Example 1: Developing of Stateless Session Bean

The purpose

Decision of the bean type

Development steps

1. First, define the remote interface with the bussiness logic methods:

      // File Comp.java
   
      public interface Comp extends javax.ejb.EJBObject {
        int add(int a, int b) throws java.rmi.RemoteException;
        int multiply(int a, int b) throws java.rmi.RemoteException;
      }
      

2. Next, create the home interface. Since the bean is stateless, only one create() method with no arguments is allowed:

      // File CompHome.java
   
      public interface CompHome extends javax.ejb.EJBHome {
        Comp create()
          throws java.rmi.RemoteException, javax.ejb.CreateException;
      }
      

3. Implement the actual bean class with the required bussiness logic:

      // File CompBean.java
   
      public class CompBean implements javax.ejb.SessionBean {
   
        private javax.ejb.SessionContext _context;
   
        public void setSessionContext(javax.ejb.SessionContext sessionContext) {
        _context = sessionContext;
        }
   
        public void ejbCreate() throws java.rmi.RemoteException { }
   
        public int add(int a, int b) throws java.rmi.RemoteException
        { return a + b; }
   
        public int multiply(int a, int b) throws java.rmi.RemoteException
        { return a * b; }
   
        public void ejbRemove() { }
        public void ejbActivate() { }
        public void ejbPassivate() { }
        public String toString() 
         { return "CompBean[context=" + _context + "]"; }
   
      }
      

   Note that the most of the notification-processing methods are empty. This is because no functionality is required in this case there.

4. The client application which uses the bean could look like the following:

      // File CompClient.java
   
      public class CompClient {
     
        public static void main(String[] args) throws Exception {
   
          // get a JNDI context using the Naming service
          javax.naming.Context context = new javax.naming.InitialContext();
   
          Object ref = context.lookup("myCompBean");
          CompHome home = 
            (CompHome) javax.rmi.PortableRemoteObject.narrow(ref, CompHome.class);
   
          Comp c = home.create();
          System.out.println("2 + 3 = " + c.add(2,3));
          System.out.println("2 * 3 = " + c.multiply(2,3));
          c.remove();
        }
      }
      

5. Write the XML deployment descriptor and specify the bean name, home and remote interface, the bean class and the bean type

   
   < ?xml version="1.0"? >
   
   < !DOCTYPE ejb-jar 
     PUBLIC "-//Sun Microsystems, Inc.//DTD Enterprise JavaBeans 1.1//EN" 
            "http://java.sun.com/j2ee/dtds/ejb-jar_1_1.dtd" >
   
   < ejb-jar >
       < description >
           This is Mour's example of a Stateless session bean
       < /description >
       < enterprise-beans >
           < session >
               < description >
                   This Stateless session bean implements a simple Computer
               < /description >
               < ejb-name > comp < /ejb-name >
               < home > CompHome < /home >
               < remote > Comp < /remote >
               < ejb-class > CompBean < /ejb-class >
               < session-type > Stateless < /session-type >
           < /session >
       < /enterprise-beans >
   < /ejb-jar >
   

6. Generate supporting classes to deploy the bean to the container (the commands presented here are specific to Inprise Application Server 4)

       vbjc CompHome.java
       java2iiop -compile CompHome
     

7. Create META-INF directory and put the development descriptor(s) there
8. Compile all previously generated container classes, the remote interface and the bean class

     vbjc *.java 

9. Pack the home and remote interface, the bean class and generated classes to the jar file, together with the deployment descriptor

    jar cMf comp_bean.jar META-INF *.class 

10. Verify the correctness of the file to be deployed

     vbj com.inprise.ejb.util.Verify comp_bean.jar
      

11. Run the container implementation, passing it the bean to be deployed to the container

     vbj com.inprise.ejb.Container ejbcontainer comp_bean.jar -jts -jns -jss