A01 chaf6542 06 se fm indd

 Three-  tier 

 client–  server

The first tier is the client 

that handles display, 

second is application 

logic and business rules, 

third is database storage.

Thin client

An   end-  user  access 

device (terminal) where 

computing requirements 

such as processing and 

storage (and so cost), are 

minimised.

Figure 11.7

 Three-  tier   client–  server  in  a  digital  business  environment

Web browser

Applications

server

Database

server

Tier 1

Tier 2

Tier 3

Internet

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Part 3  Implementation

Since digital business systems are often  customer-   or  employee-  facing systems, the impor-

tance of  human–  computer interaction in the design of web applications is high. Referring to 

website design, Nigel Bevan says:

Unless a web site meets the needs of the intended users it will not meet the needs of the 

organization providing the web site. Web site development should be  user-  centred, evalu-

ating the evolving design against user requirements. (Bevan, 1999a)

Noyes and Baber (1999) explain that