Cognitive Sensor Platform

This paper describes a platform that is used to build embedded sensor systems for low energy implantable applications. One of the key characteristics of the platform is the ability to reason about the environment and dynamically modify the operational parameters of the system. Additionally the platform provides to ability to compose application specific sensor systems using a novel computational element that directly supports a synchronous-dataflow (SDF) programming paradigm. Cognition in the context of a sensor platform is defined as the “process of knowing, including aspects of awareness, perception, reasoning, and judgment”.DOI:http://dx.doi.org/10.11591/ijece.v4i4.568

Sémantique compositionnelle et raffinement de systèmes temporisés : application aux automates temporisés d'UPPAAL et au langage FIACRE

Les systèmes temps-réel sont massivement impliqués dans de nombreuses applications, dont notre vie dépend comme les logiciels embarqués dans les voitures et les avions. Pour ces systèmes des erreurs inattendues ne sont pas acceptables. De ce fait, assurer la correction de ces systèmes est une tâche primordiale. Les systèmes temps-réel représentent un large spectre de systèmes automatisés dont la correction dépend de la ponctualité des événements (timeliness) et pas seulement de leurs propriétés fonctionnelles. Chaque événement doit être produit selon la date indiquée par la spécification du système. Les systèmes temps-réel sont concurrents et embarqués, et conçus comme un assemblage de composants en interaction. Malgré les progrès réalisés dans les techniques de model checking, la vérification et l'analyse des systèmes temps-réel représentent toujours un défi autant pour les chercheurs que les praticiens. Pour étudier le comportement des systèmes temps-réel, différents formalismes ont été considérés comme les automates temporisés, les réseaux de Petri temporisés et les algèbres de processus. Cela donne lieu à plusieurs points délicats concernant le raffinement, la composition et la vérification. Ces points représentent un champ de recherche intensif. Ma thèse présente une étude des systèmes temps-réel focalisée sur les notions de sémantique, de composition et de raffinement. Elle décrit nos efforts pour explorer et étendre les formalismes temps-réel. Nous avons abordé les concepts de base de la modélisation des systèmes temps réel tels que les variables partagées, la communication, les priorités, la dynamicité, etc. La contribution de cette thèse porte sur la définition d’un cadre formel pour raisonner sur la sémantique, la composition et le raffinement des systèmes temporisés. Nous avons instancié ce cadre pour le formalisme des automates temporisés et le langage Fiacre.Nowadays, real-time systems are intensively involved in many applications on which our life is dependent, like embedded software in cars and planes. For these systems unexpected errors are not acceptable. Real-time systems represent a large spectrum of automated systems of which correctness depends on the timing of events (timeliness) and not only on their functional properties. Each event must be produced on time. Realtime systems can be concurrent and embedded where different interactive modules and components are assembled together. Despite advances in model checking techniques, the verification and analysis of real-time systems still represent a strong challenge for researchers and practitioners. To study the behavior of real-time systems, different formalisms have been considered like timed automata, time Petri nets and timed algebra, and several challenges concerning refinement, composition and verification have emerged. These points represent an intensive field of research. This thesis describes our effort to explore and extend real-time formalisms. We have revisited real-time language semantics, focusing on composition and refinement. We have addressed high level concepts like shared variables, communication, priorities, dynamicity, etc. The main contribution consists of a theoretical study of timed systems where we establish a framework for reasoning on composition, refinement and semantics. We instantiate this framework for timed automata and the Fiacre language

Verification of Branching-Time and Alternating-Time Properties for Exogenous Coordination Models

Information and communication systems enter an increasing number of areas of daily lives. Our reliance and dependence on the functioning of such systems is rapidly growing together with the costs and the impact of system failures. At the same time the complexity of hardware and software systems extends to new limits as modern hardware architectures become more and more parallel, dynamic and heterogenous. These trends demand for a closer integration of formal methods and system engineering to show the correctness of complex systems within the design phase of large projects. The goal of this thesis is to introduce a formal holistic approach for modeling, analysis and synthesis of parallel systems that potentially addresses complex system behavior at any layer of the hardware/software stack. Due to the complexity of modern hardware and software systems, we aim to have a hierarchical modeling framework that allows to specify the behavior of a parallel system at various levels of abstraction and that facilitates designing complex systems in an iterative refinement procedure, in which more detailed behavior is added successively to the system description. In this context, the major challenge is to provide modeling formalisms that are expressive enough to address all of the above issues and are at the same time amenable to the application of formal methods for proving that the system behavior conforms to its specification. In particular, we are interested in specification formalisms that allow to apply formal verification techniques such that the underlying model checking problems are still decidable within reasonable time and space bounds. The presented work relies on an exogenous modeling approach that allows a clear separation of coordination and computation and provides an operational semantic model where formal methods such as model checking are well suited and applicable. The channel-based exogenous coordination language Reo is used as modeling formalism as it supports hierarchical modeling in an iterative top-down refinement procedure. It facilitates reusability, exchangeability, and heterogeneity of components and forms the basis to apply formal verification methods. At the same time Reo has a clear formal semantics based on automata, which serve as foundation to apply formal methods such as model checking. In this thesis new modeling languages are presented that allow specifying complex systems in terms of Reo and automata models which yield the basis for a holistic approach on modeling, verification and synthesis of parallel systems. The second main contribution of this thesis are tailored branching-time and alternating time temporal logics as well as corresponding model checking algorithms. The thesis includes results on the theoretical complexity of the underlying model checking problems as well as practical results. For the latter the presented approach has been implemented in the symbolic verification tool set Vereofy. The implementation within Vereofy and evaluation of the branching-time and alternating-time model checker is the third main contribution of this thesis

Verificare: a platform for composable verification with application to SDN-Enabled systems

Software-Defined Networking (SDN) has become increasing prevalent in both the academic and industrial communities. A new class of system built on SDNs, which we refer to as SDN-Enabled, provide programmatic interfaces between the SDN controller and the larger distributed system. Existing tools for SDN verification and analysis are insufficiently expressive to capture this composition of a network and a larger distributed system. Generic verification systems are an infeasible solution, due to their monolithic approach to modeling and rapid state-space explosion. In this thesis we present a new compositional approach to system modeling and verification that is particularly appropriate for SDN-Enabled systems. Compositional models may have sub-components (such as switches and end-hosts) modified, added, or removed with only minimal, isolated changes. Furthermore, invariants may be defined over the composed system that restrict its behavior, allowing assumptions to be added or removed and for components to be abstracted away into the service guarantee that they provide (such as guaranteed packet arrival). Finally, compositional modeling can minimize the size of the state space to be verified by taking advantage of known model structure. We also present the Verificare platform, a tool chain for building compositional models in our modeling language and automatically compiling them to multiple off-the-shelf verification tools. The compiler outputs a minimal, calculus-oblivious formalism, which is accessed by plugins via a translation API. This enables a wide variety of requirements to be verified. As new tools become available, the translator can easily be extended with plugins to support them

Recent advances in petri nets and concurrency

CEUR Workshop Proceeding