The cat is out of the bag, so we might as well publicly announce the effort. GlassFish Labs has been diligently working with Anahata Technologies on the GlassFish 4 super cluster. The joint engineering effort resulted a low-latency clustering fabric with an advanced session replication algorithm that can run on resource constrained devices like the Rasberry Pi. The source code is fully open source on glassfish.org, but has escaped public visibility due to the branch created under the ".MoveAlongNothingToSeeHere" hidden SVN tag, escaping notice.
Stay tuned, the code will be merged into GlassFish Server, Extraterrestrial Edition. In addition, we expect the lessons learned to eventually result in the creation of Java EE 10, Satellite Profile.
We'd like to thank Anahata Technologies for their ingenuity and creativity in initiating this effort.