Note that both ?«nobuffer?» and ?«overwrite?» have the same meaning for data
that arrive continually ( ?«continuous?» ). It is important to know that these object
node properties are independent of the streaming property.
These stereotypes are denoted directly next to the pin, or above the name of
an activity parameter.
It is possible to model actions and activities with optional input and output
values (i.e., with optional pins or activity parameters).
Figure 4.55 shows the section of an extension from Figure 4.50 . With this
extension, we can now optionally display special messages.
4.8 The Activity Diagram
FIGURE 4-55
Example for using ?«optional?».
?«continuous?»
act Show car usage data [with special messages; section]
Show car
usage data
Car usage data
{stream}
Special message
?«optional?»
Special message
8 First In, First Out.
9 Last In, First Out.
264 CHAPTER 4 SysML??”The Systems Modeling Language
4.8.5 Probability
FIGURE 4-56
Example for probabilities.
Defi nition
A probability describes at an outgoing edge of a choice or an object node
how probably it is that this edge will be used by a token.
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