Java™ Application Development on Linux - Dator

498Chapter 22Building an EJBExample 22.2 Sample remote interfacepackage com.jadol.budgetpro;import javax.ejb.*;import java.rmi.*;import net.multitool.util.*;/*** Remote Interface for the Money EJB*/public interfaceMoneyextends EJBObject{// the methods from the remote object which we will callpublic Costsave(double amt, double rate, double paymnt)throws java.rmi.RemoteException;public Costdebt(double amt, double rate, double paymnt)throws java.rmi.RemoteException;} // interface MoneyThe crucial thing to note with this interface is that we have defined twomethods that match the two methods in our SessionBean—the save() anddebt() methods. These are the methods that will actually be called by our application,and the J2EE mechanisms will do their work behind the scenes toconnect to the methods of our SessionBean implementation and send backthe results.22.2.3 EJBHomeBetween the SessionBean and its remote interface lies the home interface, alsocalled the remote home interface, since it pairs with the remote interface. Anobject that implements the home interface is the kind of object that is returnedafter the lookup() and then narrow() method calls. It is used to create a referenceto the EJB. The home interface for a stateless session bean needs onlyimplement a single method, the create() method with no arguments. Thebody of the method needs do nothing. All the real work is done by theunderlying object supplied by J2EE.