2,247 research outputs found

    Formal aspects of component software (FACS 2010 selected and extended papers)

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    This issue includes extended versions of selected best papers from the 7th International Workshop on Formal Aspects of Component Software (FACS 2010) held in Guimarães, Portugal on October 14–16, 2010. The component-based software development approach has emerged as a promising paradigm to cope with an ever increasing complexity of present-day software solutions by bringing sound production and engineering principles into software engineering. However, many conceptual and technological issues remain that challenge component-based software development theory and practice. To address these issues, FACS seeks to provide a forum for researchers and practitioners in the areas of component software and formal methods to foster a better understanding of the component-based paradigm and its applications as well as how formal methods can or should be used to make component-based software development succeed

    Adaptability Checking in Multi-Level Complex Systems

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    A hierarchical model for multi-level adaptive systems is built on two basic levels: a lower behavioural level B accounting for the actual behaviour of the system and an upper structural level S describing the adaptation dynamics of the system. The behavioural level is modelled as a state machine and the structural level as a higher-order system whose states have associated logical formulas (constraints) over observables of the behavioural level. S is used to capture the global and stable features of B, by a defining set of allowed behaviours. The adaptation semantics is such that the upper S level imposes constraints on the lower B level, which has to adapt whenever it no longer can satisfy them. In this context, we introduce weak and strong adaptabil- ity, i.e. the ability of a system to adapt for some evolution paths or for all possible evolutions, respectively. We provide a relational characterisation for these two notions and we show that adaptability checking, i.e. deciding if a system is weak or strong adaptable, can be reduced to a CTL model checking problem. We apply the model and the theoretical results to the case study of motion control of autonomous transport vehicles.Comment: 57 page, 10 figures, research papaer, submitte

    Improved Adaptation and Survivability via Dynamic Service Composition of Ubiquitous Computing Middleware

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    These days, ubiquitous computing has radically changed the way users access and interact with services and content on the Internet: novel smart mobile devices and broadband wireless communication channels allow users to seamlessly access them anytime and anywhere. Middleware infrastructures to support ubiquitous computing need to support an extremely dynamic and ever-changing scenario, where novel contents/services, devices, formats, and media channels become available. Service-oriented architectures and service composition techniques have proven to be the key in designing flexible and extensible platforms that are able to reliably support ubiquitous computing. However, current trends in service composition for ubiquitous computing tend to be either too formal and, therefore, poorly used by average final users, or too vertical and poorly flexible and extensible. This paper proposes novel service composition middleware for ubiquitous computing that relies on a translucent composition model to achieve a flexible, extensible, highly-available, but also easily understandable and usable platform. The proposed system has been widely tested, benchmarked, and deployed on a number of different and heterogeneous ubiquitous scenarios

    A CRITICAL REALIST INSPIRED MULTILEVEL RESEARCH METHOD: COMBINING NETNOGRAPHY AND SOCIAL NETWORK ANALYSIS TO STUDY CONSUMER BEHAVIOR IN ONLINE COMMUNITIES

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    Framed by the philosophy of critical realism, this methodological article proposes a research design involving a case-study approach that combines netnography with social network analysis to study consumer behavior and social interactions in online communities. This research strategy holds to a critical realist stratified emergent ontology, in which the empirical domain, comprising the experiences and perceptions of consumers, is qualitatively analyzed through a form of ethnography adapted to the online environment. The actual domain is explored through a quantitative method based on graph theory that investigates structure and agency processes by analyzing the patterns of social interaction. It is argued that this dualist approach allows researchers to inquire into the deepest level of reality or the real domain and to focus on structures and generative mechanisms as objects of inquiry. The philosophical reasoning for combining netnography and social network analysis is discussed as well as the quality of the research work in terms of reliability, validity, and potential for generalization.  Article visualizations

    Enhancing coverage adequacy of service compositions after runtime adaptation

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    Laufzeitüberwachung (engl. runtime monitoring) ist eine wichtige Qualitätssicherungs-Technik für selbstadaptive Service-Komposition. Laufzeitüberwachung überwacht den Betrieb der Service-Komposition. Zur Bestimmung der Genauigkeit von Software-Tests werden häufig Überdeckungskriterien verwendet. Überdeckungskriterien definieren Anforderungen die Software-Tests erfüllen muss. Wegen ihrer wichtigen Rolle im Software-Testen haben Forscher Überdeckungskriterien an die Laufzeitüberwachung von Service-Komposition angepasst. Die passive Art der Laufzeitüberwachung und die adaptive Art der Service-Komposition können die Genauigkeit von Software-Tests zur Laufzeit negativ beeinflussen. Dies kann jedoch die Zuversicht in der Qualität der Service-Komposition begrenzen. Um die Überdeckung selbstadaptiver Service-Komposition zur Laufzeit zu verbessern, untersucht diese Arbeit, wie die Laufzeitüberwachung und Online-Testen kombiniert werden können. Online-Testen bedeutet dass Testen parallel zu der Verwendung einer Service-Komposition erfolgt. Zunächst stellen wir einen Ansatz vor, um gültige Execution-Traces für Service-Komposition zur Laufzeit zu bestimmen. Der Ansatz berücksichtigt die Execution-Traces von Laufzeitüberwachung und (Online)-Testen. Er berücksichtigt Änderungen im Workflow und Software-Services eines Service-Komposition. Zweitens, definieren wir Überdeckungskriterien für Service-Komposition. Die Überdeckungskriterien berücksichtigen Ausführungspläne einer Service-Komposition und berücksichtigen die Überdeckung für Software-Services und die Service-Komposition. Drittens stellen wir Online-Testfälle Priorisierungs Techniken, um die Abdeckungniveau einer Service-Komposition schneller zu erreichen. Die Techniken berücksichtigen die Überdeckung einer Service-Komposition durch beide Laufzeitüberwachung und Online-Tests. Zusätzlich, berücksichtigen sie die Ausführungszeit von Testfällen und das Nutzungsmodell der Service-Komposition. Viertens stellen wir einen Rahmen für die Laufzeitüberwachung und Online-Testen von Software-Services und Service-Komposition, genannt PROSA, vor. PROSA bietet technische Unterstützung für die oben genannten Beiträge. Wir evaluieren die Beiträge anhand einer beispielhaften Service-Komposition, die häufig in dem Forschungsgebiet Service-oriented Computing eingesetzt wird.Runtime monitoring (or monitoring for short) is a key quality assurance technique for self-adaptive service compositions. Monitoring passively observes the runtime behaviour of service compositions. Coverage criteria are extensively used for assessing the adequacy (or thoroughness) of software testing. Coverage criteria specify certain requirements on software testing. The importance of coverage criteria in software testing has motivated researchers to adapt them to the monitoring of service composition. However, the passive nature of monitoring and the adaptive nature of service composition could negatively influence the adequacy of monitoring, thereby limiting the confidence in the quality of the service composition. To enhance coverage adequacy of self-adaptive service compositions at runtime, this thesis investigates how to combine runtime monitoring and online testing. Online testing means testing a service composition in parallel to its actual usage and operation. First, we introduce an approach for determining valid execution traces for service compositions at runtime. The approach considers execution traces of both monitoring and (online) testing. It considers modifications in both workflow and constituent services of a service composition. Second, we define coverage criteria for service compositions. The criteria consider execution plans of a service composition for coverage assessment and consider the coverage of an abstract service and the overall service composition. Third, we introduce online-test-case prioritization techniques to achieve a faster coverage of a service composition. The techniques employ coverage of a service composition from both monitoring and online testing, execution time of test cases, and the usage model of the service composition. Fourth, we introduce a framework for monitoring and online testing of services and service compositions called PROSA. PROSA provides technical support for the aforementioned contributions. We evaluate the contributions of this thesis using service compositions frequently used in service-oriented computing research

    Models for Co-Design of Heterogeneous Dynamically Reconfigurable SoCs

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    International audienceThe design of Systems-on-Chip is becoming an increasing difficult challenge due to the continuous exponential evolution of the targeted complex architectures and applications. Thus, seamless methodologies and tools are required to resolve the SoC design issues. This chapter presents a high level component based approach for expressing system reconfigurability in SoC co-design. A generic model of reactive control is presented for Gaspard2, a SoC co-design framework. Control integration in different levels of the framework is explored along with a comparison of their advantages and disadvantages. Afterwards, control integration at another high abstraction level is investigated which proves to be more beneficial then the other alternatives. This integration allows to integrate reconfigurability features in modern SoCs. Finally a case study is presented for validation purposes. The presented works are based on Model-Driven Engineering (MDE) and UML MARTE profile for modeling and analysis of real-time embedded systems
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