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Posted to oak-dev@jackrabbit.apache.org by Dominique Pfister <dp...@adobe.com> on 2014/07/15 22:23:06 UTC
Multiple oak repositories using an OSGI whiteboard
Hi,
I'd like to setup two distinct Oak repositories in the same VM, each containing an OSGI whiteboard.
Looking at the components inside oak-core that announce their availability using this whiteboard and the way the registration is implemented in the OSGI whiteboard, I was wondering whether above setup is possible without causing a clash in the OSGI service registry. If so, what would be the easiest way to create separate "namespaces" where every component is automatically associated with its designated whiteboard?
Kind regards
Dominique
Re: Multiple oak repositories using an OSGI whiteboard
Posted by Carsten Ziegeler <cz...@apache.org>.
Hi,
2014-07-16 7:59 GMT-07:00 Dominique Pfister <dp...@adobe.com>:
> Hi,
>
> Thanks everybody for their responses.
>
> Yes, there is some special code looking up the second repository, and I
> thought about registering the second repository with a separate interface,
> so it can still be bound. My concern, however, is what happens with all the
> "inner" components, that are not directly coupled to the repository but
> rather registered in a whiteboard, and still contribute to the correct
> functioning.
>
> To be more precise, let's say I'd like to create 1 oak repository of type
> Tar (T) and 1 of type Mongo (M): I give T an OSGI whiteboard, while M gets
> a default implementation that doesn't register its services in OSGI. Let's
> further say that the construction code of T @References an oak OSGI
> component (e.g. SecurityProvider), while M constructs one programmatically
> (e.g. an instance of type SecurityProviderImpl). Would this cause an
> interference, e.g. could the one explicitly built for M also be implicitly
> used for T?
>
> I assume that you don't register any of the constructed services for M in
the service registry - therefore there shouldn't be an interference as T
will never see those services through the whiteboard pattern.
Regards
Carsten
> Thanks
> Dominique
> ________________________________________
> From: Carsten Ziegeler <cz...@apache.org>
> Sent: Wednesday, July 16, 2014 3:50 PM
> To: oak-dev@jackrabbit.apache.org
> Subject: Re: Multiple oak repositories using an OSGI whiteboard
>
> As David points out subsystems might help our writing your own service
> registry hooks.
> If you're not using one of those, you have a flat/shared service registry
> and usually services using a repository service just pick up one from the
> service registry and that's the one with the highest ranking at the point
> of asking the registry. Therefore repository services which are registered
> after this point in time are not even considered and there is no rebinding
> (unless e.g. DS is used with a greedy reference). As you don't want to
> rewrite all the code using a repository service, namespacing is the only
> option.
> However, the question is, what do you do with this second repository
> service? Is there special code just looking up the second repository? Maybe
> in that case, the simpler option could be to register the repository with a
> different service interface - something like a marker interface
> SecondaryRepository etc. (maybe with a better name)
>
> Regards
> Carsten
>
>
> 2014-07-16 3:08 GMT-07:00 David Bosschaert <da...@gmail.com>:
>
> > Hi Dominique,
> >
> > You could look into OSGi Application Subsystems (OSGi Enterprise Spec
> > 5 chapter 134). Application subsystems provide separate namespaces and
> > by default don't share out services. Other subsystem types include
> > Feature subsystems (where everything is shared) and Composite
> > subsystems where you define explicitly what is shared and what is not.
> >
> > I wrote a blog a while ago on how to get Apache Aries subsystems
> > running on Apache Felix, which might be useful:
> >
> >
> http://coderthoughts.blogspot.com/2014/01/osgi-subsytems-on-apache-felix.html
> >
> > Alternatively you can create your own service namespaces by using OSGi
> > Service Registry hooks, but these are a bit more low-level than
> > subsystems...
> >
> > Best regards,
> >
> > David
> >
> > On 15 July 2014 21:23, Dominique Pfister <dp...@adobe.com> wrote:
> > > Hi,
> > >
> > >
> > > I'd like to setup two distinct Oak repositories in the same VM, each
> > containing an OSGI whiteboard.
> > >
> > >
> > > Looking at the components inside oak-core that announce their
> > availability using this whiteboard and the way the registration is
> > implemented in the OSGI whiteboard, I was wondering whether above setup
> is
> > possible without causing a clash in the OSGI service registry. If so,
> what
> > would be the easiest way to create separate "namespaces" where every
> > component is automatically associated with its designated whiteboard?
> > >
> > >
> > > Kind regards
> > >
> > > Dominique
> >
>
>
>
> --
> Carsten Ziegeler
> Adobe Research Switzerland
> cziegeler@apache.org
>
--
Carsten Ziegeler
Adobe Research Switzerland
cziegeler@apache.org
RE: Multiple oak repositories using an OSGI whiteboard
Posted by Dominique Pfister <dp...@adobe.com>.
Hi,
Thanks everybody for their responses.
Yes, there is some special code looking up the second repository, and I thought about registering the second repository with a separate interface, so it can still be bound. My concern, however, is what happens with all the "inner" components, that are not directly coupled to the repository but rather registered in a whiteboard, and still contribute to the correct functioning.
To be more precise, let's say I'd like to create 1 oak repository of type Tar (T) and 1 of type Mongo (M): I give T an OSGI whiteboard, while M gets a default implementation that doesn't register its services in OSGI. Let's further say that the construction code of T @References an oak OSGI component (e.g. SecurityProvider), while M constructs one programmatically (e.g. an instance of type SecurityProviderImpl). Would this cause an interference, e.g. could the one explicitly built for M also be implicitly used for T?
Thanks
Dominique
________________________________________
From: Carsten Ziegeler <cz...@apache.org>
Sent: Wednesday, July 16, 2014 3:50 PM
To: oak-dev@jackrabbit.apache.org
Subject: Re: Multiple oak repositories using an OSGI whiteboard
As David points out subsystems might help our writing your own service
registry hooks.
If you're not using one of those, you have a flat/shared service registry
and usually services using a repository service just pick up one from the
service registry and that's the one with the highest ranking at the point
of asking the registry. Therefore repository services which are registered
after this point in time are not even considered and there is no rebinding
(unless e.g. DS is used with a greedy reference). As you don't want to
rewrite all the code using a repository service, namespacing is the only
option.
However, the question is, what do you do with this second repository
service? Is there special code just looking up the second repository? Maybe
in that case, the simpler option could be to register the repository with a
different service interface - something like a marker interface
SecondaryRepository etc. (maybe with a better name)
Regards
Carsten
2014-07-16 3:08 GMT-07:00 David Bosschaert <da...@gmail.com>:
> Hi Dominique,
>
> You could look into OSGi Application Subsystems (OSGi Enterprise Spec
> 5 chapter 134). Application subsystems provide separate namespaces and
> by default don't share out services. Other subsystem types include
> Feature subsystems (where everything is shared) and Composite
> subsystems where you define explicitly what is shared and what is not.
>
> I wrote a blog a while ago on how to get Apache Aries subsystems
> running on Apache Felix, which might be useful:
>
> http://coderthoughts.blogspot.com/2014/01/osgi-subsytems-on-apache-felix.html
>
> Alternatively you can create your own service namespaces by using OSGi
> Service Registry hooks, but these are a bit more low-level than
> subsystems...
>
> Best regards,
>
> David
>
> On 15 July 2014 21:23, Dominique Pfister <dp...@adobe.com> wrote:
> > Hi,
> >
> >
> > I'd like to setup two distinct Oak repositories in the same VM, each
> containing an OSGI whiteboard.
> >
> >
> > Looking at the components inside oak-core that announce their
> availability using this whiteboard and the way the registration is
> implemented in the OSGI whiteboard, I was wondering whether above setup is
> possible without causing a clash in the OSGI service registry. If so, what
> would be the easiest way to create separate "namespaces" where every
> component is automatically associated with its designated whiteboard?
> >
> >
> > Kind regards
> >
> > Dominique
>
--
Carsten Ziegeler
Adobe Research Switzerland
cziegeler@apache.org
Re: Multiple oak repositories using an OSGI whiteboard
Posted by Carsten Ziegeler <cz...@apache.org>.
As David points out subsystems might help our writing your own service
registry hooks.
If you're not using one of those, you have a flat/shared service registry
and usually services using a repository service just pick up one from the
service registry and that's the one with the highest ranking at the point
of asking the registry. Therefore repository services which are registered
after this point in time are not even considered and there is no rebinding
(unless e.g. DS is used with a greedy reference). As you don't want to
rewrite all the code using a repository service, namespacing is the only
option.
However, the question is, what do you do with this second repository
service? Is there special code just looking up the second repository? Maybe
in that case, the simpler option could be to register the repository with a
different service interface - something like a marker interface
SecondaryRepository etc. (maybe with a better name)
Regards
Carsten
2014-07-16 3:08 GMT-07:00 David Bosschaert <da...@gmail.com>:
> Hi Dominique,
>
> You could look into OSGi Application Subsystems (OSGi Enterprise Spec
> 5 chapter 134). Application subsystems provide separate namespaces and
> by default don't share out services. Other subsystem types include
> Feature subsystems (where everything is shared) and Composite
> subsystems where you define explicitly what is shared and what is not.
>
> I wrote a blog a while ago on how to get Apache Aries subsystems
> running on Apache Felix, which might be useful:
>
> http://coderthoughts.blogspot.com/2014/01/osgi-subsytems-on-apache-felix.html
>
> Alternatively you can create your own service namespaces by using OSGi
> Service Registry hooks, but these are a bit more low-level than
> subsystems...
>
> Best regards,
>
> David
>
> On 15 July 2014 21:23, Dominique Pfister <dp...@adobe.com> wrote:
> > Hi,
> >
> >
> > I'd like to setup two distinct Oak repositories in the same VM, each
> containing an OSGI whiteboard.
> >
> >
> > Looking at the components inside oak-core that announce their
> availability using this whiteboard and the way the registration is
> implemented in the OSGI whiteboard, I was wondering whether above setup is
> possible without causing a clash in the OSGI service registry. If so, what
> would be the easiest way to create separate "namespaces" where every
> component is automatically associated with its designated whiteboard?
> >
> >
> > Kind regards
> >
> > Dominique
>
--
Carsten Ziegeler
Adobe Research Switzerland
cziegeler@apache.org
Re: Multiple oak repositories using an OSGI whiteboard
Posted by David Bosschaert <da...@gmail.com>.
Hi Dominique,
You could look into OSGi Application Subsystems (OSGi Enterprise Spec
5 chapter 134). Application subsystems provide separate namespaces and
by default don't share out services. Other subsystem types include
Feature subsystems (where everything is shared) and Composite
subsystems where you define explicitly what is shared and what is not.
I wrote a blog a while ago on how to get Apache Aries subsystems
running on Apache Felix, which might be useful:
http://coderthoughts.blogspot.com/2014/01/osgi-subsytems-on-apache-felix.html
Alternatively you can create your own service namespaces by using OSGi
Service Registry hooks, but these are a bit more low-level than
subsystems...
Best regards,
David
On 15 July 2014 21:23, Dominique Pfister <dp...@adobe.com> wrote:
> Hi,
>
>
> I'd like to setup two distinct Oak repositories in the same VM, each containing an OSGI whiteboard.
>
>
> Looking at the components inside oak-core that announce their availability using this whiteboard and the way the registration is implemented in the OSGI whiteboard, I was wondering whether above setup is possible without causing a clash in the OSGI service registry. If so, what would be the easiest way to create separate "namespaces" where every component is automatically associated with its designated whiteboard?
>
>
> Kind regards
>
> Dominique
Re: Multiple oak repositories using an OSGI whiteboard
Posted by Tobias Bocanegra <tr...@apache.org>.
Hi Dominique,
I don't think that this is possible, since many of the OSGi services
are kind of singletons. As long OSGi does not offer sandboxing, this
won't be possible.
I think you have better chance starting 2 oaks w/o OSGi. See the
oak-run project for examples.
Regards, Toby
On Tue, Jul 15, 2014 at 1:23 PM, Dominique Pfister <dp...@adobe.com> wrote:
> Hi,
>
>
> I'd like to setup two distinct Oak repositories in the same VM, each containing an OSGI whiteboard.
>
>
> Looking at the components inside oak-core that announce their availability using this whiteboard and the way the registration is implemented in the OSGI whiteboard, I was wondering whether above setup is possible without causing a clash in the OSGI service registry. If so, what would be the easiest way to create separate "namespaces" where every component is automatically associated with its designated whiteboard?
>
>
> Kind regards
>
> Dominique