Java 2 Platform, Enterprise Edition (J2EE)

Java™ 2 Platform, Enterprise Edition (J2EE) Bruno Souza Java Technologist, Sun Microsystems, Inc.

J1-680, Hapner/Shannon

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Contents • The Java™ 2 Platform, Enterprise Edition (J2EE) • J2EE Environment • APM and key APM questions • Application Scenarios and the Sample Application • Deployment and Security • Resources J1-677, Kassem

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A Short History of Java Enterprise Technology


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The Java™ Platform Where Have We Been? Where Are We Going? Year 1 • JDK All Things to Everyone


Year 2 • JDK “All Things to the Enterprise” • Early Development of Consumer Java • Early Development of “Enterprise” APIs”

Year 3 • Micro Edition • Standard Edition • Enterprise Edition

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Java 2 Platforms

Java Technology Enabled Devices


Java Technology Enabled Desktop

Workgroup Server

High-End Server

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Why another Java™ 2 Platform?


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The Global Enterprise D EIS Tier

Middle-Tiers

Clients J1-680, Hapner/Shannon

D

D

ERP Systems

DBMSs

Enterprise Services

Device 7

Enterprise Services Require • Concurrency (multi user)

• Scalability • Administration

• Consistency (Transactions)

• EIS Integration

• Security

• Distribution

• Availability


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The Java™ 2 Platform, Enterprise Edition • Develop – With the J2EE App Model

• Deploy – With the J2EE App unit

• Run – On the J2EE Platform


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J2EE Platform


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What is the purpose of J2EE Containers?


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J2EE Platform

HTTP/ HTTPS

JavaMail JAF

JDBC

JMS

JAF

JNDI

JavaMail

JTA

JMS

App Client Container App Client

JNDI

J2SE

EJB

RMI

RMI/IIOP

Servlet

JSP

JDBC

HTTP/ HTTPS

EJB Container

RMI/IIOP

Applet

Web Container

JTA

Applet Container

J2SE

J2SE

JDBC

RMI/IIOP

JMS

JNDI

RMI

J2SE

Database J1-680, Hapner/Shannon

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Containers and Components • The container is the car • The component is the driver • The container is the platform • The component is your application


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J2EE Containers • Containers do their work invisibly – No complicated APIs – They control by interposition

• Containers implement J2EE – Look the same to components – Have great freedom to innovate


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J2EE Containers Handle • Concurrency (multi user)

• Scalability • Administration

• Consistency (Transactions)

• Integration

• Security

• Distribution

• Availability


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J2EE Components Handle • Presentation • Business logic • Data access


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Container Perspectives • To a J2EE vendor – It is their product

• To a component developer – It is a standard app model

• To an app assembler – It is a standard app package

• To an executing component – It is god


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Why Does J2EE Focus on Deployment?


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Application Packaging EJB EJB Module

EJB

1 1

DD

DD

Web Client Module

2

APP DD

EJB

WEB

2 WEB

DD

DD

Application Client Module

3

DD


3

Deployment Tool

DD

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Application Life Cycle Creation Created by Component Developer

Assembly Assembled J2EE Modules and Augmented by Application Assembler

Deployment J2EE APP

Processed by Deployer Deploy

J2EE Container

Enterprise Components


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The Deployer • Is an expert in the operational environment – Familiar with local security practices – Familiar with local EIS configuration – Familiar with local containers and their apps

• Uses J2EE platform product tools


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Deployment Summary • Apps may be written without knowledge of the operational environment • Deployment Descriptor communicates app’s needs • A key interface between application developer and platform


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What Exactly Is in J2EE?


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J2EE API Summary • J2SE 1.2

• JNDI 1.2

• JDBC™ 2.0

• JTA 1.0

• RMI/IIOP 1.0

• JMS 1.0

• EJB 1.1

• JavaMail™ 1.1

• Servlet 2.2

• JAF 1.0

• JSP 1.1


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J2EE Standards • TCP/IP • HTTP 1.0 • HTML 3.2 • SSL 3.0 • IIOP 1.0


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The Java™ 2 Platform, Enterprise Edition • Platform Specification – Defines J2EE requirements

• Compatibility Test Suite – Validates J2EE platform compatibility

• Reference Implementation – Operational J2EE platform

• Application Programming Model – Describes how to build J2EE applications


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Java™ 2 Platform, Enterprise Edition Application Programming Model (APM) • Organized set of design patterns, templates and architectural principles – Focus is on design of manageable, deployable and maintainable J2EE applications – Results in faster product delivery time to market of enterprise solutions

• Recommends how the J2EE specifications should be applied to application domains

J1-677, Kassem

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Some Key APM Questions • Choose Servlets or JavaServer Pages™ technology (JSP)? • Access EIS Resources via Enterprise JavaBeans™ technology (EJB) server or Directly from JSP? • Session Beans or Entity Beans? • Distributed transactions or local transactions? • How to exchange Data with External Systems? J1-677, Kassem

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The J2EE Environment Enabling End-to-end Solutions Firewall

Client

Application Server

Client

Enterprise JavaBean

Enterprise Information Systems (EIS):

Enterprise JavaBean

Relational-Database, Legacy Applications, ERP Systems

Client Client

Web Server JSP, Servlet, HTML, XML

Client Other Services: JNDI, JMS, Java Mail

Client Tier J1-677, Kassem

Middle Tier

EIS Tier 7

Web Access • Exposes application logic to web client(s) as coarse grained service(s): – Responsible for handling “user” input/application presentation – Named via URI – Modeled as HTML (or XML)

• Comprised of dynamic and static content – Java Server Pages for dynamic content: • Higher level of abstraction than Servlets • Easier to generate HTML (and XML in future) J1-677, Kassem

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“Other” Clients • EJB from another “application”: – RMI/IIOP now, JMS later

• Standalone “clients”: – CORBA client: • IIOP access direct to application logic – Java technology client: • RMI/IIOP or JMS access – Desktop productivity application: • MS desktop integration solution via plug-in, JRE and RMI/IIOP J1-677, Kassem

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Application Logic • Modeled using EJBs: – SessionBean (stateless & stateful) – EntityBean (CMP or BMP) – Componentize: • Workflow, processes, business rules and entities…

• Fine grain imperative interface contract • External resources are logically named internally – Customized via deployment descriptor – Resolved by deployer at deployment time J1-677, Kassem

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Enterprise Information Services (EIS) • Integration is achieved by either: – Directly using platform API such as: • JDBC™ • JMS • Java Naming and Directory Interface™ (JNDI) – Or via Connector(s): • Connector is: – Resource adapter, Access Bean, integration tool(s)

• Ubiquitous Connector APIs for specific EIS products J1-677, Kassem

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EJB Components JNDI EJB Container

Client

Entity EJP

Data Access Bean

Connector

EIS

Session EJP

Data Access Bean

Connector

EIS

HTTP(S) Service Servlet/JSP

Middle Tier J1-677, Kassem

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Application Scenarios Web Server

App. Server

6

7

1

Web Server

Browser

EIS Resources

App. Server

Stand-alone 5

2 3 J1-677, Kassem

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Core Application Scenarios 1

• n-tier Web Access – HTML, XML, HTTP client – JSP/Servlets, RMI/IIOP – EJBs, JDBC (Connectors)

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Sample App.

• n-tier Intranet Access – EJB Client, EJB Sever

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• 2-tier Java Client – JSP/Servlets and JDBC

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• B2B Enterprise Transactions – EJBs, JMS and XML

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Sample Application High Level Requirements • Must offer Web Presence • Must be Robust and Scalable • Must leverage existing EIS resources • Must utilize core competencies of diverse development teams • Must facilitate B2B transactions • Get it done yesterday! J1-677, Kassem

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Sample Application High Level Technical Decisions • Client tier – Chose HTML Clients for End-User Web Access – Chose XML for selective Data externalization

• Web Server tier – Chose JSP/Servlets to be WS neutral

• App Server tier – Chose EJB’s to be AS neutral – JDBC Data Access Beans to encapsulate EIS access – Chose to optionally support distributed transactions J1-677, Kassem

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SA—Scenario • Web-based browsing of a product catalog • Creation and maintenance of a shopping cart • User account creation • Placing orders • Secure order processing – B2B transactions – Externalization of order data (expressed in XML) – Order confirmation using e-mail J1-677, Kassem

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SA—Activity Diagram Customer

Sales

Warehouse

View Catalog Add to Cart Select Account Process Order Pull Stock Ship Order

Receive Order

Bill Customer

Pay Bill Close Order J1-677, Kassem

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SA—DB Schema table table

product

...) table

...)

lineitem

(

orderid linenum itemid

table

orders

(

orderid userid

...)

...) table

category

(

suppid

(

productid category

table

supplier

attrdesc

(

attrcode

(

...)

catid ...)

table

account

(

userid table

inventoryitem

itemid productid supplier ...)

J1-677, Kassem

...)

( table

orderstatus

(

orderid linenum ...)

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SA—Architecture Session Beans

Entity Beans

Access Beans

Tables

Physical DBs

Account UserValidatorEJB

AccountEJB

AccountDAB Orders

MailerEJB OrderEJB

OrderDAB

OrderStatus

db1

ShoppingCartEJB

Line item EStoreKeeperEJB

CatalogDAB

J1-677, Kassem

db2

Product

CatalogEJB InventoryEJB

Category

InventoryDAB

Inventory 22

SA—JSP Usage …..

User ID:

Password:
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SA—JSP Usage … ... ... J1-677, Kassem

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SA—Controller Interface

public interface EStorekeeper extends EJBObject { public Catalog getCatalog() throws RemoteException; public ShoppingCart getShoppingCart() throws RemoteException; public Credential getCredential() throws RemoteException; public Account getAccount() throws RemoteException; public Enumeration getOrders() throws RemoteException, FinderException; public void handleEvent(EStoreEvent se) throws RemoteException; }

J1-677, Kassem

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SA—Controller Implementation public class EStorekeeperEJB implements SessionBean { public void ejbCreate() throws RemoteException { sm = new StateMachine(this); } public Catalog getCatalog() throws RemoteException { Locate Catalog if (catalog == null) { EJB’s H/I using JNDI try { Context initial = new InitialContext(); Object objref = initial.lookup (EJBUtil.jndiNameOfCatalogHome); CatalogHome catalogHome = (CatalogHome) PortableRemoteObject.narrow(objref, CatalogHome.class); catalog = catalogHome.create(); } catch (NamingException ne) { ... } return catalog; } J1-677, Kassem

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Application Model • Makes Recommendations across all tiers – – – – – – –

Client Middle-tier (includes Web server and EJB) Data access Messaging External application integration Communication protocols Deployment file formats

• Results in Faster product delivery

J1-677, Kassem

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J2EE Resources

• White paper: – http://java.sun.com/j2ee

J1-677, Kassem

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