The ORB, or Object Request Broker, is a library that enables clients to locate and communicate with servers independently of server location and network connections. The ORB is sometimes referred to as the object bus.

Programmers define their object’s interface via OMG IDL, and the ORB takes care of the rest. The ORB serves as an intermediary for requests that CORBA clients send to CORBA server applications, so that the client and server do not need to contain information about each other. The following figure shows the relationship between an ORB, a CORBA application client, and a CORBA server application.

Figure 3-6 The ORB in a CORBA Client/Server Environment

Oracle Tuxedo CORBA includes C++ server ORB and C++ client ORB. The ORBs have built-in transaction support, meaning that the CORBA Object Transaction Service (OTS), on which a CORBA OTM is based, is patterned after the XA standard for two-phase commit processing.

The C++ server ORB is linked directly into the Tuxedo CORBA server processes. Other client ORBs can communicate with Oracle Tuxedo CORBA via CORBA’s IIOP protocol.