In the design, e.g.,
we model a signal called KeySignal , which describes the communication object
that the on-board computer control receives from the key holder. In the system
context model the signal is represented by the information key ( Figure 2.25 ).
Altogether we obtain traceability of this fact in the model.
Alternatively, you can tackle this matter much more directly. SysML extends the
UML information fl ow by a property you can use to transport concrete objects rather
than abstract information. These objects are described in more detail and they can
2.3 Modeling the System Context
FIGURE 2-23
System context with information fl ow.
bdd [package] System context [with information flow]
?«system?»
On-board computer
Car management
system
Customer
Card data,
user input,
key
Reservation
system
Usage right
Car movement
data
Mileage
Central locking
system
Car
commands
Car
commands
Car drive-away
protection
Billing system
Usage data
Car service employee
Configuration
Car ignition
Engine off
Temperature
Battery
Current
Status
?«flow?»
Car
Vibration
Configuration Windshield
58 CHAPTER 2 The Pragmatic SYSMOD Approach
be present in this form directly in the design models.
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