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From Guillaume Nodet <gno...@gmail.com>
Subject Re: Features and OBR
Date Tue, 19 Oct 2010 23:02:02 GMT
I think I have a solution to partially solve the problem.  Of the main
interest in OBR imho is that it knows what is installed in the framework
already, so it can be used to avoid duplicating libraries in different
versions that are not needed (if you need spring-core 3.0.3 but spring-core
3.0.4 is installed, there's no need to install both usually).
The problem is that the use of OBR usually require OBR repositories.   I
think I can get rid of that by creating a dummy OBR repository from the
features descriptors and flagging some bundles in the features descriptor as
optional (or dependencies).

For example, in the current descriptor repoitory we have:

    <feature name="jasypt-encryption" version="2.1.99-SNAPSHOT">





But really, the key bundle here is
the mvn:org.apache.karaf.jaas/org.apache.karaf.jaas.jasypt/2.1.99-SNAPSHOT
one, whereas the three others are just dependency whith versions that could
be changed (provided they are still in the required range).  This would mean
that if commons-lang-2.5 has already been installed through another feature,
there's no need to install another version of it.

In addition, I think supporting dependency on feature ranges would be really
important as it would help greatly when depending on spring 2.x or 3.x for

On Mon, Jul 5, 2010 at 09:29, Guillaume Nodet <gnodet@gmail.com> wrote:

> That could be a good way.  I haven't experimented that really, but I
> think it would at least give the freedom to the resolver to reuse
> locally installed bundles, so that's obviously a really good start.
> As for OBR itself, I've added to the maven bundle plugin a goal that
> can be used to build an obr repository out of a maven repository in a
> directory.  This goal can also generated maven urls instead of the
> file:// urls that it would give.  Thus giving an additional
> indirection in the url instead of pointing directly to the http
> location.
> I think from a production pov, what would be needed is some kind of
> maven repository (nexus or archiva) coupled with an OBR repository.
> This way, the deployer would be responsibe for adding authorized
> artifacts in the repository and that would automatically update an obr
> repository descriptor with the added artifacts.
> The problem is that this way of seeing the problem does not work well
> in a non controlled environment such as most users do when they allow
> access to maven central ... So in that case, your approach of using
> the maven dependencies could be a good solution.
> On Fri, Jul 2, 2010 at 18:34, David Jencks <david_jencks@yahoo.com> wrote:
> >
> > On Jul 2, 2010, at 8:03 AM, Guillaume Nodet wrote:
> >
> >> I've just added support for pluggable resolvers for features.
> >> I've also created an OBR based resolver that is installed with the obr
> feature.
> >>
> >> Now you can do the following:
> >>
> >>  <feature name="xx" version="yy" resolver="obr">
> >>
>  <bundle>bundle:(&(symbolicname=org.apache.camel.camel-blueprint)(version>=2.4.0)(version<2.4.1))</bundle>
> >>  </feature>
> >>
> >> If OBR has been configured with the needed repositories, it will
> >> install camel-blueprint bundle with all the required dependencies.
> >> The benefit is that you don't have to specify all the dependencies,
> >> but only the key bundles.  The added benefit is that the deployment
> >> will leverage what is already installed and you don't have to maintain
> >> an homogeneous set of repositories (for example, you should not have
> >> to specify which version of spring you want to use and obr will reuse
> >> the one installed if possible, or choose which one to install based on
> >> the constraints expressed by the bundles).
> >>
> >> I haven't updated the feature descriptor yet, mostly because we don't
> >> have a obr repository which contain all the bundles we need.
> >> I have one locally that contain all the bundles present on maven
> >> central, but it's a bit too big to be used in this context, so not
> >> sure how to handle that yet.
> >>
> >> Anyway, just wanted to give a heads up on that.
> >
> >
> > One of the points of friction I see between maven and osgi is that in
> maven you explicitly  specify which artifacts supply your needed
> dependencies whereas in osgi they magically appear from something like OBR.
>  I've always wondered where the OBR-like info is supposed to come from.  On
> the other hand, if you are using maven to build, you have a reasonable set
> of candidate artifacts in the maven dependencies (assuming they are all
> bundles).
> >
> > Something I started experimenting with in geronimo is to, for each
> feature, construct an OBR xml file out of the maven dependencies.  Just
> before you try to install the feature, you add the obr fragment to the OBR
> instance you are using for resolving the feature.  This pretty much assures
> that something that will enable the bundles in the features to resolve will
> be available.
> >
> > Writing the code for this was easy, but we weren't relying enough on OBR
> at the time to find out how well it works in practice.  I have been
> wondering if anyone else would think this is a reasonable approach to
> investigate.
> >
> > thanks
> > david jencks
> >>
> >> --
> >> Cheers,
> >> Guillaume Nodet
> >> ------------------------
> >> Blog: http://gnodet.blogspot.com/
> >> ------------------------
> >> Open Source SOA
> >> http://fusesource.com
> >
> >
> --
> Cheers,
> Guillaume Nodet
> ------------------------
> Blog: http://gnodet.blogspot.com/
> ------------------------
> Open Source SOA
> http://fusesource.com

Guillaume Nodet
Blog: http://gnodet.blogspot.com/
Open Source SOA

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