Systems Engineering with SysML/UML: Modeling, Analysis, Design

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Tim Weilkiens

"Systems Engineering with SysML/UML: Modeling, Analysis, Design"

198 CHAPTER 3 UML??”Unifi ed Modeling Language
4. A time event is further distinguished. A relative time event occurs when the
state from which the corresponding transition originates has been active
over a certain period of time (keyword after() ). An a
bsolute time
event occurs when the defi ned absolute time occurs (keyword at() ).
3.7.5 Initial and Final States
FIGURE 3-62
Examples for the types of events.
stm Example absolute time event (Time of day)
Day Night
at(sunset)/sleep()
stm Example relative time event (traffic light)
green red
after(2 minutes)
stm Example signal event (railroad crossing)
open block
Train(arrives)
stm Example change event (coffee percolator)
heat brew
[temp MAX]
stm Example call event
off on
switchOn()
Defi nition s
An initial state is a pseudostate with one outgoing transition that points to
the initial state.
A fi nal state is a state that describes the end of a composite state or a state
machine.
A state machine or a composite state has a beginning and generally one or several
defined ends.

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Tim Weilkiens

"Systems Engineering with SysML/UML: Modeling, Analysis, Design"