Sure, I figured I would test with a simple example so I can make sure I'm
not doing anything stupid (I NEEEEEVER do anything stupid). If I created a
features xml like this:
----------------------------------------------------------
<?xml version="1.0" encoding="UTF-8"?>
<features name="${project.artifactId}-${project.version}" xmlns="
http://karaf.apache.org/xmlns/features/v1.5.0";
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
xsi:schemaLocation="http://karaf.apache.org/xmlns/features/v1.5.0
http://karaf.apache.org/xmlns/features/v1.5.0";>
<feature name="test1" version="${project.version}">
<requirement>test.env;filter:="(env=np)"</requirement>
</feature>
<feature name="test2" version="${project.version}">
<feature dependency="true">test3</feature>
</feature>
<feature name="test3" version="${project.version}">
<capability>test.env;env=np</capability>
</feature>
</features>
---------------------------------------------
It works as expected. If I do this:
--------------------------------------------------------------------------
<?xml version="1.0" encoding="UTF-8"?>
<features name="${project.artifactId}-${project.version}" xmlns="
http://karaf.apache.org/xmlns/features/v1.5.0";
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
xsi:schemaLocation="http://karaf.apache.org/xmlns/features/v1.5.0
http://karaf.apache.org/xmlns/features/v1.5.0";>
<repository>mvn:${project.groupId}/test23/${project.version}/xml/features</repository>
<feature name="test1" version="${project.version}">
<requirement>test.env;filter:="(env=np)"</requirement>
</feature>
</features>
--------------------------------------------------------------------------
and
--------------------------------------------------------------------------
<?xml version="1.0" encoding="UTF-8"?>
<features name="${project.artifactId}-${project.version}" xmlns="
http://karaf.apache.org/xmlns/features/v1.5.0";
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
xsi:schemaLocation="http://karaf.apache.org/xmlns/features/v1.5.0
http://karaf.apache.org/xmlns/features/v1.5.0";>
<feature name="test2" version="${project.version}">
<feature dependency="true">test3</feature>
</feature>
<feature name="test3" version="${project.version}">
<capability>test.env;env=np</capability>
</feature>
</features>
--------------------------------------------------------------------------
Then the requirement can't be resolved. I can however install the test2
feature so I know the test23 repo was added. What is curious to me though,
is why if the above doesn't work, why I don't get a failure when I verify
the features for the above. I figured by referencing test2 (which lives in
the other features.xml in the second case), it was discover that it
provides the required capability.
In reading the Karaf docs again (which I appreciate because they are quite
good and I know docs are time consuming and a pain to write :)) I'm
wondering if I have to install all the features and bundles in the other
features xml but not auto-start them (I think I saw an option for that)?
Thanks!
Ryan
On Thu, Jun 20, 2019 at 1:17 AM Jean-Baptiste Onofré <[email protected]>
wrote:
> Hi Ryan,
>
> Do you mean you are using resources repository (define in
> etc/org.apache.karaf.features.cfg) ?
>
> A features repository can also contains capability and requirements.
>
> To be able to find the req/cap, the resolver needs to know the cap/req.
> If they are splitted in different repositories, then you have first to
> "load" the repositories to be visible by the resolver. Else the resolver
> won't know "where" the cap is provided.
>
> Cave can help in two ways:
> 1. the features gateway is able to gather several features repositories
> in a meta-global-one.
> 2. Cave can serve as resources repositories backend
>
> Can you share your test case in order for me to take a look ?
>
> Regards
> JB
>
> On 19/06/2019 23:18, Ryan Moquin wrote:
> > Hi JB,
> >
> > I decided to try the req/cap again. The reason it didn't work for me
> > before apparently is because a capability satisfying a requirement isn't
> > detected by the resolver if they are in different feature repositories
> > (which is the same as a feature XML I believe). I tried to reference a
> > feature as a dependency in a different repository but it wouldn't work
> > unless I had it in the same repository.
> >
> > I'm not sure if that's by design or if something like Cave would be
> > needed for that scenario. Otherwise I need to rethink how I handle the
> > requirement and capabilities. I am trying to keep separate feature
> > repositories because if I aggregate, then it takes longer to create the
> > updated aggregate feature xml.
> >
> > Ryan
> >
> > On Sat, Jun 15, 2019, 12:01 PM Jean-Baptiste Onofré <[email protected]
> > <mailto:[email protected]>> wrote:
> >
> > Hi Ryan,
> >
> > I will provide a more complete answer (I don't have time right now),
> but
> > you can take a look on the way we use cap/req in Pax Web (for the
> HTTP
> > provider capability).
> >
> > Basically, the cap/req are global in the feature resolver,
> considering
> > the req/cap at feature level, but also at bundle level.
> >
> > Regards
> > JB
> >
> > On 15/06/2019 16:28, Ryan Moquin wrote:
> > > I apologize if this is a stupid question. I've been trying to
> > understand
> > > how to leverage capabilities and requirements in a way to allow
> > defining
> > > the provisioning of a system by specifying requirements in a
> feature.
> > >
> > > I've read through the posts on the mailing list about it, the docs
> and
> > > the karaf features.xml but haven't found the information I am
> looking
> > > for. I also tried some experiments with a bundle providing a
> > capability
> > > and a feature requiring it but it didn't seem to work. I am
> wondering
> > > if I am just over thinking or over complicating it in my head.
> > Here are
> > > the questions:
> > >
> > > 1. When a feature specifies a requirement, what is the "scope" of
> > > resolution used by the feature resolver? Meaning, does it only
> pick
> > > from features specified within that feature with dependency=true
> > > specified? Or from any feature defined in the features.xml and any
> > > feature repository defined that provides a satisfying capability?
> > >
> > > 2. Can you specify a requirement in a feature for a requirement
> > > provided by a bundle?
> > >
> > > 3. If a bundle or feature provides a capability, but you don't
> > specify
> > > you require it. Does it always get considered for installation if
> > it's
> > > in a feature that doesn't have dependency=true?
> > >
> > > Part of this is because I still can't understand when to use
> > > dependency=true for a feature. I am primarily talking about custom
> > > capabilities and requirements I make up myself for a system to pull
> > > things in.
> > >
> > > Not sure if the above questions fully make sense, having a hard
> time
> > > articulating exactly what I am trying to figure out.
> > >
> > > Thanks for any help!
> > >
> > > Ryan
> >
> > --
> > Jean-Baptiste Onofré
> > [email protected] <mailto:[email protected]>
> > http://blog.nanthrax.net
> > Talend - http://www.talend.com
> >
>
> --
> Jean-Baptiste Onofré
> [email protected]
> http://blog.nanthrax.net
> Talend - http://www.talend.com
>
