To this end SysML
offers the sequence diagram, which the interaction model is based on. It weaves
elements together that we already have in our model??”the system and its actors
Table 2.18 Summary: Modeling system/actor interactions.
Reference card: Model system/actor interaction.
Incoming and outdoing data
System context:
System with actors.
Use cases:
Services provided by the system.
Interaction model [system/actor]:
Interactions between the system and
actors.
Motivation/description
Why? The system context and the use cases do not look at the interaction between
the system and its actors in detail, which can lead to faulty estimates of the usability
and system integration.
What? Describe the interactions between the system and its actors each with regard
to a use case.
How? The interaction between the system and its actors is described in a sequence
diagram for selected fl ow scenarios.
Where? The system/actor interaction supplies a template for the design, especially
with regard to defi ning the interfaces.
Guiding questions
?– What requests will the actors send to the system during a use case fl ow?
?– What requests will the system send to the actors during a use case fl ow?
?– Who will make which request when?
SysML elements
Sequence diagram, lifeline, message, interaction operator.
Pages:
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253