46 . Alternative 1 involves the same number of steps as
2.4 Modeling Use Cases
FIGURE 2-43
Pragmatic fl ow description for ??? start car usage. ???
Pragmatic description
Apply customer card
Read card
Send SMS to reservation center
Receive SMS reply
Check usage right
Unlock car doors via central locking system
Poll PIN
Enter PIN
Verify PIN
Deactivate electronic drive-away protection
Remove key
Display customer welcome message
78 CHAPTER 2 The Pragmatic SYSMOD Approach
our solution. Taking a closer look reveals, however, that the steps are formulated
in more concrete terms. For example, the last step is remove key rather than start
car usage .
The phrase remove key is undoubtedly catchier. But it doesn ??™ t follow the pure
theory of an essence since it includes a technical detail: the key. I recently rented a
FIGURE 2-44
Essential fl ow description for ??? start car usage. ???
Pragmatic description Essential description
Apply customer card
Read card
Send SMS to reservation center
Receive SMS reply
Check usage right
Unlock car doors via central locking system
Poll PIN
Enter PIN
Verify PIN
Deactivate electronic drive-away protection
Remove key
Display customer welcome message
Identify customer
Check usage right
Unlock car
Check disposal right
Start car usage
Confirm usage start
FIGURE 2-45
The essence of ??? starting car usage ??? as a comment in the model.
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