The exception occurs when I run the client program.
Interesting. I didn't know that demo existed.
The demo is based on an older version of Remoting, probably 1.4. As of Remoting 2.0, it is necessary to call Client.connect() before calling Client.invoke(). I.e.,
Client remotingClient = new Client(locator); remotingClient.connect(); remotingClient.invoke("Do something, null);