There is no need to extend UnicastRemoteObject, actually. What you do need is to be able to export the object in question, which can be satisfied with the static call UnicastRemoteObject.exportObject(). Without that piece, the object itself would not bind as necessary to the registry server.
It is possible to make things work without doing this, but only if the client and server code are on the same machine and able to see the same classpath.
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Michael Ernest, co-author of:
The Complete Java 2 Certification Study Guide