A Babel Object Server (BOS) is a network server process or thread that provides babel objects via Remote Method Invocation (RMI). Normally a BOS is run as a background thread on a normal Babel process to allow the process to publish objects for access by RMI enabled clients. There is not a single protocol that a BOS must use to communicate over Babel RMI, but clients and BOSs must use the same protocol if they are expected to communicate.