One of your first tasks when debugging an ORB problem is to determine whether the problem is in the client-side or in the server-side of the distributed application. Think of a typical RMI-IIOP session as a simple, synchronous communication between a client that is requesting access to an object, and a server that is providing it. During this communication, a problem might occur in the execution of one of the following steps:

1. The client writes and sends a request to the server.
2. The server receives and reads the request.
3. The server executes the task in the request.
4. The server writes and sends a reply back.
5. The client receives and reads the reply.

It is not always easy to identify where the problem occurred. Often, the information that the application returns, in the form of stack traces or error messages, is not enough for you to make a decision. Also, because the client and server communicate through their ORBs, it is likely that if a problem occurs, both sides will record an exception or unusual behavior.

This chapter describes all the clues that you can use to find the source of the ORB problem. It also describes a few common problems that occur more frequently. The topics are:

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ORB problem determination