What? Use cases are identifi ed and allocated to the participating system actors.
How? Use cases are elaborated systematically based on the requirements and the
system context.
Where? Use cases are completed with a fl ow description and then serve as a starting
point for deriving the design.
Guiding questions
?– What can the system do for a specifi c actor?
?– What incoming information is at the beginning of a fl ow?
?– What services does each of the actors require from the system?
?– What results do the services supply to the actors?
?– Is the use case described from the actors ??™ view?
SysML elements
Use case diagram, package diagram, use case (SYSMOD: continuous use case),
actor, package, requirement, association, information fl ow, refi ne relationship.
Identify use
cases
Use cases
Requirements
System context
68 CHAPTER 2 The Pragmatic SYSMOD Approach
sentence in the form ??? actor wants use case ??? must sound meaningful. For
example, ??? customer wants to buy soft drink. ??? From the system ??™ s view, a sentence
like ??? system wants to buy soft drink ??? doesn ??™ t make sense.
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