The Blitz JavaSpace Implementation
Since Github doesn't support binary downloads, these can be found over at Google Code.
Use maven to compile and test.
Create an installer or jars using Ant (Maven has inadequate support for Jini's PreferredClassLoader infrastructure) as follows:
ant -f ant_jars.xml installer ant -f ant_jars.xml jars
These latter steps require that you have a full River distribution installed and available at the specified path.