Java™ Application Development on Linux - Dator

496Chapter 22Building an EJBwhich, for our example, we can implement as empty methods. A stateless sessionbean never needs an activation or passivation method to do anything—itis pointless to passivate a stateless session bean. Why? Since it’s stateless, anyinstance of it is as good as any other, so the instances are interchangeable andthere’s no need to passivate one to get to another—just use the one available.It follows that if a bean is never passivated, it will never have to be activated.But why no body to the ejbCreate() method? Well, our bean isn’t doinganything extra. This would only be used if our example were more complicatedand we needed to do application-specific initializations. For example, if thebean had to connect to a database (and did not use entity beans), it might establishthe JDBC connection in ejbCreate and close it in ejbRemove().Similarly, we can have an empty ejbRemove() method.Next we add our own methods, the ones that provide the applicationfunctionality. For our MoneyBean application, we’ll add save() and debt()methods which will use an SAMoney class by calling its save() and debt()methods. Example 22.1 is the listing of the SessionBean.Example 22.1 Listing of our implementation of a SessionBeanpackage com.jadol.budgetpro;import net.multitool.util.*;import javax.ejb.*;/*** Actual implementation of the EJB*/public classMoneyEJBeanimplements SessionBean{protected SessionContext sessionContext;// typical; just not used nowpublic Costsave(double amt, double rate, double paymnt)throws java.rmi.RemoteException{return SAMoney.save(amt, rate, paymnt);} // save