245 research outputs found

    Statecharting Petri nets

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    Statecharting Petri nets

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    Statechartable Petri nets

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    Semantics and Verification of UML Activity Diagrams for Workflow Modelling

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    This thesis defines a formal semantics for UML activity diagrams that is suitable for workflow modelling. The semantics allows verification of functional requirements using model checking. Since a workflow specification prescribes how a workflow system behaves, the semantics is defined and motivated in terms of workflow systems. As workflow systems are reactive and coordinate activities, the defined semantics reflects these aspects. In fact, two formal semantics are defined, which are completely different. Both semantics are defined directly in terms of activity diagrams and not by a mapping of activity diagrams to some existing formal notation. The requirements-level semantics, based on the Statemate semantics of statecharts, assumes that workflow systems are infinitely fast w.r.t. their environment and react immediately to input events (this assumption is called the perfect synchrony hypothesis). The implementation-level semantics, based on the UML semantics of statecharts, does not make this assumption. Due to the perfect synchrony hypothesis, the requirements-level semantics is unrealistic, but easy to use for verification. On the other hand, the implementation-level semantics is realistic, but difficult to use for verification. A class of activity diagrams and a class of functional requirements is identified for which the outcome of the verification does not depend upon the particular semantics being used, i.e., both semantics give the same result. For such activity diagrams and such functional requirements, the requirements-level semantics is as realistic as the implementation-level semantics, even though the requirements-level semantics makes the perfect synchrony hypothesis. The requirements-level semantics has been implemented in a verification tool. The tool interfaces with a model checker by translating an activity diagram into an input for a model checker according to the requirements-level semantics. The model checker checks the desired functional requirement against the input model. If the model checker returns a counterexample, the tool translates this counterexample back into the activity diagram by highlighting a path corresponding to the counterexample. The tool supports verification of workflow models that have event-driven behaviour, data, real time, and loops. Only model checkers supporting strong fairness model checking turn out to be useful. The feasibility of the approach is demonstrated by using the tool to verify some real-life workflow models

    Modeling Time in Computing: A Taxonomy and a Comparative Survey

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    The increasing relevance of areas such as real-time and embedded systems, pervasive computing, hybrid systems control, and biological and social systems modeling is bringing a growing attention to the temporal aspects of computing, not only in the computer science domain, but also in more traditional fields of engineering. This article surveys various approaches to the formal modeling and analysis of the temporal features of computer-based systems, with a level of detail that is suitable also for non-specialists. In doing so, it provides a unifying framework, rather than just a comprehensive list of formalisms. The paper first lays out some key dimensions along which the various formalisms can be evaluated and compared. Then, a significant sample of formalisms for time modeling in computing are presented and discussed according to these dimensions. The adopted perspective is, to some extent, historical, going from "traditional" models and formalisms to more modern ones.Comment: More typos fixe

    On UML statechart with variabilities

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    El uso de métodos formales para el diseño de software contribuye a la confiabilidad y robustez del sistema a construir. A medida que los sistemas se vuelven complejos, el enfoque formal es esencial, debido a que permite la demostrabilidad y verificabilidad del diseño. El diseño formal es un proceso que comienza con la etapa de especificación, en la cual el sistema es de nido utilizando un lenguaje de modelado; luego la etapa de verificación, en la cual el sistema es analizado mediante un enfoque de corrección basado en pruebas formales utilizando herramientas matemá ticas y, por último, la etapa de implementación, en la cual la especificación se convierte en código ejecutable. El Lenguaje de Modelado Unificado (UML por sus siglas en inglés) es un lenguaje específico ampliamente utilizado en la industria y la academia. Desafortunadamente, carece de una semántica formal que permita el desarrollo de modelos utilizando un enfoque de corrección basado en pruebas formales. Este trabajo se centra en la especificación formal de familias de sistemas, y, en particular, en la semán- tica de máquinas de estados de UML (UML Statecharts) con variabilidades y sus aplicaciones a líneas de productos de software. La principal contribución es la definición de un formalismo que permite modelar el comportamiento de una familia de sistemas. Tal comportamiento se describe utilizando UML Statecharts en combinación con Diagramas de funcionalidades (Feature Diagrams), con el fin de representar las funcionalidades comunes y variantes de una familia. Para ello se define una relación de orden entre los UML Statecharts, que representa el hecho de que un statechart posee una estructura mas rica que otro. Luego se defi ne con precisión la forma de combinar diferentes extensiones de un mismo statechart. Utilizando estos conceptos, es posible definir el efecto que cada funcionalidad tiene en los productos en los cuales se encuentra presente.Estas definiciones proporcionan una forma muy simple de obtener la especificación del comportamiento de un producto de la línea como la combinación de los UML Statecharts que implementan todas las funcionalidades presentes en un producto en particular. Mas aún, se prueba que la relación de extensión propuesta constituye un refinamiento de comportamiento. El presente enfoque se compara con el estado del arte y se estudia su aplicación práctica con el n de visualizar sus bene cios y posibles debilidades. Adicionalmente, con el fin de comprobar la adecuación de la propuesta, una gran parte de las ideas fueron implementadas en un prototipo utilizando Prolog

    Abstraction : a notion for reverse engineering.

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    A model driven approach to analysis and synthesis of sequence diagrams

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    Software design is a vital phase in a software development life cycle as it creates a blueprint for the implementation of the software. It is crucial that software designs are error-free since any unresolved design-errors could lead to costly implementation errors. To minimize these errors, the software community adopted the concept of modelling from various other engineering disciplines. Modelling provides a platform to create and share abstract or conceptual representations of the software system – leading to various modelling languages, among them Unified Modelling Language (UML) and Petri Nets. While Petri Nets strong mathematical capability allows various formal analyses to be performed on the models, UMLs user-friendly nature presented a more appealing platform for system designers. Using Multi Paradigm Modelling, this thesis presents an approach where system designers may have the best of both worlds; SD2PN, a model transformation that maps UML Sequence Diagrams into Petri Nets allows system designers to perform modelling in UML while still using Petri Nets to perform the analysis. Multi Paradigm Modelling also provided a platform for a well-established theory in Petri Nets – synthesis to be adopted into Sequence Diagram as a method of putting-together different Sequence Diagrams based on a set of techniques and algorithms

    Adapting modeling environments to domain specific interactions

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    Software tools are being used by experts in a variety of domains. There are numerous software modeling environments tailored to a specific domain expertise. However, there is no consistent approach to generically synthesize a product line of such modeling environments that also take into account the user interaction and experience adapted to the domain. The focus of my thesis is the proposal of a solution to explicitly model user interfaces and interaction of modeling environments so that they can be tailored to the habits and preferences of domain experts. We extend current model-driven engineering techniques that synthesize graphical modeling environments to also take interaction models into account. The formal semantics of our language framework is based on statecharts. We define a development process for generating such modeling environments to maximize reuse through a novel statechart refinement technique.Les outils logiciels sont utilisés par des experts dans une variété de domaines. Il existe de nombreux environnements de modélisation logicielle adaptés á une expertise spécifique. Cependant, il n’existe pas d’approche cohérente pour synthétiser génériquement une ligne de produits de tels environnements de modélisation qui prennent également en compte l’interaction et l’expérience utilisateur adaptées au domaine. L’objectif de ma thése est la proposition d’une solution pour modéliser explicitement les interfaces utilisateur et l’interaction des environnements de modélisation afin qu’ils puissent étre adaptés aux habitudes et aux préférences des experts du domaine. Nous étendons les techniques d’ingénierie actuelles pilotées par un modéle qui synthétisent des environnements de modélisation graphique pour prendre également en compte les modèles d’interaction. La sémantique formelle de notre cadre linguistique est basée sur des statecharts. Nous définissons un processus de développement pour générer de tels environnements de modélisation afin de maximiser la réutilisation à travers une nouveau technique de raffinement de statecharts
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