BASIC EJB EXAMPLE

BASIC EJB EXAMPLE

To create an EJB we need to create Home, Remote and Bean classes.
 

Home Interface
 

import java.rmi.*;
import javax.ejb.*;
import java.util.*;
public interface HelloObject extends EJBObject {
public String sayHello() throws RemoteException;
}

Remote Interface
 

import java.rmi.*;
import javax.ejb.*;
import java.util.*;
public interface HelloHome extends EJBHome {
public HelloObject create() throws RemoteException,
CreateException;
}

Bean Implementation
 

import java.rmi.RemoteException;
import javax.ejb.*;
public class HelloBean implements SessionBean {
private SessionContext sessionContext;
public void ejbCreate() {
}
public void ejbRemove() {
}
public void ejbActivate() {
}
public void ejbPassivate() {
}
public void setSessionContext(SessionContext sessionContext)
{
this.sessionContext = sessionContext;
}
public String sayHello() throws java.rmi.RemoteException {
return "Hello World!!!!!";
}

}

Deployment Descriptor
 

EJB Client
<ejb-jar>
<description>HelloWorld deployment descriptor</description>
<display-name>HelloWorld</display-name>
<enterprise-beans>
<session>
<description> HelloWorld deployment descriptor
</description>
<display-name>HelloWorld</display-name>
<ejb-name>HelloWorld</ejb-name>
<home>HelloWorldHome</home>
<remote>HelloWorld</remote>
<ejb-class>HelloWorldBean</ejb-class>
<session-type>Stateless</session-type>
<transaction-type>Container</transaction-type>
</session>
</enterprise-beans>
<assembly-descriptor>
<container-transaction>
<method>
<ejb-name>HelloWorld</ejb-name>
<method-name>*</method-name>
</method>
<trans-attribute>Required</trans-attribute>
</container-transaction>
</assembly-descriptor>
</ejb-jar>

EJB Client
<ejb-jar>
<description>HelloWorld deployment descriptor</description>
<display-name>HelloWorld</display-name>
<enterprise-beans>
<session>
<description> HelloWorld deployment descriptor
</description>
<display-name>HelloWorld</display-name>
<ejb-name>HelloWorld</ejb-name>
<home>HelloWorldHome</home>
<remote>HelloWorld</remote>
<ejb-class>HelloWorldBean</ejb-class>
<session-type>Stateless</session-type>
<transaction-type>Container</transaction-type>
</session>
</enterprise-beans>
<assembly-descriptor>
<container-transaction>
<method>
<ejb-name>HelloWorld</ejb-name>
<method-name>*</method-name>
</method>
<trans-attribute>Required</trans-attribute>
</container-transaction>
</assembly-descriptor>
</ejb-jar>
 

 EJB Client

 import java.util.Properties;
import javax.naming.InitialContext;
import javax.naming.Context;
import javax.transaction.UserTransaction;
import javax.rmi.PortableRemoteObject;
public class HelloClient {
public static void main(String args[]) {
try {
Context initialContext = new InitialContext();
Object objref =
initialContext.lookup("HelloWorld");
HelloWorldHome home =
(HelloWorldHome)PortableRemoteObject.narrow(objref,
HelloWorldHome.class);
HelloWorld myHelloWorld = home.create();
String message = myHelloWorld.sayHello();
System.out.println(message);
} catch (Exception e) {
System.err.println(" Erreur : " + e);
System.exit(2);
}
}
}