jni:
http://java.sun.com/products/jdk/faq/jnifaq.html
http://developer.java.sun.com/developer/Books/advancedprogramming/jni.pdf
jini:
http://www.sun.com/jini/
http://jini.org
Jini[tm] network technology provides a simple infrastructure for delivering
services in a network and for creating spontaneous interaction between programs
that use these services regardless of their hardware/software implementation.
Any kind of network made up of services (applications, databases, servers,
devices, information systems, mobile appliances, storage, printers, etc.) and
clients (requesters of services) of those services can be easily assembled,
disassembled, and maintained on the network using Jini Technology.
Services can be added or removed from the network, and new clients can find
existing services - all without administration.