72 ).
The customer is informed about the state of the on-board computer by means
of light-emitting diodes over the same interaction point. This is a message from the
system to an actor, i.e., a service requested by the system from a customer. The
customer is expected to understand this message. The service is also described
by an interface. The fact that the service is requested is denoted by the compact
socket notation ( ??? grabber ??? symbol) at the standard port.
In this way we proceed message by message across our interactions between
the system and its actors. You can see our result from the sequence diagram from
Figure 2.71 in Figure 2.72 . Only the interfaces of the CardReaderPort are shown
in detail. However, the entire picture remains the same: An interface contains only
one operation, or an incoming signal. This is not the normal case, but only the
FIGURE 2-72
System interfaces of our on-board computer.
bdd [package] On-board computer context [interfaces start car usage]
bdd [package] Interfaces [CardReaderPort]
IUsageRight IReservationSystem
ServerPort
ICar
CarControlPort
CarPort:Vibration
ICustomer
IStatusDisplay
CardReaderPort
IInput
IOutput IKey
IOPort KeyPort
?«system?»
On-board computer
?«interface?»
IStatusDisplay
?«interface?»
ICustomer
?«enumeration?»
Color
?«signal?» SigLED(f:Color, blinking:Boolean) Apply card
red
yellow
green
116 CHAPTER 2 The Pragmatic SYSMOD Approach
result at the beginning of our modeling work.
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