Post on 07-Apr-2018
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
8/3/2019 JSP and Servlets in J2EE [ Sun Microsystems Presentation ]
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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
8/3/2019 JSP and Servlets in J2EE [ Sun Microsystems Presentation ]
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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