In our
case it ??™ s a time event that we denote by a symbolic hourglass symbol. An edge
2.4 Modeling Use Cases
FIGURE 2-58
The detail activity for ??? check usage right. ???
94 CHAPTER 2 The Pragmatic SYSMOD Approach
with a lightning arrow begins at the event and leaves the interruptible area. Things
continue at this point when the event occurs, at which time all fl ows within the
area terminate.
There is yet another particularity at the interruptible edge: It states how
likely it is that the fl ow will take this path. This construct is not specifi c to interruptible
areas. It is an extension of SysML that can also be denoted, e.g., at outgoing
edges.
You can see the entire fl ow of the use case start car usage in Figure 2.59 . One
particularity I haven ??™ t mentioned yet is the step start car usage . Similar to the
symbol used for sending a signal, you can see here the symbol for receiving of a
signal. This step hides the key removal. We can model it as a signal. This step waits
until the customer has removed the key from the holder, which is perceived as a
signal by our system.
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