J2EE Application Development

1
J2EE Application Development

• B.Ramamurthy

2
Introduction

• We will show how to develop, deploy and run a
  simple client-server application that consists of
  a currency converter enterprise bean and two
  clients a J2EE client and a web client that
  consists of a JSP page.

3
The Setup

• Source code from http//java.sun.com/j2ee/download
  .htmltutorial
• Get the J2EE1.3 from http//java.sun.com/j2ee
• Get the ant build tool from Jakarta. This is
  similar to make utility of unix.
• Setup the environment variables
• JAVA_HOME location of J2SE installation
• J2EE_HOME location of J2EE installation
• ANT_HOME location of ant installation
• PATH include bin directories of J2EE, J2SE
  and ant installation

4
Starting the Server

• J2EE server is a web server, servlet server and
  also an application server.
• You start it by
• j2ee verbose
• You stop the server by
• J2ee -stop

5
Deployment

• Has two modes command line and GUI interface.
• In the case of GUI tool you create an ear file
  and the drop the component modules into this
  ear (enterprise archive) file.
• In the case of command line you will make the
  components first and then assemble them into an
  ear file.
• To start a deploy tool
• deploytool

6
Application source code

• An enterprise bean which represents the business
  logic of an application
• Remote interface defines the business methods
  that a client may call.
• Home interface defines the methods to create,
  find or remove an enterprise bean.
• Enterprise bean class implements the two
  interfaces and also callbacks for containers.
• Our application is called converter. Lets study
  the code representing these files.

7
Compiling the Source code

• The compile targets for this tutorial are
  available in a file build.xml.
• You compile the converter java files by
• ant converter

8
Packaging

• For this example, ear file will be
  ConverterApp.ear
• This file will contain EJB JAR file, Web
  clients WAR file and Application clients JAR
  file/class file
• Deploytool helps in configuring and packaging
  each component. It automatically creates the
  deployment descriptor.

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Packaging the enterprise bean

• Add the classes that make the bean component
  Converter.class, ConverterBean.class,
  ConverterHome.class to the jar
• Specify properties bean type (session, entity,
  etc.), transactions etc. The deploytool has
  various tabs and support to specify these.

10
Application Client

• Written in Java. Can run on any Java runtime
  (need not be J2EE).
• In this application client requires two JAR
  files JAR file for the J2EE containing clients
  deployment descriptor and its class files, and
  the second JAR files containing stub classes
  required at run time by the client.

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Application Client (contd.) and Web Client

• Basic tasks performed by the client of an
  enterprise bean
• Locating the home interface
• Creating an enterprise bean instance
• Invoking a business method
• Deploytool
• Creates clients deployment descriptor
• Puts deployment descriptor and client code into a
  JAR file
• Add the JAR file to the applications
  ConverterApp.ear file
• We use JSP for this purpose contains the same
  tasks as the application client plus web display
  elements.

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Deployment and Running the Clients

• JNDI We also specify JNDI names using the
  deploytool.
• Tools ? deploy of the tool.
• http//java.sun.com/j2ee/tutorial/1_3-fcs/doc/Tool
  s10.html
• runclient etc. to run from command line
• Webclient
• http//lthostgt8000/converter