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In the architecture, the ORB is not required to be implemented as a single component, but rather it is defined by its interfaces.
Any ORB implementation that provides the appropriate interface is acceptable. The interface is organized into three categories:
1. Operations that are the same for all ORB implementations.
2. Operations that are specific to particular types of objects.
3. Operations that are specific to particular styles of object implementations.
Different ORBs may make quite different implementation choices, and, together with the IDL compilers, repositories, and various
Object Adapters, provide a set of services to clients and implementations of objects that have different properties and qualities.
There may be multiple ORB implementations (also described as multiple ORBs), which have different representations for object
references and different means of performing invocations. It may be possible for a client to simultaneously have access to
two object references managed by different ORB implementations. When two ORBs are intended to work together, those ORBs must
be able to distinguish their object references. It is not the responsibility of the client to do so.
The ORB Core is that part of the ORB that provides the basic representation of objects and communication of requests. CORBA
is designed to support different object mechanisms, and it does so by structuring the ORB with components above the ORB Core,
which provide interfaces that can mask the differences between ORB Cores.