Developing an Enterprise Application using J2EE 5 and EJB3.0

1
Developing an Enterprise Application using J2EE 5
and EJB3.0

• B. Ramamurthy
• This presentation is based on tutorials available
  with Netbeans IDE 5.5 (www.netbeans.org and
• http//testwww.netbeans.org/kb/55/ejb30.html)

2
Creating an Enterprise Application

• File?New Project
• Select Enterprise Category, Enterprise
  Application ? next
• Name project ENewsApp, set server to JSAS
• Set J2EE version to EE5, click create EJB module
  and create web application module
• Click Finish

3
Creating a Persistence Unit

• This will name the persistence unit name, data
  source and persistence provider. In your case,
  you may substitute the entity class and
  persistence with DAO and/or direct access to
  database from the EJBs.
• Right click of EJB module of the project, choose
  New?File/Folder
• From Persistence category, select Persistent ?
  Next
• For Persistence Provider, choose TopLink
• For data source, choose JNDI name jdbc/sample
  (This could be replaced by JNDI name for your
  Oracle data source)
• Check Use Java Transaction APIs to make it
  transactional, Finish.

4
Creating Entity Class

• Right click of EJB module of the project, choose
  New?File/Folder
• From Persistence category, select Entity class ?
  Next
• Type ENewsEntity for class name, ejb for the
  package, Primary key type Long, Finish.
• Add to the class
• String title
• String body
• Right click and refactor to generate getter and
  setter for the members, id, title and body.

5
Creating Message Driven Bean

• Right click of EJB module of the project, choose
  New?File/Folder
• From Enterprise category, select Message-Driven
  Beans class ? Next
• Type NewsMessage for name, slect ejb for package
  name.
• Select Queue as Destination Type, Finish.
• In the source editor map this bean to the JMS
  queue resource referenced by its JNDI name.
• Add content to onMessage method and code to
  extract and save (persist) the message pushed on
  to the queue by the user interface.

6
Creating a Session Bean

• Right click of EJB module of the project, choose
  New?File/Folder
• From Enterprise category, select Session bean ?
  Next
• Choose NewsEntity class click Add, Next
• Check ejb as package and local interface, Finish.

7
Web Module

• Web module consists of two ListNews and
  PostMessage servlets.
• ListNews gets the list of messages from the
  database (thru session bean and entity bean) and
  lists them
• PostMessage servlet gathers the message input by
  the user.

8
Creating ListNews Servlet

• Right-click on the web module and choose New
  ?Servlet.
• Type ListNews for class name
• Enter web for Package name and Finish.
• In the source code window, right click and select
  Enterprise Resources? Call Enterprise Bean
• Select NewsEntityFacade and click OK.
• Update the processRequest method and fix imports

9
processRequest
List news newsEntityFacade.findAll()
for (Iterator it news.iterator()it.hasNext())
NewsEntity elem
(NewsEntity)it.next() out.println("
ltbgt" elem.getTitle() " lt/bgtltbr /gt")
out.println(elem.getBody() "ltbr /gt")
out.println("lta href'PostMessage'gtAdd
new messagelt/agt")
10
Creating PostMessage

• JMS resources will be directly injected into the
  servlet.
• Create and add a new servlet PostMessage to web
  module.
• In the source editor add annotations to inject
  ConnectionFactory and Queue resource
• _at_Resource(mappedName"jms/NewMessageFactory")
• private ConnectionFactory connectionFactory
• _at_Resource(mappedName"jms/NewMessage")
• private Queue queue

11
(contd.)

• Add code to processRequest methodString
  titlerequest.getParameter("title")
• String bodyrequest.getParameter("body")
• if ((title!null) (body!null))
• try
• Connection connection
  connectionFactory.createConnection()
• Session session connection.createSession
  (false, Session.AUTO_ACKNOWLEDGE)
• MessageProducer messageProducer
  session.createProducer(queue)

12
(contd.)

• ObjectMessage message session.createObjectMessag
  e()
• // here we create NewsEntity, that will
  be sent in JMS message
• NewsEntity e new NewsEntity()
• e.setTitle(title)
• e.setBody(body)
• message.setObject(e)
• messageProducer.send(message)
• messageProducer.close()
• connection.close()
• response.sendRedirect("ListNews")

13
Contd.

• Uncomment the print commands and fix imports.
• Projects Windows, right click on ENewsApp and
  select Properties.
• Select Run propery, and type relative URL to be
  /ListNews, OK
• Build and run the project.

14
Architectural Model of News Application
Application
EJB Module
Web Module
ListNews Servlet
PostNews Servlet
Message-drivenBean
MsgQueue
SessionBean
EntityBean
Persistence API