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TOTD #82: Getting Started with Servlet 3.0 and EJB 3.1 in Java EE 6 using NetBeans 6.7

EJB 3.1 (JSR 318) and Servlet 3.0 (JSR 315) are the two new JSRs in Java EE 6 (JSR 316).

The EJB 3.1 specification provides multiple new features such as WAR packaging, Optional Local Business Interfaces, EJB.lite, Portable Global JNDI Names, Singleton Session Beans (Container-managed and Bean-managed concurrency), Application Initialization and Shutdown events, Timer Service enhancements, Simple/Light-weight Asynchrony, and many other features defined in the specification.

The Servlet 3.0 specification is an update to Servlet 2.5 and focuses on ease-of-use. It also adds several new features such as "web.xml" free deployment (mostly), Dynamic Registration of servlets/filters, Pluggability of frameworks using "web-fragment.xml", Asynchronous API, Security enhancements (Constraints via annotations, programmatic container authentication and logout), and several other miscellaneous additions like default error page, file upload, etc.

GlassFish v3 provides the most complete implementation of EJB 3.1 and Servlet 3.0 along with other Java EE 6 specifications. This Tip Of The Day (TOTD) will show how to create a simple EJB and invoke it from a Servlet, all in a deployment-descriptor free way.

1. Enable support for v3 Preview in NetBeans
1. Using NetBeans 6.7 latest nightly, enable support for recent GlassFish v3 builds either using the command-line switch or the marker module.
2. Download and unzip GlassFish v3 Preview 47b. The latest promoted builds are always available here.
3. In the "Services" tab, right-click on "Servers" and click on "Add Server". Select "GlassFish v3" as shown below:
   
   
   
   and click on "Next".
4. Specify location of the previously unzipped bundle, click on "Next >", and press "Finish".
2. Create a new Web project by right-click in the "Projects" pane, select "New Project", choose "Java Web" and "Web  Application" as categories and projects.
3. Click on "Next >", choose "Java EE 5" as the Java EE version and click on "Finish". A future version of NetBeans will will provide direct support for Java EE 6.
4. Add a POJO-based EJB
1. Right-click on "Source Packages" and select "New", "Java Class..." as shown below:
   
   
   
   Give the class name as "HelloEJB" and package as "server" as shown below:
   
   
   
   and click on "Finish".
2. Add "@Stateless" class-level annotation and press Shift+Command+I (default shortcut) to fix the imports. This annotation comes from the "javax.ejb" package.
3. Add the following method:
   
   

   public String sayHello(String name) {         return "Hello " + name;     }

   
   to the class. And can you believe it, that's your complete EJB ready to be deployed and that too in a WAR file - the beauty of Java EE 6. The complete class looks like:
   
   
   

   package server; import javax.ejb.Stateless; /**  * @author arungupta  */ @Stateless public class HelloEJB {     public String sayHello(String name) {         return "Hello " + name;     } }

5. Add a Servlet to invoke this EJB
1. Add a new class "HelloServlet" in the "server" package as explained above.
2. Add "@WebServlet" class-level annotation and Shift+Command+I to fix the imports. This annotation comes from the "javax.servlet.annotation" package. And specify a URL pattern as:
   
   

   @WebServlet(urlPatterns="/hello")

3. According to the Servlet3 specification, the contract is inherited from the "javax.servlet.http.HttpServlet" interface. So add:
   
   

   extends HttpServlet

   
   to the class.
4. Inject a local EJB reference using the code:
   
   

   @EJB HelloEJB ejbClient;

5. Override the GET method as:
   
   

   @Override     public void doGet(HttpServletRequest req, HttpServletResponse res) throws IOException {         res.setContentType("text/html");         res.getOutputStream().print("<h1>Hosted at: " + req.getContextPath() + "</h1>");         res.getOutputStream().print("<h2>" + ejbClient.sayHello("Duke") + "</h2>");     }

   
   and again Shift+Command+I to fix the imports. The complete class looks like:
   
   

   package server; import java.io.IOException; import javax.ejb.EJB; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /**  * @author arungupta  */ @WebServlet(urlPatterns="/hello") public class HelloServlet extends HttpServlet {     @EJB HelloEJB ejbClient;     @Override     public void doGet(HttpServletRequest req, HttpServletResponse res) throws IOException {         res.setContentType("text/html");         res.getOutputStream().print("<h1>Hosted at: " + req.getContextPath() + "</h1>");         res.getOutputStream().print("<h2>" + ejbClient.sayHello("Duke") + "</h2>");     } }

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