Page 310 -

CHAPTER 11 ANALYSIS CONCEPTS AND PRINCIPLES 281

FIGURE 11.2
SafeHome SAFEHOME
off away stay
control panel
1 2 3
away
stay max test bypass
alarm instant 4 5 6
check bypass instant code chime
fire not ready
7 8 9
ready
armed power
* 0 #
panic

• What information does the actor desire from the system?
• Does the actor wish to be informed about unexpected changes?

In general, a use-case is simply a written narrative that describes the role of an actor
WebRef as interaction with the system occurs.
A detailed discussion of Recalling basic SafeHome requirements (Section 11.2.2), we can define three actors:
use-cases, including
examples, guidelines, and the homeowner (the user), sensors (devices attached to the system), and the moni-
templates is presented at toring and response subsystem (the central station that monitors SafeHome). For the
members.aol.com/ purposes of this example, we consider only the homeowner actor. The homeowner
acockburn/papers/
OnUseCases.htm interacts with the product in a number of different ways:
• enters a password to allow all other interactions
• inquires about the status of a security zone
• inquires about the status of a sensor
• presses the panic button in an emergency
• activates/deactivates the security system
A use-case for system activation follows:

1. The homeowner observes a prototype of the SafeHome control panel (Figure
11.2) to determine if the system is ready for input. If the system is not ready,
the homeowner must physically close windows/doors so that the ready indi-
cator is present. [A not ready indicator implies that a sensor is open; i.e., that
a door or window is open.]
2. The homeowner uses the keypad to key in a four-digit password. The pass-
word is compared with the valid password stored in the system. If the pass-
word is incorrect, the control panel will beep once and reset itself for