8/8/2019 WF3815V05_J2EE

1/27

Welcome to:

J2EE Platform Technologies

8/8/2019 WF3815V05_J2EE

2/27

Unit Objectives

After completing this unit, you should be able to:Discuss basic Java terminology

Discuss the importance of the J2EE Platform

Discuss the J2EE object model and WebSpheres

implementationDiscuss component technologies

Discuss service technologies

Discuss communication technologies

8/8/2019 WF3815V05_J2EE

3/27

What is Java?

Java programs consist of classesClasses are composed of methods

Methods perform tasks and may return information when

finished

Java Program Packaging:Related classes are grouped into Packages

Classes and/or packages and associated resources are

distributed in JAR or ZIP filesThe JVM classloader uses its classpath to locate classes

For classes in JAR files, the JAR filename must be in the

classpath

For classes not in a JAR file, the class should be in a

directory that matches the package name and the parent

directory must be in the classpath

Example: classpath=c:\WebSphere\AppServer\Java\

8/8/2019 WF3815V05_J2EE

4/27

Java Components

Java component types:Applications - stand-alone programs, run in own JVM.

Applets - client side, run in a Web browser

Servlets - server side, run in a Web container

JavaBeans - reusable componentsEnterprise JavaBeans (EJBs) - reusable components,

used for distributed applications, run in an EJB container

Java Server Pages (JSPs) - Web pages with server sidescripting using Java, run in a Web container

8/8/2019 WF3815V05_J2EE

5/27

What is J2EE 1.3?

Java 2 Platform Enterprise EditionThe specification is at level 1.3

Essentially it is.....

an approach to designing, developing, assembling and

deploying enterprise applicationsa platform with standardized tools and standard ways to

exchange information

8/8/2019 WF3815V05_J2EE

6/27

8/8/2019 WF3815V05_J2EE

7/27

Applet Container

Applet

J2SE

Application Client

Container

ApplicationClient

J2SE

Web Container

JSP

J2SE

Servlet

EJB Container

Enterprise

Bean

J2SE

HTTP

SSL

HTTP

SSL

RMI/IIOP

RMI/IIOP

Client-SidePresentation

Server-SidePresentation

Server-SideBusiness Logic

Database

JMS JNDI

RMI/IIOP

JDBC

JTA

JavaMail

JAFJMS JNDI

RMI/IIOP

JDBC JTA

JavaMail

JAFJMS JNDI

RMI/IIOP

JDBC

J2EE Object Model

8/8/2019 WF3815V05_J2EE

8/27

API Acronym WAS 5.0

Enterprise JavaBeans EJB 2.0

JDBC API JDBC 2.0

Java Servlet --2.3

JavaServer Pages JSP 1.2

Java Message Service JMS 1.0.2

Java Naming and Directory Interface JNDI 1.2

Java Transaction API JTA 1.0

JavaMailTM API -- 1.2

JavaBeans Activation Framework JAF 1.0

Java API for XML Processing XML 1.1

J2EE Connector Architecture J2C/JCA 1.0

Java Authentication and Authorization Service JAAS 1.0

J2EE 1.3 APIs

8/8/2019 WF3815V05_J2EE

9/27

J2EE Container

Each component runs inside a container which is provided bythe J2EE platform provider.

The container provides specific deployment and run-time

services to the component (Life cycle, security, transactions,

and so forth).What services are offered depends on the type of container.

8/8/2019 WF3815V05_J2EE

10/27

J2EE

Components

Communication

Services

J2EE Platform Technologies

ComponentsClient Side ComponentsApplets

Application Clients

Server Side ComponentsEJBs

Web Components (Servlets, JSP)

Services

Functions utilized by J2EE componentsAPIs implemented by J2EE platform provider (WebSphere

Application Server)

CommunicationEnable communication between collaborating components

Provided by containers

8/8/2019 WF3815V05_J2EE

11/27

Client Side Components - Applets

GUI components that normally execute in a Web browserCan also execute in other applications or devices that support

the applet programming model

Typically used to provide a user interface to J2EE

applications

AppletContainer

Applet

J2SE

Application

ClientContainer

ApplicationClient

J2SE

JNDI

JMS

R

MI/IIOP

JDBC

Web Container

JSP

J2SE

JND

I

JMS

RMI/I

IOP

JDB

C

Servlet

JTA

Java

Mail

JAF

EJB Container

EnterpriseBean

J2SE

JNDI

JM

S

RMI/IIOP

JDB

C

JTA

Java

Mail

JAF

HTTP

SSL

HTTP

SSL

RMI/IIOP

RMI/IIOP

Database

8/8/2019 WF3815V05_J2EE

12/27

Client Side Components - Application Clients

Java Programming Language programsTypically GUI programs

Have access to all the services on the J2EE middle tier

AppletContainer

Applet

J2SE

ApplicationClientContainer

ApplicationClient

J2SE

JNDI

JMS

R

MI/IIOP

JDBC

Web Container

JSP

J2SE

JND

I

JMS

RMI/I

IOP

JDB

C

Servlet

JTA

Java

Mail

JAF

EJB Container

EnterpriseBean

J2SE

JNDI

JM

S

RMI/IIOP

JDB

C

JTA

Java

Mail

JAF

HTTP

SSL

HTTP

SSL

RMI/IIOP

RMI/IIOP

Database

8/8/2019 WF3815V05_J2EE

13/27

Server-Side Components - Servlets

Servlets are Java classes that allow application logic to be

embedded in HTTP request-response process

J2EE 1.3 requires:

Servlet 2.3 specification (fully supported by WebSphere

Application Server V5.0)

AppletContainer

Applet

J2SE

ApplicationClientContainer

ApplicationClient

J2SE

JNDI

JMS

R

MI/IIOP

JDBC

Web Container

JSP

J2SE

JND

I

JMS

RMI/I

IOP

JDB

C

Servlet

JTA

Java

Mail

JAF

EJB Container

EnterpriseBean

J2SE

JNDI

JM

S

RMI/IIOP

JDB

C

JTA

Java

Mail

JAF

HTTP

SSL

HTTP

SSL

RMI/IIOP

RMI/IIOP

Database

8/8/2019 WF3815V05_J2EE

14/27

Server Side Components - Java Server Pages (JSP)

HTML document:

Embedded JSP specific tags

Inline Java Code

On the server, JSP Page is parsed and compiled into a Java

ServletWebSphere Application Server V5.0 fully supports JSP 1.2

AppletContainer

Applet

J2SE

ApplicationClientContainer

ApplicationClient

J2SE

JNDI

JMS

R

MI/IIOP

JDBC

Web Container

JSP

J2SE

JND

I

JMS

RMI/I

IOP

JDB

C

Servlet

JTA

Java

Mail

JAF

EJB Container

EnterpriseBean

J2SE

JNDI

JM

S

RMI/IIOP

JDB

C

JTA

Java

Mail

JAF

HTTP

SSL

HTTP

SSL

RMI/IIOP

RMI/IIOP

Database

8/8/2019 WF3815V05_J2EE

15/27

Server Side Components - Enterprise JavaBeans (EJB)

Entity Beans Session Beans Message-driven

Beans

Enterprise JavaBeansEnterprise JavaBeans

Container-Managed

PersistenceBean-Managed Persistence

Stateful

Stateless

S Sid C E i J B (EJB)

8/8/2019 WF3815V05_J2EE

16/27

Server Side Components - Enterprise JavaBeans (EJB)

!An example for a Session Bean

1. Client uses JNDI to find EJB Home

2. Client uses EJB Home create method to create a session EJB3. The local EJB Home tells the container to create a remote EJB component

4. The container returns the EJB Object stub to the client

5. The client then calls local methods on the EJB Object, which are forwarded to the

remote EJB

EJB Home

EJB Object

Enterprise

Bean

EJBHome

Stub

EJB

Object

Stub

remote

client

container

EJB server's JVM

client's JVM

IIOP

JNDI

E tit B

8/8/2019 WF3815V05_J2EE

17/27

Entity Beans

Represent data

Bean Managed Persistence (BMP)

the programmer controls data access

the beans contain the code to store and retrieve data.

Container Managed Persistence (CMP)the EJB container handles all aspects of data access

the programmer can concentrate on business logic.

Entity Beans

Container-Managed

Persistence

Bean-Managed Persistence

S i B

8/8/2019 WF3815V05_J2EE

18/27

Session Beans

Represent some kind of action

Stateless

useful for simple transactions where all information to

complete the transaction is present at the same time

high performance and reusableused for single-stage transaction management.

Stateful

multiple stages are required to perform the transaction

Session Beans

Stateful

Stateless

8/8/2019 WF3815V05_J2EE

19/27

Services: JNDI

8/8/2019 WF3815V05_J2EE

20/27

Services: JNDI

JNDI allows components to store and retrieve named Java

objects

J2EE 1.3 requires JNDI 1.2 level

WebSphere Application Server 5.0 provides an integrated

JNDI 1.2 compliant name serviceContainers provide two levels of naming schemes:

"Local", read-only, accessible to components

"Global", the actual JNDI namespaceLocal names are "bound" to their global counterparts at

deployment

JNDI: Binding Example

8/8/2019 WF3815V05_J2EE

21/27

}

ProcessCustomer

Session Bean

Customer

Entity Bean

Exam

Entity Bean

Context initialC = new InitialContext();

.....

Object pHomeObject =initialC.lookup("java:comp/env/ejb/Exam")

ExamHome eHome = (ExamHome)

PortableRemoteObject.narrow(...);

Exam exam = eHome.create();

Boolean passed = exam.grade();

EJB-refs

ejb/Customer

ejb/Exam

JNDI name

com/ibm/samples/CustomerHome

JNDI name

com/ibm/samples/ExamHome

Bindings

Calling

Calling

JNDI: Binding Example

Services: Transactions

8/8/2019 WF3815V05_J2EE

22/27

Services: Transactions

JTA is the API and JTS is the implementation

JTA is an implementation-neutral interface to distributed

transactions

J2EE 1.3 requires JTA level 1.0

Implemented by combining WebSphere and a JDBC driverthat supports JTA

Services: JDBC

8/8/2019 WF3815V05_J2EE

23/27

ApplicationJDBC Driver

DriverManager

Database

Services: JDBC

Provides vendor-independent database connectivity

Provides a generic way to query and update relational tables

and translate the results into Java datatypes

JDBC 2.0 is the current level of the specification

A JDBC driver makes it possible to do three things:Establish a connection to a database

Send queries and update statements to the data source

Process the results

Services: Connector Architecture (J2C)

8/8/2019 WF3815V05_J2EE

24/27

Resource Adapter for

the EIS IMS

J2EE Component

J2EE Component

J2EE Component

Provided by EIS vendor

or Third Party vendor

Common

Client

Interface

API

EIS(IMS)

Resource Adapter for

the EIS CICS EIS

(CICS)

Resource Adapter forthe EIS SAP EIS

(SAP)

J2EE Server Runtime

Included with

WebSphere

Services: Connector Architecture (J2C)

Communications: JMS

8/8/2019 WF3815V05_J2EE

25/27

Communications: JMS

JMS - Java Messaging Service

Reliable interface for asynchronously sending and receivingmessage

Standard, vendor-neutral API used to access enterprise message

systemsCore functionality for the implementation of Message-driven

Beans

Message-driven Beans consume messages from queues and

topics that are sent by a JMS client

EJB Container

Message DrivenBean

Business

Bean

Application Server

Queue

J2EE Component or

JMS Application

JMS message

Communications: RMI and RMI/IIOP

8/8/2019 WF3815V05_J2EE

26/27

Communications: RMI and RMI/IIOP

RMI - Remote Method Invocation

Specific to Java and only allows objects programmed in

Java to interact remotely

Uses a JRMP (Java Remote Messaging Protocol) for

communicationRMI/IIOP

Turns local method call into remote method calls

EJB clients use RMI/IIOP to communicate with other EJBsJ2EE 1.3 supports RMI/IIOP level 1.0

Unit Summary

8/8/2019 WF3815V05_J2EE

27/27

Unit Summary

Discussed the J2EE object model and how WebSphere

implements it.

Discussed how WebSphere implements parts of J2EE 1.3

specification.

Discussed the following technologies of J2EE:Component technologies

Service technologies

Communication technologies