Process windows

We describe a method for formally representing the behaviour of complex processes by process windows. Each window covers a part of the system behaviour, i.e. a part of the underlying transition system, and is easier to understand and analyse than the complete transition system. Process windows can overlap and have shared states and transitions so that the complete system behaviour is the union of window behaviours. We demonstrate the advantage of such representations when dealing with complex system behaviours, and discuss potential applications in circuit design and process mining. As a motivational example we consider the problem of covering transition systems by marked graphs, or more generally choicefree Petri nets. The obtained windows correspond to choice-free behavioural scenarios of the system, wherein one window can take over, or wake up, after another window has become inactive. The corresponding wake-up conditions and wake-up markings can be derived automatically.Peer ReviewedPostprint (author's final draft

Mining Branching-Time Scenarios

Specification mining extracts candidate specification from existing systems, to be used for downstream tasks such as testing and verification. Specifically, we are interested in the extraction of behavior models from execution traces

Partner datenverarbeitender Services

Diese Arbeit untersucht den Einfluss von Daten auf das Verhalten und die Korrektheit eines verteilten Systems. Ein verteiltes System besteht aus mehreren Services. Ein Service ist eine selbständige, plattformunabhängige Einheit, die anderen Services eine bestimmte Funktionalität über eine wohldefinierte Schnittstelle zur Verfügung stellt. In dieser Arbeit betrachten wir die Interaktion von jeweils genau zwei Services miteinander. Zwei Services, die erfolgreich miteinander zusammenarbeiten können, nennen wir Partner. Ein Service heißt bedienbar, wenn er mindestens einen Partner hat. Ziel der Arbeit ist es, zu untersuchen, wann zwei Services Partner sind, und für einen Service zu entscheiden, ob dieser bedienbar ist. Aufgrund der Daten kann der Zustandsraum eines Service sehr groß oder sogar unendlich groß werden. Wir untersuchen zwei Klassen von Services mit unendlich vielen Zuständen. Für diese Klassen stellen wir Algorithmen vor, welche zu einem gegebenen Service einen Partner synthetisieren, falls ein solcher existiert. Auf diese Weise entscheiden wir konstruktiv die Bedienbarkeit eines Service. Weiterhin stellen wir Transformationsregeln für Partner vor und untersuchen, wie viel Speicherplatz ein Partner eines Services mindestens benötigt.This thesis studies the influence of data on the behavior and the correctness of a distributed system. A distributed system consists of several services. A service is a self-contained, platform-independent entity which provides a certain functionality to other services via a well-defined interface.In this thesis, we consider the interaction of exactly two services. Two services that can successfully cooperate with each other are called partners. We call a service controllable, if the service has at least one partner. The goal of this thesis is to study the conditions for which two services are partners and to decide whether a given service is controllable. Due to the data, the state space of a service may be very large or even infinite. We investigate two classes of services with infinitely many states. For these classes, we present algorithms that synthesize a partner of a service, if it exists. This allows us to decide the controllability of a service constructively. Furthermore, we present transformation rules for partners and investigate the minimum amount of memory that a partner of a service needs

Oclets – scenario-based modeling with Petri nets

Abstract. Scenario-based specifications are used for modeling highlycomplex, distributed systems in terms of partial runs (scenarios) the system shall have. But it is difficult to derive an implementing, operational model from a given set of scenarios, especially if concepts like anti-scenarios which must not occur are used. In this paper, we present a novel model for scenario-based specifications with Petri nets including anti-scenarios; we provide an operational semantics for our model. 1 Operational semantics for scenario-based specifications The paradigm of scenarios is widely accepted in protocol specifications using message-sequence charts (MSCs); behavior of highly-complex distributed systems is decomposed into reasonably sized artifacts called scenarios. Some classes of MSC specifications can be transformed into Petri nets [7], but usually an implementation has to be checked against an MSC specification. Life-sequence charts (LSCs) [5] extend the MSC paradigm by adding behavioral preconditions, anti-scenarios, and annotations to scenarios and single actions for enforcin

Hardware synthesis from high-level scenario specifications

PhD ThesisThe behaviour of many systems can be partitioned into scenarios. These facilitate engineers’ understanding of the specifications, and can be composed into efficient implementations via a form of high-level synthesis. In this work, we focus on highly concurrent systems, whose scenarios are typically described using concurrency models such as partial orders, Petri nets and data-flow structures. In this thesis, we study different aspects of hardware synthesis from high-level scenario specifications. We propose new formal models to simplify the specification of concurrent systems, and algorithms for hardware synthesis and verification of the scenario-based models of such systems. We also propose solutions for mapping scenariobased systems on silicon and evaluate their efficiency. Our experiments show that the proposed approaches improve the design of concurrent systems. The new formalisms can break down complex specifications into significantly simpler scenarios automatically, and can be used to fully model the dataflow of operations of reconfigurable event-driven systems. The proposed heuristics for mapping the scenarios of a system to a digital circuit supports encoding constraints, unlike existing methods, and can cope with specifications comprising hundreds of scenarios at the cost of only 5% of area overhead compared to exact algorithms. These experiments are driven by three case studies: (1) hardware synthesis of control architectures, e.g. microprocessor control units; (2) acceleration of the ordinal pattern encoding, i.e. an algorithm for detecting repetitive patterns within data streams; (3) and acceleration of computational drug discovery, i.e. computation of shortest paths in large protein-interaction networks. Our findings are employed to design two prototypes, which have a practical value for the considered case studies. The ordinal pattern encoding accelerator is asynchronous, highly resilient to unstable voltage supply, and designed to perform a range of computations via runtime reconfiguration. The drug discovery accelerator is synchronous, and up to three orders of magnitude faster than conventional software implementations

Case-Based Decision Support for Disaster Management

Disasters are characterized by severe disruptions of the society’s functionality and adverse impacts on humans, the environment, and economy that cannot be coped with by society using its own resources. This work presents a decision support method that identifies appropriate measures for protecting the public in the course of a nuclear accident. The method particularly considers the issue of uncertainty in decision-making as well as the structured integration of experience and expert knowledge