Bill Kayser of Nagarro recently detailed his experience moving an application to OSGi from a custom infrastructure and build process. In the first of two blog entries on the endeavor, he provides an interesting introduction to OSGi from the perspective of SOA in a JVM. In the second entry he covers the conversion process itself. The driving reasons for moving to OSGi were based on business requirements. However, Kayser was pleasantly surprised by the other benefits that were gained:
...The improvements included but were not limited to:
...To this day team members still come up to me occasionally to thank me for introducing OSGi, often after being reminded what things were like by having to go back to an old release build...
- Going from 25,000 lines of ant code required for a full build down to about 200 lines of boilerplate configuration, plus about 200 lines of custom callbacks,
- We eliminated about seventy class file catalogs used to ensure extra classes were not inadvertently shipped in the wrong jar file or duplicated unnecessarily,
- Reducing the size of application distros by eliminating unused dependencies
- Surfacing previously unknown bugs based on dangling references to missing classes and libraries,
- Eliminating a large body of code devoted to managing extensions with segregated class spaces using custom class loaders.
- Going from managing four different runtime configurations for each application–the IDE classpaths, the IDE launchers, the runtime script classpaths, the build script classpaths–down to a single feature descriptor listing the OSGi bundles comprised by each application.
On a related topic Red Monk's Michael Coté recently published the OSGi in Java - Eclipse Equinox Screencast and Video Series, sponsored by the Eclipse Foundation. Coté tackles topics such as an introduction to Enterprise OSGi, Ajax with Eclipse RAP, and OSGi on the Server-Side.