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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 Shaw's 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.

This paper summarizes the discussion held among members of the IFAC TC on Real-Time Software Engineering on the distinctive features of real-time computing. It discusses the internal and external factors that characterize real-time computing as an area of science and presents some ideas about the balance between theory, abstraction, and design in the process of instruction. It also attempts to answer the question whether realtime computing is a fundamental or an applied subject area.

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.

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.

This paper describes an architecture which provides a frame for Industrial Applications development in which the distributed aspect is an important feature. This architecture is made up of three layers: Application, Equipment and Communication. The Application, the most important one, has to provide high level services by means of service modules straight available for application programmers. These services arc based upon a classification of circmnstances under which orders are sent to remote devices (polling, diary, manufacturing order, ...). These modules allow to access the equipment thanks to logical commands expressed in user trade jargon and rely upon the Equipment layer which is in charge of the implementation of the interface with the actual world. If this world is apprehended by VDM of MMS standard models, then the logical orders will use service primitives provides by such models, otherwise the architecture proposes a general development frame suited to other low level communications media and protocols (dual port memory, IЕEE488 bus, ...).This structuration of an application software is illustrated by means of an example describing the distributed control of an industnal transfer system.

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, LACATRE (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 in the previous phase. This correctness concept leads to an application of the relative correctness methods (developed in former work) for the verification. The approach is examined in the preliminary and detailed design phases for the verification of several types of properties: structure, functions, and time constraints.

This paper presents a graphical programming language, LACATRE, developed in order to improve teaching and development efficiency in Multitask Real Time Programming and Industrial Computation Application Design. LACATRE (Language d'Aide a la Conception d'Application Temps REel) is a language with a graphical and a textual mode devoted to easing both the preliminary design and the detailed design of applications involving real time multitask executives. LACATRE acts as an overlayer to industrial standard real time executives (RTXs). Based on experience from the world of education, the second part of the paper, thanks to examples, presents some LACATRE working principles in order to help the design of and obtain efficient documentation of multitasking programmes

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.

The goal of this paper is to find the most efficient architecture for distributed and adaptive systems that could provide services, which have to be executed within a given time frame. A real-time client/server architecture is proposed. This paper focuses on the server part of the architecture, the real-time server object (RTSO). Within this architecture, a client communicates with a local proxy object, which acts as a representative of one remote RTSO. The software architecture for a RTSO is based upon a reflective architecture. A metaobject controls the application and one object provides the services issued from the client request, which include some real-time constraints. The hardware architecture for a RTSO is a multiprocessor architecture in which processors are dedicated to the metaobject and the object respectively. Within the same server site, a metaobject (function and data members) is mapped onto dedicated processors named kernel processors; the methods (function members) are mapped onto task processors. Depending on their use, the attributes (data members) are mapped onto task, kernel processors or onto a real-time shared memory. Finally, the real time temporal performance of such a complex architecture is evaluated.

LACATRE is a graphical language intended to help in design for applications requiring multitasking real time executives. Within the software life cycle, it is used for both preliminary and detailed design. The paper presents new high level objects destined to facilitate the link between commonly used methods for specification and design and the detailed design using multitasking executives. The paper describes ideas concerning the use of such a tool in the frame of education, and industry in the case of medium size applications where developers have a lack of tools. >

This paper describes an architecture which provides a frame for Industrial Applications development in which the distributed aspect is an important feature. This architecture is made up of three layers: Application, Equipment and Communication. The Application, the most important one, has to provide high level services by means of service modules straight available for application programmers. These services are based upon a classification of circumstances under which orders are sent to remote devices (polling, diary, manufacturing order, …). These modules allow to access the equipment thanks to logical commands expressed in user trade jargon and rely upon the Equipment layer which is in charge of the implementation of the interface with the actual world. If this world is apprehended by VDM of MMS standard models, then the logical orders will use service primitives provides by such models, otherwise the architecture proposes a general development frame suited to other low level communications media and protocols (dual port memory, IEEE488 bus, …). This structuration of an application software is illustrated by means of an example describing the distributed control of an industrial transfer system.

Participants introduced themselves briefly, describing their major activities and interest regarding teaching “Real-Time Systems” courses, as well as their expectations regarding the work of this group. Remarkably, attending participants formed a mixture of faculty from Computer Engineering, Computer Science, and Electrical Engineering departments.

Personally, I think it seems to be tricky to give only one answer, so I’d rather ask some questions: Which answers do we have to give to whom? Do we know what the needs are? Who needs something?

The major difficulties encountered by those who have to solve Industrial Real Time Applications, in a multitask computing environment, are: the expression of the dynamic aspect of this type of applications, the number and the variety of these Real Time Executives.

The development of Real Time Applications raises a number of problems which add themselves to those, already non-trivial, generated by the development of all Information Systems, either during their design or their implementation, mainly because such applications are closely coupled to the physical world with which they interact.

In the paper some experiences of joining two methodologies, which were originally independently developed in different institutions, with the goal to overcome the possible discrepancies due to the separate design of the hardware and the software part of an embedded real-time application are presented. Based on Multiprocessor PEARL, Specification PEARL has been developed in FERI, Maribor. Hardware and system architecture of an application can be described and gradually refined. Application software can be designed using LACATRE tool, developed at INSA, Lyon. Decisions about the application design taken in each tool have influence to the ones taken in the other, thus allowing for parallel design of both parts. Both designs are subsequently verified and eventually joined for feasibility estimation by co-simulation. The application program is coded using the ObjectPEARL language. The real-time system design cycle is closed by the execution time analysis and measurements upon which it is then considered about further program and/or hardware part reconfiguration. This feature is supported by the specific compiler, which includes the execution time analyser. The article reports on the work that was done in the framework of the PROTEUS project in co-operation of the teams from FERI Maribor, Slovenia, and INSA de Lyon, France.

This paper presents a distributed operating environment based on a computing organization in which parallel processing opportunities between actions composing a process implicitly arise from their data-flow relations. The process is represented by a graph that may include loops and in which every node, which represents an action, may be decomposed into a lower-level graph until sequential machine-code is reached. The animation of graphs is performed by means of primitives therein, from which results the scheduling of actions in respect to their hierarchical and necessarly consistent description.

Downsizing and compatibility with MEMS silicon foundries is an attractive path towards a large diffusion of photoacoustic trace gas sensors. As the photoacoustic signal scales inversely with the chamber volume, a trend to miniaturization has been followed by several teams. We review in this article the approach initiated several years ago in our laboratory. Three generations of components, namely a 40 mm3 3D-printed cell, a 3.7 mm3 silicon cell, and a 2.3 mm3 silicon cell with a built-in piezoresistive pressure sensor, have been designed. The models used take into account the viscous and thermal losses, which cannot be neglected for such small-sized resonators. The components have been fabricated either by additive manufacturing or microfabrication and characterized. Based on a compilation of experimental data, a similar sub-ppm limit of detection is demonstrated. All three versions of photoacoustic cells have their own domain of operation as each one has benefits and drawbacks, regarding fabrication, implementation, and ease of use.