Internet Inter-ORB Protocol (IIOP) defines a protocol for CORBA invocation over the TCP/IP (transport layer). It is a specialization of General Inter-ORB Protocol (GIOP).
IIOP is a high-level communication protocol used by Orb (Object Request Broker) which makes platform independence. It is a binary protocol that can use both big and little endian and is efficient in transferring both simple data (like arrays) and complex structures (these must be pre-defined in IDL). Apart data transfer, IIOP supports that is required for RPC.
CORBA is not the only that uses IIOP. Java RMI-IIOP is an implementation of RMI-like functionality on the top of CORBA.
