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From Guillaume Nodet <gno...@gmail.com>
Subject Re: Some thoughts about enabling for OSGi
Date Tue, 01 Sep 2009 07:06:22 GMT
We have a maven plugin that helps a bit for building a custom karaf assembly.
Karaf has this notion of "features" which is a list of bundles and
references to other features.  When building a custom distribution,
the plugin will be given a list of features and will populate the
internal m2 repository with all the bundles needed for those features.
  However, the plugin could be enhanced because it does not really
create the assembly, this is currently done with the maven assembly
plugin, so that the pom for creating the assembly is not minimal, but
this needs to be improved obviously.
You can find an example at:
    https://svn.apache.org/repos/asf/servicemix/sandbox/karaf/nmr/assembly/pom.xml
See the configuration for the features-maven-plugin plugin.

For testing, inside Karaf, we currently use pax-exam:
  https://svn.apache.org/repos/asf/felix/trunk/karaf/itests/src/test/java/org/apache/felix/karaf/gshell/itests/FeaturesTest.java
There's also room for improvements here, but that's a good start.

On Mon, Aug 31, 2009 at 20:37, Donald Woods<dwoods@apache.org> wrote:
>
>
> Guillaume Nodet wrote:
>>
>> On Tue, Aug 25, 2009 at 17:43, Rick McGuire <rickmcg@gmail.com
>> <mailto:rickmcg@gmail.com>> wrote:
>>
>>    I've been trying to pull together some thoughts about what it might
>>    mean for Geronimo to enable itself for OSGi applications and what
>>    needs to be added to the server beyond just adopting an OSGi
>>    classloading model.  That sort of change would be primarily
>>    transparent for most existing applications, but to make the change
>>    worthwhile, we'd also want to make Geronimo into a real OSGi
>>    application platform.
>>
>>    So, beyond just having the framework environment, what would be the
>>    require elements?  Ok, to start with, most (all?) real OSGi
>>    platforms have some concept of a bundle repository.  The bundle
>>    repository is where installed bundles are stored and there is
>>    generally some sort of loading/provisioning strategy associated with
>>    the repository that eliminates the need for an application to
>>    manually install and start each of its dependent bundles.  I think
>>    the characteristics of how the Geronimo bundle repository is a
>>    discussion topic all of its own, so for now, I'll just assume this
>>    piece is there.  As part of server bootstrap, there will be a
>>    configured startup of bundles from the repository that are necessary
>>    to bring up the server.  This will be similar to the module
>>    bootstrapping the server already goes through.  There will also need
>>    to be a mechanism for adding bundles to the repository, probably
>>    both as a command line tool and via the console.
>>
>>    The Geronimo server will need to provision the framework with an
>>    initial set of services that will be available for installed bundles
>>    to use.  Some of these services will interact with other portions of
>>    the Geronimo server, while others are platform-agnostic, but provide
>>    important bundle-management services.  Looking through the OSGi
>>    compendium specifications, the following look like a good
>>    recommended set:
>>      * EventAdmin service (generalized Event broadcast service).  This is
>>        fairly self contained, and we can probably just use the Felix
>>        reference implementation.
>>      * Logging service.  This is a standardized OSGi logging API.  The
>>        reference implementation is just a circular queue and does not
>>        actually log entries to any persistent storage.  The Geronimo OSGi
>>        logging service should be integrated with the general logging
>>        support.  The PAX logging service looks like a good starting point
>>        for this.  I understand that the Geronimo Blueprint service
>>        implementation is already using this version.
>>
>>
>> The Blueprint impl uses an OSGi logging service if available but has not
>> dependency on the implementation.
>>
>>
>>      * Config Admin.  This is a persistent store for configuration
>>    data.     I think this one will be an general expectation for many
>>    bundles
>>        that are installed on Geronimo, so we'd need to provide an
>>        instance of this.
>
> How about just extending the existing Admin Console support in Felix?
> We'll still need a web ui, but it should always be optional, like it is in
> Felix and Karaf today.
>
>>      * UserAdmin service.  This is an interface to an authentication
>>        system associated with a platform.  I believe this would be fairly
>>        simple to map to the Geronimo authentication services.
>>      * Declarative services.  The ability for bundles to declaratively
>>        publish services to the services registry.  We'd need to support
>>        this to allow bundles to be used portably across framework host
>>        environments.  This should not require any special integration
>>        with the rest of Geronimo.
>>      * Blueprint services.  A more sophisticated component assembly
>>        model.  This also should not require any special Geronimo
>>        integration.   * Preferences Service.  Allows bundles to
>>    persistently store
>>        preference information.  This is a bundle-driven capability, which
>>        is a bit different than the config admin service.  I'm not sure
>>        how prevalently this is used, so this one might not be a
>>    requirement.
>>
>>    Interestingly, this diagram of Karaf architecture has quite a bit in
>>    common with what I've just described once you replace "Spring DM"
>>    with "Blueprint Service".  There could be an advantage to leverage
>>    prior experience with this environment here.
>>
>>
>> Karaf has switched to Blueprint services some time ago (I guess I need to
>> update the web site I suppose).  So there's no Spring-DM dependency anymore,
>> though it can be easily deployed using "karaf features".
>>
>
> Are there are maven plugins for using Karaf in a junit environment or to
> help build custom Karaf assemblies?
>
>
>>
>>
>>
>>    One key aspect to all of this is deployment and administration.  The
>>    Geronimo server will need to provide the conduit for deploying new
>>    bundles to this environment, as well as administrative function.
>>     The OSGi Enterprise Expert Group (EEG) is working on a
>>    specification for using JMX for managing OSGi environments.  The
>>    reference implementation for this specification includes a framework
>>    neutral set of MBeans for tracking installed bundles, registered
>>    services, config admin, etc.  These look like a good model to follow
>>    and can be the basis for providing console-like administration
>>    capabilities.  There may be additional MBeans we'd like to provide
>>    for other services, such as the Blueprint service.
>>
>>
>> Karaf embeds the RI for JMX management of OSGi.
>>
>> I really think it would make sense to see if we can Karaf and Geronimo can
>> collaborate together.  I always have in mind Karaf becoming a TLP at some
>> point.   Improvements to Karaf would be very welcomed, I'm sure.
>>
>> Karaf goal was really to be a minimal, but yet usable, OSGi runtime for
>> server side applications, such as ServiceMix, ActiveMQ.  So I don't really
>> see why it would not be a good fit for Geronimo.  And if it isn't yet, it
>> might make sense to see how it can become so ...
>>
>>
>>    This is probably a good staring point for the discussions.  There
>>    are likely other facilities we'll need to add here, but I think this
>>    is probably a good starting point for the discussions.      Rick
>>
>>
>>
>>
>> --
>> 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

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