The J2EE Framework 1 Introduction to Java 2 Enterprise Edition Presented by Communication & Collaboration Technologies Division of the Chief Information

The J2EE FrameworkThe J2EE Framework

1

Introduction to

Java 2 Enterprise Edition

Presented by

Communication & Collaboration Technologies

Division of the Chief Information Officer

Rensselaer Polytechnic Institute

Welcome!


2

Main Topics

• Introduction– The Goal

– The Problem

– The Solution

• What is J2EE?

• Motivations

• The J2EE Framework

• Case Studies / Examples


3

Motivations

Why J2EE?

• Presentation world is web-centric

• Tried other approaches

– Static HTML, CGI, Applets, ASP

• Need integration with campus-wide services

• Capitalize on developer’s strengths

– Programming

– Presentation

– DBM

• Framework is being widely adopted by vendors


4

Motivations

• Oracle 9iAS Internet Application Server Enterprise Edition used by SCT for Banner

• 100% compliant J2EE server

Oracle9i Application Serverhttp://www.oracle.com/ip/deploy/ias


5

Motivations

• “WebSphere continues the evolution to a single Web services-enabled, Java™ 2 Enterprise Edition (J2EE) application server and development environment that addresses the essential elements needed for an on demand operating environment.”

– http://www-3.ibm.com/software/info1/websphere

• IBM & Globus Project developing grid computing with JBoss and IBM WebSphere

– http://www-1.ibm.com/grid/grid_strategy.shtml

– http://www.javaworld.com/javaworld/jw-09-2002/jw-0906-grid.html


6

The J2EE Framework

ExternalApplication

Java Technologies


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J2EE Container

Component Based Architecture

• Applications are built from components– Java class files

– Configuration files (usually XML)

– Data files (html, images, directories,…)

• Components are packaged into archives for deployment

– jar : Java Application Resource

– war : Web Application Resource

– ear : Enterprise Application Resource


8

J2EE Container

Deploying Applications

• J2EE server specific

– Some provide GUI tools to build and deploy applications (WebSphere, BEA WebLogic)

– Some require editing XML configuration files (JBoss)

• JBoss

– Drop .ear archive files into a “deploy” directory

• Hot deploy & redeploy


9

Java Technologies

• JNDI – namespaces, ldap

• JDBC– database connectivity

• JAAS– authentication

• JTA– transactions

• JMX– management & monitoring

• JavaMail– email

• EJB– business logic & data

• JMS– messaging

• CORBA– remote procedure calls

• SOAP– web services

• RMI– remote method invocation

• Servlets– web logic

• JSP– web presentation

• XML– portability


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JNDI

Java Naming & Directory Interface

• Provides namespace support for J2EE

– Beans located by name within container namespace

– Application attributes located by name within application local namespace

• Controlled access from external servers

• Access to LDAP directories


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JDBC

Java DataBase Connectivity

• Java equivalent of ODBC (Open DataBase Connectivity)

• Java API that enables Java programs to execute SQL statements. This allows Java programs to interact with any SQL-compliant database


12

JAAS

Java Authentication and

Authorization Service

• Implements a Java version of the standard Pluggable Authentication Module (PAM) framework

• Supports user-based authorization

• Access control at every level


13

JTA

Java Transaction API 1 of 2

• Specifies standard interfaces between a transaction manager (e.g. JBoss) and the parties involved in a distributed transaction system:

– the resource manager

– the application server

– and the transactional applications

• Two types of transaction paradigm

– Declarative for entity & session beans

– Programmatic for session beans & servlets


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JTA

Java Transaction API 2 of 2

• Provides “ACID” transaction support

– Atomicity

– Consistency

– Isolation

– Durability


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JMS

Java Message Service

• Point to point messaging

– each message has only one consumer

– used to decouple applications

• Publish/subscribe messaging

– each message may have multiple consumers


16

EJB

Enterprise Java Bean

• Bean

– originally a Java class with get() and set() methods

– e.g.: getFirstName(), setFirstName()

• EJBs come in 3 flavors:


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EJB – Entity Bean

Entity Bean

• Represent actual data items (e.g. rows in a result set)

• Two forms of Entity Bean– Container managed persistence:

DB interactions handled by the J2EE environment

– Bean managed persistence: requires that the bean carries out DB interactions itself

• May be called across network connection (RMI)


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Session Bean

• Model a process or task

• Represent resources private to the client

• May update shared data

• Two forms of Session Bean

– Stateful: state maintained between method calls

– Stateless

• One client per session bean instance

EJB – Session Bean


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Message Driven Bean

• Used in conjunction with Java Messaging System

• Activated on JMS message arrival

• No state maintained between activations

APPLICATION

message queue

EJB – Message Driven Bean

*****

*

*session facade


20

Servlets

Servlets

• Used for web applications

• Extend functionality of an HTTP server

• Replace CGIs

• Servlet support defined by specification

• Filters are part of the spec

• Consist of get and post methods for requests


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History: Applets

Applets

• Not part of the J2EE framework

• Web-deliverable applications

• Run on client

• Problems

– Require correct JVM on client

– Difficult to write and change

– Presentation and logic combined


22

Servlets: JSP

Java Server Pages• Interactive web pages

– <jsp:include page=“/docs/footer.html”/>

– <h2><bean:write property="pageTitle“ name="swfForm"/></h2>

– <% String tempUrl = “http://www.rpi.edu”; %>

• Extension of Servlet technology

• Similar to ASP

• Standard Tag Libraries available– Struts:

• MVC framework

• Industry standard

• Extensible– Can define and implement tag libraries

– Used by numerous vendors, including ColdFusion MX


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Servlets: Filters

Filters

• Transform HTTP requests and responses

filter servlet

request requestrequest

responseresponseresponse


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XSLTstylesheet

Servlets: Filters

Filter Example: The Kiosk

Kiosk

request

XMLXHTML

response

browser


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Examples

Example Applications

• The Kiosk Clones

• Web Forms

• RCS User Profile Manager

• Conference Site Management


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Example: The Kiosk

• Departmental news service

• Role-based content management

• Proof of concept


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Example: The Kiosk

ServletsJSP/XML/XSLT

SessionBeans

EntityBeans

articlearticle

categorycategory

get articleget articleclient view

admin view

restorerestore

utility


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Kiosk Clones

http://j2ee.rpi.edu/helpdesk http://j2ee.rpi.edu/kiosk

http://www.va.rpi.edu

http://www.eng.rpi.edu/frame_news.html


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Example: Web Forms

• Process html & pdf web forms

• Generate email while hiding recipient email addresses from web

• Attach files

• Save values in DB

• Skin switching

• Generated by admin tool or externally


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Example: Web Forms


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ServletsJSP/XML/XSLT

SessionBeans

EntityBeans

MessageDriven Beans

Example: Web Forms

client view

admin view

• Form Defs• Form Values• Attachments

mail.rpi.edu

utility

submitsubmit

message queue

message queue

sendmailsendmail


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Example: RCS Profile Manager

• Billing information

• Passwords

• Web mail quota

• Disk usage

• Library passwords

• EZ-Snapshot usage

• General Info

• More to come


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Example: Conference Site

• Self registration

To come:

• Credit-card payment

• Integrated forums

• More user management

• Events scheduling

• News posting


34

Vendor Solutions

Purchased Applications

• Many vendors build in the J2EE paradigm

• Can deploy on the same application server

• Example: Jive Forums

– Servlet application– http://www.jivesoftware.com

– http://jiveforums.rpi.edu:8080/jive


35

Future Directions

Current & Future Projects

• Web Services

• Calendar Systems

• Directory

• File Services


36

Thank you

References and Useful Links• J2EE:

– http://java.sun.com/j2ee/

– http://java.sun.com/j2ee/j2ee_guide.pdf

• JBoss:

– http://www.jboss.org

• Development Tools:

– http://jakarta.apache.org

– http://www.w3.org

• IBM & Grid Computing:

– http://www.javaworld.com/javaworld/jw-09-2002/jw-0906-grid_p.html

• Oracle & Banner:

– http://www.oracle.com/ip/deploy/ias/

– http://technet.oracle.com/oramag/webcolumns/2003/opinion/otn_forms.html

– http://www.sct.com/Education/Products/Solutions/EsTechOracle.html

• Our J2EE presentations:

– http://www.rpi.edu/dept/cct/public/j2ee/

Documents

The J2EE Framework 1 Introduction to Java 2 Enterprise Edition Presented by Communication & Collaboration Technologies Division of the Chief Information