4.2. Writing Code for the Bean

4.2. Writing Code for the Bean
Prev	Chapter 4. Writing a HelloWorld Bean	Next

The HelloWorld bean is divided into two parts: the business interface, and the class implementing this interface.

4.2.1. Writing the Interface

The interface declares only one method: helloWorld()

package org.objectweb.easybeans.tutorial.helloworld;

/**
 * Interface of the HelloWorld example.
 * @author Florent Benoit
 */
public interface HelloWorldInterface {

    /**
     * Hello world.
     */
    void helloWorld();

}

	Note
	Even if this interface is used as a remote interface, it does not need to extend `java.rmi.Remote` interface.

4.2.2. Writing the Business Code

The following code implements the existing interface:

package org.objectweb.easybeans.tutorial.helloworld;

/**
 * Business code for the HelloWorld interface.
 * @author Florent Benoit
 */
public class HelloWorldBean implements HelloWorldInterface {

    /**
     * Hello world implementation.
     */
    public void helloWorld() {
        System.out.println("Hello world !");
    }

}

	Note
	At this moment, the bean is not an EJB; this is only a class implementing an interface.

4.2.3. Defining the EJB Code as a Stateless Session Bean

Now that the EJB code has been written, it is time to define the EJB application.

This bean will be a stateless session bean, thus the class will be annotated with @Stateless annotation.

In addition, the interface must be a remote interface to be available for remote clients. This is done by using the @Remote annotation.

package org.objectweb.easybeans.tutorial.helloworld;


import javax.ejb.Remote;
import javax.ejb.Stateless;

/**
 * Business code for the HelloWorld interface.
 * @author Florent Benoit
 */
@Stateless
@Remote(HelloWorldInterface.class)
public class HelloWorldBean implements HelloWorldInterface {

    /**
     * Hello world implementation.
     */
    public void helloWorld() {
        System.out.println("Hello world !");
    }

}

	Note
	If a class implements a single interface, this interface is defined as a local interface by default.

4.2.4. Packaging the Bean

The two classes ( HelloWorldInterface and HelloWorldBean) must be compiled.

Then, a folder named ejb3s/helloworld.jar/ must be created and classes placed in this folder. They will be deployed and loaded automatically.