Talk given at JavaOne 2009 discussing how to build web applications using OSGi. The source for the demo found at http://github.com/mrdon/jforum-plugins/tree/master Session Abstract: Enterprise Web applications tend to grow like weeds in monolithic complexity. OSGi, although more often associated with Java™ technology-based clients and application servers, can bring a new level of modularity, uptime, and stability that is needed with today's always-on hosted Web applications. OSGi gets really interesting when the pretty architecture diagrams meet the real world, because it consists of various deployment platforms, development environments, and application architectures. This presentation, for Java 2 Platform, Enterprise Edition (J2EE™ platform)-savvy architects and senior developers, provides a practical guide to the Web on OSGi, from integration approach to bundle development, to real-world code you can use today. The session discusses • What benefits OSGi brings to the J2EE platform • Three integration strategies • How to use Spring DM and Maven to ease development • Lessons learned from Atlassian's recent OSGi deployment • A production-ready example to use immediately

1. OSGi on the Web: Here’s How Don Brown Atlassian

6. Raising the abstraction with Struts

7. Raising the abstraction with OSGi

8. Why we needed OSGi

9. One feature * five products = Dashboard

10. Multiple teams across the globe Gda ń sk, Poland San Francisco, USA Kuala Lumpur, Malaysia Sydney, Australia

17. Sandboxed plugins

18. Architecture options

24. Services: The old school reality public class MovieFinderTracker extends ServiceTracker { private final MovieListerImpl lister = new MovieListerImpl(); private int finderCount = 0; private ServiceRegistration registration = null; public MovieFinderTracker(BundleContext context) { super(context, MovieFinder.class.getName(), null); } private boolean registering = false; public Object addingService(ServiceReference reference) { MovieFinder finder = (MovieFinder) context.getService(reference); lister.bindFinder(finder); synchronized(this) { finderCount ++; if (registering) return finder; registering = (finderCount == 1); if (!registering) return finder; } ServiceRegistration reg = context.registerService( MovieLister.class.getName(), lister, null); synchronized(this) { registering = false; registration = reg; } return finder; } public void removedService(ServiceReference reference, Object service) { MovieFinder finder = (MovieFinder) service; lister.unbindFinder(finder); context.ungetService(reference); ServiceRegistration needsUnregistration = null; synchronized(this) { finderCount --; if (finderCount == 0) { needsUnregistration = registration; registration = null; } } if(needsUnregistration != null) { needsUnregistration.unregister(); } } }

33. Plugins architecture

35. Available modules General Confluence JIRA Servlet Job Search Servlet filter Macro Custom field Link Theme Issue tab Link section Workflow Portlet REST (JAX-RS) Language pack RPC Component Editor Workflow Component import Event listener User format Module type RPC Report

39. DEMO: Using Atlassian Plugins http://atlassian.com/opensource

40. Lessons learned

46. Questions

47. Don Brown [email_address]