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Annex 1  
5.8.2.2 Statecharts (STC)  

  Statecharts (STC)

Contents  
  • 1 Identification/Definition of the Method
  • 2 Brief Characteristic of the Method
  • 3 Appraisal of the Method
  • 4 Application of the Method in the V-Model
  • 5 Interfaces
  • 6 Further Information
  • 7 Literature
  • 1 Identification/Definition of the Method

    /Harel, 1987/

    2 Brief Characteristic of the Method

    Statecharts (STCs) are a method applied for the specification of reactive systems (see /Seifert, 1991/), i. e. of systems that must react to external and internal events in real-time. The method is based on an upgrade of the notation of finite automata suggested in /Harel, 1987/. Event-oriented (sub-) systems are modeled by means of STCs; they may be in combined, nested states-subautomata nested accordingly-and which may have concurrently processing components. STCs are practically oriented on engineering requirements.

    3 Appraisal of the Method

    The STC strong points are:

    Peculiarities to be taken into consideration when modeling with STCs:

    Method Familiarization

    4 Application of the Method in the V-Model

    The method is utilized in SD1.5 - User-Level System Structure and SD3.3 - Definition of Requirements for the Functionality to model the courses of functions.

    For systems with a high criticality, only causal logical synchronizing and lock mechanisms can usually be accepted, i. e. they have to be specified in the state model, independent of temporal aspects.

    5 Interfaces

    In the method allocation (submodel SD), the modeling aspect is most important. Explicit assessment or verification steps are controlled by submodel QA. In this connection, particularly SIMU - Simulation Models is considered as subsequent method for STC. The behavior model generated by STC can be systematically assessed and verified by means of the simulation.

    6 Further Information

    Published versions of the method are not known. Under certain conditions, STCs can be imaged on so-called structured Petri Nets (S-nets) and afterwards analyzed by means of the network theory.

    Tool support is absolutely required in order to reconstruct and comprehend the specification of larger systems. So far, one tool is known in connection with the method.

    7 Literature

    /Harel, 1987/ Reference publication of the developer of Statecharts, suited for the introduction, with examples
    /Seifert, 1991/ Additional description of the method
    /SEMSTC, 1990/ Precise and valid description of the semantics of statecharts

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