Creating a No-Interface View  Session Bean and Packaging in a WAR File

Overview

    Purpose

    This tutorial covers  creating a EJB 3.1 application that demonstrates  the no-interface Local view of a Session Bean and WAR-based packaging.

    Time to Complete

    Approximately 45 minutes.

    Introduction

    This example demonstrates the simplified programming and packaging model changes provided in EJB 3.1. Since the mandatory use of Java interfaces  has been removed in EJB 3.1, plain old Java objects can be annotated and used as EJB components. It also supports  the ability to place EJB components directly inside Web applications, thereby removing the need to produce archives to store the Web and EJB components and combine them together in an enterprise archive (EAR) file.

    Normally, accessing this bean from a Servlet would require one .war,  ejb-jar, and an .ear file to wrap the two modules together. With the new packaging alternative, everything fits into a single .war thus reducing the complexity of JEE development. 

    In this tutorial, you will create a Java EE 6 Web Application and add the following components to it - no-interface  view  Stateless Session Bean,  Servlet and a JSP.  The  index.jsp will contain a form  with a submit button, Run, allowing you to execute the application. The form will submit to a Servlet which will  invoke sayHello method in Session bean you will create and the response is re-directed to response.jsp. 

    In the Web Application you will create in this tutorial,@Stateless annotation is provided to an  plain old Java class that exposes it as an EJB session bean. This is then injected into an  Servlet  using an @EJB annotation. The EJB session bean and Servlet classes are then packaged and deployed together in a single WAR file, which demonstrates the simplified packaging and deployment changes available in Java EE 6.

    No-interface view

  • Each session bean exposes a no-interface Local view. 
  • This client view has the same semantics as the EJB 3.0 Local business interface, except that it does not require a separate interface. 
  • All public methods of the bean class are automatically exposed to the caller. 
  • By default, any session bean that has an empty implements clause and does not define any other Local/Remote client views exposes a no-interface client view.
  • A client of the no-interface view always acquires an EJB reference, either through injection or JNDI lookup.



    Hardware and Software Requirements

    The following is a list of hardware and software requirements:

    • Download and install Java JDK 7 from this link.
    • Download and install   NetBeans 7.1.2 with Java EE which includes GlassFish 3.1.2 (Java EE download bundle) from this link. During installation, be sure to check the box to install GlassFish. JUnit is an optional installation and not required for this tutorial.

    Prerequisites

    Before starting this tutorial, you should:

    •  Have the software installed as listed under Hardware and Software Requirements section.
    •  Ensure NetBeans is running.

Create a Java  EE Web Application

    To create a Java EE  Web Application, perform the following steps in the NetBeans IDE.


    Create a new Web Application.

    Select File->New Project from the NetBeans menu.

    Select the Java Web category and a project type of  Web Application.

    Click Next.


    Enter  project name as NoInterfaceInWarDemo. Click Next.


    Verify the following :

    GlassFish Server 3.1.2 is  selected as the server.

    Java EE 6 Web is selected as  Java EE Version.

    Click Finish.

    You should now have a Web Application project with an index.jsp file.

Create Session Bean

    To create a no-interface stateless session bean, perform the following steps in NetBeans IDE.

    Right-click on the NoInterfaceInWarDemo project and select New->Java Class.

    Specify the Session Bean information as follows:

    Class Name: HelloWorldSessionBean

    Package Name: com.example

    Click Finish.

    Double-click HelloWorldSessionBean.java in the Source Packages node to open  in the code editor.

    a.  Import the following package.

        import javax.ejb.Stateless;  

    b. Add @Stateless annotation to the class

      @Stateless

    c. Implement  sayHello method.

     public String sayHello()
        {
            return "Hello EJB World";
        }
       


    Plain old Java class, HelloWorldSessionBean, is exposed as an  EJB session bean by adding an @Stateless annotation.



Create Servlet

    To create a Servlet, perform the below steps in NetBeans IDE.

    Right-click on the  NoInterfaceInWarDemo project and select New->Other.

    In the New File window, select a category of  Web and a file type of Servlet.

    Click Next.


    Specify the Servlet  information as follows:

    Class Name: WelcomeServlet

    Package Name: com.example

    Click Finish.

    Perform the following changes to the WelcomeServlet.

    a.  Import the following package.

             import javax.ejb.EJB;

    b. Add a field of type HelloWorldSessionBean named helloWorldSessionBean.

     @EJB
 private HelloWorldSessionBean helloWorldSessionBean;



    The session bean, HelloWorldSessionBean is  injected into WelcomeServlet using an @EJB annotation.

    Modify the doGet() method in WelcomeServlet.

    Expand the editor fold and add the below lines of code to the doGet() method.

           String str = "Greetings from the Servlet calling the no interface EJB.<br>";
           String msg = str + helloWorldSessionBean.sayHello();
           request.setAttribute("message", msg);
           request.getRequestDispatcher("response.jsp").forward(request,response);

Create JSP

    To create response.jsp, perform the following steps in NetBeans IDE.

    Right-click NoInterfaceInWarDemo project and select project and select New->Other.

    In the New File window, select a category of  Web and a file type of JSP.

    Click Next.


    Specify the name as response and click Finish.


    Make the following changes to response.jsp.

    a. Modify the title  of the page to Example of Using no-interface View and EJB in WAR.

    b. Modify the body section, add the below line of code.

    <% out.println(request.getAttribute("message")); %>


Modify  index.jsp

    To modify index.jsp, perform the following steps in NetBeans IDE.

    Open the existing index.jsp file from the Web Pages portion of the NoInterfaceInWarDemo project.


    Make the following changes to index.jsp.

    a. Modify the title of the page to Example of Using no-interface View and EJB in WAR.

    b. Modify the heading  of the page to Click Run to execute this example

    Add a form to the body of the index.jsp page which contains a submit button named, Run.

    <form action="./WelcomeServlet" >
               <input value="Run" type="submit"/>
       </form>

     

Deploy the Web Application

    To deploy and run the application, perform the following steps in NetBeans IDE.

    Right-click NoInterfaceInWarDemo  project in the projects window and select  Build. 


    In the Output console, you see a message that NoInterfaceInWarDemo.war has been created.

    In the Projects window, right-click NoInterfaceInWarDemo and select Deploy.


    Verify  the deployed application in GlassFish server.

    a. In the Services tab, expand the Servers node.

    b. Expand the GlassFish  Server node.

    c. In the GlassFish  Server node, expand the Applications node, you  see NoInterfaceInWar deployed.



    In the Projects window, right-click NoInterfaceInWarDemo and select Run.



    Verify the output, click Run.



    The output will be as shown below.



Summary

    In this tutorial, you have learned how to:

     

    • Create a  no-interface View Session Bean- @Stateless annotation is provided to an  plain old Java class that exposes it as an EJB session bean.
    • Access the Session Bean in a  Servlet
    • Package the application as a WAR file and deploy.

    Resources

    Credits

    • Lead Curriculum Developer: Anjana Shenoy

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