FIGURE 3-58
Example for state behavior.
stm Railroad crossing
closed
open
do/open()
exit/blink(off)
release
do/close()
entry/blink(on)
block
endPosition(down) train(leaves)
endPosition(up) train(arrives)
195
A system can also have several states concurrently. When looking out of
the window now I fi nd not only that it is afternoon, but also that it is a warm
afternoon. To map this on a state machine, we need a so-called orthogonal state.
An orthogonal state is divided into an arbitrary number of independent regions,
which are each separated from the others by a dashed line. In Figure 3.60 , the
state Day (with the substate afternoon ) and the state warm can now be active at
the same time.
3.7.3 Transition
3.7 The State Machine Diagram
FIGURE 3-59
Example for a state detailing.
stm Time of day
stm Day
Day
afternoon
morning
noon
Day Night
at(sunset)/goToSleep()
at(sunrise)/getUp()
Terminate
Defi nition
A transition specifies a state transition. It is a directed relationship between
two states, and defines a trigger and a condition that both lead to the state transition,
as well as a behavior that is executed during the transition.
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