J2 ee

SEPTEMBER 27, 2000

Writing Enterprise Applications with
Java™ 2 SDK, Enterprise Edition

by Monica Pawlan

SEPTEMBER 27, 2000

copyright ® 1995-99 Sun Microsystems, Inc.

As used in this document, the terms “Java™ virtual machine” or “Java VM” mean a virtual machine for the Java
platform.

SEPTEMBER 27, 2000 III

Preface

This tutorial introduces you to the APIs, tools, and services provided in the Java™ 2 Enter-
prise Edition (J2EE) Software Developer Kit (SDK). You can get the free J2EE SDK
(http://java.sun.com/j2ee/download.html) to use for demonstrations, prototyping,
educational use, and verifying J2EE application portability.
To support these uses the J2EE SDK comes with J2EE development and deployment tools, a
Web server, Cloudscape database, Java Software application server, Extensible Markup Lan-
guage (XML) support, the J2EE APIs, and Java Plug-In. Java Plug-In lets you run Java 2
applets in browsers that support an earlier release of the Java Runtime Environment (JRE).

Note: This is a work in progress. Links to new lessons are turned on when they become
available. Submit comments and suggestions to jdcee@sun.com

PREFACE

IV SEPTEMBER 27, 2000

PREFACE

SEPTEMBER 27, 2000 V

Contents

Preface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
Lesson 1
A Simple Session Bean. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
Example Thin-Client Multitiered Application 2
J2EE Software and Setup 3
Unix: 3
Windows: 3
Path and ClassPath Settings 3
Path Settings 3
Class Path Settings 4
J2EE Application Components 4
Create the HTML Page 5
HTML Code 6
Create the Servlet 6
Import Statements 7
init Method 7
doGet Method 7
Servlet Code 9
Create the Session Bean 10
CalcHome 11
Calc 12
CalcBean 12
Compile the Session Bean and Servlet 13
Compile the Session Bean 13
Compile the Servlet 13
Start the J2EE Application Server 14
Unix: 14
Windows: 14
Start the Deploy Tool 14
Unix: 14
Windows: 14
Deploy Tool 15
Assemble the J2EE Application 16
Create J2EE Application 16
Create Session Bean 16
Create Web Component 19
Specify JNDI Name and Root Context 22

CONTENTS

SEPTEMBER 27, 2000 VI

Verify and Deploy the J2EE Application 23
Run the J2EE Application 25
Updating Component Code 26
Lesson 2
A Simple Entity Bean . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Create the Entity Bean 28
BonusHome 28
Bonus 29
BonusBean 30
Change the Servlet 32
Compile 34
Compile the Entity Bean 34
Start the Platform and Tools 35
Unix 35
Windows 35
Assemble and Deploy 35
Update Application File 36
Create Entity Bean 36
Lesson 3
Cooperating Enterprise Beans . . . . . . . . . . . . . . . . . . . . . .45
Change the Session Bean 46
CalcHome 46
Calc 47
CalcBean 47
Change the Servlet 49
Compile 50
Compile the Session Bean 51
Unix 52
Windows 52
Assemble the Application 52
Create New J2EE Application 52
Create New Web Component 53
Bundle Session and Entity Beans in one JAR File 54
Lesson 4
JavaServer Pages Technology. . . . . . . . . . . . . . . . . . . . . . .61

CONTENTS

SEPTEMBER 27, 2000 VII

Create the JSP Page 62
Comments 64
Directives 64
Declarations 64
Scriptlets 65
Predefined Variables 65
Expressions 65
JSP-Specific Tags 66
Change bonus.html 66
Unix 67
Windows 67
Remove the WAR File 67
Create New WAR FIle 67
More Information 71
Lesson 5
Adding JavaBeans Technology to the Mix . . . . . . . . . . . .73
About the Example 74
Create bonus.jsp 76
Specify the JavaBean 78
Get the Data 78
Pass the Data to the JavaBean 78
Retrieve Data from the JavaBean 78
Create the JavaBeans Class 79
Bean Properties 81
Constructor 81
Set Methods 81
Get Methods 82
Unix 84
Windows 84
Remove the WAR File 85
Create New WAR FIle 85
More Information 87
Lesson 6
Extensible Markup Language (XML) . . . . . . . . . . . . . . . .89
Marking and Handling Text 90

CONTENTS

VIII SEPTEMBER 27, 2000

Change the JavaBean Class 90
XML Prolog 91
Document Root 91
Child Nodes 91
Other XML Tags 91
JavaBean Code 92
The APIs 95
SAX and DOM 95
J2EE 95
Update and Run the Application 96
More Information 96
Lesson 7
JDBC Technology and Bean-Managed Persistence . . . . 97
Bean Lifecycle 98
Change the BonusBean Code 99
Import Statements 99
Instance Variables 100
Business Methods 100
LifeCycle Methods 100
Change the CalcBean and JBonusBean Code 106
Create the Database Table 107
createTable.sql 107
cloudTable.bat 108
cloudTable.sh 108
Remove the JAR File 109
Verify and Deploy the Application 111
Run the Application 112
More Information 113
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

CONTENTS

SEPTEMBER 27, 2000 1

Lesson 1
A Simple Session Bean

This lesson introduces you to J2EE applications programming, and the J2EE SDK by show-
ing you how to write a simple thin-client multitiered enterprise application that consists of
an HTML page, servlet, and session bean.

Browser/HTML
Servlet Session Bean
Page

The J2EE SDK is a non-commercial operational deﬁnition of the J2EE platform and speciﬁ-
cation made freely available by Sun Microsystems for demonstrations, prototyping, and edu-
cational uses. It comes with the J2EE application server, Web server, database, J2EE APIs,
and a full-range of development and deployment tools. You will become acquainted with
many of these features and tools as you work through the lessons in this tutorial.
• Example Thin-Client Multitiered Application (page 2)
• J2EE Software and Setup (page 3)
• Path and ClassPath Settings (page 3)
• J2EE Application Components (page 4)
• Create the HTML Page (page 5)
• Create the Servlet (page 6)
• Create the Session Bean (page 10)
• Compile the Session Bean and Servlet (page 13)
• Start the J2EE Application Server (page 14)
• Start the Deploy Tool (page 14)
• Deploy Tool (page 15)
• Assemble the J2EE Application (page 16)
• Verify and Deploy the J2EE Application (page 23)
• Run the J2EE Application (page 25)
• Updating Component Code (page 26)

LESSON 1 A SIMPLE SESSION BEAN

2 SEPTEMBER 27, 2000

Example Thin-Client Multitiered Application
The example thin-client multitiered application for this lesson accepts user input through an
HTML form that invokes a servlet. The servlet uses Java Naming and Directory Interface™
(JNDI) APIs to look up a session bean to perform a calculation on its behalf. Upon receiving
the results of the calculation, the servlet returns the calculated value to the end user in an
HTML page.
This example is a thin-client application because the servlet does not execute any business
logic. The simple calculation is performed by a session bean executing on the J2EE applica-
tion server. So, the client is thin because it does not handle the processing; the session bean
does.
Multitiered applications can consist of 3 or 4 tiers. As shown in Figure 1, the multitiered
example for this tutorial has four tiers. Three-tiered architecture extends the standard two-
tier client and server model by placing a multithreaded application server between the non-
web-based client application and a backend database. Four-tiered architecture extends the
three-tier model by replacing the client application with a Web browser and HTML pages
powered by servlet/JavaServer Pages™ technology.

Web Browser Tier 1:
HTML Pages Client Tier

Network

Web Server
(Thin-Client Tier 2:
Servlet) Web Tier

Network

Enterprise Beans
Application Tier 3:
Server Business Tier

Network

Database Tier 4:
Server EIS Tier

Figure 1 Multitiered Architecture



While this lesson uses only three of the four tiers, Lesson 2 expands this same example to
access the database server in the fourth tier. Later lessons adapt the example to use JavaSer-
ver™ Pages and Extensible Markup Language (XML) technologies.

J2EE Software and Setup
To run the tutorial examples, you need to download and install the Java 2 SDK Enterprise
Edition (J2EE), Version 1.2.1 Release (http://java.sun.com/j2ee/download.html), and
Java 2 SDK, Standard Edition (J2SE), Version 1.2 or later (http://java.sun.com/jdk/
index.html).

The instructions in this tutorial assume J2EE and J2SE are both installed in a J2EE directory
under monicap's home directory.

Note: Everywhere monicap is used in a path name, please change it to your own user
name.

Unix:
/home/monicap/J2EE/j2sdkee1.2.1
/home/monicap/J2EE/jdk1.2.2

Windows:
homemonicapJ2EEj2sdkee1.2.1
homemonicapJ2EEjdk1.2.2

Path and ClassPath Settings
The download has the J2EE application server, Cloudscape database, a Web server using
secure socket layer (SSL) also known as HTTP over HTTPS, development and deployment
tools, and the Java APIs for the Enterprise. To use these features, set your path and class path
environment variables as described here.

Path Settings
Path settings make the development and deployment tools accessible from anywhere on your
system. Make sure you place these path settings before any other paths you might have for
other older JDK installations.

Unix:
/home/monicap/J2EE/jdk1.2.2/bin
/home/monicap/J2EE/j2sdkee1.2.1/bin



Windows:
homemonicapJ2EEjdk1.2.2bin
homemonicapJ2EEj2sdkee1.2.1bin

Class Path Settings
Class path settings tell the Java 2 development and deployment tools where to find the vari-
ous class libraries they use.

Unix:
/home/monicap/J2EE/j2sdkee1.2.1/lib/j2ee.jar

Windows:
homemonicapJ2EEj2sdkee1.2.1libj2ee.jar

J2EE Application Components
J2EE applications programmers write J2EE application components. A J2EE component is a
self-contained functional software unit that is assesmbled into a J2EE application and inter-
faces with other application components. The J2EE specification defines the following
application components:
• Application client components
• Enterprise JavaBeans components
• Servlets and JavaServer Pages components (also called Web components)
• Applets
In this lesson, you create a J2EE application and two J2EE components: a servlet and ses-
sion bean. The servlet is bundled with its HTML file into a Web Archive (WAR) file, and the
session bean interfaces and classes are bundled into a JAR file. The WAR and JAR files are
added to the J2EE application and bundled into an Enterprise Archive (EAR) file for verifi-
cation testing and deployment to the production environment.
While you do all of these steps for this lesson, you are actually performing several different
functions. Writing the servlet and session bean code is a developer function, while creating a
J2EE application and adding J2EE components to an application assembly function. In real-
ity, these functions would be performed by different people in different companies.



Create the HTML Page
The HTML page for this lesson is called bonus.html. It’s HTML code is after Figure 2,
which shows how the HTML page looks when displayed to the user. The bonus.html file
has two data fields so the user can enter a social security number and a multiplier. When the
user clicks the Submit button, BonusServlet retrieves the end user data, looks up the ses-
sion bean, and passes the user data to the session bean. The session bean calculates a bonus
and returns the bonus value to the servlet. The servlet then returns another HTML page with
the bonus value for the end user to view.

Figure 2 HTML Page

Figure 3 shows how data flows between the browser and the session bean. The session bean
executes in the J2EE application server.

Component Component

HTML Form Servlet Session Bean
Browser (Web Server) (Application Server)

bonus.html BonusServlet.class CalcBean.class
Calc.class
CalcHome.class

Figure 3 Data Flow



HTML Code
The interesting thing about the HTML form code is the alias used to invoke BonusServlet.
When the user clicks the Submit button on the HTML form, BonusServlet is invoked
because it is mapped to the BonusAlias during application assembly described in Assemble
the J2EE Application (page 16).
The example assumes bonus.html is in the /home/monicap/J2EE/ClientCode directory on
Unix. Here and hereafter, Windows users can reverse the slashes to get the correct directory
pathname for their platform.
<HTML>
<BODY BGCOLOR = "WHITE">
<BLOCKQUOTE>
<H3>Bonus Calculation</H3>
<FORM METHOD="GET"
ACTION="BonusAlias">
<P>
Enter social security Number:
<P>
<INPUT TYPE="TEXT" NAME="SOCSEC"></INPUT>
<P>
Enter Multiplier:
<P>
<INPUT TYPE="TEXT" NAME="MULTIPLIER"></INPUT>
<P>
<INPUT TYPE="SUBMIT" VALUE="Submit">
<INPUT TYPE="RESET">
</FORM>
</BLOCKQUOTE>
</BODY>
</HTML>

Create the Servlet
The example assumes the BonusServlet.java ﬁle is in the /home/monicap/J2EE/Client-
Code directory on Unix. At run time, the servlet code does the following:

• Retrieves the user data
• Looks up the session bean
• Passes the data to the session bean
• Upon receiving a value back from the session bean, creates an HTML page to display
the returned value to the user.
The next sections describe the different parts of the servlet code. The servlet code is shown
in its entirety in Servlet Code (page 9).



Import Statements
The servlet code begins with import statements for the following packages:
• javax.servlet, which contains generic (protocol-independent) servlet classes. The
HTTPServlet class uses the ServletException class in this package to indicate a
servlet problem.
• javax.servlet.http, which contains HTTP servlet classes. The HttpServlet class
is in this package.
• java.io for system input and output. The HttpServlet class uses the IOException
class in this package to signal that an input or output exception of some kind has
occurred.
• javax.naming for using the Java Naming and Directory Interface (JNDI™) APIs to
look up the session bean home interface.
• javax.rmi for looking up the session bean home interface and making its remote
server object ready for communications.

init Method
The BonusServlet.init method looks up the session bean home interface and creates its
instance. The method uses the JNDI name speciﬁed during component assembly (calcs) to
get a reference to the home interface by its name. The next line passes the reference and the
home interface class to the PortableRemoteObject.narrow method to be sure the reference
can be cast to type CalcHome.
InitialContext ctx = new InitialContext();
Object objref = ctx.lookup("calcs");
homecalc = (CalcHome)PortableRemoteObject.narrow(obj
ref, CalcHome.class);

doGet Method
The parameter list for the doGet method takes a request and response object. The browser
sends a request to the servlet and the servlet sends a response back to the browser. The
method implementation accesses information in the request object to ﬁnd out who made
the request, what form the request data is in, and which HTTP headers were sent, and uses
the response object to create an HTML page in response to the browser's request.
The doGet method throws an IOException if there is an input or output problem when it
handles the request, and a ServletException if the request could not be handled. To calcu-
late the bonus value, the doGet method creates the home interface and calls its calcBonus
method.



public void doGet (HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
String socsec = null;
int multiplier = 0;
double calc = 0.0;
PrintWriter out;
response.setContentType("text/html");
String title = "EJB Example";
out = response.getWriter();
out.println("<HTML><HEAD><TITLE>)
out.println(title);
out.println("</TITLE></HEAD><BODY>");

try{
//Retrieve Bonus and Social Security Information
String strMult = request.getParameter(
"MULTIPLIER");
Integer integerMult = new Integer(strMult);
multiplier = integerMult.intValue();
socsec = request.getParameter("SOCSEC");

//Calculate bonus
double bonus = 100.00;
theCalculation = homecalc.create();
calc = theCalculation.calcBonus(
multiplier, bonus);
}catch(Exception CreateException){
CreateException.printStackTrace();
}

//Display Data
out.println("<H1>Bonus Calculation</H1>");
out.println("<P>Soc Sec: " + socsec + "<P>");
out.println("<P>Multiplier: " +
multiplier + "<P>");
out.println("<P>Bonus Amount: " + calc + "<P>");
out.println("</BODY></HTML>");
out.close();
}



Servlet Code
Here is the full code.
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import javax.naming.*;
import javax.rmi.PortableRemoteObject;
import Beans.*;

public class BonusServlet extends HttpServlet {
CalcHome homecalc;

public void init(ServletConfig config)
throws ServletException{

//Look up home interface
try{
homecalc =
(CalcHome)PortableRemoteObject.narrow(
objref,
CalcHome.class);
} catch (Exception NamingException) {
NamingException.printStackTrace();
}
}
public void doGet (HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
String socsec = null;
int multiplier = 0;
double calc = 0.0;
PrintWriter out;
response.setContentType("text/html");
String title = "EJB Example";
out = response.getWriter();
out.println("<HTML><HEAD><TITLE>");
out.println(title);
out.println("</TITLE></HEAD><BODY>");
try{
Calc theCalculation;
//Get Multiplier and Social Security Information
String strMult =
request.getParameter("MULTIPLIER");
//Calculate bonus



calc =
theCalculation.calcBonus(multiplier, bonus);
} catch(Exception CreateException){
}
//Display Data
out.println("<P>Soc Sec: " + socsec + "<P>");
out.println("<P>Multiplier: " +
out.println("<P>Bonus Amount: " + calc + "<P>");
out.close();
}
public void destroy() {
System.out.println("Destroy");
}
}

Create the Session Bean
A session bean represents a transient conversation with a client. If the server or client
crashes, the session bean and its data are gone. In contrast, entity beans are persistent and
represent data in a database. If the server or client crashes, the underlying services ensure
the entity bean data is saved.
Because the enterprise bean performs a simple calculation at the request of BonusServlet,
and the calculation can be reinitiated in the event of a crash, it makes sense to use a session
bean in this example.
Figure 4 shows how the servlet and session bean application components work as a complete
J2EE application once they are assembled and deployed. The container, shown in the shaded
box, is the interface between the session bean and the low-level platform-speciﬁc functional-
ity that supports the session bean. The container is created during deployment.



Home
Interface
Session
HTML Form Text Bean
Servlet
Browser
Remote
Interface
Container

Application Server

Figure 4 Application Components

The next sections show the session bean code. The example assumes the CalcBean.java,
Calc.java, and CalcHome.java files are placed in the /home/monicap/J2EE/Beans direc-
tory on Unix. The package Beans statement at the top of the CalcBean interface and class
files is the same name as the name of this directory. When these files are compiled, they are
compiled from the directory above Beans and the Beans package (or directory) name is
prepended with a slash to the interface and class files being compiled. See Compile the Ses-
sion Bean (page 13).

Note: While this example shows how to write the example session bean, it is also pos-
sible to purchase enterprise beans from a provider and assemble them into a J2EE
application.

CalcHome
BonusServlet does not work directly with the session bean, but creates an instance of its
home interface. The home interface extends EJBHome and has a create method for creating
the session bean in its container. CreateException is thrown if the session bean cannot be
created, and RemoteException is thrown if a communications-related exception occurs dur-
ing the execution of a remote method.
package Beans;

import java.rmi.RemoteException;
import javax.ejb.CreateException;
import javax.ejb.EJBHome;

public interface CalcHome extends EJBHome {
Calc create() throws CreateException,
RemoteException;
}



Calc
When the home interface is created, the J2EE application server creates the remote interface
and session bean. The remote interface extends EJBObject and declares the calcBonus
method for calculating the bonus value. This method is required to throw javax.rmi.Remo-
teException, and is implemented by the CalcBean class.

package Beans;

import javax.ejb.EJBObject;

public interface Calc extends EJBObject {
public double calcBonus(int multiplier,
double bonus)
throws RemoteException;
}

CalcBean
The session bean class implements the SessionBean interface and provides behavior for the
calcBonus method. The setSessionContext and ejbCreate methods are called in that
order by the container after BonusServlet calls the create method in CalcHome.
The empty methods are from the SessionBean interface. These methods are called by the
bean's container. You do not have to provide behavior for these methods unless you need
additional functionality when the bean is, for example, created or removed from its con-
tainer.
package Beans;

import javax.ejb.SessionBean;
import javax.ejb.SessionContext;

public class CalcBean implements SessionBean {
public double calcBonus(int multiplier,
double bonus) {
double calc = (multiplier*bonus);
return calc;
}
//These methods are described in more
//detail in Lesson 2
public void ejbCreate() { }
public void setSessionContext(
SessionContext ctx) { }
public void ejbRemove() { }
public void ejbActivate() { }
public void ejbPassivate() { }
public void ejbLoad() { }
public void ejbStore() { }
}



Compile the Session Bean and Servlet
To save on typing, the easiest way to compile the session bean and servlet code is with a
script (on Unix) or a batch ﬁle (on Windows).

Compile the Session Bean
Unix
#!/bin/sh
cd /home/monicap/J2EE
J2EE_HOME=/home/monicap/J2EE/j2sdkee1.2.1
CPATH=.:$J2EE_HOME/lib/j2ee.jar
javac -d . -classpath "$CPATH" Beans/CalcBean.java
Beans/CalcHome.java Beans/Calc.java

Windows
cd homemonicapJ2EE
set J2EE_HOME=homemonicapJ2EEj2sdkee1.2.1
set CPATH=.;%J2EE_HOME%libj2ee.jar
javac -d . -classpath %CPATH% Beans/CalcBean.java

Compile the Servlet
Unix
#!/bin/sh
cd /home/monicap/J2EE/ClientCode
CPATH=.:$J2EE_HOME/lib/j2ee.jar:
/home/monicap/J2EE
javac -d . -classpath "$CPATH" BonusServlet.java

Windows
cd homemonicapJ2EEClientCode
set J2EE_HOME=homemonicapJ2EEj2sdkee1.2
set CPATH=.;%J2EE_HOME%libj2ee.jar;
homemonicapJ2EE
javac -d . -classpath %CPATH% BonusServlet.java



Start the J2EE Application Server
You need to start the J2EE application server to deploy and run the example. The command
to start the server is in the bin directory under your J2EE installation. If you have your path
set to read the bin directory, go to the J2EE directory (so your live version matches what you
see in this text) and type:
j2ee -verbose

Note: Sometimes the J2EE server will not start if Outlook is running.

If that does not work, type the following from the J2EE directory:

Unix:
j2sdkee1.2.1/bin/j2ee -verbose

Windows:
j2sdkee1.2.1binj2ee -verbose

The verbose option prints informational messages to the command line as the server starts
up. When you see J2EE server startup complete, you can start the depoloyer tool. For
now, you can ignore the other messages that scrolled by.

Start the Deploy Tool
To assemble and deploy the J2EE application, you have to start the deploy tool. If you have
your path set to read the bin directory, go to the J2EE directory (so your live version matches
what you see in this text) and type:
deploytool

If that does not work, do the following from the J2EE directory:

Unix:
j2sdkee1.2.1/bin/deploytool

Windows:
j2sdkee1.2.1bindeploytool

Notes: If a memory access error is encountered when starting deploytool, add an
environment variable called JAVA_FONTS and set the path to c: <font directory>.
For example c:winntfonts. Also, If a NullPointerException for BasicFi-



leChooserUI is encountered when starting deploytool, be sure you are not starting
the tool from the root directory (i.e. c:). If you run it somewhere else, such as the bin
directory for your j2sdkee1.2 installation, you will not encounter the problem.

Deploy Tool
The Deploy tool shown in Figure 5 has four main windows. The Local Applications window
displays J2EE applications and their components. The Inspecting window displays informa-
tion on the selected application or components. The Servers window tells you the application
server is running on the local host. And the Server Applications window tells you which
applications have been installed. As you go through the steps to assemble the example J2EE
application, you will see the Local Applications, Inspecting, and Server Applications win-
dows display information.

Figure 5 Deploy Tool

Note: To the right of the Server Applications window is a grayed Uninstall button.
After you deploy the application, you will see the application listed in the Server
Applications window. You can click Uninstall to uninstall the application, make
changes, and redeploy it without having to stop and restart the application server.



Assemble the J2EE Application
Assembling a J2EE application involves creating a new application, and adding the applica-
tion components to it. Here is a summary of the assembly steps, which are discussed in more
detail below.
1. Create a new J2EE application (BonusApp.ear).
2. Create a new enterprise bean (CalcBean.jar).
3. Create a new web component (Bonus.war).
4. Specify JNDI name for the enterprise bean (calcs).
5. Specify the Root Context for the J2EE application (BonusRoot).

Create J2EE Application
J2EE components are assembled into J2EE application Enterprise Archive (EAR) files.
File menu: Select New Application.
New Application dialog box,:
• Type BonusApp.ear for the Application File Name.
• Click the right mouse button in the Application Display Name field. BonusApp
appears as the display name.
• Click the Browse button to open the file chooser to select the location where you want
the application EAR file to be saved.
New Application file chooser:
• Locate the directory where you want to place the application EAR file
• In this example, that directory is /home/monicap/J2EE.
• In the File name field, type BonusApp.ear.
• Click New Application.
• Click OK.
The BonusApp display name is now listed in the Local Applications window, and the Inspec-
tor window to the right shows the display name, location, and contents information for
BonusApp. The meta information shown in the contents window describes the JAR file and
J2EE application, and provides runtime information about the application.

Create Session Bean
Enterprise beans (entity and session beans) are bundled into a Java Archive (JAR) file.
File menu: Select New Enterprise Bean. The New Enterprise Bean Wizard starts and
displays an Introduction dialog box that summarizes the steps you are about to take. After
reading it over, click Next.
EJB JAR dialog box: Specify the following information:



• Enterprise Bean will go in: BonusApp
Display name: CalcJar
Description: A simple session bean that
calculates a bonus. It has one method
• Click Add. There are two Add buttons on this screen. Make sure you click the second
one down that is next to the Contents window.
Add Files to .JAR dialog box: go to the J2EE directory. You can either type the path name or
use the browser to get there. Once at the J2EE directory, double click on beans to display the
contents of the beans directory.
• Select Calc.class.
• Click Add.
• Select CalcHome.class.
• Click Add.
• Select CalcBean.class.
• Click Add.

Important Note: The Add Contents to .JAR dialog box should look like the one in
Figure 6. The Enterprise Bean JAR classes must show the Beans directory preﬁxed
to the class names.



Figure 6 Select Session Bean Class Files

• Click OK. You should now be back at the EJB JAR dialog box. Beans/Calc.class,
Beans/CalcHome.class, and Beans/CalcBean.class should appear in the Contents
window.
• Click Next.
General dialog box: Make sure the following information is selected:
• classname: Beans.CalcBean
Home interface: Beans.CalcHome
Remote interface: Beans.Calc
Bean type: Session and Stateless
• Specify the display name (the name that appears when when the JAR ﬁle is added to
BonusApp in the Local Applications window), and provide a description of the JAR
ﬁle contents.



•Display Name: CalcBean
•Description: This JAR file contains the CalcBean session bean.
• Click Next.
Environment Entries dialog box: This example does not use properties (environment
entries) so you can:
• Click Finish.
Verify the JAR file was indeed added to the J2EE application:
• Go to the Local Applications window
• Click the key graphic in front of the BonusApp. You will see the CalcJar JAR file.
• Click the key graphic in front of the CalcJar to see the CalcBean session bean.

Create Web Component
Web components (servlets, or JavaServer Pages™ technology) are bundled into a Web
Archive (WAR) file.
File menu: Select New Web Component. The New Web Component Wizard starts and
displays a window that summarizes the steps you are about to take. After reading it over,
click Next.
WAR File General Properties dialog box: Provide the following information:
• WAR file: BonusApp
Display name: BonusWar
Description: This war file contains a servlet and an html page.
• Click Add.
Add Contents to WAR dialog box:
• Go to the ClientCode directory by typing ClientCode after J2EE in the Root Direc-
tory field.
• Select bonus.html. Make sure the WAR contents shows the listing as bonus.html
without the ClientCode directory prefixed to the name.
• Click Add.

Note: Make sure you add bonus.html before you add BonusServlet.class



Figure 7 Add BonusServlet.class

• Click Next.
• Choose the ClientCode directory again.
• Select BonusServlet.class. Be sure the WAR contents shows the listing as
BonusServlet.class without the ClientCode directory preﬁxed to the name.
• Click Add.
Add Contents to WAR dialog box: The display should look like Figure 8.



Figure 8 Add bonus.html

• Click Finish.
WAR File General Properties dialog box:
• Click Next.
Choose Component Type dialog box:
• Select Servlet (if it is not already selected)
• Click Next.
Component General Properties dialog box:
• Make sure BonusServlet is selected for the Servlet Class.



• Enter a display name (BonusServlet) and description.
• You can ignore the Startup and load sequence settings here because this example
uses only one servlet.
Component Initialization Parameters dialog box:
• Click Next. BonusServlet does not use any initialization parameters.
Component Aliases dialog box:
• Click Add.
• Type BonusAlias and press Return. This is the same alias name you put in the ACTION
field of the HTML form embedded in the bonus.html file.
• Click Finish.
In the Content pane, you can see that the WAR file contains an XML file with structural and
attribute information on the web application, the bonus.html file, and the BonusServlet
class file. The WAR file format is such that all servlet classes go in an entry starting with
Web-INF/classes. However, when the WAR file is deployed, the BonusServlet class is
placed in a Context Root directory under public_html. This placement is the convention for
Servlet 2.2 compliant web servers.
To change the display name or description:
• Put your cursor in the appropriate field in the window
• Change them as you wish.
• Press the Return key for the edits to take effect.

Specify JNDI Name and Root Context
Before you can deploy the BonusApp application and its components, you have to specify the
JNDI name BonusServlet uses to look up the CalcBean session bean, and specify a context
root directory where the deployer will put the web components.
JNDI Name:
• Select the BonusApp file in the Local Applications window. The Inspecting window
displays tabs at the top, and one of those tabs is JNDI Names.
• Select JNDI Names. The Inspecting window shows a three-column display with one
row. CalcBean is listed in the middle column.
• In the far right column under JNDI name, type calcs. This JNDI name is the same JNDI
name passed to the BonusServlet.lookup method.
• Press the Return key.
Context Root:
• Click the Web Context tab at the top of the Inspecting window. You will see
BonusWar in the left column.
• Type BonusRoot in the right column



• Press the Return key. During deployment the BonusRoot directory is created under
the public_html directory in your J2sdkee1.2 installation, and the bonus.html
file and BonusServlet class are copied into it as shown in Figure 9.

j2sdkee1.2

public_html

BonusRoot

WEB-INF bonus.html

classes

BonusServlet.class

Figure 9 Context Root Directory Structure

Aliases:
• In the LocalApp window, click BonusWar and then click BonusServlet
• Click the Aliases tab at the top of the Inspecting window. You should see Bonu-
sAlias in the field.
• If BonusAlias is not there, type it in and press Return.

Verify and Deploy the J2EE Application
Before you deploy the application, it is a good idea to run the verifier. The verifier will pick
up errors in the application components such as missing enterprise bean methods that the
compiler does not catch.
Verify:
• With BonusApp selected, choose Verifier from the Tools menu.
• In the dialog that pops up, click OK. The window should tell you there were no failed
tests.



• Close the verifier window because you are now ready to deploy the application.

Note: In the Version 1.2 software you might get a tests app.WebURI error. This
means the deploy tool did not put a .war extension on the WAR file during WAR file cre-
ation. This is a minor bug and the J2EE application deploys just fine in spite of it.

Deploy:
• From the Tools menu, choose Deploy Application. A Deploy BonusApp dialog box
pops up. Verify that the Target Server selection is either localhost or the name of the
host running the J2EE server.

Note: Do not check the Return Client Jar box. The only time you need to check this
box is when you deploy a stand-alone application for the client program. This example
uses a servlet and HTML page so this box should not be checked. Checking this box
creates a JAR file with the deployment information needed by a stand-alone applica-
tion.

• Click Next. Make sure the JNDI name shows calcs. If it does not, type it in yourself,
and press the Return key.
• Click Next. Make sure the Context Root name shows BonusRoot. If it does not, type it
in yourself and press the Return key.
• Click Next.
• Click Finish to start the deployment. A dialog box pops up that displays the status of
the deployment operation.
• When it is complete, the three bars on the left will be completely shaded as shown in
Figure 10. When that happens, click OK.



Figure 10 Deploy Application

Run the J2EE Application
The web server runs on port 8000 by default. To open the bonus.html page point your
browser to http://localhost:8000/BonusRoot/bonus.html, which is where the Deploy
tool put the HTML ﬁle.

Note: If you need to use a different port because port 8000 is being used for something
else, edit the web.properties ﬁle in the ~/J2EE/j2sdkee1.2/config directory and
restart the J2EE server.

• Fill in a social security number
• Fill in a multiplier
• Click the Submit button. BonusServlet processes your data and returns an HTML
page with the bonus calculation on it.



Bonus Calculation

Soc Sec: 777777777
Multiplier: 25

Bonus Amount 2500.0

Updating Component Code
The Tools menu has two menu options of interest. they are Update Application Files and
Update and Redeploy Application. These options let you change code and redeploy your
application with ease. Simply make your code changes, recompile the code, and choose one
of these menu options.
• Update Application Files updates the application files with your new code. At this
point you can either verify the application again or deploy it.
• Update and Redeploy Application updates the application files with your new code
and redeployes the application without running the verifier.



Lesson 2
A Simple Entity Bean

This lesson expands the Lesson 1 example to use an entity bean. BonusServlet calls on the
entity bean to save the social security number and bonus information to and retrieve it from a
database table. This database access functionality adds the fourth and ﬁnal tier to the thin-
client, multitiered example started in Lesson 1.
The J2EE SDK comes with Cloudscape database, and you need no additional setup to your
environment for the entity bean to access it. In fact in this example, you do not write any
SQL or JDBC™ code to create the database table or perform any database access operations.
The table is created and the SQL code generated with the Deploy tool during assembly and
deployment. Lesson 7 JDBC Technology and Bean-Managed Persistence (page 97) shows
you how to write the SQL code for an entity bean.
• Create the Entity Bean (page 28)
• Change the Servlet (page 32)
• Compile (page 34)
• Start the Platform and Tools (page 35)
• Assemble and Deploy (page 35)

LESSON 2 A SIMPLE ENTITY BEAN


Create the Entity Bean
An entity bean represents persistent data stored in one row of a database table. When an
entity bean is created, the data is written to the appropriate database table row, and if the data
in an entity bean is updated, the data in the appropriate database table row is also updated.
The database table creation and row updates all occur without your writing any SQL or
JDBC code.
Entity bean data is persistent because it survives crashes.
• If a crash occurs while the data in an entity bean is being updated, the entity bean data
is automatically restored to the state of the last committed database transaction.
• If the crash occurs in the middle of a database transaction, the transaction is backed out
to prevent a partial commit from corrupting the data.

BonusHome
The main difference between the CalcHome session bean code from Lesson 1 and the
BonusHome entity bean code for this lesson (below) is the findByPrimaryKey method. This
ﬁnder method takes the primary key as a paramete. In this example, the primary key is a
social security number, which is used to retrieve the table row with a primary key value that
corresponds to the social security number passed to this method.
The create method takes the bonus value and primary key as parameters. When
BonusServlet instantiates the home interface and calls its create method, the container
creates a BonusBean instance and calls its ejbCreate method. The BonusHome.create and
BonusBean.ejbCreate methods must have the same signatures, so the bonus and primary
key values can be passed from the home interface to the entity bean by way of the entity
bean's container. If a row for a given primary key (social security) number already exists, a
java.rmi.RemoteException is thrown that is handled in the BonusServlet client code.

package Beans;

import javax.ejb.FinderException;

public interface BonusHome extends EJBHome {
public Bonus create(double bonus, String socsec)
throws CreateException, RemoteException;
public Bonus findByPrimaryKey(String socsec)
throws FinderException, RemoteException;
}



Bonus
After the home interface is created, the container creates the remote interface and entity
bean. The Bonus interface declares the getBonus and getSocSec methods so the servlet can
retrieve data from the entity bean.
package Beans;


public interface Bonus extends EJBObject {
public double getBonus() throws RemoteException;
public String getSocSec() throws RemoteException;
}

Component Component

Browser Servlet Session Bean

bonus.html BonusServlet.class CalcBean.class
Calc.class
CalcHome.class

Component

Entity Bean

BonusBean.class
Bonus.class
BonusHome.class

Database



BonusBean
BonusBean is a container-managed entity bean. This means the container handles data per-
sistence and transaction management without your writing code to transfer data between the
entity bean and the database or define transaction boundaries.
If for some reason you want the entity bean to manage its own persistence or transactions,
you would provide implementations for some of the empty methods shown in the BonusBean
code below. The following references take you to documents that describe bean-managed
persistence and transactions.
• Chapter 3 of the Writing Advanced Applications tutorial.
developer.java.sun.com/developer/onlineTraining/Programming/JDCBook
• Chapter 4 of the Java 2 Enterprise Edition Developer's Guide.
java.sun.com/j2ee/j2sdkee/techdocs/guides/ejb/html/DevGuideTOC.html
When BonusServlet calls BonusHome.create, the container calls the BonusBean.setEnti-
tyContext method. The EntityContext instance passed to the setEntityContext method
has methods that let the bean return a reference to itself or get its primary key.
Next, the container calls the ejbCreate method. The ejbCreate method assigns data to the
bean's instance variables, and then the container writes that data to the database. The ejb-
PostCreate method is called after the ejbCreate method and performs any processing
needed after the bean is created. This simple example does no post-create processing.
The other empty methods are callback methods called by the container to notify the bean
that some event is about to occur. You would provide behavior for some of these methods if
you are using bean-managed persistence, and others if you need to provide bean-specific
cleanup or initialization operations. These cleanup and initialization operations take place at
specific times during the bean's lifecycle, and the container notifies the bean and calls the
applicable method at the appropriate time. Here is a brief description of the empty methods:
• The ejbPassivate and ejbActivate methods are called by the container before the
container swaps the bean in and out of storage. This process is similar to the virtual-
memory concept of swapping a memory page between memory and disk.
• The container calls the ejbRemove method if the home interface has a corresponding
remove method that gets called by the client.
• The ejbLoad and ejbStore methods are called by the container before the container
synchronizes the bean's state with the underlying database.
The getBonus and getSocSec methods are called by clients to retrieve data stored in the
instance variables. This example has no set<type> methods, but if it did, clients would call
them to change the data in the bean's instance variables. Any changes to the instance vari-
ables result in an update to the table row in the underlying database.



package Beans;

import javax.ejb.EntityBean;
import javax.ejb.EntityContext;

public class BonusBean implements EntityBean {

public double bonus;
public String socsec;
private EntityContext ctx;

public double getBonus() {
return this.bonus;
}
public String getSocSec() {
return this.socsec;
}

public String ejbCreate(double bonus,
String socsec)
throws CreateException{
//Called by container after setEntityContext
this.socsec=socsec;
this.bonus=bonus;
return null;
}

public void ejbPostCreate(double bonus,
String socsec) {
//Called by container after ejbCreate
}

//These next methods are callback methods that
//are called by the container to notify the
//Bean some event is about to occur

public void ejbActivate() {
//Called by container before Bean
//swapped into memory
}

public void ejbPassivate() {
//Called by container before
//Bean swapped into storage
}



public void ejbRemove() throws RemoteException {
//Called by container before
//data removed from database
}

public void ejbLoad() {
//Called by container to
//refresh entity Bean's state
}

public void ejbStore() {
//Called by container to save
//Bean's state to database
}

public void setEntityContext(EntityContext ctx){
//Called by container to set Bean context
}

public void unsetEntityContext(){
//Called by container to unset Bean context
}
}

Change the Servlet
The BonusServlet code for this lesson is very similar to the Lesson 1 version with changes in
the init and doGet methods. The init method for this lesson looks up both the CalcBean
session bean, and the BonusBean entity bean.
CalcHome homecalc;
BonusHome homebonus;
Bonus theBonus, record;

try {
Object objref = ctx.lookup("bonus");
Object objref2 = ctx.lookup("calcs");
homebonus=(
BonusHome)PortableRemoteObject.narrow(
objref, BonusHome.class);
homecalc=(CalcHome)
PortableRemoteObject.narrow(
objref2, CalcHome.class);



}
}

The try statement in the doGet method creates the CalcBean and BonusBean home inter-
faces. After calling calcBonus to calculate the bonus, the BonusHome.create method is
called to create an entity bean instance and a corresponding row in the underlying database
table. After creating the table, the BonusHome.findByPrimaryKey method is called to
retrieve the same record by its primary key (social security number). Next, an HTML page is
returned to the browser showing the data originally passed in, the calculated bonus, and the
data retrieved from the database table row.
The catch statement catches and handles duplicate primary key values (social security num-
bers). The underlying database table cannot have two rows with the same primary key, so if
you pass in the same social security number, the servlet catches and handles the error before
trying to create the entity bean. In the event of a duplicate key, the servlet returns an HTML
page with the original data passed in, the calculated bonus, and a duplicate key error mes-
sage.
try {
"MULTIPLIER");//Calculate bonus
//Calculate bonus
calc = theCalculation.calcBonus(
multiplier, bonus);
//Create row in table
theBonus = homebonus.create(calc, socsec);
record = homebonus.findByPrimaryKey(socsec);
//Display data
out.println("<P>Soc Sec passed in: " +
theBonus.getSocSec() + "<P>");
out.println("<P>Multiplier passed in: " +
out.println("<P>Bonus Amount calculated: " +
theBonus.getBonus() + "<P>");
out.println("<P>Soc Sec retrieved: " +
record.getSocSec() + "<P>");
out.println("<P>Bonus Amount retrieved: " +



record.getBonus() + "<P>");
//Catch duplicate key error
} catch (javax.ejb.DuplicateKeyException e) {
String message = e.getMessage();
//Display data
out.println("<P>Soc Sec passed in: " +
socsec + "<P>");
out.println("<P>Bonus Amount calculated: " +
calc + "<P>");
out.println("<P>" + message + "<P>");
} catch (Exception CreateException) {
}
}

Compile
First, compile the entity bean and servlet. Refer to Lesson 1 for path and classpath settings,
and information on where to place the source ﬁles.

Compile the Entity Bean
Unix
#!/bin/sh
javac -d . -classpath "$CPATH" Beans/BonusBean.java
Beans/BonusHome.java Beans/Bonus.java

Windows
cd homemonicapJ2EE
javac -d . -classpath %CPATH% Beans/BonusBean.java
Beans/BonusHome.java Beans/Bonus.java



Compile the Servlet
Unix:
CPATH=.:$J2EE_HOME/lib/j2ee.jar:/home/monicap/J2EE

Windows:
set CPATH=.;%J2EE_HOME%libj2ee.jar;
homemonicapJ2EE

Start the Platform and Tools
To run this example, you need to start the J2EE server, the Deploy tool, and Cloudscape
database. In different windows, type the following commands:
j2ee -verbose
deploytool
cloudscape -start

If that does not work, type this from the J2EE directory:

Unix
j2sdkee1.2.1/bin/cloudscape -start

Windows
j2sdkee1.2.1bincloudscape -start

Assemble and Deploy
The steps in this section are:



• Update Application File
• Create Entity Bean

Update Application File
The web archive (WAR) file contains BonusServlet and bonus.html. Because you have
changed BonusServlet, you have to update the J2EE application with the new servlet code.
• Local Applicatons Window: Highlight the BonusApp application.
• Tools Menu: Select Update Application Files.

Note: The BonusApp application from the previous lesson is automatically uninstalled

Create Entity Bean
The steps to creating the EJB JAR for the entity bean are very similar to the steps for the ses-
sion bean covered in Lesson 1. There are a few differences, however, and those differences
are explained here.

Note: In this lesson, the entity bean goes in a separate JAR file from the session bean
to continue the example from Lesson 1 with the least number of changes. Because
these beans have related functionality, however, you could bundle and deploy them in
the same JAR file. You will see how to bundle related beans in the same JAR file in
Lesson 3.

File Menu:
• Select New Enterprise Bean.
Introduction:
• Read and click Next.
EJB JAR:
• Make sure BonusApp shows in the Enterprise Bean will go in field.
• Specify BonusJar as the display name.
• Click Add (the one next to the Contents window).
Add Contents to JAR:
• Toggle the directory so the beans directory displays with its contents.
• Select Bonus.class
• Click Add.



• Select BonusBean.class
• Click Add.
• Select BonusHome.class
• Click Add.
• Click OK.

Figure 11 Adding Classes to BonusJar

EJB JAR:
• Click Next.
General:



• Beans.BonusBean is the classname
• Beans.BonusHome is the Home interface
• Beans.Bonus is the Remote interface.
• Enter BonusBean as the display name.
• Click Entity.
• Click Next.
Entity Settings:
• Select Container-Managed persistence.
• In the bottom window, check bonus and socsec.
• Specify java.lang.String for the primary key class. Note that the primary key has
to be a class type. Primitive types are not valid for primary keys.
• Specify socsec for the primary key ﬁeld name.
• Click Next.
Environment Entries:
• Click Next. This simple entity bean does not use properties (environment entries).
Enterprise Bean References:
• Click Next. This simple entity bean does not reference other enterprise beans.
Resource References:
• Click Next. This simple entity bean does not look up a database or JavaMail™ session
object.
Security:
• Click Next. This simple entity bean does not use security roles.
Transaction Management:
• Select Container-managed transactions (if it is not already selected.
• In the list below make create, findByPrimaryKey, getBonus and getSocSec
required. This means the container starts a new transaction before running these meth-
ods. The transaction commits just before the methods end. There is more information
on these transaction settings in Enterprise JavaBeans Developer's Guide, Chapter 6
(java.sun.com/j2ee/j2sdkee/techdocs/guides/ejb/html/DevGuideTOC.html).



Figure 12 Transaction Management

• Click Next.
• Click Finish.
Local Applications:

• Select BonusApp.
• In the Inspecting window, select JNDI names
• Give BonusBean the JNDI name of bonus
• Press the Return key
Before the J2EE application can be deployed, you need to specify deployment settings for
the entity bean and generate the SQL. Here is how to do it:



Local Applications window:
• Select BonusBean.
Inspecting window:
• Select Entity
• Click the Deployment Settings button to the lower right.
Deployment Settings:
• Specify jdbc/Cloudscape (with a capital C on Cloudscape) for the Database JNDI
name
• Press Return
• Make sure the Create table on deploy and Delete table on Deploy boxes are
checked.
• Click Generate SQL now.

Note: If you get an error that the connection was refused, start the database as
described in Start the Platform and Tools (page 35).



Figure 13 Generate SQL and Database Table

• When the SQL generation completes, select the findByPrimaryKey method in the EJB
method box. To the right a SQL statement appears. It should read SELECT “socsec”
FROM “BonusBeanTable” WHERE “socsec”=?. The question mark (?) represents the
parameter passed to the findByPrimaryKey method.
• Click OK.



Verify:
• With BonusApp selected, choose Verifier from the Tools menu.
• In the dialog that pops up, click OK. The window should tell you that no tests failed.

Note: In the Version 1.2 software you might get a tests app.WebURI error. The J2EE
application deploys in spite of it.

Deploy:
• Tools Menu: Select Tools.Deploy Application.

box is when you use bean-managed persistence or deploy a stand-alone application for
the client program. This example uses a servlet and HTML page so this book should
not be checked. Checking this box creates a JAR ﬁle with deployment information
needed by a stand-alone application.

• Click Next. Make sure the JNDI names show calcs for CalcBean and bonus for
BonusBean. Type any missing JNDI names in yourself, and press the Return key.
• Click Next.
• Click Finish to start the deployment.
• When deployment completes, click OK.



Fill in a social security number and multiplier, and click the Submit button. BonusServlet
processes your data and returns an HTML page with the bonus calculation on it.
Bonus Calculation

Soc Sec passed in: 777777777
Multiplier passed in: 25
Bonus Amount calculated: 2500.0
Soc Sec retrieved: 7777777777
Bonus Amount retrieved: 2500.0

If you go back to bonus.html and change the multiplier to 2, but use the same social secu-
rity number, you see this:
Bonus Calculation
Bonus Amount calculated: 200.0
Duplicate primary key.



Lesson 3
Cooperating Enterprise Beans

In Lesson 2 A Simple Entity Bean (page 27), the servlet looks up and creates a session bean
to perform a bonus calculation, and then looks up and creates an entity bean to store the
bonus value and related social security number. This lesson modifies the example so the ses-
sion bean looks up and creates the entity bean. Because the session and entity bean work
together, they are bundled into one JAR file for deployment.
• Change the Session Bean (page 46)
• Change the Servlet (page 49)
• Compile (page 50)
• Assemble the Application (page 52)

Note: Some people have trouble getting this lesson to work with 2 beans in one JAR
file. If this happens to you, delete the JAR file with the two beans and put each bean in
its own JAR file. You might need to stop and restart the server and tools before you can
generate SQl and deploy.

LESSON 3 COOPERATING ENTERPRISE BEANS


Change the Session Bean
In this lesson and as shown in Figure 14, the entity bean is a client of the session bean. This
means the entity bean gets its data from the session bean instead of from BonusServlet as it
did in Lesson 2 A Simple Entity Bean (page 27). So, the calcBonus method in the session
bean is modiﬁed to take the social security number as a parameter and create the entity bean.

HTML Form Servlet Session Bean
Browser (Web Server) (Application Server)

bonus.html BonusServlet.class calcBonus method
getRecord method

Entity Bean

Database

Figure 14 Beans Working Together

CalcHome
The CalcHome interface is unchanged. It has the same create method that returns an
instance of the remote interface.
package Beans;


public interface CalcHome extends EJBHome {
public Calc create()
throws CreateException, RemoteException;
}



Calc
The calcBonus method in the Calc interface is changed to take the social security number as
a parameter. This is so CalcBean can pass the bonus and social security number to the entity
bean after calculating the bonus value. A new getRecord method is added so CalcBean can
ﬁnd an entity bean by its primary key (the social security number).
Also, the calcBonus method signature throws DuplicateKeyException and CreateExcep-
tion. This is so BonusServlet can catch and handle either of these exception conditions.
DuplicateKeyException descends from CreateException. If you design the calcBonus
method to throw DuplicateKeyException, but catch CreateException, DuplicateKeyEx-
ception is not thrown. The way around this is to have calcBonus throw both Dupli-
cateKeyException and CreateException.

package Beans;

import javax.ejb.DuplicateKeyException;

public interface Calc extends EJBObject {
public Bonus calcBonus(int multiplier,
double bonus,
String socsec)
throws RemoteException,
DuplicateKeyException,
CreateException;
public Bonus getRecord(String socsec)
throws RemoteException;

}

CalcBean
The code to create the entity bean is moved from BonusServlet to the calcBonus method so
the bonus and social security number can be written to the entity bean after the bonus is cal-
culated. The homebonus variable is an instance variable so it can be used in the calcBonus
method to look up the entity bean and in the getRecord method to locate the entity bean cor-
responding to the social security number.
package Beans;

import javax.ejb.SessionBean;
import javax.ejb.SessionContext;



import javax.naming.InitialContext;
import javax.ejb.DuplicateKeyException;

//Throw DuplicateKeyException and CreateException
//so BonusServlet can catch and handle these
//exception conditions.
double bonus, String socsec)
throws DuplicateKeyException,
CreateException {
Bonus theBonus = null;
try {
homebonus = (BonusHome)
}
//Store data in entity bean
try {
theBonus = homebonus.create(calc, socsec);
} catch (java.rmi.RemoteException e) {
e.printStackTrace();
}
return theBonus;
}

public Bonus getRecord(String socsec) {
Bonus record = null;
//Use primary key to retrieve data from entity bean
try {
record = homebonus.findByPrimaryKey(socsec);
} catch (javax.ejb.FinderException e) {
}
return record;
}
public void ejbCreate() { }



public void setSessionContext(
SessionContext context){
}
public void ejbRemove() { }
public void ejbActivate() { }
public void ejbPassivate() { }
public void ejbLoad() { }
public void ejbStore() { }
}

Change the Servlet
The BonusServlet program is very similar to the version in Lesson 2 A Simple Entity Bean
(page 27) with changes in the init and doGet methods. The init method for this lesson
looks up the CalcBean session bean only.
CalcHome homecalc;
//Need Bonus variables because CalcBean methods
//called in the doGet method return instances
//of type Bonus
Bonus theBonus, record;

try {
homecalc = (CalcHome)
objref, CalcHome.class);
}
}

The try statement in the doGet method calculates the bonus, creates the session bean home
interface, and calls the calcBonus and getRecord methods. If the methods successfully
complete, an HTML page is returned showing the data retrieved from the entity bean. If
DuplicateKeyException is thrown by the calcBonus method, an HTML page is returned
showing the social security number and multiplier passed in, and the exception message,
Duplicate primary key.

As before in Lesson 2 A Simple Entity Bean (page 27), the catch statement catches and
handles duplicate primary key values (social security numbers).



try {
"MULTIPLIER");//Calculate bonus
//Calculate bonus
//Call session bean
//Pass 3 parameters:multiplier, bonus, and socsec
theBonus = theCalculation.calcBonus(
multiplier, bonus, socsec);
record = theCalculation.getRecord(socsec);
//Display data returned by session bean
out.println("<P>Soc Sec retrieved: " +
record.getSocSec() + "<P>");
out.println("<P>Bonus Amount retrieved: " +
record.getBonus() + "<P>");
out.println("<P>Soc Sec passed in: " + socsec +
"<P>");
} catch (Exception CreateException) {
}

Compile
First, compile the session bean and servlet. Refer to Lesson 1 for path and classpath settings,
and information on where to place the source ﬁles.



Compile the Session Bean
Unix
#!/bin/sh
javac -d . -classpath "$CPATH" Beans/CalcBean.java

Windows
cd homemonicapJ2EE
javac -d . -classpath %CPATH% Beans/CalcBean.java

Compile the Servlet
Unix:
J2EE_HOME=/home/monicap/J2EE/j2sdkee1.2
CPATH=.:$J2EE_HOME/lib/j2ee.jar:
/home/monicap/J2EE

Windows:
set J2EE_HOME=homemonicapJ2EEj2sdkee1.2 set
CPATH=.;%J2EE_HOME%libj2ee.jar:homemonicapJ2EE

j2ee -verbose
deploytool
cloudscape -start




Unix

Windows

Assemble the Application
The steps for this section include the following:
• Create New J2EE Application
• Create New Web Component
• Bundle Session and Entity Beans in One JAR File

Create New J2EE Application
Rather than update the J2EE application from Lessons 1 and 2, these steps create a new
J2EE application.
Delete BonusApp:
• Click BonusApp so it is highlighted
• Select Delete from the Edit menu
Create 2BeansApp:
• From the File menu, select New Application.
• Click the right mouse button in the Application Display Name field. 2BeansApp
appears as the display name.
• Click the Browse button to open the file chooser to select the location where you want
the application EAR file to be saved.
New Application file chooser:
• Locate the directory where you want to place the application EAR file
• In this example, that directory is /export/home/monicap/J2EE.
• In the File name field, type 2BeansApp.ear.



• Click New Application.
• Click OK.

Create New Web Component
Now, go through the steps to create the WAR ﬁle. These steps are outlined in Lesson 1 and
summarized below. With 2BeansApp selected,
File Menu:
• Select New Web Component.
Introduction:
• Read and Click Next
War File General Properties:
• Specify BonusWar for the display name.
• Click Add
• Go to the ClientCode directory and add bonus.html
• Click Next
• Go to the ClientCode directory and add BonusServlet.class
• Click Finish.
• Click Next.
Choose Component Type:.
• Make sure Describe a servlet is selected.
• Click Next.
Component General Properties:
• Make BonusServlet the servlet class
• Make the display name BonusServlet.
• Click Next.
Component Initialization Parameters.
• Click Next.
Component Aliases:
• Specify BonusAlias
• Click Finish.



Inspecting window:
• Select Web Context
• Specify BonusRoot.

Bundle Session and Entity Beans in one JAR File
In this lesson, you will put both the session and entity beans in the same JAR file. To do this,
you first create the JAR file with only the session bean in it, and then add the entity bean to
that JAR file.

Create JAR with Session Bean
With 2BeansApp selected,
File Menu:
• Select New Enterprise Bean
Introduction:
EJB JAR:
• Make sure 2BeansApp shows in the Enterprise Bean will go in field.
• Specify 2BeansJar as the display name.
• Toggle the directory so the Beans directory displays with its contents.
• Select Calc.class
• Click Add.
• Select CalcBean.class
• Click Add.
• Select CalcHome.class
• Click Add.
Enterprise Bean JAR classes:
• Make sure you see Beans/Calc.class, Beans/CalcHome.class, and Beans/Cal-
cBean.class in the display.
• Click OK.
EJB JAR:
• Click Next.



General:
• CalcBean is the classname, Beans.CalcHome is the Home interface, and Beans.Calc
is the Remote interface.
• Enter CalcBean as the display name.
• Click session and stateless.
• Click Next.
• Click Next. This simple session bean does not use properties (environment entries).
• lick Next. The references are handled during deployment rather than here.
• Click Next. This simple session bean does not look up a database or JavaMail™ session
object.
Security:
• Click Next. This simple session bean does not use security roles.
• Select Container-managed transactions (if it is not already selected).
• In the list below make calcBonus, and getRecord required. This means the container
starts a new transaction before running these methods. The transaction commits just
before the methods end. You can ﬁnd more information on these transaction settings
in Chapter 6 of the Enterprise JavaBeans Developer's Guide.
• Click Next.
Review Settings:
• Click Finish.
Local Applications:
• Select 2BeansApp.
• In the Inspecting window, select JNDI names, give CalcBean the JNDI name of calcs,
and press the Return key.

Add the Entity Bean
With 2BeansApp selected,
File Menu:



• Select New Enterprise Bean
Introduction:
EJB JAR:
• Make sure 2BeansJar shows in the Enterprise Bean will go in field. This setting will
add the new bean to the existing JAR file instead of putting the new bean in its own
JAR file.
• Click Add.
• Click Add.
• Click Add.
• Make sure you see Beans/Bonus.class, Beans/BonusHome.class, and Beans/
BonusBean.class in the display.
• Click OK.
EJB JAR:
• Click Next.
General:
• Make sure Beans.BonusBean is the classname, Beans.BonusHome is the Home inter-
face, and Beans.Bonus is the Remote interface.
• Click Entity.
• Click Next.
Entity Settings:
• Select Container managed persistence.
• n the window below, check bonus and socsec. The primary key class is
java.lang.String, and the primary key field name is socsec. Note that the primary
key has to be a class type. Primitive types are not valid for primary keys.
• Click Next.



• Click Next. This simple entity bean does not reference other enterprise Beans.
• Click Next. This simple entity bean does not look up a database or JavaMail™ session
object.
Security:
ods. The transaction commits just before the methods end. You can ﬁnd more informa-
tion on these transaction settings in Chapter 6 of the Enterprise JavaBeans Developer's
Guide.
• Click Next.
Review Settings:
• Click Finish.
Local Applications:
• Select 2BeansApp.
• In the Inspecting window, select JNDI names, give BonusBean the JNDI name of bonus
and CalcBean the JNDI name of calcs
• Press the Return key after each entry.
Before the J2EE application can be deployed, you need to specify deployment settings for
the entity bean and generate the SQL. Here is how to do it:
Local Applications window:
• Select BonusBean.
Inspecting window:
• Select Entity
• Click the Deployment Settings button to the lower right.
Deployment Settings window:



• Specify jdbc/Cloudscape (with a capital C on Cloudscape) for the Database JNDI
name
• Press Return
• Make sure the Create table on deploy and Delete table on Deploy boxes are
checked
• Click Generate SQL now.

Note: If you get an error that the connection was refused, start the database as
described in Start the Platform and Tools (page 51).

When the SQL generation completes,
• Select the findByPrimaryKey method in the EJB method box.
• To the right a SQL statement appears. It should read SELECT “socsec” FROM “Bonus-
BeanTable” WHERE “socsec”=?. The question mark (?) represents the parameter
passed to the findByPrimaryKey method.
• Click OK.


Note: If you get a Save error when you verify or deploy, shut everything down and
restart the server and tools.

Verify:
• With 2BeansApp selected, choose Verifier from the Tools menu.
tests.

Note: In the Version 1.2.1 software you might get a tests app.WebURI error. This

Deploy:



pops up.
• Verify that the Target Server selection is either localhost or the name of the host run-
ning the J2EE server.

box is when you use bean-managed persistence or deploy a stand-alone application for
the client program. This example uses a servlet and HTML page so this book should
not be checked. Checking this box creates a JAR ﬁle with deployment information
needed by a stand-alone application.

• Click Next.
• Make sure the JNDI names show for calcs for CalcBean and bonus for BonusBean. If
they do not, type the JNDI names in yourself, and press the Return key.
• Click Next.




• Fill in a social security number and multiplier.
• Click the Submit button. BonusServlet processes your data and returns an HTML
page with the bonus calculation on it.
Bonus Calculation

Soc Sec retrieved: 777777777
Bonus Amount Retrieved: 200.0

If you supply the same social security number twice, you will see something similar to this:
Bonus Calculation

Duplicate primary key



Lesson 4
JavaServer Pages Technology

JavaServer Pages™ (JSP) technology lets you put segments of servlet code directly into a
static HTML page. When the JSP Page is loaded by a browser, the servlet code executes and
the application server creates, compiles, loads, and runs a background servlet to execute the
servlet code segments and return an HTML page or print an XML report.
This lesson changes the WAR ﬁle from Lesson 3 Cooperating Enterprise Beans (page 45) to
use a JSP Page instead of BonusServlet.
• Create the JSP Page (page 62)
• Change bonus.html (page 66)
• Remove the WAR File (page 67)
• Create New WAR FIle (page 67)
• More Information (page 71)

LESSON 4 JAVASERVER PAGES TECHNOLOGY


Create the JSP Page
A JSP Page looks like an HTML page with servlet code segments embedded between vari-
ous forms of leading (<%) and closing (%>) JSP tags. There are no HttpServlet methods
such as init, doGet, or doPost. Instead, the code that would normally be in these methods
is embedded directly in the JSP Page using JSP scriptlet tags.
The following JSP Page (Bonus.jsp) is equivalent to BonusServlet from Lesson 3 Cooperat-
ing Enterprise Beans (page 45). A more detailed description of the JSP tags follows the code
listing. Note that JSP tags cannot be nested. For example, you cannot nest a JSP comment
tag within a JSP scriptlet tag.
<HTML>
<HEAD>
<TITLE>Bonus Calculation</TITLE>
</HEAD>
<%-- Comment
Scriptlet for import statements
<%@ indicates a jsp directive --%>
<%@ page import="javax.naming.*" %>
<%@ page import="javax.rmi.PortableRemoteObject" %>
<%@ page import="Beans.*" %>
<%-- Comment
Scriptlet to get the parameters,
convert string to Integer to int for bonus
calculation, and declare/initialize bonus
variable. <% indicates a jsp scriptlet --%>
<%! String strMult, socsec; %>
<%! Integer integerMult; %>
<%! int multiplier; %>
<%! double bonus; %>
<%
strMult = request.getParameter("MULTIPLIER");
integerMult = new Integer(strMult);
bonus = 100.00;
%>
<%-- Comment
Scriptlet to look up session Bean --%>
<%
CalcHome homecalc = (CalcHome)
%>



<%-- Comment
Scriptlet to create session Bean,
call calcBonus method, and retrieve a database
record by the social security number
(primary key) --%>
<%
try {
Calc theCalculation = homecalc.create();
Bonus theBonus = theCalculation.calcBonus(
multiplier,
bonus,
socsec);
Bonus record = theCalculation.getRecord(socsec);
%>
<%-- Comment
HTML code to display retrieved data
on returned HTML page. --%>
Social security number retrieved:
<%= record.getSocSec() %>
<P>
Bonus Amount retrieved: <%= record.getBonus() %>
<P>
<%-- Comment
Scriptlet to catch DuplicateKeyException --%>
<%
%>
<%-- Comment
HTML code to display original data passed to JSP
on returned HTML page --%>
Social security number passed in: <%= socsec %>
<P>
Multiplier passed in: <%= strMult %>
<P>
Error: <%= message %>
<%-- Comment
Scriptlet to close try and catch block --%>
<%
}
%>
<%-- Comment
HTML code to close HTML body and page --%>
</BODY>
</HTML>


Comments
The ﬁrst seven lines of Bonus.jsp show straight HTML followed by a JSP comment. JSP
comments are similar to HTML comments except they start with <%-- instead of <!--,
which is how they look in HTML. You can use either JSP or HTML comments in a JSP ﬁle.
HTML comments are sent to the client’s web browser where they appear as part of the
HTML page, and JSP comments are stripped out and do not appear in the generated HTML.

Note: I found that putting a colon in a JSP comment as in <%-- Comment: Scriptlet
for import statements . . . created a runtime error that went away when I took
the colon out.

<HTML>
<HEAD>
</HEAD>
<%-- Comment
Scriptlet for import statements
<%@ indicates a jsp directive --%>

Directives
JSP directives are instructions processed by the JSP engine when the JSP Page is translated
to a servlet. The directives used in this example tell the JSP engine to include certain pack-
ages and classes. Directives are enclosed by the <%@ and %> directive tags.
<%@ page import="javax.naming.*" %>
<%@ page import="javax.rmi.PortableRemoteObject" %>
<%@ page import="Beans.*" %>

Declarations
JSP declarations let you set up variables for later use in expressions or scriptlets. You can
also declare variables within expressions or scriptlets at the time you use them. The scope is
the entire JSP Page, so there is no concept of instance variables. That is, you do not have to
declare instance variables to be used in more than one expression or scriptlet. Declarations
are enclosed by the <%! and %> declaration tags. You can have multiple declarations. For
example, <%! double bonus; String text; %>.
<%! String strMult, socsec; %>
<%! Integer integerMult; %>
<%! int multiplier; %>
<%! double bonus; %>


Scriptlets
JSP scriptlets let you embed java code segments into the JSP page. The embedded code is
inserted directly into the generated servlet that executes when the page is requested. This
scriptlet uses the variables declared in the directives described above. Scriptlets are enclosed
by the <% and %> scriptlet tags.
<%
bonus = 100.00;
%>

Predefined Variables
A scriptlet can use the following predefined variables: session, request, response, out,
and in. This example uses the request predefined variable, which is an HttpServletRe-
quest object. Likewise, response is an HttpServletResponse object, out is a Print-
Writer object, and in is a BufferedReader object.

Predefined variables are used in scriptlets in the same way they are used in servlets, except
you do not declare them.
<%
bonus = 100.00;
%>

Expressions
JSP expressions let you dynamically retrieve or calculate values to be inserted directly into
the JSP Page. In this example, an expression retrieves the social security number from the
Bonus entity bean and puts it on the JSP page.

<%= record.getSocSec() %>
<P>
Bonus Amount retrieved: <%= record.getBonus() %>
<P>



JSP-Specific Tags
The JavaServer Pages 1.1 specification defines JSP-specific tags that let you extend the JSP
implementation with new features and hide a lot of complexity from visual designers who
need to look at the JSP page and modify it. The JSP example in this lesson does not use any
JSP-specific tags, but you will see an example of these tags in the next lesson. The JSP-spe-
cific tags defined in the 1.1 specification are the following:
jsp:forward and jsp:include to instruct the JSP engine to switch from the current page to
another JSP page.
jsp:useBean, jsp:setProperty, and jsp:getProperty let you embed and use JavaBeans
technology inside a JSP Page.
jsp:plugin automatically downloads the appropriate Java Plug-In to the client to execute an
applet with the correct Java platform.

Change bonus.html
The only change you need to make to bonus.html is to have the ACTION parameter in the
HTML form invoke Bonus.jsp instead of BonusServlet.
<HTML>
<BLOCKQUOTE>
<FORM METHOD="GET" ACTION="Bonus.jsp">
<P>
<P>
<P>
Enter Multiplier:
<P>
<P>
</FORM>
</FORM>
</BLOCKQUOTE>
</BODY>
</HTML>



j2ee -verbose
deploytool
cloudscape -start


Unix

Windows

Remove the WAR File
Because a JSP page is added to the Web component, you have to delete the WAR ﬁle from
the previous lesson and create a new one with the JSP page in it.
Local Applications:
• Click the 2BeansApp icon so you can see its application components.
• Select BonusWar so it is outlined and highlighted.
• Select Delete from the Edit menu.

Create New WAR FIle
File menu:
• Select New Web Component
Introduction:
• Read and Click Next.




Note: There appears to be a bug in the Deploy tool. Make sure you add Bonus.jsp first
followed by bonus.html. If you add bonus.html first, Deploy tool puts bonus.html
where Bonus.jsp should go, and Bonus.jsp where bonus.html should go. If this hap-
pens, you can manually fix the problem by copying them to their correct locations.
This is where they correctly belong after deployment:
~/j2sdkee1.2/public_html/JSPRoot/bonus.html
~/j2sdkee1.2/public_html/JSPRoot/WEB-INF/classes/Bonus.jsp

• Click Add
• Go to the ClientCode directory and add Bonus.jsp,
• Click Next
• Go to the ClientCode directory and add bonus.html
• Click Finish.
• Click Next.
• Make sure Describe a JSP is selected. Click Next.
• Make Bonus.jsp the JSP filename
• Make the display name BonusJSP.
• Click Finish.
Inspecting window:
• Specify JSPRoot.

up errors in the application components such as missing enterprise Bean methods that the
Verify:



• In the dialog that pops up, click OK. The window should tell you no tests failed.
Deploy:
pops up.

uses an HTML and JSP page so this book should not be checked. Checking this box
creates a JAR ﬁle with deployment information needed by a stand-alone application.

BonusBean. If they do not show these names, type them in yourself, and press the
Return key.
• Click Next. Make sure the Context Root name shows JSPRoot. If it does not, type it in
yourself and press the Return key.
• Click Next.




browser to http://localhost:8000/JSPRoot/bonus.html, which is where the Deploy

Note: Deploy tool puts Bonus.jsp under public_html/JSPRoot, and bonus.html
under public_html/JSPRoot/WEB-INF/classes, which is opposite of where they
really belong. Manually copy them to their correct locations as follows: public_html/
JSPRoot/bonus.html and public_html/JSPRoot/WEB-INF/classes/Bonus.jsp.

• Fill in a social security number and multiplier
• Click the Submit button. Bonus.jsp processes your data and returns an HTML page
with the bonus calculation on it.



Bonus Calculation

Social Security number retrieved: 777777777
Bonus Amount Retrieved: 200.0

If you supply the same social security number twice, you will see something similar to this:
Bonus Calculation

Error: Duplicate primary key

More Information
Another way to use JavaServer pages technology is in combination with JavaBeans™ tech-
nology where the JSP page presents a form to the user and calls on the JavaBean to process
the data entered on the form. You can see an example at the following URL: http://
java.sun.com/j2ee/j2sdkee/techdocs/guides/ejb/html/Client.fm.html#10649

This next URL takes you to an article with a great explanation of JavaServer pages and Java-
Beans technologies: Building Your own JSP Components
http://developer.iplanet.com/viewsource/fields_jspcomp/fields_jspcomp.html



Lesson 5
Adding JavaBeans Technology
to the Mix

You can use JavaBeans™ technology to put a JavaBean between the JSP page and CalcBean
session bean to get a better Model, View, Controller (MVC) separation. MVC is a design
pattern that consists of three kinds of objects. The Model provides the application business
logic, the View is its screen presentation, and the Controller is an object that manages what
happens when the user interacts with the View. A design pattern describes a recurring prob-
lem and its solution where the solution is never exactly the same for every recurrence.
Lesson 4 JavaServer Pages Technology (page 61) is set up so the HTML and JSP pages pro-
vide the screen presentation (View) and manage what happens when the user interacts with
the data (Controller). The entity and session bean (BonusBean and CalcBean) are the appli-
cation objects or Model.
This lesson uses a JSP page for the screen presentation (View), a JavaBean to manage what
happens when the user interacts with the View (Controller), and the entity and session beans
for the application objects (Model). Separating the Controller from the View like this lets the
JavaBean serve as a wrapper for the session bean and gives the example a much cleaner
MVC separation. An application that uses clear design patterns is easier to update, maintain,
and manage.
• About the Example (page 74)
• Create bonus.jsp (page 76)
• Create the JavaBeans Class (page 79)
• Bean Properties (page 81)
• Remove the WAR File (page 85)
• Create New WAR FIle (page 85)

LESSON 5 ADDING JAVABEANS TECHNOLOGY TO THE MIX


About the Example
In Lesson 4 JavaServer Pages Technology (page 61), the application user interface consisted
of an HTML page with an HTML form. The HTML form calls the JSP page when the user
clicks the Submit button on the HTML page.
Another way to create the user interface is with one JSP page that includes the HTML form,
JSP scriptlets, and JSP-specific tags for interacting with the JavaBean. When the JSP page
loads, the HTML form is displayed and the scriptlet and JSP-specific tags for interacting
with the JavaBean are executed. Because no data has been supplied yet, the display looks
like Figure 17:

Figure 17 When bonus.jsp Loads

After the user enters some data and clicks the Submit button, the HTML form is redisplayed
and the scriptlet and JSP-specific tags for interacting with the JavaBean execute again with
the data supplied. The display looks something like Figure 18. This is because the ACTION
parameter for the HTML form on bonus.jsp recursively calls itself.



Figure 18 After User Enters Data and Clicks Submit

If the user enters the same social security number, a duplicate key error is returned and dis-
played on the JSP page as shown in Figure 19.



Figure 19 Duplicate Key Error

Create bonus.jsp
The code for bonus.jsp is fairly straight forward because the code to look up the session
bean and calculate the bonus is now in the JavaBean. The first part of the file contains the
HTML code to create the form. The code to pass the HTML form data to the JavaBean is in
the second part of the file. The complete bonus.jsp file appears below. Look it over before
going on to the discussion of its scriptlet and JSP-specific tags for interacting with the Java-
Bean.
<HTML>
<HEAD>
</HEAD>

<BLOCKQUOTE>


<FORM METHOD="GET" ACTION="bonus.jsp">

<P>
<P>
<P>

Enter Multiplier:
<P>

<P>
</FORM>


<jsp:useBean id = "jbonus" class = "JBonusBean"/>

<%! String sMult, ssec; %>
<%
sMult = request.getParameter("MULTIPLIER");
ssec = request.getParameter("SOCSEC");
%>

<jsp:setProperty name = "jbonus" property="strMult" value="<%=sMult%>"/>
<jsp:setProperty name = "jbonus" property="socsec" value="<%=ssec%>"/>

<jsp:getProperty name="jbonus" property="socsec"/>

<P>
Bonus Amount retrieved:
<jsp:getProperty name="jbonus" property="bonusAmt"/>

<P>
Error messages:
<jsp:getProperty name = "jbonus" property="message"/>

</BLOCKQUOTE>
</BODY>
</HTML>


Specify the JavaBean
The following HTML tag specifies the JavaBean being used in this example. The id param-
eter defines an alias to use to reference the JavaBean, and the class parameter specifies the
JavaBeans class. In this example the id is jbonus and the class is JBonusBean.
<jsp:useBean id = "jbonus" class = "JBonusBean"/>

Get the Data
The following JSP scriptlets retrieve the user-supplied data from the HTML form input
fields. The multiplier is stored in the sMult String variable, and the social security number
is stored in the ssec String variable.
<%! String sMult, ssec; %>
<%
sMult = request.getParameter("MULTIPLIER");
ssec = request.getParameter("SOCSEC");
%>

Pass the Data to the JavaBean
The following HTML tags set two properties in the JavaBean. A property is a private field in
the JavaBean class. The first line uses the jsp:setProperty name tag to set the strMult
field in the JBonusBean class (aliased by the jbonus id) to the value stored in the sMult
variable. The second line performs a similar operation for the socsec field in the JBonus-
Bean class.

The value="<%=ssec%>" expression sends the data contained in the ssec vari-
able to the socsec field in the JavaBean.

Retrieve Data from the JavaBean
Retrieving data from a JavaBean is similar to sending data to it. You use the jsp:getProp-
erty name tag and indicate the property (private field) whose data you want to get. The fol-
lowing getProperty name tag retrieves the data stored in the socsec private field of the
JBonusBean class (aliased by the jbonus id).

The following tags perform similar operations for the bonusAmt and message fields in the
JBonusBean class.



<P>

<P>
Error messages:

Create the JavaBeans Class
A JavaBeans™ class (or bean for short) looks just like any ordinary Java™ programming lan-
guage class. But to be a bean, a JavaBeans class must follow a set of simple naming and
design conventions as outlined in the JavaBeans specification. Because beans follow the Jav-
aBeans specification, they can be accessed and managed by other programs and tools that
follow the same conventions.
In the Create bonus.jsp (page 76) section, HTML tags and JSP scriptlets are used to get and
set data in the private fields of the JBonusBean class. This is possible because the JBonus-
Bean class follows the JavaBeans naming and design conventions.

This section describes the JBonusBean code and gives you a very simple introduction to Jav-
aBeans technology as it is used with JSP pages. Visit the JavaBeans home page at http://
java.sun.com/beans/index.html for further information on JavaBeans technology.

Here is the JBonusBean class in its entirety. A discussion of its pertinent parts follows.
import Beans.*;

public class JBonusBean {
private String strMult, socsec, message;
private double bonusAmt;
CalcHome homecalc;

public JBonusBean() {
try{
} catch (javax.naming.NamingException e) {
}
}



public double getBonusAmt() {
if(strMult != null){
int multiplier = integerMult.intValue();
try {
Bonus record = theCalculation.getRecord(
socsec);
bonusAmt = record.getBonus();
socsec = record.getSocSec();
message = e.getMessage();
} catch (javax.ejb.CreateException e) {
}
return this.bonusAmt;
} else {
this.bonusAmt = 0;
this.message = "None.";
}
}

public String getMessage(){
return this.message;
}
public String getSocsec(){
return this.socsec;
}
public String getStrMult(){
return this.strMult;
}
public void setSocsec(String socsec) {
this.socsec = socsec;
}
public void setStrMult(String strMult) {
this.strMult = strMult;
}
}



Bean Properties
Properties define the data that a JavaBean makes accessible to other programs and tools
through get and set methods. The data might do things such as define the JavaBeans appear-
ance or behavior, or be used in or the result of a series of calculations and computations.
Properties are actually private class fields that should always be private and only accessible
through get and set methods.
The following code segment shows the private properties for the JBonusBean class. The
JBonusBean class has a corresponding get<property> method for each field and corre-
sponding set<property> methods for the strMult and socsec fields.
public class JBonusBean {
private String strMult, socsec, message;
private double bonusAmt;

Constructor
The JBonusBean constructor looks up the session Bean.
public JBonusBean() {
try{
} catch (javax.naming.NamingException e) {
}
}

Set Methods
JBonusBean has two setter methods (methods prefixed with the word set). Setter methods
set properties (private fields) to specified values. The two setter methods are setSocsec and
setStrMult for setting the socsec and strMult private fields (JavaBean prop-
erties).

In this example, the values used to set the socsec and strMult properties come from the
setProperty name tags in the JSP page. The J2EE server uses the information supplied in
the following setProperty name tags to locate the corresponding set methods in the JBo-
nusBean (aliased by the jbonus id):



In the JBonusBean class, the set<property> methods follow naming conventions so the
J2EE server can map the setProperty name tags in the JSP file to the correct set<prop-
erty> methods to pass the data from the JSP page to the JavaBean.

With setter methods, the method name consists of the word set and the property name. The
property name is the name of one of the JBonusBean private fields. While field names begin
with a lowercase letter by convention, the second word in a method name is always capital-
ized. So to set the socsec private field, the method name is setSocsec. The J2EE server
maps the uppercase Socsec in the method name to the lowercase socsec field. Setter meth-
ods have no return value and have one argument of the appropriate type.
}
}

Get Methods
JBonusBean has four getter methods (methods prefixed with the word get). Getter methods
get and return property values (private field values). The four getter methods are getBo-
nusAmt, getMessage, getSocsec, and getStrMult for returning data from the bonusAmt,
message, socsec, and strMult private fields (JavaBean properties).

In this example, the values used to set the bonusAmt and message fields come from the get-
BonusAmt method. The JSP page retrieves data from the JBonusBean properties using the
following getProperty name tags. The JSP page retrieves only the values it is interested in,
so you might notice that although there is a JBonusBean property for the multiplier (the str-
Mult field), that value is not retrieved by the JSP page.

<P>

<P>
Error messages:



Getter methods follow the same naming conventions as setter methods so the JSP page can
retrieve data from the JBonusBean.Getter methods always have a return value and no argu-
ments. You might notice that although the getBonusAmt method sets property values and
does not really need to return a value in this example, it returns this.bonusAmt to avoid a
runtime J2EE server error.
The getBonusAmt method uses an if-else statement to handle the case where no strMult
value is supplied. When the JSP page is ﬁrst loaded, the end user has not supplied any data,
but all tags and scriptlets on the page are executed anyway. In this event, the data value for
the strMult property passed to JBonusBean is null, which results in a null multiplier and a
null bonusAmt value. A runtime server error occurs when the JSP page gets and tries to dis-
play the null bonusAmt value. To prevent this runtime error, bonusAmt is set to 0 in the event
a null strMult value is received from the JSP page.
try {
socsec);
message = e.getMessage();
}
} else {
this.bonusAmt = 0;
}
}
public String getMessage(){



return this.message;
}
public String getSocsec(){
return this.socsec;
}
public String getStrMult(){
return this.strMult;
}
}
}

j2ee -verbose
deploytool
cloudscape -start


Unix

Windows



Remove the WAR File
Because you are adding a completely new class to the application, you have to delete the
War ﬁle from the previous lesson and create a new one.
Local Applications:
• Click the 2BeansApp icon so you can see its application components.
• Select BonusWar so it is outlined and highlighted.
• Select Delete from the Edit menu.

Create New WAR FIle
File menu:
• Select New Web Component.
Introduction:
• Read and Click Next.
• Click Add.
• In the next window, go to the ClientCode directory, and add bonus.jsp.
• Click Next, go to the ClientCode directory, add JBonusBean.class
• Click Finish.

Note: Make sure you add bonus.jsp before you add JBonusBean.class.

• Click Next.
• Make Bonus.jsp the JSP ﬁlename
• Make sure Describe a JSP is selected.
• Click Next.
• Make the display name BonusJSP.
• Click Finish.
Inspecting window:



• Specify JSPRoot.

Verify:
tests. That is, if you used the session bean code provided for this lesson.


Deploy:
pops up.

uses an HTML and JSP page so this book should not be checked. Checking this box
creates a JAR ﬁle with deployment information needed by a stand-alone application.

BonusBean. If they do not show these names, type them in yourself, and press the
Return key.
• Click Next.




The web server runs on port 8000 by default. To open the bonus.jsp page point your
browser to http://localhost:8000/JSPRoot/bonus.jsp, which is where the Deploy tool
put the JSP page.
See About the Example (page 74) for screen captures showing the application in action.

More Information
Visit the JavaBeans home page at http://java.sun.com/beans/index.html for further
information on JavaBeans technology.



Lesson 6
Extensible Markup Language
(XML)

eXtensible Markup Language (XML) is a language for representing and describing text-
based data so the data can be read and handled by any program or tool that uses XML APIs.
Programs and tools can generate XML files that other programs and tools can read and han-
dle.
For example, a company might use XML to produce reports so different parties who receive
the reports can handle the data in a way that best suits their needs. One party might put the
XML data through a program to translate the XML to HTML so it can post the reports to the
web, another party might put the XML data through a tool to produce a stockholder booklet,
and yet another party might put the XML data through a tool to create a marketing presenta-
tion. Same data, different needs, and an array of platform-independent programs and tools to
use the same data in any number of different ways. These highly flexible and cost-effective
capabilities are available through XML tags, Document Type Definitions (DTDs) also
known as XML schemas, and XML APIs.
This lesson adapts the example from Lesson 5 Adding JavaBeans Technology to the Mix
(page 73) so the JavaBean class uses XML APIs to print a simple report where the data is
marked with XML tags.
• Marking and Handling Text (page 90)
• Change the JavaBean Class (page 90)
• The APIs (page 95)
• Update and Run the Application (page 96)

LESSON 6 EXTENSIBLE MARKUP LANGUAGE (XML)


Marking and Handling Text
With XML you define markup tags to represent the different elements of data in a text file.
For example, if you have a text file that consists of a short article, you define XML tags to
represent the title, author, first level heads, second level heads, bullet lists, article text, and so
on. Once the data is represented by XML tags, you can create a Document Type Definition
(DTD) and/or eXtensible Style sheet Language (XSL) file to describe how you want the data
handled.
• XSL styles let you do things like map XML to HTML. For example, you can define an
XML title tag to represent the title of an article, and create an XSL file that maps the
XML title tag to the HTML H1 heading tag for display to the end user.
• A DTD (also known as an XML schema) contains specifications that allow other pro-
grams to validate the structure of an XML file to ensure the tagged data is in the correct
format. For example, a DTD for an article might allow one title tag, but zero or more
first and second level heads.
Any program capable of parsing XML can check for well-formed XML tags, and any pro-
gram capable of applying XSL styles or DTD specifications to XML data can handle the
tagged data intelligently. For example, if an article has two title tags, but the DTD allows
only one, the program returns an error. Checking an XML document against a DTD is what
is known as verification.
The nice thing about XML is the tagging is separate from the style sheet and DTD. This
means you can have one XML document and one to many style sheets or DTDs. Different
style sheets let you have a different presentation depending on how the document is used.
For example, an article on XML can have a style sheet for the different web sites where it is
to be published so it will blend with the look and feel of each site.
The current J2EE release does not have an eXtensible Style sheet Language Transformation
(XSLT) engine so it is not currently possible to use a style sheet to do things such as trans-
form an XML document into HTML for display.

Change the JavaBean Class
In this lesson, a genXML method is added to the JBonusBean class to generate the XML doc-
ument shown below. A description of the code to generate this file comes after the discussion
here of the XML document tags and structure.
<?xml version="1.0"?>
<report>
<bonusCalc ssnum="777777777" bonusAmt="300.0" />
</report>



XML Prolog
The <?xml version=”1.0”?> line is the XML prolog. An XML file should always start with
a prolog that identifies the document as an XML file. The prolog is not required and is read
only by humans, but it is good form to include it. Besides version information, the prolog
can also contain encoding and standalone information.
• Encoding information: indicates the character set used to encode the document data.
Uncompressed Unicode is shown as <?xml version=”1.0” encoding=”UTF-8”?>.
The Western European and English language character set is indicated by:
<?xml version=”1.0” encoding=”ISO-8859-1”?>.
• Standalone information: indicates if this document uses information in other files.
For example, an XML document might rely on a style sheet for information on how to
create the user interface in HTML, or a DTD for valid tag specifications.

Document Root
The <report> tag is the first XML tag in this file. It is the top-level XML tag and marks the
beginning of the document data. Another name for this level tag is root. XML tags have a
matching end tag, so the end of this document has the corresponding </report> tag to close
the pair.
You can give XML tags any name you want. This example uses report because the XML
file is a bonus report. It could just as well be named <root> or <begin> or whatever. The
name takes on meaning in the style sheet and DTD because that is where you assign specifi-
cations to tags by their names.

Child Nodes
The <bonusCalc> tag represents the bonus report. This tag is a child node that is added to
the root. It uses attributes to specify the social security number and bonus amount values
(ssnum and bonusAmt). You can define a DTD to check that the bonusCalc tag has the ssnum
attribute and bonusAmt attributes, and have your program raise an error if an attribute is
missing or if attributes are present that should not be there.

Other XML Tags
There are a number of ways to tag data. This example uses empty tags, which are tags that
do not enclose data, use attributes to specify data, and are closed with a slash. The following
empty tag from this example, could be created so the data is enclosed by XML tags instead.
The XML parser checks that all data enclosed by data has what are called well-formed tags.
Well-formed tags consist of an opening tag and a closing tag as shown in the well-formed tag
example below.


Empty tag:

Well-formed tags:
<bonusCalc>
<ssnum>"777777777"</ssnum>
<bonusAmt>300.0</bonusAmt>
</bonusCalc>

XML comment tags look just like HTML comment tags.


Processing Instructions give commands or information to an application that is processing
the XML data. Processing instructions have the format <? target instructions?> where
target is the name of the application doing the processing, and instructions embodies the
information or commands for the application to process. The prolog is an example of a pro-
cessing instruction, where xml is the target and version=”1.0” embodies the instructions.
Note that the target name xml is reserved for XML standards.
<?xml version=”1.0”?>
You can also use processing instructions to do things like distinguish between different ver-
sions of a presentation such as the high-level executive version and the technical version.

JavaBean Code
The JBonusBean class for this lesson has import statements for creating the XML docu-
ment, handling errors, and writing the document out to the terminal. This lesson writes the
XML output to the terminal to keep things simple. The XML output could just as well be
written to a file, but you would need to configure your browser to use Java Plug-In and
include a security policy file granting the JavaBean code permission to write to the file.
To generate the XML file for this lesson, you need to import the ElementNode and XmlDocu-
ment classes. You also need the StringWriter and IOException classes to write the XML
data to the terminal.
import Beans.*;
import java.io.StringWriter;
import java.io.IOException;
import com.sun.xml.tree.ElementNode;
import com.sun.xml.tree.XmlDocument;

This version of the JBonusBean class has one more instance variables. The session bean’s
remote interface, theCalculation, needs to be accessed from the getBonusAmt and genXML
methods. This is because genXML reads the database to generate XML for all records stored
in the database and has to be able to access the session bean’s getRecord method.



The JBonusBean.genXML method is called from the getBonusAmt method after the process-
ing completes in the event strMult is not null. The ﬁrst thing this method does is create an
XMLDocument object and the root node, and adds the root to the document. The root node
represents the top-level point in the document hierarchy (or tree) and is the point at which
processing begins.
private void genXML(){
Bonus records = null;
//Create XML document
XmlDocument doc = new XmlDocument();
//Create node
ElementNode root = (ElementNode)
doc.createElement("report");
//Add node to XML document
doc.appendChild(root);

The try and catch block that comes next, gets the record out of the database, retrieves the
bonus amount and social security number from the record, converts the bonus amount to a
string, creates a child node (bonusCalc), and adds the social security number and bonus
amount to the bonusCalc child node as attributes. The child node represents the second
level in the document hierarchy or tree, and the attributes represent the third level.
try{
//Get database record
records = theCalculation.getRecord(socsec);
//Retrieve the social security number from record
String ssRetrieved = records.getSocSec();
//Retrieve bonus amount from record
double bRetrieved = records.getBonus();
//Convert double to string
Double bonusObj = new Double(bRetrieved);
String bString = bonusObj.toString();
//Create child node
ElementNode bonusCalc = (ElementNode)
doc.createElement("bonusCalc");
//Add attributes to child node
bonusCalc.setAttribute("ssnum", ssRetrieved);
bonusCalc.setAttribute("bonusAmt", bString);
//Add child node to root
root.appendChild(bonusCalc);
}

The last part of the genXML method creates a StringWriter object, writes the document
hierarchy or tree to the StringWriter object, and writes the StringWriter object to the ter-
minal.



try{
StringWriter out = new StringWriter();
doc.write(out);
System.out.println(out);
} catch (java.io.FileNotFoundException fe) {
System.out.println("Cannot write XML");
} catch (IOException ioe) {
System.out.println("cannot write XML");
}

The hierarchy or tree structure for the XML document is called the Document Object Model
(DOM). Figure 21 shows a simpliﬁed representation of the DOM for this lesson’s example.
The API calls in the genXML method create the DOM and you can make API calls to access
the DOM to do such things as add, delete, and edit child nodes, or validate the DOM against
a DTD. You can also create a DOM from an XML ﬁle.

Document Root
report

Child Node
bonusCalcs

Social Security Number Attribute Bonus Amount Attribute
ssnum bonusAmt

Figure 21 Document Object Model (DOM)



The APIs
The j2ee.jar file that comes with your J2EE installation provides APIs for parsing and
manipulating XML data. The JAR file currently provides SAX, DOM, and J2EE XML APIs.
You can use whichever API best suits your needs because as shown in Figure 22, XML text
is independent of the platform and language of its creation..

DTD

Application written in XML Application written in
Java programming DOM SAX C++ running on
language running on Windows.
Unix. HTTP

Figure 22 Platform and Language Neutral Text

SAX and DOM
The SAX API is an event-driven, serial-access mechanism that does element by element pro-
cessing.
The DOM API provides a relatively familiar tree structure of objects. You can use the DOM
API to manipulate the hierarchy of application objects it encapsulates. The DOM API is
ideal for interactive applications because the entire object model is present in memory,
where it can be accessed and manipulated by the user.
Constructing the DOM requires reading the entire XML structure and holding the object tree
in memory, so it is much more CPU and memory intensive. For that reason, the SAX API
will tend to be preferred for server-side applications and data filters that do not require an in-
memory representation of the data.

Note: You can find more information on the DOM and SAX APIs at this location:
http://java.sun.com/xml/docs/tutorial/overview/3_apis.html

J2EE
The platform-independent J2EE XML APIs use a DOM tree and provide a wealth of meth-
ods for manipulating the DOM hierarchy. The J2EE XML APIs are in the package com.sun
and were used in this lesson’s example. Please note that these APIs are subject to change.



Update and Run the Application
Because all you have done in this lesson is change the JBonusBean class, you can simply
update and redeploy the application.
• Local Applicatons Window: Highlight the 2BeansApp application.
• Tools Menu: Select Update and Redeploy Application.

Note: The BonusApp application from the previous lesson is automatically uninstalled

put the JSP page.

More Information
There is a lot of information about XML on the Web that you can access with a good search
engine. A very good web site is www.xml.com. The java.sun.com site has an XML tutorial
at http://java.sun.com/xml/docs/tutorial/index.html.



Lesson 7
JDBC Technology and Bean-
Managed Persistence

Up to this point, the example J2EE application has written data to and read data from the
underlying Cloudscape database without your writing and SQL code. This is because the
container has been handling data storage and retrieval on behalf of the entity bean. Con-
tainer-managed persistence is the term used to describe the situation where the container
handles data storage and retrieval. This lesson shows you how to override the default con-
tainer-managed persistence and implement bean-managed persistence.
Bean-managed persistence is when you override container-managed persistence and imple-
ment entity or session bean methods to use the SQL commands you provide. Bean-managed
persistence can be useful if you need to improve performance or map data in multiple beans
to one row in a database table.
This lesson changes the entity bean in the example J2EE application to use bean-managed
persistence.
• Bean Lifecycle (page 98)
• Change the BonusBean Code (page 99)
• Change the CalcBean and JBonusBean Code (page 106)
• Create the Database Table (page 107)
• Remove the JAR File (page 109)
• Verify and Deploy the Application (page 111)
• Run the Application (page 112)

LESSON 7 JDBC TECHNOLOGY AND BEAN-MANAGED PERSISTENCE


Bean Lifecycle
The BonusBean (page 30) section in Lesson 3 shows the container-managed BonusBean
class. The only methods with implementations are getBonus to return the bonus value, get-
SocSec to return the social security number, and ejbCreate to create an entity bean with the
bonus and socsec values passed to it. The container takes care of such things as creating a
row in the database table for the data, and ensuring the data in memory is consistent with the
data in the table row. With bean-managed persistence, you have to implement all of this
behavior yourself, which means adding JDBC™ and SQL code, and implementing the empty
methods in the container-managed example.
A session or an entity bean consists of business methods and lifecycle methods. In the exam-
ple, CalcBean has two business methods, calcBean and getRecord, and BonusBean has two
business methods, getBonus and getSocsec. Both CalcBean and BonusBean have the fol-
lowing lifecycle methods. Business methods are called by clients and lifecycle methods are
called by the bean’s container.
• setEntityContext: The container calls this method ﬁrst to pass an entity context
object to the entity bean. The entity context is dynamically updated by the container
so even if the entity bean is invoked by many clients over its lifetime, the context con-
tains current data for each invocation. A session bean has a corresponding setSes-
sionContext method that performs a similar function as the setEntityContext
method.
• ejbCreate: The container calls this method when a client calls a create method in the
bean’s home interface. For each create method in the home interface, the bean has a
corresponding ejbCreate method with the same signature (parameters and return
value).
• ejbPostCreate: The container calls this method after the ejbCreate method completes.
There is an ejbPostCreate method for every ejbCreate method that takes the same
arguments as its corresponding create method. However, ejbPostCreate has no return
value. Use ejbPostCreate to implement any special processing needed after the bean
is created, but before it becomes available to the client. Leave this method empty if no
special processing is needed.
• ejbRemove: The container calls this method when a client calls a remove method in the
bean’s home interface. The example J2EE application for this tutorial does not include
a remove method in the home interface.
• unsetEntityContext: The container calls this method after the ejbRemove has been
called to remove the entity bean from existence. Only entity beans have an unsetEn-
tityContext method. A session bean does not have a corresponding unsetSession-
Context method.
• ejbFindByPrimaryKey: The container calls this method when a client calls the find-
ByPrimaryKey method in the bean’s home interface. For each ﬁnd method in the home
interface, the bean has a corresponding ejbFind<type> method with the same signa-
ture (parameters and return value).



• ejbLoad and ejbStore: The container calls these methods to synchronize the bean’s
state with the underlying database. When a client sets or gets data in the bean such as
in the case of a get method, the container calls ejbStore to send the object data to the
database and calls ejbLoad to read it back in again. When a client calls a finder
method, the container calls ejbLoad to initialize the bean with data from the underly-
ing database.
• ejbActivate and ejbPassivate: The container calls these methods to activate and
passivate the bean’s state. Activation and passivation refer to swapping a bean in and
out of temporary storage to free memory, which might occur if a given bean has not
been called by a client in a long time. Implementations for ejbPassivate might
include things like closing connections or files used by the bean, and for ejbActivate
might include things like reopening those same connections or files.

Change the BonusBean Code
This section walks through the bean-managed persistence BonusBean code. The first thing
you will notice is that there is a lot more code here than for the container-managed persis-
tence version.

Import Statements
The InitialContext, DataSource, and Connection interfaces are imported for establishing
a connection to the database. The PreparedStatement interface is imported to be used as a
template to create a SQL request. The ResultSet interface is imported to manage access to
data rows returned by a query. The FinderException and SQLException classes are
imported to handle lookup and database access exceptions.
package Beans;
import javax.ejb.EntityBean;
import javax.ejb.EntityContext;
import javax.naming.InitialContext;
import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import javax.ejb.FinderException;
import java.sql.SQLException;



Instance Variables
The instance variables added to this lesson let you establish and close database connections.
The string java:comp/env/jdbc/BonusDB indicates the resource reference name, which you
also specify when you add the entity bean to the J2EE application using the Deploy tool. In
this example, the resource reference is an alias to the Cloudscape database (CloudscapeDB)
where the table data is stored.
Later, you will create the BONUS table in the CloudscapeDB, and during deployment, you will
map jdbc/BonusDB to jdbc/CloudscapeDB.
public class BonusBean implements EntityBean {
private EntityContext context;
private Connection con;
private String dbName =
"java:comp/env/jdbc/BonusDB";
private InitialContext ic = null;
private PreparedStatement ps = null;
private double bonus;
private String socsec;

Business Methods
The business methods have not changed for this lesson except for calls to Sys-
tem.out.println, which let you see the order in which business and lifecycle methods are
called at runtime.
public double getBonus() {
System.out.println("getBonus");
return this.bonus;
}
public String getSocSec() {
System.out.println("getSocSec");
return this.socsec;
}

LifeCycle Methods
These methods include calls to System.out.println so you can see the order in which
business and lifecycle methods are called at runtime.

ejbCreate
The ejbCreate method signature for this lesson throws RemoteException and SQLException
in addition to CreateException. SQLException is needed because the ejbCreate method
for this lesson provides its own SQL code (it does not rely on the container to provide it),
and RemoteException is needed because this method performs remote access.
One thing to notice about this class is that it returns a String value which is the primary key,
but the declaration for this method in the home interface expects to receive a Bonus class



instance. The container uses the primary key returned by this method to create the Bonus
instance.
public String ejbCreate(double bonus, String socsec)
CreateException,
SQLException {
this.socsec=socsec;
this.bonus=bonus;

System.out.println("Create Method");
try {
//Establish database connection
ic = new InitialContext();
DataSource ds = (DataSource) ic.lookup(dbName);
con = ds.getConnection();
//Use PreparedStatement to form SQL INSERT statement
//to insert into BONUS table
ps = con.prepareStatement(
"INSERT INTO BONUS VALUES (? , ?)");
//Set 1st PreparedStatement value marked by ? , with
//socsec and the 2nd value marked by ?) with bonus
ps.setString(1, socsec);
ps.setDouble(2, bonus);
ps.executeUpdate();
} catch (javax.naming.NamingException ex) {
ex.printStackTrace();
} finally {
//Close database connection
ps.close();
con.close();
}
//Return primary key
return socsec;
}

ejbPostCreate
This method has the same signature as ejbCreate, but no implementation because this sim-
ple example performs no post create processing or initialization.
public void ejbPostCreate(double bonus,
String socsec)
CreateException,
SQLException {
System.out.println("Post Create");
}



ejbFindByPrimaryKey
The container-managed version of BonusBean did not include an ejbFindByPrimaryKey
implementation because the container can locate database records by their primary keys if
you specify container-managed persistence and provide the primary key ﬁeld during deploy-
ment. In this lesson, BonusBean is deployed with bean-managed persistence so you must
provide an implementation for this method and throw the SQLException. The container-
managed version throws RemoteException and FinderException only.
If the ﬁnd operation locates a record with the primary key passed to ejbFindByPrimaryKey,
the primary key value is returned so the container can call the ejbLoad method to initialize
BonusBean with the retrieved bonus and socsec data.

One thing to notice about this class is that it returns a String value which is the primary key,
but the declaration for this method in the home interface expects to receive a Bonus class
instance. The container uses the primary key returned by this method to create the Bonus
instance.
public String ejbFindByPrimaryKey(String primaryKey)
throws RemoteException,FinderException,
SQLException {
System.out.println("Find by primary key");
try {
//Use PreparedStatement to form SQL SELECT statement
//to select from BONUS table
"SELECT socsec FROM BONUS WHERE socsec = ? ");
ps.setString(1, primaryKey);
//Use ResultSet to capture SELECT statement results
ResultSet rs = ps.executeQuery();
//If ResultSet has a value, the find was successful,
//and so initialize and return key
if(rs.next()) {
key = primaryKey;
} else {
System.out.println("Find Error");
}
} finally {
ps.close();
con.close();
}
//Return primary key
return key;
}



ejbLoad
This method is called after a successful call to ejbFindByPrimaryKey to load the retrieved
data and synchronize the bean data with the database data.
public void ejbLoad() {
System.out.println("Load method");
try {
//Use PreparedStatement to form SQL SELECT statement
//to select from BONUS table
"SELECT * FROM BONUS WHERE SOCSEC = ?");
ps.setString(1, this.socsec);
//Use ResultSet to capture SELECT statement results
ResultSet rs = ps.executeQuery();
//If ResultSet has a value, the find was successful
if(rs.next()){
this.bonus = rs.getDouble(2);
} else {
System.out.println("Load Error");
}
} catch (java.sql.SQLException ex) {
} finally {
try {
ps.close();
con.close();
}
}
}

ejbStore
This method is called when a client sets or gets data in the bean to send the object data to the
database and keep the bean data synchronized with the database data.
public void ejbStore() {
System.out.println("Store method");
try {
DataSource ds = (DataSource)ic.lookup(dbName);
//Use PreparedStatement to form SQL UPDATE statement



//to update BONUS table
"UPDATE BONUS SET BONUS = ? WHERE SOCSEC = ?");
//Set 1st PreparedStatement value marked by ? with
//bonus and the 2nd value marked by ?) with socsec
ps.setDouble(1, bonus);
int rowCount = ps.executeUpdate();
} finally {
try {
ps.close();
con.close();
}
}
}

ejbRemove
This method is called when a client calls a remove method on the bean’s home interface. The
JavaBean client in this example does not provide a remove method that a client can call to
remove BonusBean from its container. Nevertheless, the implementation for an ejbRemove
method is shown here. When the container calls ejbRemove, ejbRemove gets the primary key
(socsec) from the socsec instance variable, removes the bean from its container, and deletes
the corresponding database row.
public void ejbRemove()
throws RemoteException {
System.out.println("Remove method");
try {
DataSource ds = (DataSource)ic.lookup(dbName);
"DELETE FROM BONUS WHERE SOCSEC = ?");
ps.executeUpdate();
} catch (Exception ex) {
try {
ps.close();
con.close();
}
}



ejbActivate
When a bean has not been used in a long time, the container passivates it or moves it to tem-
porary storage where the container can readily reactivate the bean in the event a client calls
one of the bean’s business methods. This method calls the getPrimaryKey method on the
entity context so the primary key is available to clients querying the bean. When a query is
made, the container uses the primary key to load the bean data.
public void ejbActivate() {
System.out.println("Activate method");
socsec = (String)context.getPrimaryKey();
}

ejbPassivate
When a bean has not been used in a long time, the container passivates it or moves it to tem-
porary storage where the container can readily reactivate the bean in the event a client calls
one of the bean’s business methods. This method sets the primary key to null to free mem-
ory while the bean is in the passive state.
public void ejbPassivate() {
System.out.println("Passivate method");
socsec = null;
}

setEntityContext
This method is called by the container to initialize the bean’s context instance variable.
This is needed because the ejbActivate method calls the getPrimarykey method on the
context instance variable to move a passive bean to its active state.

public void setEntityContext(
javax.ejb.EntityContext ctx){
System.out.println("setEntityContext method");
this.context = ctx;
}

unsetEntityContext
This method is called by the container to set the context instance variable to null after the
ejbRemove method has been called to remove the entity bean from existence. Only entity
beans have an unsetEntityContext method.
public void unsetEntityContext(){
System.out.println("unsetEntityContext method");
ctx = null;
}
}



Change the CalcBean and JBonusBean Code
Because BonusBean provides its own SQL code, the CalcBean.calcbonus method, which
creates BonusBean instances, has to be changed to throw java.sql.SQLException. Here is
one way to do make that change:

double bonus, String socsec)
SQLException,
CreateException {

Bonus theBonus = null;

try {
homebonus = (BonusHome)
}

//Store data in entity Bean
theBonus=homebonus.create(calc, socsec);
return theBonus;
}

The JBonusBean class has to be changed to catch the SQLException thrown by CalcBean.
DuplicateKeyExcpetion is a sublcass of CreateException, so it will be caught by the
catch (javax.ejb.CreateException e) statement.

try {
socsec);
} catch (java.sql.SQLException e) {
this.bonusAmt = 0.0;



this.socsec = "000";
this.message = e.getMessage();
}
genXML();
} else {
this.bonusAmt = 0;
}
}

Create the Database Table
Because this example uses bean-managed persistence, you have to create the BONUS database
table in the CloudscapeDB database. With container-managed persistence, the table is cre-
ated for you.
To make things easy, the database table is created with two scripts: createTable.sql and
cloudTable.sh (Unix) or cloudTable.bat (Windows/NT). For this example, the cre-
ateTable.sql script goes in your ~/J2EE/Beans directory, and the cloudTable.sh (Unix)
or cloudTable.bat (Windows/NT) script goes in your ~/J2EE directory.
To execute the scripts, go to the Beans directory and type the following:
Unix:
../cloudTable.sh

Windows/NT:
..cloudTable.bat

createTable.sql
This ﬁle is provided in the code download for this lesson.



drop table bonus;

create table bonus
(socsec varchar(9) constraint pk_bonus primary key,
bonus decimal(10,2));

exit;

cloudTable.bat
rem cloudTable.bat
rem Creates BONUS table in CloudscapeDB.
rem
rem Place this script in ~J2EE
rem To run: cd ~J2EEcloudTable.sh
rem
rem Change this next line to point to *your*
rem j2sdkee1.2.1 installation
rem
rem
rem Everything below goes on one line
java -Dij.connection.CloudscapeDB=
jdbc:rmi://localhost:1099/jdbc:cloudscape:
CloudscapeDB;create=true -Dcloudscape.system.home=
%J2EE_HOME%cloudscape -classpath
%J2EE_HOME%ıibcloudscapeclient.jar;
%J2EE_HOME%ıibcloudscape tools.jar;
%J2EE_HOME%ıibcloudscapecloudscape.jar;
%J2EE_HOME%ıibcloudscapeRmiJdbc.jar;
%J2EE_HOME%ıibcloudscapeıicense.jar;
%CLASSPATH% -ms16m -mx32m
COM.cloudscape.tools.ij createTable.sql

cloudTable.sh
#!/bin/sh
#
# cloudTable.sh
# Creates BONUS table in CloudscapeDB.
#
# Place this script in ~J2EE
# To run: cd ~J2EEcloudTable.sh
#
# Change this next line to point to *your*
# j2sdkee1.2.1 installation
#
J2EE_HOME=/home/monicap/J2EE/j2sdkee1.2



#
# Everything below goes on one line
java -Dij.connection.CloudscapeDB=jdbc:rmi:
//localhost:1099/jdbc:cloudscape:CloudscapeDB;
create=true -Dcloudscape.system.home=
$J2EE_HOME/cloudscape -classpath
$J2EE_HOME/lib/cloudscape/client.jar:
$J2EE_HOME/lib/cloudscape/tools.jar:
$J2EE_HOME/lib/cloudscape/cloudscape.jar:
$J2EE_HOME/lib/cloudscape/RmiJdbc.jar:
$J2EE_HOME/lib/cloudscape/license.jar:
${CLASSPATH} -ms16m -mx32m
COM.cloudscape.tools.ij createTable.sql

Remove the JAR File
You have to update the bean JAR file with the new entity bean code. If you have both beans
in one JAR file, you have to delete the 2BeansJar and create a new one. The steps to adding
CalcBean are the same as in Create JAR with Session Bean (page 54). The steps to adding
BonusBean are slightly different and described here.

If you have the beans in separate JAR files, you have to delete the JAR file with BonusBean
and create a new one as described here.
These instructions pick up at the point where you add the BonusBean interfaces and classes
to the JAR file.
EJB JAR:
• Click Add.
• Click Add.
• Click Add.
• Make sure you see Beans/Bonus.class, Beans/BonusHome.class, and Beans/
BonusBean.class in the display.
• Click OK.
EJB JAR:
• Click Next.



General:
• Make sure Beans.BonusBean is the classname, Beans.BonusHome is the Home inter-
face, and Beans.Bonus is the Remote interface.
• Click Entity.
• Click Next.
Entity Settings:
• Select Bean-managed persistence.
• The primary key class is java.lang.String, Note that the primary key has to be a
class type. Primitive types are not valid for primary keys.
• Click Next.
• Click Next.
• Click Add
• type jdbc/BonusDB in the ﬁrst column under Coded Name. Make sure Type is
javax.sql.DataSource, and Authentication is Container.
• Click Next.
Security:
ods. The transaction commits just before the methods end. You can ﬁnd more informa-
tion on these transaction settings in Chapter 6 of the Enterprise JavaBeans Developer's
Guide.
• Click Next.
Review Settings:
• Click Finish.
Inspecting window:
• With 2BeansApp selected, click JNDI names.
• Assign calcs to CalcBean, bonus to BonusBean, and jdbc/Cloudscape to jdbc/
BonusDB.



Verify and Deploy the Application

Note: If you get a Save error when you verify or deploy, shut everything down and
restart the server and tools.

Verify:
tests.


Deploy:
pops up.
• Check the Return Client Jar box. Checking this box creates a JAR ﬁle with deploy-
ment information needed by the entity bean.
• Click Next.
• Make sure the JNDI names show for calcs for CalcBean, bonus for BonusBean, and
jdbc/Cloudscape for BonusDB. If they do not, type the JNDI names in yourself, and
press the Return key.
• Click Next.
• When it is complete, click OK.



Run the Application
put the JSP page.
The J2EE server output might show the following message each time database access is
attempted. The message means no user name and password were supplied to access the data-
base. You can ignore this message because a user name and password are not required to
access the Cloudscape database, and this example works just ﬁne regardless of the message.
Cannot find principal mapping information for data source with JNDI name
jdbc/Cloudscape

Here is a cleaned up version of the J2EE server output (the above message was edited out).
setEntityContext method
Create Method
Post Create

setEntityContext method
Find by primary key
Load method

getBonus
Store method
Load method

getSocSec
Store method
Find by primary key
Load method

getSocSec
Store method
Load method

getBonus
Store method

<?xml version="1.0"?>
<report>
</report>



More Information
You can get more information on entity Beans and bean-managed persistence here:
http://java.sun.com/j2ee/j2sdkee/techdocs/guides/ejb/html/Entity.fm.html

You can get more information on making database connections here:
http://java.sun.com/j2ee/j2sdkee/techdocs/guides/ejb/html/Database.fm.html


SEPTEMBER 27, 2000

Index
A E
application assembly 16 editing information 22
application components ejbCreate method 12, 28
editing information 22 EJBObject class 12
working together 10 entity Bean
application deployment 24, 58, 69, 86, 111 container managed 30
application verification 23, 58, 68, 86 defined 28
avax.rmi.RemoteException 12 F
B findByPrimaryKey method 28
bonus.html file 6 G
BonusServlet code 6
getBonus method 29
C getSocSec method 29
Cloudscape database 27 H
container managed
home interface
persistence 30
looking up 7
transaction management 30
role of 11
Content pane 22
HTTP headers 7
context root
HttpServlet class 7
calling a servlet in an HTML form 6
specify 22 I
create method 12, 28 IOException class 7
CreateException class 11 J
D
J2EE application components
deploy application 24, 58, 69, 86, 111 defined 4
deploy tool j2ee -verbose command 14
assemble application 16 java.io 7
deploy application 24, 58, 69, 86, 111 javax.naming 7
described 15 javax.rmi 7
editing information 22 javax.servlet 7
verify application 23, 58, 68, 86 javax.servlet.http 7
view application components 19 JNDI name
deploytool command 14 how used 7
doGet method 7 specify 22

INDEX

SEPTEMBER 27, 2000

L W
looking up the home interface 7 Web Archive (WAR) file 19
M
meta information 16
method signatures 28
Multitier architecture
defined 2
multitier architecture
example 3
P
persistent data 28
PortableRemoteObject class 7
primary key 28
duplicate 28
R
remote interface 12
request object 7
response object 7
run application 25, 60, 70, 87
S
ServletException class 7
session Bean
defined 10
SessionBean interface 12
setSessionContext method 12
signatures, methods 28
T
thin-client application defined 2
transaction management 30
transaction rollback 28
U
Uninstall button 15
V
verify application 23, 58, 68, 86

INDEX

J2 ee

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