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Copyright 2009, Oracle. All rights reserved.

Defining Java Enterprise Edition

Terminology and Architecture


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Copyright 2009, Oracle. All rights reserved.2 - 2

Objectives

After completing this lesson, you should be able to:

Explain the motivation behind distributed systems

List the major components of the Java Platform Enterprise

Edition 5 (Java EE) specification


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Distributed Systems

Distributed systems divide the work among several

independent modules.

The failure of a single module has less impact on the

overall system, which makes the system more:

Available Scalable

Maintainable


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How Standards Help

Many advantages of distributed systems come from

standards.

Standards allow:

Modularization of complex hardware and software

A larger portion of the project costs to go toward solvingbusiness software needs


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Java EE Standard

Java Platform Enterprise Edition 5 (Java EE) helps you to

overcome distribution liabilities.

Applications deployed with Java EE technologies are:

Standardized

Adherent to specification guidelines Written in Java

Deployable in any compliant application server

Java Community Process (JCP) is the oversight (custodial)

process for moderating Javas future direction.

http://jcp.org/en/home/index

http://jcp.org/en/introduction/faq


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Java EE Architecture

Oracle WebLogic Server

Java EE Application Server

Web ContainerWeb client

RDBMS

Message queue

Directory service

CORBA

Java app

Web service

EJB Container

Applet JSPs

Servlets

Session EJBs

Entity EJBs

JAX-

WS

RMI JTA JDBC JMS JMX JAAS JNDI

Client

application


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Java Servlets

A servlet is a Java program that executes on the server,

accepting client requests and generating dynamic

responses.

The most prevalent type of servlet is an HttpServlet that

accepts HTTP requests and generates HTTP responses. Servlets:

Do not just generate HTML

Can also be used to generate other MIME types, such as

images


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SimplestServlet.java

Creates HTML

package mypackage;

import java.io.*;

import javax.servlet.*;

import javax.servlet.http.*;

public class SimplestServlet extends HttpServlet {public void service(HttpServletRequest request,

HttpServletResponse response)

throws ServletException, IOException {

response.setContentType("text/html");

PrintWriter out = response.getWriter();

out.println("");out.println("Hello, World!");

out.println("");

}

}


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JavaServer Pages (JSPs)

Are HTML documents that are interwoven with Java

Provide a dynamic response that is based on the clients

request

Provide for the separation of responsibilities between the

Web presentation and the dynamic content Are portable (write once, run anywhere)

Compile and run as servlets

May include JavaServer Faces tags


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realsimple.jsp

My title

A big heading

Blah blah blah blah blah.


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Enterprise JavaBeans (EJBs)

Are distributed components written in the Java

programming language

Provide distributable and deployable business services

(logic) to clients

Have well-defined interfaces Are reusable across application servers

Execute within a container that provides management and

control services

Oracle WebLogic Server 10.3.1 supports the EJB 3.0

specification.


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Java Database Connectivity (JDBC)

The standard Java interface for

accessing heterogeneous

databases

The specification that defines four

driver types for connecting todatabases

Purchased or

obtained

DB API

Purchased or

obtained

JDBC driver

JDBC APIJDBC API

Written by

developerApplication

Database


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Java Naming and Directory Interface (JNDI)

Java API for accessing naming and directory services

Built as a layer over DNS, LDAP, and so on

WLS

server

WLS

driver

Naming manager

Service

Purchased or obtained

JNDI API

Written by developer

OtherDNS

system

File

system

LDAP

server

OtherDNS

driver

File sys

driver

LDAP

driver

JNDI SPI

JNDI API

Application code


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JNDI Tree

Context B

is bound to

the initialcontext.

Object O3

is bound to both

contexts A and B.

A binding

associates an

object with a

logical name

and a context.

IC

A

C

Object O1

is bound to

the initial

context.

Object O2

is bound to

context A.

RRootcontext

Initial context

O2 O4O3 O3

BO1


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If the following context exists:com.oracle.examples

Then you cannot bind:com.oracle.examples.ejb.SomeObject

Without first creating:com.oracle.examples.ejb

JNDI Contexts and Subcontexts

Subcontexts are referenced through dot delimiters (.).

Subcontexts must be created before objects are placed

into them.

Typically, when objects are bound to a JNDI tree,

subcontexts are automatically created based on theJNDI name.


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Java Transaction API (JTA)

JTA is a standard Java API for demarcating transactions within

a program.

EJB JDBC

JTA

Written by developers

Transaction monitor

implementation

Java Transaction API

JMSJCA

Application code


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Java Message Service (JMS)

JMS is a Java API foraccessing message-oriented

middleware.

The interface supports:

Point-to-point domain

Publish/subscribe

(pub/sub) domain

Guaranteed message

delivery

Transactional participation

Dynamically configurable

services

Application- or system-

scoped resources

Interoperability with other messaging systems

Producer

Consumer

Producer

Consumer Consumer

JMS

server

Destination


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Java Authentication and Authorization (JAAS)

Java Authentication and Authorization Service (JAAS) is a

Java-based security management framework.

JAAS supports:

Single sign-on

A Pluggable Authentication Module (PAM) JAAS enables flexible control over authorization whether it

is based on:

Users

Groups

Roles


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Java Management Extensions (JMX)

Java Management Extensions (JMX):

Defines a standard infrastructure to manage a device from

Java programs

Decouples the managed device from the management tools

The specification describes MBeans, which are thebuilding blocks of JMX.

MBeansManagement tool


MBeanMBean

MBeanMBean


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Java EE Connector Architecture (JCA)

Connects Enterprise Information Systems (EIS) with

resource adapters

Resource adapters can be deployed in a Resource

Adapter Archive (RAR)

Application

server

container

Client

components

Resource

adapter

App server

implementationEIS

System

contracts

JCA

client API(CCI) Inbound/

Outbound

EIS API


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Client Application

The client application interacts with WLS through

JRMP/T3, IIOP, and jCOM.

The types of clients include:

Stand-alone Java applications

Applets within a browser


Web

container

Applet

Client

application

Web client

HTML/XMLEJB container

SessionEJBs

Entity

EJBs

WebService

Client


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Web Client

A Web client interacts with Oracle WebLogic Server via

HTTP using servlets or JSPs.

The types of Web clients include:

Browser

WebService (SOAP over HTTP)

WebLogic

ServerWeb container

Servlets

JSPs

Web clientHTML/XML


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Proxy Server

The proxy server:

Forwards requests to

other machines

Can be used as a level of

indirection and security

Can be used to load-

balance a system

A reverse proxy is a Web

page cache.

Proxy

serverClient

Server

A

ServerC

Server

B


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Web Server

Web servers:

Provide Web content

Communicate via HTTP, FTP, and so forth

Can handle CGI requests

Proxy some requests to application servers

Web server

WebLogic

Server

plug-in

HTTP

HTTPS

HTTP

HTTPS


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Firewalls

Provide filtering,

authorization, and

authentication services

Help keep out hackers

Map port requests Can act as proxy servers

Can decrease back-end

network activity

Firewall

HTTP

HTTPS

HTTP

HTTPS


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Application Servers

Provide services that

support the execution

and availability of

deployed applications

Handle heavierprocessing chores than

Web servers

Oracle WebLogic ServerJava EE Application Server

Web container

Servlets

JSPs

EJB container

Session

EJBs

Entity

EJBs

JAAS

JNDI

JMX

JMS

JDBC

JTA

RMI

JAX-WS


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Web Application Server Configuration

Your network

Inner

network

Client

app

Client

app

Firewall Firewall

Extranet

or

Internet

App servers

SvrC

SvrB

SvrA

SvrD

SvrE

SvrX

SvrW

SvrV

SvrY

SvrZ

Client

app

Web

server

WLSplug-

In

DB


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Application Server Configuration

Your network

Client

app

Client

app

Firewall Firewall

Extranet

or

Internet

App servers

SvrC

SvrB

SvrA

SvrD

SvrE

SvrX

SvrW

SvrV

SvrY

SvrZ

Local

client

app

Client

app

DB


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Quiz

Oracle WebLogic Server 10.3.1 is certified with JDK 1.6.

1. True

2. False


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Summary

In this lesson, you should have learned how to:

Explain the motivation behind distributed systems

List the major components of the Java EE specification


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Practice 2Overview:

Defining Terminology and Architecture

There is no practice for this lesson.


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Documents

Les 02 Term Arch