Information Technology Reference
In-Depth Information
Figure 13.1
A Sequence Diagram to Add a
New KayakItem Scenario
KayakItem
Kayak rental clerk
create( )
getID
ID
getDatePurchased
datePurchased
You read a sequence diagram starting at the top and moving down.
1. The Create arrow at the top is a message from the kayak rental clerk to the KayakItem
object to create information on a new kayak to be placed into the rental program.
2. The KayakItem object knows that it needs the ID for the kayak and sends a message to
the clerk requesting the information. See the getID arrow.
3. The clerk then types the ID into the computer. This is shown with the ID arrow. The
data is stored in the KayakItem object.
4. Next, KayakItem requests the purchase date. This is shown in the getDatePurchased
arrow.
5. Finally, the clerk types the purchase date into the computer. The data is also transferred
to KayakItem object. This is shown in the datePurchased arrow at the bottom of
Figure 13.1.
This scenario is only one example of a sequence of events. Other scenarios might include
entering information about life jackets, paddles, suntan lotion, and other accessories. The
same types of use case and generalization/specialization hierarchy diagrams discussed in
Chapter 12 can be created for each event, and additional sequence diagrams will also be
needed.
Interface Design and Controls
Some special system characteristics should be considered during both logical and physical
design. These characteristics relate to how users access and interact with the system, including
sign-on procedures, interactive processing, and interactive dialogue.
•
sign-on procedure
Identification numbers, passwords,
and other safeguards needed for
someone to gain access to computer
resources.
A
sign-on procedure
consists of identification numbers, passwords, and other safeguards
needed for someone to gain access to computer resources. The new system or modified
IS worker for a large U.S. company operating in India was caught stealing about 4,000
sensitive corporate documents using the identification number and password of another
employee. See Figure 13.2.
