Remote method invocations can fail in very different ways from local method invocations, due to network related communication problems and server problems. To indicate that it is a remote object, an object implements a remote interface, which has the following characteristics:

• The remote interface must be public. Otherwise, a client will get an error when attempting to load a remote object that implements the remote interface.

• The remote interface extends the interface java.rmi.Remote.

• Each method must declare java.rmi.RemoteException in its throws clause, in addition to any application-specific exceptions.

• A remote object passed as an argument or return value (either directly or embedded within a local object) must be declared as the remote interface, not the implementation class.

Next is the interface definition for a thermometer.