Ludovic Champenois's Blog

Ludovic Champenois (ludo) is a senior staff engineer at Sun Microsystems since 1996, working in between the Application Server (J2EE) organization and the Java tools organization. He is currently the chief architect for the J2EE developer support effort in the NetBeans open source project (http://j2ee.netbeans.org). This project is used as the foundation for other tools like Sun Java Creator and Sun Java Studio.

Worst ever Java EE 6 Blog

• Annotated Servlets 3.0, avoiding the need for web.xml!!!
• EJB without local Interface: 100% POJO, and transactional (managed by the container) and securable
• EJB inside a Web Application
• JPA (still needs a persistence.xml ,  here it's defined as creating the tables at deploy time, assuming the database is already running)
• EclipseLink Implementation
• Default GlassFish v3 JavaDB database registered as "jdbc/__default" datasource.
• Beans Validation framework (JSR 303...Merci Emmanuel)
• Injection of EJBs inside a Servlet

package monster;

import java.io.*;
import java.util.*;
import javax.ejb.*;
import javax.servlet.annotation.*;
import javax.servlet.http.*;
import javax.naming.*;
import javax.persistence.*;
import javax.servlet.*;
import javax.validation.*;
import javax.validation.constraints.*;
/**
 * @author: Not Me!!!
 **/
@Stateless @Entity @WebServlet(urlPatterns = "/monster")
@Table(name = "MONSTERTABLE")
@NamedQueries({@NamedQuery(name = "MonsterEJB.findAll", query = "SELECT c FROM MonsterServlet c")})
@PersistenceContext(name = "monsterContext", unitName = "MonsterWebAppPU")
public class MonsterServlet extends HttpServlet {
    @Id @GeneratedValue(strategy = GenerationType.SEQUENCE) private int monsterId;
    @Max(2) @NotNull private String name;
    @Transient @EJB MonsterServlet monsterEJB;
    /*@Transient @PersistenceUnit(unitName = "MonsterWebAppPU") //does not work see EclipeLink bug
    private EntityManagerFactory emf;*/ //https://bugs.eclipse.org/bugs/show_bug.cgi?id=277550 
    
    @Override
    public void doGet(HttpServletRequest request, HttpServletResponse response) 
               throws ServletException, IOException {
       response.getWriter().println("In Servlet calling the EJB side " + monsterEJB.EJBBusinessMethod("" + this));
    }

    public String EJBBusinessMethod(String name) {
    try {
        InitialContext ic = new InitialContext();
        EntityManager em = (EntityManager) ic.lookup("java:comp/env/monsterContext");
        this.name = name;

        em.persist(this);

        Query allMonsterQuery = em.createNamedQuery("MonsterEJB.findAll");
        List allMonsters = allMonsterQuery.getResultList();
        String error = validateTheMonsterJPA((MonsterServlet) allMonsters.get(0));
        return "BusinessMethod from EJB" + allMonsters.toString() + error;
    } catch (NamingException ex) {
       return "Error in EJBBusinessMethod "+ex.getMessage();
    }
   }

    private String validateTheMonsterJPA(MonsterServlet m) {
       String error=" ";
       ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
       Validator validator = factory.getValidator();
       Set<ConstraintViolation<MonsterServlet>> s = validator.validate(m);
       for (ConstraintViolation<MonsterServlet> c : s) {
            error = error+ " Contraint Violation: " + c.getMessage());
       }
      return error;
    }
 }

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence" 
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
 xsi:schemaLocation=
"http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
    <persistence-unit name="MonsterWebAppPU" transaction-type="JTA">
    <jta-data-source>jdbc/__default</jta-data-source>
 <properties>
    <property name="eclipselink.ddl-generation" value="drop-and-create-tables"/>
 </properties>
 </persistence-unit>
</persistence>

1. Explain the following statement: @Stateless @Entity @WebServlet
2. what do you need to change in the code to remove the Contraint Violation statement in the output?
3. Why do we need to inject the EJB aspect of this class into the servlet and cannot  just use "this" ?
4. Do you think this bug will be fixed?  https://bugs.eclipse.org/bugs/show_bug.cgi?id=277550 

GlassFish Tooling

Eclipse 3.4.2 IDE with WTP Java EE support GlassFish v2.1 pre-registered and configured GlassFish v3 Prelude pre-registered and configured JavaDB sample database pre-registered and configured GlassFish Plugins GlassFish documentation And optionally, a JDK 1.6.

EclipseCon GlassFish Slides

GlassFish and Eclipse

   



Talk to you soon.

May 2009

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