"Eclipse, Equinox, and OSGi" by Jeff McAffer and Simon Kaegi shows how the Eclipse Equinox modular runtime works, from Eclipse' perspective, and then discusses how Equinox can be embedded in a serverside application.

Both Equinox and OSGi are seeing a surge in interest from a wide range of communities from embedded, the traditional domain of OSGi, to desktop tools and applications to mobile devices and servers. The server side work is of particular interest. The Equinox project has a server side effort that seeks to integrate the dynamic module capabilities of OSGi into standard application server scenarios. There are two main approaches; embedding Equinox in the servlet container or embedding the servlet container in Equinox. To a large extent, the choice made here does not impact your server application or functionality. The choice is more a function of the infrastructure needs of your environment.

I for one can't wait to see an app server that uses OSGi as its underlying component model. Add the spring integration of OSGi and you've got a JBoss killer.

I for one can't wait to see an app server that uses OSGi as its underlying component model.

IBM Websphere 6.1 uses OSGI: $WEBSPHERE_HOME/plugins/org.eclipse.osgi_3.1.2.jar In Websphere 6.1, the server components are located in the plugins folder: plugins/com.ibm.ws.runtime_6.1.0.jar plugins/com.ibm.ws.webcontainer_2.0.0.jar plugins/com.ibm.ws.portletcontainer_2.0.0.jar etc.

http://publib.boulder.ibm.com/infocenter/ieduasst/v1r1m0/index.jsp?topic=/com.ibm.iea.was_v6/was/6.1/Architecture/WASv61_Componentization/player.html

Okay... let me rephrase that... I for one can't wait to see an affordable, easy to use app server that uses OSGi as its underlying component model. :)

ROTFLMAO ;-) +1

I'm a developer on the Newton project, which might be of interest to you. Newton provides a lightweight OSGi based component model with support for dynamic deployment of applications across multiple JVMs and IOC style wireup of their dependencies. Support for Spring based components is available. See http://newton.codecauldron.org for info, downloads etc.

Newton provides a lightweight OSGi based component model ...

I have read that Newton also uses Jini. Could you elaborate more on: - Why use OSGI and Jini, and not Jini only? - What are the differences from project Rio?

Why use OSGI and Jini, and not Jini only?

Jini provides an inter-VM services model. OSGi complements this with an intra-VM services model. Also, OSGi's use of bundles and their peer based approach to classloading provides us with the ability to deploy and undeploy services in a very fine grained manner, to automate a great deal of dependency resolution and provisioning, and to avoid the ordering and class mismatch problems which are frequently encountered when using traditional hierarchically arranged classloaders. Actually - for us the real question is why use OSGi and Jini, and not OSGi only? The answer is that as yet there is no suitable all OSGi remoting solution.

What are the differences from project Rio

They are really quite different projects, although I can see why you have linked them. Rio is very much oriented around Jini. It makes using Jini to create distributed systems a lot easier and has some very nice dynamic provisioning, monitoring and recovery capabilities. Newton is fundamentally OSGi based, and makes use of Jini for native remoting. This gives Newton the ability to deploy composite applications to a single VM as well as across multiple VMs. It also means that Newton can use Bundle metadata to statically analyse and deploy service dependencies. Newton systems are described using the emerging SCA standard. Newton's provisioning system dynamically deploys, monitors and maintains distributed systems based on their SCA description and SLA requirements. Newton wires up service dependencies IOC style. Newton's provisioning system is self maintaining - i.e. if part of it fails the other parts reprovision it. It is difficult to do justice to either project in a short post so for more information the best thing would be to look at the two projects' websites and examples at http://newton.codecauldron.org and https://rio.dev.java.net

Jonas, ObjectWeb's open source Java EE implementation will integrate OSGi as the base of its core architecture in its next release (Jonas 5) scheduled for February 2007. There are already 2 working prototypes that can be downloaded from https://wiki.objectweb.org/jonas/Wiki.jsp?page=JONAS5 The specifics of the integration of OSGi to Jonas are presented in http://objectwebcon06.objectweb.org/xwiki/bin/download/Main/DetailedSession/M-Desertot-T-Abdellatif.pdf For those interested, the general ideas of the integration of the service approach inside the application server were presented in Mikael Desertot, Didier Donsez and Philippe Lalanda A Dynamic Service-Oriented Implementation for Java EE Servers Published 3th IEEE International Conference on Service Computing, SCC'06 September 2006, Chicago, USA

As mentioned in JSR 277 " The R3 version of the Open Services Gateway Initiative (OSGi) specification defines a framework that enables the deployment of service-oriented applications (called bundles). However, the framework only supports package dependency based on the minimum version of a specification, and there is no support for exact version or version range. The framework also supports package dependency based on an implementation, but there is no support for versioning. Moreover, the framework must choose one bundle that will be the provider of the exported package for all bundles which have dependencies on that package, so it is impossible to support more than one version of shared package at runtime. Besides, the selection of exported package provider is anonymous, and there is no way to influence the selection. Because the versioning semantics in the OSGi R3 framework is simplistic, it is not a sufficient solution to address the JAR referencing problem."

version ranges, including exact matches. package scopes and bundle scopes. A.

If you are interested in OSGi for the server side, you can have a look at Nuxeo Runtime (http://www.nuxeo.org/sections/projects/runtime/). It is powering Nuxeo Enterprise Platform (our Open Source ECM platform: http://www.nuxeo.org/). Components are OSGi bundles that can mutually extend themselves using extension point (in the spirit of Equinox). Those components can then run directly on Equinox (in Eclipse RCP) or on the server side using JBoss thanks to the OSGi adapter for JBoss provided by Nuxeo Runtime (other application servers are planned to be supported). Thanks, EB.