When a remote procedure call fails, the cause falls into one of two categories: an unexpected exception or a checked exception. In either case, you want to handle the exception and, if necessary, provide feedback to the user.
Any number of unexpected occurrences could cause the call to a remote procedure to fail: the network could be down, the HTTP server on the other end might not be listening, the DNS server could be on fire, and so forth.
Another type of unexpected exception can occur if GWT is able to invoke the service method, but the service implementation throws an undeclared exception. For example, a bug may cause a
When unexpected exceptions occur in the service implementation, ...