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Here is an example of Simple Stateless Session Bean:

@Stateless
public class StatelessBean implements StatelessBeanRemote
{
public void SimpleFunction()
{
System.out.println("This is a stateless session bean");
}
}

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1. Right click under the Project Explorer and Create an EJB project as shown.
   
   
   
   
2. On the next screen give the project name as StatelessSessionEJB.
   
   
   
   
3. Right click on ejbModule and create a new Interface RegisterBeanRemote.
   
   
   
   
4. On the New Java Interface window give the package name as statelessejb and Interface name as RegisterBeanRemote.
   
   
   
   
5. Populate the RegisterBeanRemote interface with the following code. borderStyle

   Code Block
   solid title RegisterBeanRemote.java borderStyle solid
   package statelessejb; import javax.ejb.Remote; @Remote public interface RegisterBeanRemote { public void register(String FirstName, String LastName, String Sex, String UserName, String Password); public boolean verify(String username, String password); }

   In the above code @Remote is a metadata annotation which marks the interface to be a Remote Interface. Metadata annotations are used to declare a class, interface or functions to have particular attributes. In this case the interface is marked to be a Remote Interface.
6. Right click on StatelessSessionEJB project and create a new class RegisterBean as shown in the figure.
   
   
   
   
7. Populate the class RegisterBean with the following data: borderStyle

   Code Block
   solid title RegisterBean.java borderStyle solid
   package statelessejb; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import javax.annotation.PostConstruct; import javax.annotation.PreDestroy; import javax.annotation.Resource; import javax.ejb.Stateless; import javax.sql.DataSource; @Stateless public class RegisterBean implements RegisterBeanRemote{ @Resource(name="jdbc/userds") private DataSource dbsource; private Connection dbconnect; @PostConstruct public void initialize() { try{ dbconnect= dbsource.getConnection(); } catch(Exception e) { e.printStackTrace(); } } public void register(String FirstName, String LastName, String Sex, String UserName, String Password) { try { String insert="INSERT INTO USERINFO (" + "FIRSTNAME," + "LASTNAME," + "SEX," + "USERNAME," + "PASSWORD)" + " VALUES(?,?,?,?,?)"; PreparedStatement ps=dbconnect.prepareStatement(insert); ps.setString(1,FirstName); ps.setString(2,LastName); ps.setString(3,Sex); ps.setString(4,UserName); ps.setString(5,Password); int rs =ps.executeUpdate(); } catch(Exception e) { e.printStackTrace(); } } public boolean verify(String username, String password) { boolean ret=false; String select="SELECT * FROM USERINFO"; try{ PreparedStatement ps=dbconnect.prepareStatement(select); ResultSet rs= ps.executeQuery(); while(rs.next()) { String str=(rs.getString("USERNAME")).trim(); String str1=(rs.getString("PASSWORD")).trim(); if (str.compareTo(username)==0) { if(str1.compareTo(password)==0) { ret=true; break; } else ret=false; } else ret=false; } } catch(Exception e) { e.printStackTrace(); } System.out.println(ret); return ret; } @PreDestroy public void destroy(){ try { dbconnect.close(); dbconnect=null; } catch(Exception e) { e.printStackTrace(); } } }

   Lets try to understand this code.
   1. The very first line has an annotation @Stateless which declares the POJO to be a Stateless Session Bean. This annotation tells the container that the class is a Stateless Session Bean class. The container now automatically takes care of the various services like pooling, thread safety, transactions and so on.
   2. The second line suggests that the bean class implements the remote interface. Every EJB application has to have at least one interface. In this case we are having a remote interface.
   3. Next we have the @Resource(name="jdbc/userds") annotation which suggests jdbc/userds datasource being injected on to EJB. This is called dependency injection. The main idea behind dependency injection is that a component should call the resource through interfaces. This in turn will create a loosely coupled architecture between component and resource. Dependency injection is actually JNDI lookup in reverse order. In JNDI lookup the Bean looks up the resources itself and that is why it has to be hardcoded in the bean code itself whereas in Dependency Injection the Container reads the Bean and finds out what resources are required by the bean class. Later it injects the resources at runtime. How to create jdbc/userds datasource is discussed in the next section.
   4. Next interesting part is the @PostConstruct annotation. This annotation is used for lifecycle callbacks. A lifecycle callback method is used by container to inform the bean class of the state transitions in the bean lifecycle. @PostConstruct annotation is used once a bean instance is created. In our example we have our bean instance created and Dependency injected. Later @PostConstruct callback is invoked and a connection to the datasource is established.
   5. Next we have the register function which is used to populate the database USERINFO with user information. This function uses PreparedStatement to query the database.
   6. Next is the verify function which is used for the authentication of user credentials.
   7. @PreDestroy is again a lifecycle callback which suggests to release the resources before the bean is destroyed.

      Warning
      title Warning
      Due to some limitations in Geronimo Eclipse Plugin the generated deployment plan(openejb-jar.xml) does not have the correct namespace. Replace the existing namespace as shown in the figure with the following <openejb-jar xmlns="http://www.openejb.org/xml/ns/openejb-jar-2.2" xmlns:nam="http://geronimo.apache.org/xml/ns/naming-1.2" xmlns:pkgen="http://www.openejb.org/xml/ns/pkgen-2.0" xmlns:sec="http://geronimo.apache.org/xml/ns/security-1.2" xmlns:sys="http://geronimo.apache.org/xml/ns/deployment-1.2">

      
      
      
      This completes the development of EJB project.

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1. Start the server and launch the Administrative Console using the URL http://localhost:8080/console.
2. Enter default username and password.
3. In the welcome page, Under Embedded DB, Select DB Manager.
   
   
   
   
4. On the next page create a database userdbs and Select Create.
   
   
   
   
5. Once done you can see the userdbs database listed in DB Viewer portlet under Databases. This confirms that the database has been successfully created.
   
   
   
   
   
   
6. As shown in the figure under Use DB, select userdbs from the dropdown box.
   
   
   
   
   
   
7. Run the query as shown in the figure. This query will create table USERINFO with the columns FIRSTNAME, LASTNAME, SEX, USERNAME, PASSWORD.
   
   
   
   
   
   solid

   Code Block
   borderStyle
   title CreateTable.sql borderStyle solid
   CREATE TABLE USERINFO ( FIRSTNAME char(20), LASTNAME char(20), SEX char(7), USERNAME char(20), PASSWORD char(20) )

8. To verify the table creation is successful. Under View Tables for userdbs Database, Select Application.
   
   
   
   
9. The next window will show the table USERINFO associated with userdbs Database.
   
   
   
   

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1. Create a new dynamic Web Project with the name ApplicationClient.
2. Right click on WebContent and create the following login.jsp: solid

   Code Block
   borderStyle
   title login.jsp borderStyle solid
   <%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Welcome to Apache Geronimo</title> </head> <body bgcolor="white"> <form method="post" action="passCredentials.jsp"> <h2 align="center"><font color="blue">Welcome to Apache Geronimo</font></h2> <h2 align="center"><font color="blue">Enter your credentials</font></h2> Enter your Username <input type="text" name="username" size=20><br> Enter your Password <input type="password" name="password" size=20><br> <input type="submit" value="Login"> <a href="http://localhost:8080/ApplicationClient/register.jsp">NewUser</a> </form> </body> </html>

   This form is the login page for our application. Once the user enters his/her credentials, these are passed to another jsp passCredentials.jsp (checkout the action in the form tag) to verify the authenticity of user credentials. In case the user is new he has to go through the registration process. This statement <a href="http://localhost:8080/ApplicationClient/register.jsp">NewUser</a> is used to route the user to registration page. solid

   Code Block
   borderStyle
   title passCredentials.jsp borderStyle solid
   <%@ page import="java.util.Properties,javax.naming.Context,javax.naming.InitialContext,statelessejb.RegisterBeanRemote" %> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Insert title here</title> </head> <body bgcolor="white"> <%!boolean i; %> <% Properties prop=new Properties(); prop.put(Context.INITIAL_CONTEXT_FACTORY, "org.apache.openejb.client.RemoteInitialContextFactory"); prop.put("java.naming.provider.url", "ejbd://localhost:4201"); Context context = new InitialContext(prop); RegisterBeanRemote myejb=(RegisterBeanRemote)context.lookup("RegisterBeanRemote"); String s= request.getParameter("username"); String s1= request.getParameter("password"); i=myejb.verify(s,s1); %> <% if (i==true){ %> <jsp:forward page="/resources.jsp"></jsp:forward> <% } else { %> <jsp:forward page="/login.jsp"></jsp:forward> <% } %> </body> </html>

   <%!boolean i; %> is a declaration for a global variable. The other part is a scriptlet which does a JNDI lookup to the remote interface. Later the user credentials are passed to verify function. In case the credentials are correct user is routed to the resources page else he is redirected to login page to re-login.

   Tip
   title Why is the lookup name RegisterBeanRemote??
   This will be explained in the deploy an run section

   solid

   Code Block
   borderStyle
   title resources.jsp borderStyle solid
   <%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Welcome to Apache Geronimo</title> </head> <body bgcolor="white"> <h3><font color="blue">Welcome to Apache Geronimo Resource Center</font></h3> Apache Geronimo Home Page <a href="http://geronimo.apache.org">Apache Geronimo Home page</a><br> Join our mailing list <a href="http://geronimo.apache.org/mailing-lists.html">Apache Geronimo Mailing List</a><br> Come and Contribute to Apache Geronimo V2.1 Documentation <a href="http://cwiki.apache.org/GMOxDOC22/">Apache Geronimo V2.1 Documentation</a> </body> </html>

   This is the final page of the application which displays the various resources. solid

   Code Block
   borderStyle
   title register.jsp borderStyle solid
   <%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Welcome to Apache Geronimo</title> </head> <body bgcolor="white"> <script type="text/javascript"> function valForm() { if (this.document.form1.username.value=="" || this.document.form1.username.value=="") { alert("You cannot leave the field blank"); this.document.form1.firstname.focus(); return false; } else { return true; } } </script> <h2 align="center"><font color="blue">Welcome to Apache Geronimo User Registration</font></h2> <form method="post" name="form1" action="passVariables.jsp" onSubmit=" return valForm();"> FirstName <INPUT type="text" name="firstname" SIZE=20><br> LastName <INPUT type="text" name="lastname" SIZE=20 ><br> Sex<br> <input type="radio" name="sex" value="male"> Male <br> <input type="radio" name="sex" value="female"> Female <br> Select a UserName<br> <input type="text" name="username" size=20><br> Select a Password<br> <input type="password" name="password" size=20><br> <br> <input type="submit" value="Submit"> </form> </body> </html>

   This page is the registration page. Once th user fills up the form and press Submit a valform() function is called which validates the field username and password. In case any of them is empty an alert is send which suggests empty fields in the form. If all is fine passVariables.jsp is called. borderStyle

   Code Block
   solid title passVariables.jsp borderStyle solid
   <%@ page import="java.util.Properties,javax.naming.Context,javax.naming.InitialContext,statelessejb.RegisterBeanRemote" %> <html> <head> <meta http-equiv="Refresh" content="5;URL=http://localhost:8080/ApplicationClient/login.jsp"> <title>Welcome to Apache Geronimo</title> </head> <% Properties prop=new Properties(); prop.put(Context.INITIAL_CONTEXT_FACTORY, "org.apache.openejb.client.RemoteInitialContextFactory"); prop.put("java.naming.provider.url", "ejbd://localhost:4201"); Context context = new InitialContext(prop); RegisterBeanRemote myejb=(RegisterBeanRemote)context.lookup("RegisterBeanRemote"); String s= request.getParameter("firstname"); String s1= request.getParameter("lastname"); String s2= request.getParameter("sex"); String s3= request.getParameter("username"); String s4= request.getParameter("password"); myejb.register(s,s1,s2,s3,s4); %> <h3 align="center"><font color="blue">Thank you for registering with Apache Geronimo</font></h3> <h3 align="center"><font color="blue">Redirecting to Login Page</font></h3> </html>

   In this page the fields are retrieved from register.jsp and the register function in the bean class is called to populate the database.
   The code <meta http-equiv="Refresh" content="5;URL=http://localhost:8080/ApplicationClient/login.jsp"> suggests to wait for 5 seconds and then move to login.jsp borderStyle

   Code Block
   solid title index.jsp borderStyle solid
   <%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <body> <jsp:forward page="/login.jsp" /> </body> </html>

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1. In the EJB Project. Under META-INF, edit openejb-jar.xml and add the following solid

   Code Block
   borderStyle
   title datasource dependency borderStyle solid
   <sys:dependencies> <sys:dependency> <sys:groupId>console.dbpool</sys:groupId> <sys:artifactId>jdbc_userds</sys:artifactId> </sys:dependency> </sys:dependencies>

   Finally the openejb-jar.xml will look like this solid

   Code Block
   borderStyle
   title openejb-jar.xml borderStyle solid
   <?xml version="1.0" encoding="UTF-8"?> <openejb-jar xmlns="http://www.openejb.org/xml/ns/openejb-jar-2.2" xmlns:nam="http://geronimo.apache.org/xml/ns/naming-1.2" xmlns:pkgen="http://www.openejb.org/xml/ns/pkgen-2.0" xmlns:sec="http://geronimo.apache.org/xml/ns/security-1.2" xmlns:sys="http://geronimo.apache.org/xml/ns/deployment-1.2"> <sys:environment> <sys:moduleId> <sys:groupId>default</sys:groupId> <sys:artifactId>StatelessSessionEJB</sys:artifactId> <sys:version>1.0</sys:version> <sys:type>car</sys:type> </sys:moduleId> <sys:dependencies> <sys:dependency> <sys:groupId>console.dbpool</sys:groupId> <sys:artifactId>jdbc_userds</sys:artifactId> </sys:dependency> </sys:dependencies> </sys:environment> <enterprise-beans/> </openejb-jar>

   Info
   title Where did the above dependencies come from??
   To make the datasource visible to EJB we need to add a dependency to the EJB deployment plan that is openejb-jar.xml. The above element can be obtained automatically from Geronimo Database Pool wizard. Select usage against the database pool jdbc/userds

2. In the WEB Project. Under WEB-INF, Edit geronimo-web.xml and add the following solid

   Code Block
   borderStyle
   title EJB dependency borderStyle solid
   <sys:dependencies> <sys:dependency> <sys:groupId>default</sys:groupId> <sys:artifactId>StatelessSessionEJB</sys:artifactId> <sys:version>1.0</sys:version> <sys:type>car</sys:type> </sys:dependency> </sys:dependencies>

   Finally the geronimo-web.xml will look like this solid

   Code Block
   borderStyle
   title geronimo-web.xml borderStyle solid
   <?xml version="1.0" encoding="UTF-8"?> <web-app xmlns="http://geronimo.apache.org/xml/ns/j2ee/web-1.2" xmlns:nam="http://geronimo.apache.org/xml/ns/naming-1.2" xmlns:sec="http://geronimo.apache.org/xml/ns/security-1.2" xmlns:sys="http://geronimo.apache.org/xml/ns/deployment-1.2"> <sys:environment> <sys:moduleId> <sys:groupId>default</sys:groupId> <sys:artifactId>ApplicationClient</sys:artifactId> <sys:version>1.0</sys:version> <sys:type>car</sys:type> </sys:moduleId> <sys:dependencies> <sys:dependency> <sys:groupId>default</sys:groupId> <sys:artifactId>StatelessSessionEJB</sys:artifactId> <sys:version>1.0</sys:version> <sys:type>car</sys:type> </sys:dependency> </sys:dependencies> </sys:environment> <context-root>/ApplicationClient</context-root> </web-app>

3. Right click on the ApplicationClient Project and select properties. Select Java Build Path->Projects. Click Add and add Stateless Session EJB. This is required for the compilation of the Client code.

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