Thanks a lot Joel. I'm kind of out just checking email once and a
while until Monday so when I get back I'll commit the patch and we
can talk some more.
Jim
On Aug 10, 2006, at 1:06 PM, Joel Hawkins (JIRA) wrote:
[ http://issues.apache.org/jira/browse/TUSCANY-610?
page=comments#action_12427336 ]
Joel Hawkins commented on TUSCANY-610:
--------------------------------------
Hi Thomas.
I'm trying to write up some documentation now. In short, however,
the code breaks down into 2 parts:
1. The OSGi hosting of the SCA core. This is a bundle that
bootstraps SCA instances for bundles that have SCA components (scdl
files). The host makes a distinction between system extension and
applications. For example, the OSGi binding code that supports
interacting with the OSGi service framework is packaged as a system
extension. The samples are packaged as applications. To me, these
application instances feel like web apps.
2. The OSGi Services system extension, which in turn has two major
parts:
a. An OSGi Service binding, which allows SCA components to be
exposed as OSGi services. This is pretty straightforward. The only
tricky bit (assuming away the intricacies of SCA's wiring) is
dealing with the need for a ServiceFactory during service
registration. This is added to the target class using a dynamic
proxy if required.
b. An OSGi implementation, which wraps OSGi services as SCA
components, allowing them to be wire in seamlessly (once I'm
done :-) )into SCA applications. This binding allows the
specification of a filter for aquiring an appropriate service
reference, and acts as a service listener to clean up stale
references. The code currently attempts to rebind the service if
the service has changed (using the same reference) or gone away
(using a different reference). Not sure if this is desirable in all
cases, but it gives good demo. :-)
Please remember this is an 'initial' implementation! There's enough
code to get my simple scenarios working - but I'm sure there's
plenty left to do. Also, the recent work that's been checked in to
have some of the wiring handled by the wire service probably means
some of this code can go away.
Some of the things I like about the combination of SCA and OSGi is
that OSGi services provide a really simple and efficient way to
communicate between SCA applications running in a single OSGi
instance, and OSGi's bundle isolation characteristics make dealing
with multiple application deployments much more "deterministic".
From my perspective (having a toe dipped in both worlds), SCA and
OSGi look really complementary.
I'll also try and package the rest of my eclipse environment so
that you can get this running. It's mostly bundle-izing the
required Tuscany jars.
Initial OSGi support effort
---------------------------
Key: TUSCANY-610
URL: http://issues.apache.org/jira/browse/TUSCANY-610
Project: Tuscany
Issue Type: New Feature
Environment: Equinox implementation of OSGi
Reporter: Joel Hawkins
Attachments: ClassloaderHook.java, OSGI-SCA.zip
An initial implementation of an OSGi binding for exposing SCA
services as OSGi services.
An initial implementation of an OSGi implementation for reusing
OSGi services as SCA atomic components
An OSGi-aware bootstrap environment (which can probably be reduced
a bit)
A repackaging of some of the SupplyChain example
There's one class derived from an EPL-copyrighted class - I left
the EPL copyright intact.
The zip contains the samples, the OSGi binding, and a patch for
the core. Most of the patch is the OSGi launcher code. I don't
think it belongs in the core, but that's where I had it while
developing. The only other bit in the patch is a change of two of
the Defaultbootstrapper's fields from private to protected.
Also, some of the OSGi packaging for existing jars (spi, commands,
etc) aren't part of the zip. Not sure how you want to deal with
the repackaging issue.
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