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Fig. 6. Statechart of the Elevator Control System
Weaving of Time-Aspect
The time aspect can be woven into the real time system by using the UML's state-
charts, as statecharts refine the model. Libraries of core and time aspect statecharts
can be developed concurrently and independently, and combined only when needed
for a particular application.
In this paper, we weave the time aspect with high-level declarations about how an
event in the time statechart can be treated like a completely different event in the core
statechart. The weaving framework permits statecharts design to be translated into
skeleton code for a class. The time aspect and core statecharts objects may be joined
to create orthogonal regions. In addition, the time aspect statechart can be woven by
specifying which events shall be reinterpreted to have meaning in other statechart .
The declarations of events reinterpretation of the elevator example can be described
as follows according to the timing constraints:
 If the core statechart is in the 'ElevatorStopping' state and a 'openDoor' event
is introduced, and if the time aspect statechart is in the state 'InitState' satisfy-
ing 't>=Min_Time&&t<=Max_Time'. Then the time aspect statechart
transfers to the 'Normal' state, the core statechart treats the 'openDoor' event
exactly and transfers to the 'DoorOpening' state.
 If the core statechart is in the 'DoorOpening' state and a 'closeDoor' event is
introduced, and if the time aspect statechart is in the state 'InitState' satisfying
' t>=Min_Time '. Then the time aspect statechart transfers to the 'Normal' state,