1. Web Applications

2. Contents: Introduction to web?
 What is web applications
 Components
 Web application interaction?
 Webservers?
 Examples of web servers?
 Website vs web servers?
 Web application deployments?
 Advantages of web application?
 Disadvantages of web applications?

3. Introduction to Web
• Web features
• Clent/Server
• HTTP
• HyperText Markup Language
• URL addresses
• Web server - a computer program that is
responsible for accepting HTTP requests from
clients and serving them HTTP responses
• Web application - a dynamic extension of a
web or application server

4. What is web application?
 Web applications run through a web browser like Internet
Explorer. The program sits on a web server, rather than on the
PC, or local server for traditional applications.
 On a basic website pages are static. Web application pages
interact with users requesting and responding to users
 . The most common example is online shopping application.
 Web applications typically use a database to store permanent
information such as product descriptions and costs, and
customer orders.
 Web Applications deliver many business benefits compared to
office based solutions.

5. Web Applications & Components• Two types of web applications:
• Presentation-oriented (HTML, XML pages)
• Service-oriented (Web services)
• Web components provide the dynamic extension capabilities for
a web server:
• Java servlets
• JSP pages
• Web service endpoints

6. Web Application Interaction• client sends an HTTP request to the web server
• web server HTTP request  HTTPServletRequest
• This object is delivered to a web component, which can interact
with JavaBeans or a DB to generate dynamic content
web component generates an HTTPServletResponse or pass the
request to another web component
• web server HTTPServletResponse  HTTP response
• web server returns HTTP response to the client

7. Web Application Interaction

8. Web Components• Servlets - Java classes that dynamically
process requests and construct responses
• JSP pages - text-based documents that
execute as servlets but allow a more natural
approach to creating static content
• Servlets - service-oriented applications, control
functions
• JSP - generating text-based markup
(HTML, SVG, WML, XML)

9. Java Web Application
Technologies
Java Servlet technology is the foundation of all
the web application technologies

10. What are web servers ?
• The software (the computer application) that helps to deliver
content that can be accessed through the Internet.
• The most common use of web servers is to host websites
• There are other uses such as gaming, data storage or
running enterprise applications.
• A web server serves web pages to clients across the Internet
or an Intranet. The web server hosts the pages, scripts,
programs, and multimedia files and serves them using HTTP, a
protocol designed to send files to web browsers and other
protocols.

11. What is a Web Server?Web Server is a computer with special software
to host the web pages And web applications.
Commonly used web server software
applications are
 Apache
 IIS

12. Web Site Vs Web Servers
 Web site – Collection of web pages
associated particular host name.
 Web Server – A program that satisfies the
client’s requests for web resources.

13. How Web Servers Work?

14. Example of Web Servers….
• Apache HTTP Server
-Developed by Apache software foundation.
- Supports most of the OS like Unix, Linux, Novell Netware,
Windows, Mac OS X, Solaris, and FreeBSD.
• Microsoft Internet Information Services (IIS)
- Supports only on Windows platform
• Sun Java System Web Server
- Web Server is designed for medium to large business
applications. Sun Java System Web Server is available for
most operating systems.

15. How it Works ….?

16. Web Containers• Web components are supported by the
services of a runtime platform called a web
container
• In J2EE, a web container "implements the web
component contract of the J2EE architecture“
• Web container services:
• request dispatching
• security
• concurrency
• life-cycle management

17. Web Container Examples• Non-commercial
• Apache Tomcat
• Jetty
• Commertial
• Sun Java System Application Server
• BEA WebLogic Server
• Oracle Application Server
• WebSphere
• Open source
• JBoss

18. Deployment• Web components have to be installed or deployed to the web
container
• Aspects of web application behaviour can be configured during
application deployment
• The configuration information is maintained in a XML file called a
web application deployment descriptor

19. Web Application Development• A web application consists of:
• Web components
• Static resource files (such as images)
• Helper classes and libraries
• The process for creating and running a web application is
different from that of traditional stand-alone Java classes

20. Advantage of web
applications???
 Zero install - all PCs have a browser
 Reduce business costs - less time spent talking to
customers over the phone; eliminate printed materials; allow
users to update their own details
 Centralised data is secure and easy to backup
 Quick and easy updates
 Reach anybody, anywhere in the world.
 Available 24 hours a day, 7 days a week
 Direct access to latest information - for Employees where
every they are located.
 Always up-to-date

21. Disadvantages of Web
Applications
 Slower, as run over the internet
 Internet not always 100% available
 Can take longer to develop as they are more complex
 Have to support different browsers, and different versions
 Security risks