We now know the system environment (actors, information
fl ows) and the catalog of services, including essential descriptions (use cases).
Table 2.13 Summary: Modeling use case fl ows.
Reference card: Model use case fl ows.
Incoming and outgoing data
Requirements:
General requirements to the system
::Use cases [essential]:
Use cases with an essential step description
::Use cases [detailed]:
Detailed fl ow description, including
exceptions and variants.
Motivation/description
Why? The fl ow descriptions of use cases belong to the core information of our
requirements analysis. They provide a detailed view of the behavior required of the
system.
What? Describe the use case fl ows, including all exceptions and variants, in
appropriately detailed form.
How? The use case fl ows are described using SysML activities.
Where? The activities form a direct basis for the system design. Their clear
representation in the activity diagram allows you to have the principal deeply
involved in the system development process.
Guiding questions
?– What steps are required for the use case?
?– What exceptions and variants can occur during the fl ow?
?– Is the use case suffi ciently detailed and clearly described?
SysML elements
Activity diagram, activity, SYSMOD: essential/continuous activity, action, edge,
control node (e.
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