Hi,
When using RMI-IIOP, u can't simply cast an object u recieve over the network, because the stub class file may not exist with the client.RMI-IIOP does not allow downloadable class files as CORBA does not support it.
So u need to safe cast by calling PortableRemoteObject.narrow(). This static method converts the object to the desired remote interface 4 u.Pass to narrow() the object u desire to cast and the class to which u wish to cast.The narrow() method returns the resultant object or will throw an exception.
Hope this answer ur query.
Praveen