Stefan Jähnichen

KORSO - Methods, Languages, and Tools for the Construction of Correct Software

Correct software: From experiments to applications.- A method for the development of correct software.- Realizing sets by hash tables.- Event automata as a generic model of reactive systems.- On object-oriented design and verification.- Design of modular software systems with reuse.- AVL trees revisited: A case study in Spectrum.- KORSO reference languages concepts and application domains.- How to cope with the Spectrum of Spectrum.- A fine-grain sort discipline and its application to formal program construction.- TROLL light - The language and its development environment.- Formalization of algebraic specification in the development language Deva.- Construction and deduction methods for the formal development of software.- Experiences with a specification environment.- Towards correct, efficient and reusable transformational developments.- The verification system Tatzelwurm.- Seduct - A proof compiler for first order logic.- Traverdi - Transformation and verification of distributed systems.- The Kiv-approach to software verification.- Three selected case studies in verification.- Case study production cell: A comparative study in formal specification and verification.- The Korso case study for software engineering with formal methods: A medical information system.

Specification of software controlling a discrete-continuous environment

In this paper, we present an object-oriented approach to the specification of discrete software controllers that are embedded in discrete-continuous (or hybrid) environments. The structure of the controller and its environment is specified using object notations extended to include continuous and hybrid objects. Control behavior is specified with state automata and pre/postconditions using the statechart notation and constructive Z-schemata. The behavior of the environment is specified ith systems of differential equations using an object-oriented extension of Z for the specification of hybrid systems. We use a case study on control of a high-pressure steam boiler to illustrate how the environment structure can help to design the controller and how environment simulation can be used to derive control parameters.

Simulation-Based Testing of Embedded Software in Space Applications

This paper deals with the software-in-the-loop test approach being developed nby the consortium project SiLEST (DLR, TU-Berlin, IAV, FhG FIRST, Webdynamix). We present a layer structure of the control loop that allows components of the environment simulation to be used for hardware-in-the-loop and software-in-the-loop testing of embedded systems software. The approach is specifically designed to test software behaviour in disturbed operating conditions, such as in a harsh environment, for example. In space applications, intensive radiation can corrupt computations and stored data. In addition, electronic devices such as sensors age much faster than on earth so that changed sensor deviations must be expected. Much the same is true of numerous other embedded systems, e.g. in automotive applications. Here, too, the electronic components are exposed to extreme conditions (temperature) and are subject to ageing processes.

Selbstverwaltete digitale Identitäten – Chancen und Herausforderungen für die weltweite Digitalisierung

Die Vernetzung von Personen, Diensten und Geraten ist ein wesentlicher Aspekt der Digitalisierung. Neben dem Ausbau der Netz-Infrastruktur sind sichere digitale Identitaten eine zentrale Voraussetzung fur den sicheren und rechtskonformen Austausch von Informationen. Vorherrschende Ansatze sind an ID-Provider wie nationale Behorden oder Internet-Dienstanbieter gebunden. Ein Umzug an einen neuen Wohnort oder der Wechsel zu einem neuen Dienstanbieter bedeutet haufig die Daten neu aufzubauen, da personliche Daten nicht vollstandig portiert werden. Der Ansatz der selbstverwalteten digitalen Identitaten bindet die digitalen Identitaten stattdessen an die Individuen selbst und ermoglicht so die gezielte und sparsame Freigabe personlicher Daten, unabhangig ihres Wohnortes, nationaler eID-Infrastruktur und marktbeherrschender Dienstanbieter.

Was, bitte, bedeutet Objektorientierung?

Informatik Spektrum (25/1) vorgebracht haben [5]. Rein äußerlich enthält jener Artikel einige Ungenauigkeiten und Fehler, die eine Richtigstellung verlangen.

Formalization of Algebraic Specification in the Development Language DEVA

We show how software development based on algebraic specification can formally be represented in the development language Deva. We have formalized essential parts of the algebraic specification language Spectrum and a semantic development relation. The use of such a representation is three-fold: It makes developments amenable to consistency checks by machine, it documents the development for human readers, and it makes explicit the correspondence of development steps and resulting proof obligations.

Ein Rahmenwerk zur Protokollierung von Transaktionen in Distributed Ledgers

ZusammenfassungDistributed Ledger Technologien werden – nach der anfänglich ausschließlichen Nutzung für die Verwaltung digitaler Geldeinheiten wie Bitcoin – auch für weitere Anwendungen vorgeschlagen: Die manipulationssichere, verteilte Speicherung replizierter Daten ohne zentrale Vertrauensinstanzen erlaubt die konsistente Protokollierung von Transaktionen digitaler und realer Güter in diversen Anwendungsfällen. Wir betrachten den Anwendungsfall Identitätsmanagement, extrahieren zentrale Anforderungen und definieren darauf basierend ein Rahmenwerk zur Protokollierung von Transaktionen in Distributed Ledgers.

Adaptation to the Unforeseen: Do we Master our Autonomous Systems? Questions to the Panel - Panel Introduction

This short paper gives an introduction to a panel held as part of the track on “Rigorous Engineering of Collective Adaptive Systems” at ISOLA 2016. The moderator Stefan Jahnichen (TU Berlin) and the panelists Saddek Bensalem (VERIMAG), Michele Loreti (University of Florence), Giovanna di Marzo Serugendo (University of Geneva), and Emil Vassev (LERO) discussed how to master the engineering of autonomous systems that have to cope with unforeseen events and situations. The discussion was structured along 14 questions ranging from the evolution and universality of autonomous systems to correctness, reliability, and legal issues.

A Library and Scripting Language for Tool Independent Simulation Descriptions

In modeling and simulation it is often necessary to simulate a model with a variety of settings and evaluate the simulation results with measured data or previously acquired results. As doing this manually is error-prone and ineffective, scripting languages are often used to automate this process. In general a simulation description is tool and model dependent. Therefore, simulating the same model with the same simulation description in different simulation tools or comparing two different models with the same settings is often not easily achieved. We propose an object-oriented, tool-independent, easy-to-use, domain-specific scripting language to describe simulations in an exchangeable and uniform manner. Through this simulation description the simulation settings and the simulation environment can easily be changed while syntax and sequence of commands remain the same. The language is Python based and is designed to be simple, well-readable and intuitive even with marginal programming experience while maintaining Pythons’ strength. The language uses an in-house Python library which provides interfaces to different simulation environments (so far Dymola, OpenModelica, Simulink). This library can also be used directly in Python, enabling experienced Python users to keep describing their simulations in Python but benefiting from our efforts to achieve tool-independence.

Teaching software engineering—experience from the past, needs for the future

Abstract The field of software engineering evolved during the last decade from pure (but excellent) programming towards an engineering discipline including managerial, organizational, hardware and even commercial aspects. Nowadays, engineers have to cope with the development of very complex systems which are composed of various components such as software, hardware, interfaces, etc., and which are expected to guarantee robustness, reliability and even correctness for their products. Thus, the width of the discipline poses a variety of problems to the teaching of the field, but sometimes resulting in courses just tackling the surface of those problems. The paper presents a curriculum for a software engineering course and identifies directions for further evolution.