Internet Applications

1
Internet Applications

• Notes for Chapter 19
• Digital Domain, 2 ed

2
E-Commerce

• E-Commerce is rapidly emerging as an essential
  business strategy
• E-Commerce has the following components
• Web interface on the client side
• backend databases on the server side
• scripts to enable the interaction of these two

3
Client-Side Scripting in E-Commerce

• Resides on the client machine (downloaded with
  the Web interface)
• Creates client interactivity
• Collects data from the user
• Does preliminary analysis and validation on
  user-supplied data
• Sends validated data to the server

4
Server-Side Scripting in E-Commerce

• Resides on the server
• Accepts data from the client
• Uses that data to
• search backend databases
• write to databases
• initiate credit card processes, etc.
• Returns response data to the client

5
Client-Side Processing and DHTML

• Dynamic HTML (DHTML) is
• a collection of technologies to make client-side
  interactions better and more interactive
• is a bit of a misnomer it is not an extension
  of HTML
• DHTML is not standardized
• different browser companies compete with their
  own DHTML features
• as long as the browser wars persist, DHTML is
  unlikely to be standardized
• Two important components of DHTML
• CSS (cascading style sheets)
• client-side scripting

6
Cascading Style Sheets (CSS)

• Define styles for formatting and displaying
  information
• provides for better Web site internal consistency
• makes Web site style modifications much easier
• Three types of CSS
• inline
• embedded
• external
• applied with precedence inline-gtembedded-gtexterna
  l

7
Client-Side Scripting and Forms

• Scripting works hand-in-hand with HTML forms
• HTML forms have built-in mechanisms for
  soliciting and collecting user data
• Forms are a part of standard HTML
• Client-side scripts are used to take action on
  the data collected before sending it to the
  server
• Such scripts are invoked using the onSubmit event
  handler

8
Server-Side Scripting

• Accepts data from client
• Often written in
• CGI (Common Gateway Interface)
• actually an interface rather than a scripting
  language
• can be written in a number of different scripting
  languages
• PHP HyperText Preprocessor
• ASP (Active Server Pages Microsoft)

9
Java Programming

• Java is an object-oriented full-purpose (as
  opposed to scripting only) programming language
• Java is noted for its excellent cross-platform
  capability
• accomplished by first compiling into bytecodes
• bytecodes are machine-independent
• a given machines Java RTE (Runtime Environment)
  then interprets the bytecodes into the
  appropriate machine language at run-time
• Java applets are small Java programs designed
  specially for the Web

10
XML (eXtensible Markup Language)

• XML is a very flexible language designed to
  facilitate exchange of information across the Web
• It is actually a meta-language that allows the
  creation of domain specific markup languages
• HTML is but one example of a language that could
  be created with XML
• Languages especially designed for the exchange of
  financial information, medical information,
  graphical information, and mathematics are other
  examples of existing XML specifications

11
Summary

• E-Commerce is rapidly emerging as an essential
  business strategy
• E-Commerce has the following components
• Web interface on the client side
• backend databases on the server side
• scripts to enable the interaction of these two
• Client-side scripts
• create client interactivity
• collect data from the user
• send data to the server
• Server-side scripts
• accept data from the client
• use that data to access backend databases or
  other server resources
• return response data to the client

12
Summary (contd)

• Dynamic HTML (DHTML) is
• a collection of technologies to improve
  client-side interactivity and Web site usability
• two important components of DHTML
• CSS (cascading style sheets)
• client-side scripting
• scripting works hand-in-hand with HTML forms
• Java is an object-oriented full-purpose (as
  opposed to scripting only) programming language
• Java applets are small Java programs designed
  specially for the Web

13
Summary (contd)

• XML is a meta-language that allows the creation
  of domain specific markup languages
• It is designed to facilitate exchange of
  information across the Web