Mandy Chung's Blog

April 2008 Archives

Supporting OSGi Bundles in the Java Module System

A draft specification for supporting OSGi bundles in the Java Module System is put together based on the past EG discussion in particular the proposals and inputs from Glyn Normington, Richard Hall, and Bryan Atsatt. It is expected to evolve based on further inputs from the JSR 277 Expert Group.

With the OSGi expertise from the JSR 277 EG and their contributions, we expect that this specification can be finalized soon. Your feedback is welcome and please send them to jsr-277-comments@jcp.org.

Just to highlight a few main points:
1. One or more module system implementations can run on a single Java virtual machine (e.g. JAM module system and OSGi module system).
2. A Java module can import an OSGi bundle.
3. OSGi bundles are exposed as ModuleDefinitions in the Java Module System.
4. Other module system can find OSGi bundles via the repository delegation model.
5. OSGi bundles are resolved by the OSGi module system using its own algorithm.

One thing noteworthy:

JSR 277 defines the framework and API for the Java Module System and also defines the JAM module system as the default module system implementation for the Java SE platform and the JAM file format as its distribution format.

JSR 277 Early Draft (EDR2) is being updated to clearly separate the distinction between the Java Module System framework and the JAM module system implementation.

We recognized the issue with the JSR 277 EDR that didn't clearly separate the framework/abstraction from the JAM module system implementation that led to confusion and also skeptic about the OSGi interoperability support. Bryan Atsatt also identified and raised this concern to the EG. We hope that the EDR2 will be available in a few weeks after JavaOne. In the mean time, the draft spec includes some spec clarification relevant for this support.

In addition, Bryan has a nice blog about JSR 277 interoperation that serves very well to set up the context ready for the coming discussion (thanks Bryan). I'd also like to blog more about this work but probably after JavaOne when I get some time.

JSR 277 and OSGi interoperability

I recently take on a new challenge and join the JSR 277 project working on JSR 277 and OSGi interoperability. There are lots to learn and I am trying to come up to speed as quickly and effectively as I can. Thanks to all the interests and excitements around this topic! I appreciate in advance the participation and contribution from the JSR 277 and 291 Expert Groups and the OSGi experts.

Our goal is to ensure that existing OSGi bundles can be used in Java SE 7. Like everywhere else, resource has always been tight. But we are revamping the effort to move forward quickly.

Stay tuned and please be patient with this new member on board :)

Digress:
Although I won't have time to work on Java SE serviceability, monitoring and management technologies in the near future, I'd still like to meet with you all at JavaOne 2008 to talk about these areas. I highly recommend to check out VisualVM (the next generation of Java SE troubleshooting GUI tool) at the Java SE booth. Very cool!

Hope we can show a demo on using VisualVM to monitor and manage Java modules some time soon!

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