In our application, the observer methods must be remotely callable by the thermometer so that the thermometer can inform the observer(s) of any change in its state. Thus the observers must be implemented as remote objects also.

Next we have the code for the ThermObserver interface and the ThermObserver implementation.

package therm;
 
public interface ThermObserver extends java.rmi.Remote
{
    public void update(Object o, Object x) throws java.rmi.RemoteException;
}