Middleware Technology (J2EE/EJB)
February 2011
Course Information
• Lecturer: 尹皓
• Contact:
– yinhao@scu.edu.cn, 13551277539
• Course website:
– http://swjx.scu.edu.cn/moodle
• TA: 石丹
• Contact:
– standing06@yahoo.com.cn, 13541298431
– QQ:284451824
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Contents
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JSP/Servlet
EJB Fundamentals
Java RMI & Message Service
EJB 2.1
EJB 3.0
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Assessment
• 70% Final Examination
• 20% Project Presentation
• 10% On-class Practice
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Your Role – Learning With Doing
• Attend all lectures
• Work out the exercise on your own or after a
discussion with your group, don’t make copy
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You end up learning more in less
time when you are actually doing
stuff instead of just reading.
Reference Book & Course Material
• Mastering EJB 3.0 Rima Patel Sriganesh, Gerald Brose,
and Micah Silverman, Wiley Publishing, Inc. 2006
• JBoss EJB3.0 Tutorial
• http://java.sun.com (Oracle)
• http://java.sun.com/docs/books/tutorial/
• http://www-900.ibm.com/developerWorks/cn (IBM
WebSphere)
• BEA WebLogic
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Application realm
• Java technology could be used in the following fields:
Website, Electronic Business, Mobile Business, Grid
Computing, Game, etc.
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1. Overview
• Now a typical business application is a distributed system,we
should break up a monolithic application into a distributed system
with multiple clients connecting to multiple servers and database
over network.
• What should we think about according to the above scheme?
 Remote method invocation
 Load balance
 Back-end integration
 Transaction
 Clustering
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The motivation for EJB
• In the past, most companies built their own middleware.
• These days, rather than build them yourself, you could buy these
middleware services because of the appearance of application
server (standard).
Application servers provide you with common middleware services,
such as resource pooling (database, socket), network, transaction,
security, and more.
• We build our application out of components.
Components are not entire applications, they can not run alone.
• A company can purchase a well-defined module that solve a
problem and combine it with other components to solve larger
problem.
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The motivation for EJB
• An example – a pricing component
Different customers can reuse a generic component provided by the
same vendor.
• The advantages of reusing components
 The IT shop needs less in-house expertise
 The application is assembled faster
 There is a lower total cost of ownership
• Therefore we need a standard between application servers and
components. This will allow components to be switched in and out
of various application servers without having to change code or
potentially even recompile the components.
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Thin-Client Multi-tier Application
Web Browser
HTML Page
Tier 1:
Client Tier
Network
Web Server
(Thin-Client
Servlet)
Tier 2:
Web Tier
Network
Enterprise Beans
Application
Server
Tier 3:
Business Tier
Network
Database
Server
Tier 4:
EIS Tier (Enterprise Information System)
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Introducing EJB
• Enterprise JavaBean(EJB) is a server-side component
architecture.(different from Java Beans)
• Scalable、reliable 、secure application (thin client)
• Rapid application development for server-side
• EJB Standard is a component architecture for deployable serverside components in Java
• Specification、interface
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Top three values of EJB
• It is agreed upon by industry. (“Train once, code anywhere”)
• Portability is easier. EJB specification is published and available
freely to all. (java.sun.com)
• Rapid application development.
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Why Java
• EJB components must be written in Java only. (restriction)
• Interface/Implementation separation (JDBC)
• Safe and secure (no pointers/automatic garbage collection)
• Cross platform (windows/Unix)
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What EJB can do
• Performing business logic (back end)
• Access a database (JDBC)
• Access another system (JCA: Java Connector Architecture)
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EJB Ecosystem(6 roles)
• The Bean Provider (Application Component Provider)
• The Application Assembler (Application Assembler)
create a .ear file
• The EJB Deployer (Deployer)
deploy transaction and security, etc.
• The System Administrator (System Administrator)
monitoring the runtime environment (Log Analyzer、Resource
Analyzer)
• The Container and Server Provider (J2EE Product Provider)
IBM’s WebSphere、BEA’s WebLogic、Macromedia’s JRun
• The Tool Vendors (Tool Provider)
IBM’s Visual Age for Java (WSAD)、Borland’s JBuilder、
Oracle’s JDeveloper (IDE)
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J2EE Application
J2EE Application
Application
Client
Component
Web
Component
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EJB
Component
J2EE Application Files
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J2EE Application
J2EE Application Deployment Descriptor
.ear
.xml
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EJB Component
EJB Deployment Descriptor
EJB Class
Remote Interface
Home Interface
.jar
.xml
.class
.class
.class
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Web Component
Web Component Deployment Descriptor
JSP Files
Servlet Class
HTML Files
.war
.xml
.jsp
.class
.html
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J2EE Application Client
J2EE Application Client Deployment Descriptor
Java Application
.jar
.xml
.class
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J2EE Architecture
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Glossary
J2EE：Java 2 Platform, Enterprise Edition
SSL：Secure Sockets Layer
RMI：Remote Method Invocation
JMS：Java Message Service
JNDI：Java Naming and Directory Interface
JTA：Java Transaction API
JAF：JavaBeans Activation Framework
RMI/IIOP：RMI over IIOP
JDBC：Java Database Connectivity
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J2EE
• The Java 2 Platform, Enterprise Edition (J2EE)
Providing a platform-independent, portable, multi-user, secure and standard
enterprise-class platform for server-side deployment written in the Java
language.
• Three different Java platforms
 The Java 2 Platform, Micro Edition (J2ME)
A development platform for Java-enabled device (small devices)
 The Java 2 Platform, Standard Edition (J2SE)
JDK
 The Java 2 Platform, Enterprise Edition (J2EE)
A complete development platform for enterprise-class server-side
deployment in Java. J2EE builds on J2SE.
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Microsoft SQL Server JDBC
Java Platform
Grid project Globus Toolkit 3.0
Platforms
J2SDK
J2EE
J2ME
Core/Desktop
Enterprise/Server
Mobile/Wireless
Application,Applet,
Swing, Awt
JSP/Servlet, EJB
Midlet (Cell Phone/PDA)
Borland JBuilder,
JCreator, or Text
Editor
IBM WebSphere, WSAD
BEA WebLogic, Workshop
Sun One Studio
Oracle JDeveloper
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Nokia, Motorola,
Siemens SDK
JBuilder,Sun One
Studio
The J2EE Technologies (API)
• Enterprise JavaBeans (EJB)
• Java Remote Method Invocation (RMI) and RMI-IIOP
RMI-IIOP is an extension of RMI that can be used for CORBA integration. RMIIIOP is the official API used in J2EE (not RMI).
• Java Naming and Directory Interface (JNDI)
EJB components, Data Source and other resources across network
• Java Database Connectivity (JDBC)
accessing relational database
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The J2EE Technologies (API)
• Java Transaction API (JTA) and Java Transaction Services
(JTS)
Commit/Rollback, container management
• Java Messaging Service (JMS)
Message-Driven Bean, asynchronous invocation
• Java Servlets
Taking requests from some client host (such as a web browser) and
issue a response back to that host.
• Java Pages (JSPs)
The largest difference between JSP scripts and Servlets is that JSP
scripts are not pure Java code.
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The J2EE Technologies (API)
• Java IDL
Java-based implementation of CORBA.
• JavaMail
Allowing you to send email message in a platform-independent,
protocol-independent manner from your Java programs.
• J2EE Connector Architecture (JCA)
Handling transaction and security concerns.
• The Java API for XML Parsing (JAXP)
SAX/DOM
• The Java Authentication and Authorization Services (JAAS)
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