Jean-Jacques Schwarz

Hierarchical correctness verification in multiphase real-time software design

Abstract A hierarchical approach to correctness verification of real-time software specifications is presented. The verification is distributed into successive steps that correspond to the design phases. The three languages: Rule Charts, LACTATRE (graphical specification) and Communicating Real Time State Machines are used for specification of real-time software within corresponding abstraction levels. The correctness is defined as a coincidence of a system specified in a phase w.r.t. requirements established ing the previous phase. This correctness concept leads to an application of the relative correctness methods (developed in former works) for the verification. The approach is examined in Preliminary and Detailed Design phases for the verification of several types of properties: structure, functions, and time constraints.

Applicative object interconnection in a graphical design for real-time applications

Abstract The LACATRE environment is dedicated to multitasking real-time application developments. At the lowest level, it handles basic objects close to those supported by realtime executives (tasks, messages, semaphores…), and at the highest one, it manipulates applicative objects which are near to the application programmers preoccupations. The aim of this paper is to show how it is possible to build re-usable graphical communication interfaces, easily and efficiently, for the interconnection of these high-level applicative objects when they are involved in a client-server relation.

GRAPHICAL PROGRAMMING FOR REAL TIME SYSTEMS. AN EXPERIENCE FROM THE WORLD OF EDUCATION

Abstract This paper first presents the graphical method we have developed in our University in order to improve the teaching efficiency in Multitasking Real Time Programming and Industrial Computation Application Design. This method is based upon the LA CATRE graphical language (Langage d’Aide a la Conception d’Application Temps REel) which acts as an overlayer to industrial standard real time executives (RTXs). Then, we expose what has been our lecturing experience for 5 years now.

Temporal Verification of Real-Time Multitasking Application Properties Based on Communicating Timed Automata

This paper proposes a method for temporal verification of real-time multitasking applicationproperties based on a communicating timed automata IF language. The properties are divided into two kinds: local properties of application elements like object creation/destruction, object length, task deadlocks and secondly global properties such as data age, deadline, and time interval verification. These properties are represented by observer automata and verified by the IF2C tool exhaustive simulation. The notion of phrase is used to reduce the IF representation graph by partitioning the application on the basis of phases.

Practice of Real-time Software Architectures: Collider, Satellites, and Tanks Combined

ABSTRACT Three real-time mission-critical applications are discussed from the following domains: scientific (highenergy physics experiments), commercial (satellite control), and military (embedded simulations). Problems facing designers of real-time software architectures are grouped into two categories: architectural patterns and design tools. Consistent solutions proposed by the authors and applied in these applications are presented.

From CRSM specification to a real-time multitasking execution model

This paper introduces elements allowing an easier crossing of the gap between analysis and design in the case of real-time applications relying on a multitasking operating system. The chosen specification method is based on the use of Shaws (1992) CRSM (Communicating Real-time States Machines) and our purpose is to put the basis of a method allowing an easier translation of a CRSM based modelling of a system into a real-time multitasking execution model. In order to do this, we present guidelines for translating the basic constructs of a CRSM model (communicating machines, channels, transitions) into programs involving the usual objects and primitives found in off-the-shelf real-time multitasking operating systems (tasks or threads, message passing, event signalling). The guidelines are illustrated with the classical specification example of the Martian Lander. The aim is to overcome the gap between a specification made with the CRSM and a multitasking execution model: there will then be good possibilities for verification. The specification can be executed, the design can be verified for correctness (liveliness, safety) and eventually a comparison between the behaviour of the specified model and that of the target program can be done.

Time requirement specification in the graphical design of real-time software

Abstract The aim of the LACATRE graphical environment, described in this paper, is to facilitate the design of multitasking real-time applications. It covers the preliminary and detailed design steps of the software life-cycle. It permits an easy description of both the behaviour and the transformational aspects of an application. The introduction in this environment of task time characteristics offers the developer the possibility of choosing a scheduling policy adapted to a particular application, and of verifying the adequacy of a design relative to time constraints (for the respect of deadlines, etc.). The application of the environment to a mining robot is illustrated in the paper.

Modeling of Real-Time Embedded Systems using SDL

SDL is used increasingly for the development of real-time embedded systems. Because SDL does not have a clear interpretation of time, the associated code generators do not integrate the management of temporal constraints. In this paper, we propose a real-time semantics to SDL for the modeling of real-time embedded systems in order to prepare a real-time implementation.

Techniques for the Behaviour Verification of Real-Time Multitasking Components

Abstract The aim of the paper is to contribute to the building of reusable and verified software components in real-time complex systems. A means to verify the behavioural correctness of a real-time application supported by an off-the-shelves real-time multitasking operating system is proposed. The verification is based on a simulation of the application modelled with Shaws CRSM. It is also shown how the splitting of the verification process according to the different running modes of the application can dramatically reduce the complexity of the verification.

Applicative Object Interconnection in a Graphical Design of Real-Time Applications

Abstract The LACATRE environment is dedicated to multitasking real-time application developments. At the lowest level, it handles basic objects close to those supported by real-time executives (tasks, messages, semaphores...), and at the highest one, it manipulates applicative objects (agencies, processes) which are near to the application programmer’s preoccupations. The aim of this paper is to show how it is possible to easily and efficiently build graphical re-usable interfaces for the interconnection of these high-level applicative objects when they are involved in a client-server relation.