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chaPter 7 • Using Data Flow Diagrams 201

Figure 7.21

1 Partitioning is important for
Dates and Web-based systems, as this
Airports physical data flow diagram of an
Customer Select Flight D1 Flight
Days and online ticket purchasing system
Airports demonstrates.

Email E-Ticket Available
Confirmation Dates and Flights
Airport Codes Screen

8 2

Produce Display D2 Flight Details Airline
Customer Available Available
E-Ticket Flights Flight
Details

Flight Price
and Availability

Available Flight Details
4 3
Selected Flight and Seat Information
Flight Select Select
Information Available Flights
Seats Seat Selection Selected Flight

Flight
Selection

5 Credit Rejection
Customer Record
D3 Customer Master
Customer Customer
Flight Reservation Book Information
D5 Flight Reservation Flight
Flight Information

Credit Card Credit
Information Confirmation

Credit Card
7 6
Flight Information
Purchase Credit
Airline Update Charge Card
Airline Customer Credit Status System
Flights Credit Card

either use separate web pages or use Ajax to facilitate a change in a drop-down list or to change
a small amount of data.
A good example of partitioning can be seen in the development of a Web-based travel book-
ing site. To simplify, we will only look at the airline booking portion of the website, shown in
the data flow diagram in Figure 7.21. Notice that the Web designer has chosen to create several