Re: Improving support for running in OSGi

[Raymond Feng]

More comments inline.

Thanks,
Raymond
--------------------------------------------------
From: "Graham Charters" <[EMAIL PROTECTED]>
Sent: Wednesday, April 30, 2008 9:43 AM
To: <tuscany-dev@ws.apache.org>
Subject: Re: Improving support for running in OSGi
2008/4/30 Raymond Feng <[EMAIL PROTECTED]>:
"Enforcing" the modularity via OSGi is a good way to validate our
modularity/extensibility story in Tuscany. I think we already have a 
fairly
well organized module structure in Tuscany (from the maven dependency
perspective). To be consistent, should we consider directly mapping our
module structure into OSGi bundles (one bundle per existing Tuscany 
module)?


I wonder if that might be too fine-grained and unmanageable.
Personally, I'd prefer an approach which took into consideration how
we see folks extending or sub-setting the runtime (e.g. the things
Yang referred to - implementation types, etc.).


IMHO, big bundles lead to defeat modularity and increase coupling. It also 
become difficult to embed subset of the Tuscany runtime. But anyway, we can 
adjust the scheme over time as the picture becomes clearer.

 There may be different levels for the OSGi enablement.

 1) Add OSGi entries to the META-INF/MANIFEST.MF so that Tuscany jars can 
be
consumed as OSGi bundles
 2) Run Tuscany bundles with an OSGi runtime (using OSGi as the
modularization mechanism for the Tuscany runtime, system level)

I think we need this step to occur regularly and frequently to stop
the support decaying.  I've fixed these kinds of issues twice in the
last week, which occur because new modules are added to Tuscany, but
not the OSGi support (not surprising since the OSGi support is outside
the main build).


Is there a checklist we can use to make sure new modules or changes won't 
break the OSGi support? If not, can we produce one and post it to the 
Tuscany wiki?

 3) Support OSGi bundles as SCA contributions (application level, how 
does
the OSGi import/export relate to the sca-contributions.xml?).

 The other interesting issue is how we deal with the 3rd party jars, most 
of
which are not OSGi bundles. To support the case that different Tuscany
extensions may require different versions of the same 3rd party jar, we 
need
to figure out a good way to "turn" 3rd party jars into OSGi bundles.


This is a knotty problem.  It's not a new problem and is discussed
here:  https://mail.osgi.org/pipermail/jsr-291-eg/2006-March/000023.html

Licensing and signing can prevent us from adding information to the
jars, which leaves us with three options, I think:

1.  Create wrapper bundles which contain the jars, which raises
concerns about disk space.
2.  Use a non-OSGi mechanism to refer to jars outside a bundle
(Equinox allows this).
3.  Devise a new mechanism to create 'virtual bundles' on the fly (see
https://www.osgi.org/members/bugzilla/show_bug.cgi?id=277).


Unfortunately, the URL requires a log-in. Is it possible to post the content 
here?

3 might be the best solution longer term, but is the most work.

 Thanks,
 Raymond

 --------------------------------------------------
 From: "Yang Lei" <[EMAIL PROTECTED]>
 Sent: Tuesday, April 29, 2008 9:09 PM
 To: <tuscany-dev@ws.apache.org>
 Subject: Re: Improving support for running in OSGi




> I think enabling OSGI can help modularity with a clear definition of
> package visibility, so we can have a much cleaner "module"
> dependencies through osgi bundle import/export on package.   I think
> it will help Tuscany adopters a lot in the scenarios such as: when
> implementing new implementation type, binding type, or data binding
> types, there is clear indication which set of packages can be used
> (exported API/SPI ). So upgrading to new Tuscany level can be as
> simple as plug and play if there is no API/SPI changes, and  version
> control (multiple version co-existence) can also be made available
> through OSGI capabilities.
>
> Regards,
>
> Yang
>
> On Tue, Apr 29, 2008 at 1:49 PM, Konradi, Philipp (CT)
> <[EMAIL PROTECTED]> wrote:
>
> > Hi,
> >
> > > I'd like to get people's thoughts on whether the idea of 
> > > 'promoting'
> > > OSGi is a good one,
> > IMHO support of OSGi is very important and I glad to see increasing
interest of the community here.
> >
> > > and get ideas on how best to proceed.
> > I personally have currently not a very deep insight into 
> > implementation
details yet, but we are currently prototyping and have there also OSGi
services.
> > What I could offer today is only to feed our findings about 
> > limitations
and rooms for improvement back.
> > Another important thing which I see on the horizon, is the ongoing
standardization of Distributed OSGi (RFC119) and the benefit to support 
that
standard in Tuscany's OSGi bits. So from mid-term perspective I suggest 
to
keep an eye on that as well.
> >
> > Regards,
> > Philipp
> >
> > -----Ursprüngliche Nachricht-----
> > Von: Graham Charters [mailto:[EMAIL PROTECTED]
> > Gesendet: Montag, 28. April 2008 09:48
> > An: tuscany-dev@ws.apache.org
> > Betreff: Improving support for running in OSGi
> >
> >
> > Hi All,
> >
> > I'd like to get more involved in the OSGi support in Tuscany (both 
> > the
> > modularity work (itest/osgi-tuscany) and the implementation.osgi).  I
> > recently started looking at the work to run Tuscany in OSGi, embodied
> > in itest/osgi-tuscany and described in the thread entitled
> > "Classloading in Tuscany".  I've noticed a couple of others on the
> > list also interested in Tuscany running in OSGi and wondered if it
> > might be worth considering making this a "first-class" option.  At 
> > the
> > moment the five bundles are only built by folks who want the OSGi
> > support and go into the itest/osgi-tuscany directory to create it.
> > This can result in any problems being discovered late, but also could
> > create the impression that OSGi is considered a second-class
> > environment (which I don't believe is the case).
> >
> > Aside from the obvious benefits to OSGi users in doing this, I think
> > there's a potential for Tuscany to use the OSGi build as a test-bed
> > for highlighting and working through modularity issues, which would
> > also benefit Tuscany in general, not just in an OSGi runtime.
> >
> > I'd like to get people's thoughts on whether the idea of 'promoting'
> > OSGi is a good one, and get ideas on how best to proceed.  We could
> > then start discussing what some of the issues might be (e.g. size of
> > builds, time to build, etc...).
> >
> > Regards,
> >
> > Graham.
> >
> >
>