senior Member of Technical Staff, Wind River
> > > Target Management Project Lead, DSDP PMC Member
> > > http://www.eclipse.org/dsdp/tm
> > >
> > >
> > >
> > > > -----Original Message-----
> > > > From: Niall Pemberton [mailto:niall.pemberton@gmail.com]
> > > > Sent: Tuesday, January 29, 2008 11:30 PM
> > > > To: Commons Developers List
> > > > Cc: dev@felix.apache.org
> > > > Subject: Re: Support for OSGi
> > > >
> > > > I have created a JIRA ticket for the changes to the
> > commons-parent pom
> > > > to add the bundle plugin:
> > > >   https://issues.apache.org/jira/browse/COMMONSSITE-23
> > > >
> > > > I have also tested out the plugin by generating the
> > jars/manifest for
> > > > all but three components:
> > > >   http://people.apache.org/~niallp/commons-osgi/
> > > >
> > > > I'll leave the ticket open for a few days - but unless there are
> > > > objections/issues raised I plan to apply the changes to
> > > > commons-parent.
> > > >
> > > > Niall
> > > >
> > > > On Dec 19, 2007 2:38 PM, Carsten Ziegeler
> > > > <cziegeler@apache.org> wrote:
> > > > > Hi,
> > > > >
> > > > > the products of commons are highly used throughout many
> > projects.
> > > > >
> > > > > It would be great, if the projects here at Apche
> > Commons could help
> > > > > those projects that are using OSGi.
> > > > >
> > > > > OSGi is based around the concept of a bundle - a bundle is
> > > > a jar file
> > > > > with additional meta data like the packages it exports
> > and a list of
> > > > > external packages it is using (please forgive me if I'm
> > > > simplifying here
> > > > > too much).
> > > > >
> > > > > As many projects are using artifacts from Apache Commons,
> > > > they need the
> > > > > specific jars as bundles. This is most often done by
> > > > creating so called
> > > > > wrapper bundles: these are jars that have the same
> > contents as the
> > > > > original library with the addition of the required meta data.
> > > > > You can find several examples here:
> > > > >
> > > > > http://svn.apache.org/repos/asf/felix/trunk/commons/
> > > > >
> > > > > Now, it would be great, if the projects here at Apache
> > Commons would
> > > > > already provide artifacs that can be directly used in an
> > > > OSGi environment.
> > > > >
> > > > > All that has to be done is adding some entries to the
> > > > manifest. This is
> > > > > usually a list of imported packages, a list of exported
> > packages, a
> > > > > symbolic name for the bundle and a version. (There are
> > some more but
> > > > > these are the most important ones).
> > > > >
> > > > > Adding these entries can be done by hand (not recommended)
> > > > or with tools
> > > > > automatically. For example the Apache Felix maven
> > > > bundleplugin requires
> > > > > just some lines of configuration and that's it.
> > > > >
> > > > > It would be great if some of the projects here could add
> > > > these meta data
> > > > > as part of their next release. This will make the life of
> > > > all projects
> > > > > using OSGi much much easier.
> > > > >
> > > > > So if you're interested in helping us, just let us
> > know. We would be
> > > > > happy to make the required changes to the poms or whatever
> > > > needs to be
> > > > > done. I cc'ed the Felix dev list as some Felix developers
> > > > might not be
> > > > > subscribed to the commons dev list, so please keep them
> > > > cross posted.
> > > > >
> > > > > Thanks
> > > > > Carsten
> > > > > --
> > > > > Carsten Ziegeler
> > > > > cziegeler@apache.org
> > > > >
> > > > >
> > > >
> > ---------------------------------------------------------------------
> > > > > To unsubscribe, e-mail: dev-unsubscribe@commons.apache.org
> > > > > For additional commands, e-mail: dev-help@commons.apache.org
> > > > >
> > > > >
> > > >
> > > >
> > ---------------------------------------------------------------------
> > > > To unsubscribe, e-mail: dev-unsubscribe@commons.apache.org
> > > > For additional commands, e-mail: dev-help@commons.apache.org
> > > >
> > > >
> > >
> >
> >
> >
> > --
> > Cheers, Stuart
> >
>
> ---------------------------------------------------------------------
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