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From Milen Dyankov <milendyan...@gmail.com>
Subject Re: Specifying dependency between a bundle and a fragment bundle
Date Thu, 14 Jan 2016 11:52:32 GMT
I'm not sure what you mean by "via services". As for subsystems, my
understanding is this is more of a packaging/delivery option. It may help
but I still need a soliton that will work for deploying individual bundles.

Anyway, I experimented a bit more and it seams it's fully possible to use
requirement and capabilities with fragment bundles.
I don't know why it wasn't working before but my understanding that
capabilities related headers in fragment bundle are applied to the host
bundle is wrong!

So, by putting

Fragment-Host: original.ui.bundle
Provide-Capability: myUI
Require-Capability: myService

in my UI bundle and then in my service bundle

Provide-Capability: myService
Require-Capability: myUI

I can actually define the dependency I need.
With that in place, I can uninstall (too bad I can not only unresolve) my
service bundle if my service fails. There are still some quirks with
refreshing the original UI bundle but it generally works.
It's probably not the best solution but I couldn't figure out anything
better so far.

Thanks for your help!
Milen


On Wed, Jan 13, 2016 at 3:02 PM, CLEMENT Jean-Philippe <
jean-philippe.clement@fr.thalesgroup.com> wrote:

> I would have made this via services, but there might be other ways such as
> subsystems (?)
>
> JP
>
> [@@ OPEN @@]
>
>
> -----Message d'origine-----
> De : Milen Dyankov [mailto:milendyankov@gmail.com]
> Envoyé : mercredi 13 janvier 2016 14:49
> À : users@felix.apache.org
> Objet : Re: Specifying dependency between a bundle and a fragment bundle
>
> Conceptually I guess you can put it that way, yes.
>
> On Wed, Jan 13, 2016 at 2:43 PM, CLEMENT Jean-Philippe <
> jean-philippe.clement@fr.thalesgroup.com> wrote:
>
> > Do you mean ensure that fragments and services are deployed as a
> > single transaction?
> >
> > JP
> >
> > [@@ OPEN @@]
> >
> >
> > -----Message d'origine-----
> > De : Milen Dyankov [mailto:milendyankov@gmail.com] Envoyé : mercredi
> > 13 janvier 2016 13:57 À : users@felix.apache.org Objet : Re:
> > Specifying dependency between a bundle and a fragment bundle
> >
> > Thank you for your thoughts regarding replacing the service. However
> > that is not really my concern. There are 2 aspects in the picture -
> > the service itself and the UI to communicate with it.
> > In traditional layered architecture one would refer to those as
> > service layer an UI layer. Both are developed independenty and in more
> > complex scenarios there could be N bundles providing UIs for working
> > with M bundles providing services. In non-OSGi environment if I start
> > application having correct modules (jar files and resources on the
> > classpath) at runtime, I am kind of guaranteed to have a consistent
> > change in both layers. In OSGi (or any dynamic modular system I guess)
> > one change can be applied and the other one not (due to configuration,
> > resolve issues, removed dependencies, ...) which can lead to UI
> > functionality not matching the actual underlying services providing
> > it. So what I'm struggling with is finding a way to keep the changes
> > consistent across both layers. As in this particular case the changes
> > to the UI layer are applied via fragment bundles and the changes to
> > the service layer are applied by providing "regular" bundles, I'm
> > looking for a way to express the relationship between those. I guess
> > using Requirements and Capabilities would be perfect but to my
> understanding you can not use it for fragments.
> >
> >
> >
> > On Wed, Jan 13, 2016 at 1:24 PM, CLEMENT Jean-Philippe <
> > jean-philippe.clement@fr.thalesgroup.com> wrote:
> >
> > > I'm not too sure what you need, but I would say first that you
> > > consider what you have (a text file) rather than what you need (a
> > > service or services). It seems you see things through the provider
> > > instead of the consumer.
> > >
> > > So, you have a button which calls a service S. Fine. Then you want S
> > > to be the best service. So you just have to implement a service S
> > > which is a proxy to T services and which will forward calls to the
> > > best
> > T service.
> > >
> > > You can even reuse S instead of another T service. So, S is a proxy
> > > to other S services. The proxy has the better ranking in order the
> > > button to "find it". The proxy has to exclude itself from S service
> candidates.
> > >
> > > ...just a quick thought...
> > >
> > > JP
> > >
> > > [@@ OPEN @@]
> > >
> > > -----Message d'origine-----
> > > De : Milen Dyankov [mailto:milendyankov@gmail.com] Envoyé : mercredi
> > > 13 janvier 2016 11:10 À : users@felix.apache.org Objet : Specifying
> > > dependency between a bundle and a fragment bundle
> > >
> > > Lets say I have a UI bundle that renders a button from template. The
> > > template is just a text file(s) inside UI bundle. Clicking the
> > > button calls a service (for the purpose of this example say one with
> > > the
> > highest rank).
> > >
> > > The requirement is: change both the service that is called and the
> > > button in consistent manner.
> > >
> > > The first part is easy:
> > >  - To change the service one can simply provide a new bundle (call
> > > it
> > > S) containing the new service implementation (with higher rank or
> > > whatever else it takes to make it the one that service registry will
> > > give to the UI bundle).
> > >  - To change the button (or even replace it with something else) one
> > > can provide a fragment bundle (call it FB) with updated template
> file(s).
> > >
> > > The question is, how to keep those consistent? That is, make sure
> > > that either both S and FB are applied or none of them (lets assume S
> > > will somehow ensure the service is registered or stop itself if it
> > > can't do
> > so)!
> > >
> > > It seams one needs to somehow declare a bidirectional dependency (I
> > > hate the way it sounds, but that's what it in fact is, isn't it)
> > > between a bundle and a fragment bundle. AFAIK this is not really
> > > possible as anything specified in fragment is applied to the host!
> > > Has anyone faced similar challenge before?
> > >
> > >
> > > --
> > > http://about.me/milen
> > >
> > > --------------------------------------------------------------------
> > > - To unsubscribe, e-mail: users-unsubscribe@felix.apache.org
> > > For additional commands, e-mail: users-help@felix.apache.org
> > >
> >
> >
> >
> > --
> > http://about.me/milen
> >
> > ---------------------------------------------------------------------
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> >
>
>
>
> --
> http://about.me/milen
>



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