The World Wide Web

1
Chapter 3

• The World Wide Web

2
Topics

• Client-side interactivity
• Web information systems
• Role of cookie

3
Interactivity

• Early browsers limited to static pages
• Business need for
• Animation, sound, flashing logo
• Client side data input
• Need for client side interactivity

4
Data entry form
http//www.awl.com/search
5
Client-side Interactivity

• Scripts
• Macro-like instructions
• JavaScript, Jscript, VBScript
• Embedded in HTML stream
• Applet
• Small program executed within browser
• In HTML between ltappletgt tags
• Java

6
Some popular plug-ins

• Plug-in is software routine
• Process proprietary file formats
• Often available as free download

7
Web Information Systems

• Client-side interactivity
• Server-side interactivity
• Personalized marketing
• JIT inventory
• Inter- and intra-corporate communication

8
Multiple servers running on the same host
   
 

• Server is software

 
 
9
Multiple servers running on multiple
interconnected hosts

• Server is software!!

10
Security using firewalls

• Firewall protects
• Internal network
• from public network
• Runs on
• Router
• Host
• Server
• Workstation

11
Web Applications

• Applications that support a Web information
  system
• Client/server
• Browser on client side
• Server software on server side
• Middleware translates between
• HTML
• Non-Web server format

12
Middleware

• Server-side middleware links
• Web server
• Database server

13
Maintaining State

• The Web is stateless
• Each transaction is independent
• No problem for Web surfing
• Web information system is stateful
• Series of related transactions
• Must remember previous steps
• Cookies provide one solution

14
Shopping cart

• A cookie is the key to maintaining state

15
Initializing the shopping cart
Session data remembers server-side state.
Cookie remembers client-side state.
16
Changing contents of cart
Cookie points to session data
17
A personalized web page

• A cookie is the key to personal-ization

18
The e-commerce infrastructure