InfoQ has a discussion thread summarizing the reactions to the announcement of the SpringSource Application Plaform. Michael Burke asked a great question on that thread which can be paraphrased as “forgetting the hype surrounding OSGi, what benefits can I expect to see if I port an application currently packaged as an EAR to OSGi bundles?”.
I started answering this question on the InfoQ thread, but my answer was growing too long for a comment so instead I’ll address it here.
The question is a good one. The main difference you will see in an OSGi-based application versus a traditional JEE EAR-based application is improved modularity. So the question becomes, does this improved modularity bring me any benefits, and if so what are they? The book “Design Rules, The Power of Modularity” gives a very thorough treatment of the question. It’s great background but I get that feeling that Michael may be looking for something a little less theoretical than what you’ll find in that book! Let’s break the modularity benefits down into two categories: benefits you should expect to experience during development time, and benefits you should expect to experience during runtime: