J. Skubich

Real time multitasking design with a graphical tool

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.<<ETX>>

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.

Data flow modelling in real time multitasking graphical design

LACATRE is a graphical tool intended to help the design of applications requiring multitasking real time executives. Within the software life cycle, it covers both preliminary and detailed design. The first version of this tool gave preference to the tasking aspect of an application by the modelling of both low level objects, issued from real time kernels, and high level application objects, close to specification methods. This paper presents the data modelling introduced in the LACATRE language, in order to lead to a quasi complete code generation of an application target programme. Two other issues are brought up with data modelling: the introduction of control variables used for simulation and programme correctness verification, and the definition of a graphical formalism for data flow representation.<<ETX>>

Real-Time Computing Education: Responding to a Challenge of the Next Century

Abstract 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.

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.

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.

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.

Time Requirement Specification in 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.

STRUCTURING IN THE DESIGN OF REAL TIME DCCS APPLICATION TO AN INDUSTRIAL TRANSFER SYSTEM

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.