This exception means the client attempted to download a stub from the server and couldn't find it.
You can get this exception for a variety of reasons:
1) The server-side doesn't have the stub. This is done by running the rmic tool against the implementation of a remote Interface
2) The server doesn't store the stub where the client can find it. This may be due to setting the System property java.rmi.server.codebase incorrectly, or not at all.
3) The server doesn't serve ("export") the stub. The server must have rmiregistry runnning on the server, and must make sure the rmiregistry CANNOT see the exportable object via its CLASSPATH.
3) The client is looking in the wrong place for the stub.
One of the unfortunate elements of learning RMI initially is that a great number of things can go wrong; there are a lot of details to handle correctly before you get a satisfying result.
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Michael Ernest, co-author of:
The Complete Java 2 Certification Study Guide
[This message has been edited by Michael Ernest (edited December 21, 2000).]