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EJB: Enterprise Java Beans (Intro and Environment Setup)

EJB stands for Enterprise Java Beans. EJB is an essential part of a J2EE platform. J2EE platform has component based architecture to provide multi-tiered, distributed and highly transactional features to enterprise level applications.

EJB provides an architecture to develop and deploy component based enterprise applications considering robustness, high scalability, and high performance. An EJB application can be deployed on any of the application server compliant with the J2EE 1.3 standard specification.

We'll be discussing EJB 3.0 in detail in this tutorial.

Types

EJB is primarily divided into three categories; following table lists their names with brief descriptions −

S.NoType & Description
1

Session Bean

Session bean stores data of a particular user for a single session. It can be stateful or stateless. It is less resource intensive as compared to entity bean. Session bean gets destroyed as soon as user session terminates.

2

Entity Bean

Entity beans represent persistent data storage. User data can be saved to database via entity beans and later on can be retrieved from the database in the entity bean.

3

Message Driven Bean

Message driven beans are used in context of JMS (Java Messaging Service). Message Driven Beans can consumes JMS messages from external entities and act accordingly.

Benefits

Following are the important benefits of EJB −

  • Simplified development of large-scale enterprise level application.

  • Application Server/EJB container provides most of the system level services like transaction handling, logging, load balancing, persistence mechanism, exception handling, and so on. Developer has to focus only on business logic of the application.

  • EJB container manages life cycle of EJB instances, thus developer needs not to worry about when to create/delete EJB objects.

EJB is a framework for Java, so the very first requirement is to have a Java Development Kit (JDK) installed in your machine.

System Requirement

JDK1.5 or above.
Memoryno minimum requirement.
Disk Spaceno minimum requirement.
Operating Systemno minimum requirement.

Step 1 - Verify Java Installation in Your System

Now open console and execute the following java command.

OSTaskCommand
WindowsOpen Command Consolec:\> java -version
LinuxOpen Command Terminal$ java -version
MacOpen Terminalmachine:~ joseph$ java -version

Let's verify the output for all the operating systems −

OSOutput
Windows

java version "1.6.0_21"

Java(TM) SE Runtime Environment (build 1.6.0_21-b11)

Java HotSpot(TM) 64-Bit Server VM (build 23.21-b01, mixed mode)

Linux

java version "1.6.0_21"

Java(TM) SE Runtime Environment (build 1.6.0_21-b11)

Java HotSpot(TM) 64-Bit Server VM (build 23.21-b01, mixed mode)

Mac

java version "1.6.0_21"

Java(TM) SE Runtime Environment (build 1.6.0_21-b11)

Java HotSpot(TM) 64-Bit Server VM (build 23.21-b01, mixed mode)

If you do not have Java installed, install the Java Software Development Kit (SDK) from www.oracle.com. We are assuming that Java 1.6.0_21 as installed version for this tutorial.

Step 2 – Set JAVA Environment

Set the JAVA_HOME environment variable to point the base directory location where Java is installed on your system. For example,

OSOutput
WindowsSet the environment variable JAVA_HOME to C:\Program Files\Java\jdk1.6.0_21
Linuxexport JAVA_HOME=/usr/local/java-current
Macexport JAVA_HOME=/Library/Java/Home

Append Java compiler location to System Path.

OSOutput
WindowsAppend the string ;C:\Program Files\Java\jdk1.6.0_21\bin to the end of the system variable, Path.
Linuxexport PATH=$PATH:$JAVA_HOME/bin/
Macnot required

Verify Java Installation using java -version command explained above.

Step 3 – Download and Install NetBeans IDE

Download the latest version of NetBeans IDE from netbeans.org. At the time of writing this tutorial, I downloaded Netbeans 7.3 which comes bundled with JDK 1.7 using the following link www.oracle.com

OSInstaller name
WindowsNetbeans 7.3
LinuxNetbeans 7.3
MacNetbeans 7.3

Step 4 – Setup JBoss Application Server

You can download the latest version of JBoss Server from www.jboss.org. Download the archive as per the platform. Extract the Jboss to any location on your machine.

OSFile name
Windowsjboss-5.1.0.GA-jdk6.zip
Linuxjboss-5.1.0.GA-src.tar.gz
Macjboss-5.1.0.GA-src.tar.gz

Step 5 - Configure JEE Plugins to Netbeans

Open Plugin window using Tools > Plugins. Open "Available Plugin" tab and select "Java EE Base" and "EJB and EAR" under "Java Web and EE" category. Click install button. Netbeans will download and install the respective plugins. Verify plugins installation using "Installed" tab (as shown in the image given below).

Installed plugins

Step 6 - Configure JBoss Server in Netbeans

Go to Services tab and right click on servers to add a new server.

Add Server

Add Server Instance wizard will open. Select JBoss and in next step enter the relevant details to configure server in netbeans.

Choose Server

Once everything is configured, you will see the following screen.

Installed servers

Step 7 - Install Database Server (PostGreSql)

Download latest version of PostGreSql database server from www.postgresql.org. At the time of writing this tutorial, I downloaded PostGreSql 9.2

OSInstaller name
WindowsPostGreSql 9.2
LinuxPostGreSql 9.2
MacPostGreSql 9.2

Anurag Rana

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