The ORB is primarily used by EJB components via:
RMI/IIOP path from an application client (or rich client) using the application client container.
RMI/IIOP path from another Application Server instance ORB.
RMI/IIOP path from another vendor’s ORB.
In-process path from the Web Container or MDB (message driven beans) container.
When a server instance makes a connection to another server instance ORB, the first instance acts as a client ORB. SSL over IIOP uses a fast optimized transport with high-performance native implementations of cryptography algorithms.
It is important to remember that EJB local interfaces do not use the ORB. Using a local interface passes all arguments by reference and does not require copying any objects.