Understand how the components of the OMA commonly function.
The OMA is designed to reuse functionality wherever possible. This is most obvious at the fundamental ORB level, where the ORB is used by all components as a communications mechanism.
In addition, since the CORBAservices provide fundamental object-level functionality, components of the CORBAservices are reused in much of the CORBAfacilities specifications and even frequently reused within the CORBAservices specifications themselves. In fact, there are no usage restrictions and any part of the OMA may make use of existing OMA components.

The diagram above roughly depicts how specific portions of the OMA commonly function. Even though there are no component usage restrictions, reuse usually takes place at successively higher levels.
What this means architecturally is that CORBA applications developers will make use of both CORBAfacilities and CORBAservices, while the CORBAfacilities will make use of many of the CORBAservices, and all of the components will make use of the ORB to provide CORBA communication.
The bulk of the remaining concepts that make up the CORBA specification are based upon the simple but powerful Object Management Architecture (OMA) and the fundamental request/reply services provided by the ORB. But before we begin looking deeper into CORBA, we will take an opportunity in the next lesson to analyze our fundamental understanding of CORBA.