Page 253 - Using MIS

Q3 How Does the Cloud Work? 221

Instructions
and Data

Commerce Other
Server
Commerce Applications
Other
Server
Commerce
..... Other
Web Browsers Application Applications
..... Other
Commerce
Server
Web Browsers Application Applications
Web Server
Server
.....
Web Browsers Application Applications
(Apache, IIS)
Web Server
Web Browsers Application ..... DBMS
Web Browsers (Apache, IIS) DB
Web Server
Web Server
(Apache, IIS)
html
via http (Apache, IIS)
Figure 6-10 User Computers Web Server Computers DBMS Computer
Three-Tier (User Tier) (Server Tier) (Database Tier)
Architecture
server. It passes requests for other applications to those applications. In Figure 6-10, the server-
tier computers are running a Web server program, a commerce server application, and other
applications having an unspecified purpose.
Watch the Three Tiers in Action!
Suppose the user of the Web page in Figure 6-9 clicks on shoes and then selects a particular
shoe, say the Darkish Gray Dorine Mary Jane shoe. When the user clicks on that shoe, the com-
merce server requests that shoe’s data from the DBMS, which reads it from the database and
then returns the data (including pictures) to the commerce server. That server then formats the
Web page with the data and sends the html version of that page to the user’s computer. The re-
sult is the page shown in Figure 6-11.

Figure 6-11
Product Page
Source: Reprinted by permission of
zulily. www.zulily.com