OSGi bundles as SOAP web services in a plugin architecture

Question

I would like to expose OSGi bundles as SOAP web services or in other words publish web service endpoints which are provided by OSGi bundles.

The architectural model/idea is that there is a host web application which is a normal war file deployed on JBoss (5.1.0 GA) offering a SOAP web service interface (JAX-WS).
This host application starts the OSGi framework embedded (via ServletContextListener - currently Equinox) and loads a number of OSGi bundles which function as plugins.
The plugin bundles have a dependency to the host application as part of the request processing is delegated to them via internally defined interfaces.
At the same time the plugin bundles should also be able to contribute an own public SOAP web service interface (endpoint implementations and the respective WSDL files to be published and made available by the application server).

The first approach we followed was that the host web application deploys a dispatcher/proxy servlet which delegates the processing to the relevant endpoints provided by the OSGi bundles.
There is the servlet bridge solution in OSGi/Equinox (BridgeServlet/HTTPServiceServlet) which enables the programmatic registration of servlets (for ex. in BundleActivators of the plugin bundles) using the HTTP Service specification.
The problem is that I have SOAP-based web service endpoints and would need to be able to wrap them in a javax.servlet.Servlet implementation.
That's usually an interna of the WS stack implementations of Java EE 5 servers which follow the servlet–based web services approach (endpoints defined as servlets in web.xml) and internally use to install native endpoint servlets for web service endpoints.
I did not find such a public endpoint servlet implementation which could be registered with the HTTP Service (maybe something similar like com.sun.jersey.spi.container.servlet.ServletContainer which can be used to publish REST-based services for JAX-RS applications in OSGi)
I am a little surprised that I did not find as much about registering SOAP-based WS endpoints with the OSGi HTTP Service or may be I do not see the obvious.

I have found something similar, JAX-WS-Commons/Spring (spring support for configuring JAX-WS, http://jax-ws-commons.java.net/spring/ ), which internally uses the class WSServletDelegate of the JAX-WS RI (metro) to process web requests for the endpoints. But I am not sure about it, it seems kind of deprecated and I need to provide the metro WS stack jars to JBoss (or in the war file) in order to make it work on JBoss 5.1.0 GA.

Another approach seems to be distributed OSGI, which allows to publish OSGi services for remote access.
However, I could not find clear information about how to provide these services as web services on JBoss.

Other realisation aspects are:

• we are bound to JBoss 5.1.0 GA and changes to the JBoss configuration should be as minimal as possible (in order to have minimal constraints to the setup of our customers)
• All web services are developed contract-first which means that the original WSDL's are to be used by the providing container.
• the plugin components should be as simple as possible concerning dependencies or technologies (in order to have minimal requirements to the skill of the plugin developers)
• we use Spring 3 and Gemini Blueprint.

Finally, there are some ambiguities and unclear aspects and unfortunately I could not find reports on projects with similar requirements.

So, I would be eager to hear some suggestions or comments of the experts.
Maybe there are options I don't see, or maybe somebody has realised similar projects before and likes to share experiences.
Thanks a lot.

Answer 1

I am not an expert but another approach I have seen is to put the whole app server with an application into the OSGi container. It is an option in Sling launchpad http://sling.apache.org/documentation/the-sling-engine/architecture.html#launchpad

HTH