Web Applications

1
Web Applications

• Harry R. Erwin, PhD
• University of Sunderland
• CIT304/CSE301

2
Resources

• Hans Bergsten, 2002, JavaServer Pages, 2nd
  edition, OReilly, ISBN 0-596-00317-X
• http//java.sun.com/products/jsp/
• http//www.apl.jhu.edu/hall/java/Servlet-Tutorial
  /
• Farley, et al., 2002, Java Enterprise in a
  Nutshell, 2nd edition, OReilly, ISBN
  0-596-00152-5
• Brittain and Darwin, 2003, Tomcat the Definitive
  Guide, OReilly.
• Kurniawan and Deck, 2004, How Tomcat Works,
  BrainySoftware.com.
• Knuckles and Yuen, 2005, Web Applications
  Concepts and Real World Design, Wiley.
• Nakhimovsky and Myers, 2004, Google, Amazon and
  Beyond, Apress.

3
What is a Web Application?

• According to Wikipedia
• In software engineering, a Web application or
  webapp is an application that is accessed with a
  Web browser over a network such as the Internet
  or an intranet.
• Web applications are popular due to the ubiquity
  of the browser as a thin client.
• The ability to update and maintain Web
  applications without distributing and installing
  software on client computers is a key reason for
  their popularity.
• Web applications are used to implement webmail,
  online retail sales, online auctions, wikis,
  discussion boards, Weblogs, MMORPGs and many
  other functions.

4
W3C Comments

• Many developers are using the Web as a
  platform-independent application environment.
• Examples of Web applications include reservation
  systems, online shopping or auction sites, games,
  multimedia applications, calendars, maps, chat
  applications, clocks, interactive design
  applications, stock tickers, currency converters
  and data entry/display systems.
• A number of different proprietary and
  platform-specific technologies have targeted
  application development on the Web.
• Should standards be defined to ease this?

5
Typical Web Applications (W3C)

• Web applications typically have some form of
  programmatic control, either on the client, on
  the server or a combination of both.
• A Web application is typically downloaded on
  demand each time it is "executed", allowing a
  developer to update the application for all users
  when needed.
• Web applications are usually smaller than regular
  desktop applications, and can have rich graphical
  interactive interfaces.

6
Questions To Consider (W3C)

• What functionality is needed for Web
  applications?
• What should the hosting environment provide?
• How much of a Web application should be
  declarative?
• How much should be in script?
• How are webapps related to Web documents, which
  are normally static?

7
User Interface Issues (W3C)

• Is there a need for a standard set of user
  interface controls?
• Should these controls use the native platform
  look and feel?
• What APIs are needed for Web applications (eg.
  retrieving and sending data over the network,
  parsing XML, client-side storage)?

8
Packaging Questions (W3C)

• How should a Web application and its related
  resources (e.g. images, sounds) be packaged?
• What security issues need to be addressed??
• To what extent can application behaviour be
  usefully abstracted from platform specific
  details of UI controls?
• How can the application integrate different
  modality interfaces (eg. voice, pen, keystrokes)?
  
• How to address richer models of interaction
  management that go beyond simple event handlers?

9
Struts as an Approach

• According to the website, Apache Struts is a free
  open-source framework for creating Java web
  applications.
• Web applications differ from conventional
  websites in that they can create a dynamic
  response. They can interact with databases and
  business logic engines to customize a response.
• Web applications based on JavaServer Pages often
  commingle database code, page design code, and
  control flow code. Unless these concerns are
  separated, larger applications become difficult
  to maintain.

10
What is Struts?

• The Struts framework is designed to help
  developers create web applications that utilize a
  Model-View-Controller (MVC) architecture.
• The framework provides three key components
• A "request" handler provided by the application
  developer that is mapped to a standard URI.
• A "response" handler that transfers control to
  another resource which completes the response.
• A tag library that helps developers create
  interactive form-based applications with server
  pages.
• Struts works well with conventional REST
  applications and with new technologies like SOAP
  and AJAX.

11
Topics to be Covered

• JSP1.pptbasics of server-side development.
• JSP2.pptJava Server Pages
• JSP3.pptScripting JSP
• JSP4.pptrunning Jakarta/Tomcat
• JSP5.pptIntroduction to Structs

12
Perspectives

• For students from the Business School, look at
  managing web application development and
  understanding the options available to you.
• For students from the School of Computing, we
  will discuss developing web applications.
• The tutorials are for people who want to explore
  further.