RPC is remote procedure call, it's a very old technology. RMI is Java's verison of RPC. Microsoft's version of RMI is COM/DOM, which extended their earlier OLE technology. Roughly, RPC, RMI, DCOM, are all very simiar. CORBA is also similar, although is a bit more heavyweight. I've heard claims that EJB and/or JMX are the next logical evolutionary steps after RMI.
Jini uses RMI, since Jini services use stubs to make calls on remote objects on the network, but Jini really isn't quite the same as RPC or RMI. --Mark email@example.com [This message has been edited by Mark Herschberg (edited February 07, 2001).]