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From Guillaume Nodet <gno...@gmail.com>
Subject Re: Features and OBR
Date Wed, 20 Oct 2010 14:28:21 GMT
Ok, so i've raise KARAF-251 and KARAF-252 and committed some patches, but
i'd like to discuss those before closing the jiras.

So, KARAF-251 is about using range on features.
I've modified the parser and installation service to allow using ranges when
specifying a dependency on a feature.
I've also modified the karaf feature descriptor to leverage that by adding a
spring2 feature:

    <feature name="spring" version="2.5.6.SEC01">
        <bundle
dependency='true'>mvn:org.apache.servicemix.bundles/org.apache.servicemix.bundles.aopalliance/1.0_4</bundle>
        <bundle>mvn:org.springframework/spring-core/2.5.6.SEC01</bundle>
        <bundle>mvn:org.springframework/spring-beans/2.5.6.SEC01</bundle>
        <bundle>mvn:org.springframework/spring-aop/2.5.6.SEC01</bundle>
        <bundle>mvn:org.springframework/spring-context/2.5.6.SEC01</bundle>

 <bundle>mvn:org.springframework/spring-context-support/2.5.6.SEC01</bundle>
    </feature>
    <feature name="spring" version="3.0.3.RELEASE">
        <bundle
dependency='true'>mvn:org.apache.servicemix.bundles/org.apache.servicemix.bundles.aopalliance/1.0_4</bundle>
        <bundle>mvn:org.springframework/spring-core/3.0.3.RELEASE</bundle>
        <bundle>mvn:org.springframework/spring-asm/3.0.3.RELEASE</bundle>

 <bundle>mvn:org.springframework/spring-expression/3.0.3.RELEASE</bundle>
        <bundle>mvn:org.springframework/spring-beans/3.0.3.RELEASE</bundle>
        <bundle>mvn:org.springframework/spring-aop/3.0.3.RELEASE</bundle>

 <bundle>mvn:org.springframework/spring-context/3.0.3.RELEASE</bundle>

 <bundle>mvn:org.springframework/spring-context-support/3.0.3.RELEASE</bundle>
    </feature>
    <feature name="spring-dm" version="1.2.0">
        <feature version="[2.5.6,4)">spring</feature>

 <bundle>mvn:org.apache.servicemix.bundles/org.apache.servicemix.bundles.cglib/2.1_3_6</bundle>
        <bundle>mvn:org.springframework.osgi/spring-osgi-io/1.2.0</bundle>
        <bundle>mvn:org.springframework.osgi/spring-osgi-core/1.2.0</bundle>

 <bundle>mvn:org.springframework.osgi/spring-osgi-extender/1.2.0</bundle>

 <bundle>mvn:org.springframework.osgi/spring-osgi-annotation/1.2.0</bundle>

 <bundle>mvn:org.apache.karaf.deployer/org.apache.karaf.deployer.spring/2.1.99-SNAPSHOT</bundle>
    </feature>

When installing a feature, the dependant features are installed as
following:
  * if no version is indicated, it means [0, +oo)
  * if a version is indicated, the range is closed [x, x]
  * if a feature matching the range is already installed, use that one
  * else find the highest version matching the range

So if you 'features:install spring-dm' it will install spring 3.0.3 by
default.  If you want to install the 2.5 version, you need to
'features:install spring 2.5.6' and then 'features:install spring-dm'.

The second improvement, KARAF-252 is about leveraging OBR to avoid
installing duplicate dependencies while not forcing the user into using and
maintaining OBR repositories.  It can now be done by flagging dependencies
with a dependency='true' flag and resolver="(obr)".   Note the parentheses
that mean the obr resolver is optional (so it will default to the previous
behavior if obr isn't installed and in that case will install all the listed
bundles).   If obr resolver is present, the feature will be transitively
resolved by creating an obr repository containing all the listed bundles and
resolving only the bundles marked as not 'dependency'.  So in the example
above, the aopalliance bundle is marked as a dependency, so that if another
aopalliance bundle satisfying the constraint (imported packages, etc...) is
already installed, it won't be installed.

Thoughts?


On Wed, Oct 20, 2010 at 12:17, Guillaume Nodet <gnodet@gmail.com> wrote:

> I was mostly thinking about versioning at the feature dependency level.
> The mvn url already supports range, so i don't think we need to do anything
> here.
> Afaik, you can already write:
>
> mvn:org.apache.servicemix.bundles/org.apache.servicemix.bundles.commons-codec/[1.3_3,2)
>
> I'll post a bit more later today or tomorrow.
>
> On Wed, Oct 20, 2010 at 09:32, Ioannis Canellos <iocanel@gmail.com> wrote:
>
>> It sounds good.
>>
>>
>> On Wed, Oct 20, 2010 at 10:18 AM, Jean-Baptiste Onofré <jb@nanthrax.net
>> >wrote:
>>
>> > Hi Guillaume
>> >
>> > +1 to support dependency on features range.
>> > Anyway, the dependency resolution is already performed by the bundle (if
>> it
>> > uses Import-Package statement with a version range, for instance, in
>> your
>> > exemple org.apache.commons.lang;version="[2.4,2.5)").
>> >
>> > I guess that we need to "construct" the URL compatible with PAX URL
>> before
>> > delegating to PAX. The bundle will be added in the OBR repositories
>> (locally
>> > to Karaf) with a "dependency" flag.
>> >
>> > The question is how to upgrade the descriptor repository to work like
>> this.
>> >
>> > I propose:
>> > 1/ the bundle version could be optional as:
>> >
>> >
>> <bundle>mvn:org.apache.servicemix.bundles/org.apache.servicemix.bundles.commons-lang</bundle>
>> > In that case, Karaf will looking for the OBR to get an existing
>> > commons-lang bundle. It fails if the bundle is not present in the OBR
>> > 2/ define a bundle version range as
>> >
>> >
>> <bundle>mvn:org.apache.servicemix.bundles/org.apache.servicemix.bundles.commons-lang/[2.4,2.5)</bundle>
>> > In that case, Karaf will looking for the OBR to get the first bundle
>> > matching the version range.
>> > 3/ define the bundle version is still supported (to be backward
>> > compatible).
>> >
>> > What do you think ?
>> >
>> > Regards
>> > JB
>> >
>> >
>> > On 10/20/2010 01:02 AM, Guillaume Nodet wrote:
>> >
>> >> 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">
>> >>
>> >>
>> >>
>>  <bundle>mvn:org.apache.servicemix.bundles/org.apache.servicemix.bundles.commons-codec/1.3_3</bundle>
>> >>
>> >>
>> >>
>>  <bundle>mvn:org.apache.servicemix.bundles/org.apache.servicemix.bundles.commons-lang/2.4_4</bundle>
>> >>
>> >>
>> >>
>>  <bundle>mvn:org.apache.servicemix.bundles/org.apache.servicemix.bundles.jasypt/1.6_1</bundle>
>> >>
>> >>
>> >>
>>  <bundle>mvn:org.apache.karaf.jaas/org.apache.karaf.jaas.jasypt/2.1.99-SNAPSHOT</bundle>
>> >>     </feature>
>> >>
>> >> 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
>> >> example.
>> >>
>> >> 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
>> >>>
>> >>>
>> >>
>> >>
>> >>
>>
>>
>> --
>> *Ioannis Canellos*
>> http://iocanel.blogspot.com
>>
>> Integration Engineer @ Upstream S.A. <http://www.upstreamsystems.com>
>>
>
>
>
> --
> 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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