The design, implementation, integration and evaluation of a Statechart service.

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The design, implementation, integration and
evaluation of a Statechart service.
By Xin Bai Feb 7, 2002
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Why use statecharts?

1. Statechart extends the classical state transition
   diagram.
2. It saves the number of the state and arrow in the
   diagram.
3. Most importantly it supports concurrency.

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Backgrounds

1. David Harel invented this language in 1983.
2. The STATEMATE system by I-Logix Israel., Ltd. has
   implemented statechart language.

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Statecharts extend classical state transition
diagrams
State transition diagrams Statecharts
Depth, hierarchy or modularity support No Yes
Number of transition arrows Uneconomical Economical
Number of states Grow exponentially Economical
Concurrency Support No (sequential in nature) Yes
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From state transition diagrams to statecharts
States A, B, C, D Events e, f, g Condition c
D A XOR C gc triggers the transition from A
to C if and when g occurs, but only if c is true
at that time
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History entrance to a state overrides the default
arrow
A
e
B
H
f
D
C
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AND decomposition, actions and chain reaction
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Objectives

1. Design a textual expression for a simplified
   statechart just like blueprint.
2. Implement a statechart service so that users can
   use this textual expression to develop concurrent
   application.
3. Implement a sample application

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Literature

1. D. Harel, Statecharts A Visual Formalism for
   Complex Systems, Science of Computer Programming
   8 (1987), pp. 231-274
2. D. Harel, A. Pnueli, J.P. Schmidt, and R.
   Sherman, On the Formal Semantics of Statecharts,
   in Proc. 2nd Symp. on Logic in Computer Science
   (LICS 87), pages 54-64. IEEE Computer Society
   Press, 1987

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Thank you!