CORBA (contd.)

IDL is the language in which object interfaces are defined and advertised. It is purely declarative in the sense that an IDL interface definition is independent of the actual object implementation.
An Interface Repository is an on-line database of object definitions that can be queried at run-time for dynamic method calls, for locating potentially reusable software components and for type-checking of method signatures.
The Object Adapter provides the run-time environment for the server application. It provides the mechanism for an object’s implementation to access the services provided by the ORB and handles incoming client calls.
CORBA Services augment the functionality provided by the ORB. CORBA defines services for persistence, transactions, concurrency, database queries, licensing, etc..

CORBA 2.0 also defines a standard for inter-ORB communication, called the Internet Inter-ORB Protocol (IIOP). IIOP is basically TCP/IP with some CORBA-defined message exchanges that serve as a common backbone protocol.