I started out with the starter kit, and recoded the examples a little so they didn't have to use so much space.
Lesson One,
If "Hello World" requires more than 15 classes, there is probably a good reason for it.
I plugged, poked, prodded and puted; I had jininess everywhere. Then I uploaded to the server network, hehe.
Jini is built amidst the RMI architecture. It is complicated, involved, and generally not cost-efficient outside of an enterprise system. I imagine, that, if you had been working with RMI for some time, then perhaps the limitations of RMI that Jini overcomes, would help you make sense of Jini.
If, like me, you know very little about RMI, it could be hellish. There are a lot of gotchas. Codebase problems, classLoader madness, serialisation issues, to name a few. Object proxies, marshalled instances, invocation handling to name some more.
Some notes. RMI uses object implementations, not interfaces. Read the RMI api carefully. Particularly RMI parameters and return types. Identify your class loaders and codebases early. The JVM will not "just download all necessary classes and interfaces for you".