Portlets and OSGi

OSGi is today used in many places, for desktop applications, complex application servers and even for web applications. But what about portlets?
In the last weeks I developed some portlets for our product offerings. The portlets allow you to display, edit and manage content inside a JSR 286 (portlet API 2.0) compliant portal server. As our whole product offering is based on OSGi for the obvious reasons, I thought about using the same technology for implementing the portlets.
By using the great Apache Felix implementation, togther with some of the nice things we developed in the Apache Sling project I could easily manage to start the OSGi framework inside the portlet web application. A simple generic portlet implementation running outside the OSGi world receives the portlet calls, like events, actions and render invocations. This generic portlet just forwards them to a receiving portlet running as an OSGi service. Once you are inside the OSGi world you can use all the benefits of OSGi for your implementation and it was quite simple to develop the “real” portlets. Besides using the same base for all of our products and being able to reuse stuff through well defined bundles and services, one of the main advantages during development has been the easy update of the portlet code. While the whole portal application has been deployed to some portal container, updating the portal did not require an update/redeployment of the portal web application. Just updating a bundle through OSGi is enough and your new code is deployed. This makes the development and testing way faster.
I really don’t want to miss OSGi in everyday development, it creates clear boundaries, enables real modularization and reuse and makes the development much easier. Start your server once and just update the parts that have changed. No need to restart, no need to update the whole application. Priceless!