8/3/2019 JSP and Servlets in J2EE [ Sun Microsystems Presentation ]

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Slide 1

JSP and Servlets in J2EE

Danny CowardJava Servlet specification lead,

Sun Microsystems

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Slide 2 Sun Microsystems Inc 

Agenda

" The role of JSPs and Servlets in the J2EEplatform

" Why and when to use JSPs and Servlets inJ2EE platform

" A particular example" Conclusion

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Slide 3 Sun Microsystems Inc 

Multi-Tiered Enteprise Apps

Application

PureHTML Web Server

XML

J2EE PlatformBrowser

JSP

Servlet

EJB

EJB

EJB

EnterpriseInformation

Systems

JavaApplication

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Slide 4 Sun Microsystems Inc 

Web Components in J2EE

" Web Components form the window to J2EE" Allows web layer to focus on what its good

at - presentation" Allows reuse of business logic elsewhere"

Allows scalability

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Slide 5 Sun Microsystems Inc 

J2EE Services

" Security" Naming" Database" Transactions"

Enterprise Java Beans (EJB)" JavaMail

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Slide 6 Sun Microsystems Inc 

Migrate or not ?

" If you want to make your business logicre-usable to other parts of the organisation

" If you want to take advantage of a secure,robust, transactional infrastructure

"If you want to connect into an interoperableenvironment and access InformationSystems

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Slide 7 Sun Microsystems Inc 

How to Migrate

" Separate semantics within a web application" Use JSP and Servlet components as

presentation layer for data" Move business logic out of web components

into separate components e.g. Tag Libraries" Migrate business logic to EJB

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Slide 8 Sun Microsystems Inc 

Interaction with EJB: Example

" Example: Online music store" Web front end, with functionality to:-

" Browse catalog

" Sign in

" Make purchases using 'shopping cart'

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Slide 9 Sun Microsystems Inc 

Example application contents:-

" Web Layer:-" Static content

" Catalog browsing JSPs" Checkout form Servlet

" EJB layer" Catalog entity bean" Shopping cart session bean" Account entity bean

"

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Slide 10 Sun Microsystems Inc 

Code example: Checkout Servlet

import javax.naming.*; 

 // create JNDI initial context

Context context = new InitialContext();

 // lookup EJB Home

Object objref = context.lookup("java:comp/env/AccountEJB");

HelloHome hello =

PortableRemoteObject.narrow(objref, HelloHome.class);

Hello ejb = hello.create();

servletOutput.println("<bold>You ordered " +

ejb.getOrderCount() + " CDs today.</bold>");

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Slide 11Sun Microsystems Inc 

Resources

" www.java.sun.com/j2ee" J2EE Reference Implementation

" Samples

" APM" Best practices document

" Example application

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Slide 12 Sun Microsystems Inc 

Summary

" The web layer is the window into J2EE