JBoss Microcontainer

With the release of JBoss Application Server 5 (after three years, unbelievable!), I came across the JBoss Microcontainer subproject. It’s a standalone container independent of the application server. Besides the obvious IoC, it supports AOP and deployment of all sorts of components, from OSGi bundles and old-style MBeans to JARs with Spring or Guice objects. If you’re wondering whether it can combine those models, here’s the answer.

Yes, and that’s the beauty of it. Since all the components in JBoss irrespective of type (POJOs, MBean, Spring Beans, OSGi bundles, etc.) share the same back-plane they have the potential of being wired together by the MicroContainer with dependencies and aspects applied across the different component models. We are still at the early stages of understanding the capabilities and limits of the MicroContainer technology, designed by our mastermind Adrian Brock, but the possibilities look certainly very interesting.

It sounds interesting on paper. But the idea of mixing everything together, OSGi bundles and POJOs described in Spring and Guice, makes me wonder whether it’ll turn out like the cake baked by the little dog and cat. And what looks easy in simple cases may fall down in the harder cases we almost always encounter…

On the other hand, it’s good to have another application server supporting OSGi as a deployment model. You’ll find a list of the others in OSGi in the Enterprise.

Sources

• Releasing JBoss AS 5: Q&A with Project Lead Dimitris Andreadis
• A Look Inside the JBoss Microcontainer, Part I — Component Models