A CORBA object never talks directly with another. Instead, the object makes requests through a remote stub to the Internet Inter-Orb Protocol (IIOP) running on the local host. The local ORB then passes the request to an ORB on the other host using IIOP. The remote ORB then locates the appropriate object, processes the request, and returns the results.
IIOP can be used as a Remote Method Invocation (RMI) protocol by applications or objects using RMI-IIOP. Remote clients of enterprise beans (EJB modules) communicate with Enterprise Server by using RMI-IIOP.