Property driven verification framework: application to real time property for UML MARTE software design

Les techniques formelles de la famille « vérification de modèles » (« model checking ») se heurtent au problème de l’explosion combinatoire. Ceci limite les perspectives d’exploitation dans des projets industriels. Ce problème est provoqué par la combinatoire dans la construction de l’espace des états possibles durant l’exécution des systèmes modélisés. Le nombre d’états pour des modèles de systèmes industriels réalistes dépasse régulièrement les capacités des ressources disponibles en calcul et stockage. Cette thèse défend l’idée qu’il est possible de réduire cette combinatoire en spécialisant les outils pour des familles de propriétés. Elle propose puis valide expérimentalement un ensemble de méthodes pour le développement de ce type d’outils en suivant une approche guidée par les propriétés appliquée au contexte temps réel. Il s’agit donc de construire des outils d’analyse performants pour des propriétés temps réel qui soient exploitables pour des modèles industriels de taille réaliste. Les langages considérés sont, d’une part UML étendu par le profil MARTE pour la modélisation par les utilisateurs, et d’autre part les réseaux de Petri temporisés comme support pour la vérification. Les propositions sont validées sur un cas d’étude industriel réaliste issu du monde avionique : l’étude de la latence et la fraicheur des données dans un système de gestion des alarmes exploitant les technologies d’Avionique Modulaire Intégrée. Ces propositions ont été mise en oeuvre comme une boite à outils qui intègre les cinq contributions suivantes: la définition de la sémantique d’exécution spécifiques aux propriétés temps réel pour les modèles d’architecture et de comportement spécifiés en UML/MARTE; la spécification des exigences temps réel en s’appuyant sur un ensemble de patrons de vérification atomiques dédiés aux propriété temps réel; une méthode itérative d’analyse à base d’observateurs pour des réseaux de Petri temporisés; des techniques de réduction de l’espace d’états spécifiques aux propriétés temps réel pour des Réseaux de Petri temporisés; une approche pour l’analyse des erreurs détectées par « vérification des modèles » en s’appuyant sur des idées inspirées de la « fouille de données » (« data mining »). ABSTRACT : Automatic formal verification such as model checking faces the combinatorial explosion issue. This limits its application in indus- trial projects. This issue is caused by the explosion of the number of states during system’s execution , as it may easily exceed the amount of available computing or storage resources. This thesis designs and experiments a set of methods for the development of scalable verification based on the property-driven approach. We propose efficient approaches based on model checking to verify real-time requirements expressed in large scale UML-MARTE real-time system designs. We rely on the UML and its profile MARTE as the end-user modeling language, and on the Time Petri Net (TPN) as the verification language. The main contribution of this thesis is the design and implementation of a property-driven verification prototype toolset dedicated to real-time properties verification for UML-MARTE real-time software designs. We validate this toolset using an avionic use case and its user requirements. The whole prototype toolset includes five contributions: definition of real-time property specific execution semantics for UML-MARTE architecture and behavior models; specification of real- time requirements relying on a set of verification dedicated atomic real- time property patterns; real-time property specific observer-based model checking approach in TPN; real-time property specific state space reduction approach for TPN; and fault localization approach in model checking

The International Trade Commission's Assessment of the Trans-Pacific Partnership: Main Findings and Implications

In May of 2016 the United States International Trade Commission (ITC) issued its assessment of the impact of the Trans-Pacific Partnership (TPP). This paper highlights the main findings of the ITC report and explains their derivation and implications. It also examines several issues that were explicitly excluded from analysis in the ITC report

Mining structured Petri nets for the visualization of process behavior

Visualization is essential for understanding the models obtained by process mining. Clear and efficient visual representations make the embedded information more accessible and analyzable. This work presents a novel approach for generating process models with structural properties that induce visually friendly layouts. Rather than generating a single model that captures all behaviors, a set of Petri net models is delivered, each one covering a subset of traces of the log. The models are mined by extracting slices of labelled transition systems with specific properties from the complete state space produced by the process logs. In most cases, few Petri nets are sufficient to cover a significant part of the behavior produced by the log.Peer ReviewedPostprint (author's final draft

Algorithmic Verification of Asynchronous Programs

Asynchronous programming is a ubiquitous systems programming idiom to manage concurrent interactions with the environment. In this style, instead of waiting for time-consuming operations to complete, the programmer makes a non-blocking call to the operation and posts a callback task to a task buffer that is executed later when the time-consuming operation completes. A co-operative scheduler mediates the interaction by picking and executing callback tasks from the task buffer to completion (and these callbacks can post further callbacks to be executed later). Writing correct asynchronous programs is hard because the use of callbacks, while efficient, obscures program control flow. We provide a formal model underlying asynchronous programs and study verification problems for this model. We show that the safety verification problem for finite-data asynchronous programs is expspace-complete. We show that liveness verification for finite-data asynchronous programs is decidable and polynomial-time equivalent to Petri Net reachability. Decidability is not obvious, since even if the data is finite-state, asynchronous programs constitute infinite-state transition systems: both the program stack and the task buffer of pending asynchronous calls can be potentially unbounded. Our main technical construction is a polynomial-time semantics-preserving reduction from asynchronous programs to Petri Nets and conversely. The reduction allows the use of algorithmic techniques on Petri Nets to the verification of asynchronous programs. We also study several extensions to the basic models of asynchronous programs that are inspired by additional capabilities provided by implementations of asynchronous libraries, and classify the decidability and undecidability of verification questions on these extensions.Comment: 46 pages, 9 figure

An Operational Petri Net Semantics for the Join-Calculus

We present a concurrent operational Petri net semantics for the join-calculus, a process calculus for specifying concurrent and distributed systems. There often is a gap between system specifications and the actual implementations caused by synchrony assumptions on the specification side and asynchronously interacting components in implementations. The join-calculus is promising to reduce this gap by providing an abstract specification language which is asynchronously distributable. Classical process semantics establish an implicit order of actually independent actions, by means of an interleaving. So does the semantics of the join-calculus. To capture such independent actions, step-based semantics, e.g., as defined on Petri nets, are employed. Our Petri net semantics for the join-calculus induces step-behavior in a natural way. We prove our semantics behaviorally equivalent to the original join-calculus semantics by means of a bisimulation. We discuss how join specific assumptions influence an existing notion of distributability based on Petri nets.Comment: In Proceedings EXPRESS/SOS 2012, arXiv:1208.244

Petri nets for systems and synthetic biology

We give a description of a Petri net-based framework for modelling and analysing biochemical pathways, which uni¯es the qualita- tive, stochastic and continuous paradigms. Each perspective adds its con- tribution to the understanding of the system, thus the three approaches do not compete, but complement each other. We illustrate our approach by applying it to an extended model of the three stage cascade, which forms the core of the ERK signal transduction pathway. Consequently our focus is on transient behaviour analysis. We demonstrate how quali- tative descriptions are abstractions over stochastic or continuous descrip- tions, and show that the stochastic and continuous models approximate each other. Although our framework is based on Petri nets, it can be applied more widely to other formalisms which are used to model and analyse biochemical networks

Unfolding-Based Process Discovery

This paper presents a novel technique for process discovery. In contrast to the current trend, which only considers an event log for discovering a process model, we assume two additional inputs: an independence relation on the set of logged activities, and a collection of negative traces. After deriving an intermediate net unfolding from them, we perform a controlled folding giving rise to a Petri net which contains both the input log and all independence-equivalent traces arising from it. Remarkably, the derived Petri net cannot execute any trace from the negative collection. The entire chain of transformations is fully automated. A tool has been developed and experimental results are provided that witness the significance of the contribution of this paper.Comment: This is the unabridged version of a paper with the same title appearead at the proceedings of ATVA 201

Analyzing safety and fault tolerance using time Petri nets

The application of time Petri net modelling and analysis techniques to safety-critical real-time systems is explored and procedures described which allow analysis of safety, recoverability, and fault tolerance. These procedures can be used to help determine software requirements, to guide the use of fault detection and recovery procedures, to determine conditions which require immediate miti gating action to prevent accidents, etc. Thus it is possible to establish important properties duing the synthesis of the system and software design instead of using guesswork and costly a posteriori analysis