Transformational design of an interactive component straddling communication streams
Journal of Computational Methods in Sciences and Engineering - Selected papers from the International Conference on Computer Science, Software Engineering, Information Technology, e-Business, and Applications, 2004
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The paper studies the systematic design and implementation of interactive components whose input interface is enriched by undo commands. An undo command inverts the interaction history returning to a previously visited state. We formalize different policies for undo commands cancelling the most recent input, the most recent occurrence of a specified input, and the final history segment after a user defined checkpoint. For each undo policy, we specify the component's modified input/output behaviour in terms of the original behaviour as a function from input streams to output streams. Then we systematically transform the modified input/output behaviour into an implementation by a state transition machine. The resulting formal method extends the state transition table of an interactive component in a systematic way when its input interface is enriched by undo commands under different policies.