13.2.2 ORB Services and Object Requests

   Interoperability between ORBs extends the scope of distribution transparencies and other request attributes to span multiple ORBs. This requires the establishment of relationships between supporting ORB Services in the different ORBs.

   In order to discuss how the relationships between ORB Services are established, it is necessary to describe an abstract view of how an operation invocation is communicated from client to server object.

1. The client generates an operation request, using a reference to the server object, explicit parameters, and an implicit invocation context. This is processed by certain ORB Services on the client path.

2. On the server side, corresponding ORB Services process the incoming request, transforming it into a form directly suitable for invoking the operation on the server object.

3. The server object performs the requested operation.

4. Any result of the operation is returned to the client in a similar manner.

   The correspondence between client-side and server-side ORB Services need not be one-to-one and in some circumstances may be far more complex. For example, if a client application requests an operation on a replicated server, there may be multiple server-side ORB service instances, possibly interacting with each other.

   In other cases, such as security, client-side or server-side ORB Services may interact with Object Services such as authentication servers.