The fl ow outgoing
from the initial node sends a signal, status display . There upon, this fl ow
visits the step request usage right . All start conditions for the step are now met,
and customer and car objects can be consumed.
The activity is regularly terminated with an outgoing usage authorization
when the outgoing activity parameter is reached. However, no usage authorization
can be returned if the fl ow reaches the activity fi nal node. Since outgoing activity
parameters must not be empty at the end of the activity, we place a so-called null
token into the parameter. The two possible results??” usage authorized and usage
not authorized ??”are taken into account in the calling activity, start car usage , in
the subsequent decision ( Figure 2.62 ).
In closing this section, let ??™ s have a look at the fl ow of another use case that
introduces a new and important aspect. Show car usage data is a continuous use
case. SysML extends the UML activity model by properties for modeling continuous
systems. You can see several new SysML elements modeled in Figure 2.
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