01 JavaEE Overview

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1Copyright 2007, Oracle. All rights reserved.

Java EE: Overview


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1-2 Copyright 2007, Oracle. All rights reserved.

Objectives

After completing this lesson, you should be able to do

the following:

Describe the Java Platform, Enterprise Edition

(Java EE) platform Define the components of Java EE

Identify the deployment options for a Java EE

application Describe the architecture of Oracle Application

Server Containers for Java EE (OC4J) Describe the directory structure and the uses of

the configuration files of OC4J List the security options available in Java EE

applications


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Java Platform, Enterprise Edition

The Java Platform, Enterprise Edition (Java EE) is a

standard for developing and implementing

enterprisewide applications:

It provides multitier applications support. It is designed to help improve the process of

developing, deploying, and implementing

enterprisewide applications.


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Java EE Platform

Multitiered, distributed application model

Supports component-based Java EE applications

Distributes the application logic to the appropriate

tier on the multitiered architecture


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Distributed Multitiered Applications

Java EE Application 1

Application Client

Java EE Application 2

Dynamic HTML Pages

Client tier

JSP Pages

Enterprise Beans Enterprise Beans

Web tier

Business tier

EIS tier

Client

Machine

Database

Server

Java EE

Server


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Benefits of the Java EE Platform

Write once, run anywhere provides simplified

component development.

Multiple server products and vendors support the

Java EE standard, thus giving more deploymentchoices.

Integration with legacy systems through standardAPIs is possible.

Java EE separates client requirements from

business logic. It provides multiple development and design

scenarios.

It allows multiple clients to share server businesslogic.



Benefits of the Java EE Platform

Java EE separates development tasks into specific

skill areas:

Web designers create JSF components.

Java programmers and business experts createbusiness logic and rules.

Production environment teams handle assembly

and deployment.



Java EE Components

Java EE applications are made up of components. A

component:

Is an application-level software unit

Can be easily updated as business needs change Is reusable

There are several types of components:

Client-side components

Web components Business-tier components



Java EE 5.0 Components

The Java EE 5.0 Specification lists the following

components:

Java Servlet 2.5

JavaServer Pages 2.1 Enterprise

JavaBeans 3.0

Java API for XML-based

Web Services 2.0

Java API for XML-based

RPC 1.1

Web Service Metadata

for the Java Platform

Java Message Service API

Java Transaction API Java Persistence API

J2EE Connector

Architecture 1.5

SOAP with AttachmentsAPI for Java (SAAJ)

Streaming API for XML



Business-Tier Components

Business-tier components:

Are EJBs

Handle business logic

Receive data from client programs Retrieve data from database storage

Process the data and communicate with the

database and the client program

Can be invoked by the Web-tier components



Enterprise JavaBeans (EJB)

Enterprise JavaBeans:

Are server-side components written in Java

Contain the business logic of an enterprise

application Are hosted in EJB containers

Are based on Remote Method Invocation (RMI)

communication

Are platform independent Provide remote services for clients

Can be exposed as Web services

Use JDBC to connect to a database



Types of EJB

Entity Bean

Used to model the persistence part of an

application

Session Bean Invoked by a client to perform a specific business

operation

Message-driven Bean

Triggered by messages sent to a messaging server,

which enables sending asynchronousmessages between system components



Java Persistence API

The Java Persistence API (JPA) deals with:

The way relational data is mapped to Java objects

(persistent entities)

The way these objects are stored in a relationaldatabase so that they can be accessed at a later

time

The continued existence of an entitys state even

after the application that uses it, ends



Web Services

Web services are Web-based enterprise

applications that use open XML-based standards

and transport protocols to exchange data with

calling clients.

The Java EE platform provides the XML APIs and

tools needed to design, develop, test, and deploy

Web services and clients that fully interoperate

with other Web services and clients running on

Java-based or non-Java-based platforms.



Client-Tier Components

A Web browser:

Is used for a Web-based Java EE application

Downloads static or dynamic Web pages fromWeb-tier components

Is a thin client

An application client:

Is used for a non-browser-based Java EEapplication

Executes on the client machine Can contain a graphical or command-line interface

Is a thick client

Accesses middle-tier services

Requires installation on the client machine



Java EE Web-Tier Components

A Web tier may consist of:

Java servlets

JavaServer Pages (JSPs)

JavaServer Faces (JS`Fs) Servlets and JSPs:

Work on a request-response model

Generate HTML dynamically

Access the database through JDBC

Access the business-tier components Handle user-centric events, such as an HREF link or

form submission

Usually generate visual interfaces, such as a Web

page



Client info (host name,

form data)

Success or failure

Process results

(access database)

Format results and produce

HTML

Send page back to client

Browser Servlet

What Is a Servlet?

Request

Response



What Is a JavaServer Page?

A JavaServer Page (JSP):

Is a text-based document that includes:

HTML

JSP tags Java code (including calls to JavaBeans

and servlets)

Cleanly separates content creation from

presentation logic

Focuses on rapid development and easy

modification of the user interface

Focuses on presentation



What Is JavaServer Faces?

JavaServer Faces (JSF):

Is a server-side component framework for Web

applications

Implements the Model-View-Controller (MVC)framework

Provides separation of navigational and data flow

Is built for rapid application development (RAD)

style development



Web-Tier Components: Summary

Web-tier components generate dynamic content.

Servlets:

Extend Web server functionality

Are best used for business logic JSPs:

Combine HTML (or other markup) and Java

Are best used for presentation logic

JSFs:

Are component based

Implement MVC



Java EE Communication APIs

Java EE provides component communication

through APIs that include:

Remote Method Invocation (RMI)

Java Naming and Directory Interface (JNDI)

Java Database Connectivity (JDBC)

These APIs facilitate communication:

Between the Java EE components

With the database

Java Message Service (JMS) enables components

to create, send, receive, and read messages.


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Java EE Server

The Java EE server provides:

Containers for each component type of a Java EE

application

System-level services to components: Naming and directory services (JNDI)

Security services for Web components and EJBs

(JAAS)

Transaction architecture (JTA)

Remote client connectivity:

Enterprise beans (RMI/IIOP, ORMI)

Servlet/JSP (HTTP, HTTPS, FTP)


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Java EE Applications

Java EE applications consist of Java EE components

and are deployed in the form of modules:

Web modules contain the user interface: HTML,

JSP, and servlets.

EJB modules contain reusable EJB components.

Client modules provide access to remote

application code.

Packaging information identifies dependencies

between modules.


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Packaging Java EE Applications

Assembly

Root

META-INF

Web

Module

EJB

Module

Application

Client Module

Resource

Adapter Module

application.xml Ear File Structure


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Packaging Java EE

Application Components

4. ejb.jarClass files for enterprise beans and an

EJB deployment descriptor

1. webtier.warJava servlets, JSP files, HTML, GIF files, and

a Web application deployment descriptor

2. JavaEEappClient.jar

Java EE application client (Java class), andan application client deployment descriptor

3. Resource adapter (.rar)Java interfaces, classes, native libraries,

and other documentation and the resourceadapter deployment descriptor

Java EE application.ear


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Oracle Application Server Containers for

J2EE (OC4J)

OC4J is the Java EE server implementation in

Oracle Application Server 10g.

Key features:

Implements Java EE 1.4 Specification

Runs on standard JVM

Provides high performance and scalability

Is productive for developers to use

Is simple to manage and deploy

Provides clustering for high availability and failover


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OC4J Architecture

Web

container

JNDI

JMS

EJB

container

AJP13

ORMI

JDBC

JTA

JavaMail

JAF

mod_oc4j

Client

EJB client

Oracle HTTP

Server

ORMI

AJPHTTP

OC4J server process

JAAS

JCA


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Java EE Application Deployment to

Oracle Application Server 10g

Deploying to OC4J can be performed in multiple ways:

Step 2: Deploy

Use JDeveloper specify an

Application Server and click 'Deploy'

Step 1: Create WAR,EAR file

Step 2: Deploy

Use a command-line tool (such asANT).

Use JDeveloper.

Use Oracle Enterprise Manager(installed with Oracle Application

Server 10g): Access the Enterprise

Manager Web site

http://localhost:1810(requires login).

Use JDeveloper: Specify an

application server and click

Deploy.


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Security in Java EE Applications

Security for Java EE application components is

provided by their containers.

A container provides two types of security:

Declarative security through deployment

descriptors

Programmatic security embedded in the application

Annotations are used to specify information about

security within a class file.


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Using Deployment Descriptors for

Declarative Security

A deployment descriptor:

Is an XML document with an .xml extension

Is used by application developers to communicate

how security is to be set up for the deployedapplication

Enables an applications security structure,

including roles, access control and authentication

requirements to be expressed in a form external to

the application Is read at run time by the Java EE server which

then acts upon the application, module, or

component accordingly


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JDeveloper and Java EE

JDeveloper provides:

Integrated development, deployment, and testing

support for Web-tier and business-tier

components

A Java EE framework for rapid development

Application Development Framework (ADF)

business components

Data tags

Integration with Struts

UML modeling

Visual editors for Web clients

Easy deployment to Oracle Application Server 10g

JDeveloper


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Oracle JDeveloper 10gEnvironment

Wizards for

JSPs,

servlets, and

EJBs

Error

checking

for HTML

and JSPs

Code Insight

EAR, WAR

deployment

to Java EE

server

Customizable Code Editor


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Oracle JDeveloper 10g

Visual Design Tools

Drag JSP and HTML

elements

Modify

values

in

Property

Inspector

Design in visual

or code views,

see revisions


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Summary

In this lesson, you should have learned that:

Java EE is a set of Java technologies that

supports end-to-end application development

Components are the foundation of the Java EEarchitecture

Business components (EJBs) are server-side

components that contain business logic

Web components (servlets, JSPs, and JSFs)

generate dynamic content

Applications can be built by using Oracle

JDeveloper 10gand deployed to a Java EE server,

such as Oracle Application Server 10g


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01 JavaEE Overview

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