GlassFish Project - Simple Enterprise JavaBeansTM (EJB) 3.0 Stateless Session Bean Example 

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Overview

This is a very simple EJB 3.0 Stateless Session Bean with a Remote business interface.  

Click here to get the ZIP file with the complete example.

Contact us at ejb@glassfish.dev.java.net with any comments or questions.

Business Interface

The Stateless Session bean has a Remote business interface with a single business method.


package ejb30;
import javax.ejb.Remote;

@Remote
public interface Sless {

    public String hello();

}

Note that unlike prior versions of EJB, the Remote interface is not required to extend java.rmi.Remote and its business methods are not required to throw java.rmi.RemoteException.

The business interface is designated as a remote business interface via the @javax.ejb.Remote annotation.

Stateless Session Bean Class

Here's the bean implementation :

package ejb30;
import javax.ejb.Stateless;

@Stateless
public class SlessBean implements Sless {

    public String hello() {
        return "hello, world!\n";
    }

}

@javax.ejb.Stateless is a component-defining annotation that designates this class as the bean class for a Stateless Session Bean.  

Deployment Descriptor

The good news is the deployment descriptor is no longer required!!!  The two java files above are sufficient to completely describe this stateless session bean.  

Application Client

Here's a Java EE Application Client that accesses the Stateless Session Bean using the @EJB annotation and dependency injection :

package ejb30;
import javax.ejb.EJB;

public class SlessAppClient {

    @EJB
    private static Sless sless;

    public static void main(String args[]) {

        System.out.println("Sless bean says : " + sless.hello());

    }
}

The @EJB annotation tells the container that this component has a dependency on a business interface of an EJB.  At initialization time, the Application Client container will inject the variable "sless" with a reference to a Stateless Session bean.  There's no JNDI lookup or casting required.

Note that the Java EE 5 specification requires that annotations within Application Client classes be static since the entry point for the application is the static main() method.  

Standalone Java Client

Here's an example of a plain Java client that runs outside of a Java EE container.  In this case, it does a global JNDI lookup since dependency injection is not available outside of a Java EE component.  

package ejb30;
import javax.naming.InitialContext;

public class SlessJavaClient {

    public static void main(String args[]) {

        try {

            InitialContext ic = new InitialContext();
            Sless sless = (Sless) ic.lookup("ejb30.Sless");
            System.out.println("Sless bean says : " + sless.hello());

        } catch(Exception e) {
            e.printStackTrace();
        }

    }

}

SUN App Server Specific Deployment Configuration

There is no need to define any SUN App Server-specific deployment descrpitors (e.g. sun-ejb-jar.xml, sun-application-client.xml) for this example.   The JNDI name for the Remote Stateless Session bean will default to the fully-qualified class name of its Remote business interface  : ejb30.Sless.    The Application Client's Remote @EJB dependency will be resolved to the same value since its business interface type is also ejb30.Sless.  

Running the example


Use the following steps to build and execute the test.

  1. Set the glassfish.home property within build.xml.
  2. Set JAVA_HOME to point to a JDK 1.5 (or later) installation.
  3. ant build
  4. ant deploy
  5. ant run  

This will execute the Application Client and produce the following output :

Sless bean says : hello, world!

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