Under what circumstances would I get a java.rmi.NoSuchObjectException?

Quoting from the RMI Javadocs: "A NoSuchObjectException is thrown if an attempt is made to invoke a method on an object that no longer exists in the remote virtual machine. If a NoSuchObjectException occurs attempting to invoke a method on a remote object, the call may be retransmitted and still preserve RMI's 'at most once' call semantics. A NoSuchObjectException is also thrown by the method java.rmi.server.RemoteObject.toStub and by the unexportObject methods of java.rmi.server.UnicastRemoteObject and java.rmi.activation.Activatable."