Jean-Paul Rigault

Teaching object-oriented modeling and UML to various audiences

This paper summarizes the experience of teaching object-oriented modeling and UML for more than a decade to various audiences (academic or corporate, software developers or not). We present the characteristics of the audiences. We investigate which modeling concepts are well accepted and which are not. We identify several general problems: attendee background, object-oriented language as a prerequisite, limitations of tools, methodological issues, impact of company organizations. We propose (partial) solutions and a list of pragmatic advices.

Scenario and property checking of real-time systems using a synchronous approach

This paper addresses the design of control-dominated systems using a synchronous approach and UML. The work aims at formally checking the design: scenario/controller consistency, and safety properties. For this, a strengthening of UML behavioral models is necessary: SyncCharts are used instead of Statecharts, and sequence diagrams are modified by adding synchronously sound constructs akin to message sequence charts. The formal foundations of the approach and the associated tools are briefly presented.

Run time adaptation of video-surveillance systems: a software modeling approach

Video-surveillance processing chains are complex software systems, exhibiting high degrees of variability along several dimensions. At the specification level, the number of possible applications and type of scenarios is large. On the software architecture side, the number of components, their variations due to possible choices among different algorithms, the number of tunable parameters... make the processing chain configuration rather challenging. In this paper we describe a framework for design, deployment, and run-time adaptation of video-surveillance systems--with a focus on the run time aspect. Starting from a high level specification of the application type, execution context, quality of service requirements... the framework derives valid possible system configurations through (semi) automatic model transformations. At run-time, the framework is also responsible for adapting the running configuration to context changes. The proposed framework relies on Model-Driven Engineering (MDE) methods, a recent line of research in Software Engineering that promotes the use of software models and model transformations to establish a seamless path from software specifications to system implementations. It uses Feature Diagrams which offer a convenient way of representing the variability of a software system. The paper illustrates the approach on a simple but realistic use case scenario of run time adaptation.

Towards formalizing behavioral substitutability in component frameworks

When using a component framework, developers need to respect the behavior implemented by the components. Static information about the component interface is not sufficient. Dynamic information such as the description of valid sequences of operations is required. In this paper we propose a mathematical model and a formal language to describe the knowledge about behavior We rely on a hierarchical model of deterministic finite state-machines. The execution model of these state-machines follows the Synchronous Paradigm. We focus on extension of components, owing to the notion of behavioral substitutability. A formal semantics for the language is defined and a compositionality result allows us to get modular model-checking facilities. From the language and the model, we can draw practical design rules that are sufficient to preserve behavorial substitutability. Associated tools may ensure correct (re)use of components, as well as automatic simulation and verification, code generation, and run-time checks.

Variations on the semantics of graphical models for reactive systems

The goal of this paper is to study concepts underlying graphical instant-based models. They are useful for reactive system modeling. They should be formal models (mathematical semantics). Some are able to express in an unambiguous and concise way complex reactive behaviors. The expressiveness may be an impediment to the readability and the intuitive understanding. We analyze the influence of some primitives on the computation (compilation or interpretation) of the behavior.

Distributed Intelligent Medical Assistant for Osteoporosis Detection

This paper describes a distributed knowledge- based system managing medical image processing programs to assist physicians in establishing image analysis protocols. We rely on program supervision techniques that aim to automatically plan and control complex software usage. Our main contribution is to allow physicians who are not experts in computing to efficiently use various osteoporosis detection programs in a distributed environment. A distributed supervision system allows either to simply consult knowledge bases, or to execute remote queries, or to collaborate with distant partners to design knowledge bases and programs.

Open Implementation of UML Meta-model(s) Making Meta-modeling and Meta-programming Meet

From the origin the UML meta-model has been a valuable mechanism to describe the semantics of UML models as well as to extend UML itself. However the approach is purely declarative. In particular the meta-model does not define any behavior nor operation. Thus the implementation of UML CASE tools cannot directly benefit from it, nor can the realization of UML extensions.

Semantic Studies of a Synchronous Approach to Activity Recognition

Many important and critical applications such as surveillance or healthcare require some form of (human) activity recognition. Activities are usually represented by a series of actions driven and triggered by events. Recognition systems have to be real time, reactive, correct, complete, and dependable. These stringent requirements justify the use of formal methods to describe, analyze, verify, and generate effective recognition systems. Due to the large number of possible application domains, the researchers aim at building a generic recognition system. They choose the synchronous approach because it has a well-founded semantics and it ensures determinism and safe parallel composition. They propose a new language to represent activities as synchronous automata and they supply it with two complementary formal semantics. First a behavioral semantics gives a reference definition of program behavior using rewriting rules. Second, an equational semantics describes the behavior in a constructive way and can be directly implemented. This paper focuses on the description of these two semantics and their relation.

Model, Notation, and Tools for Verification of Protocol-Based Components Assembly

Assembly of blackbox components is made difficult by the lack of precise information on the way components interact. What is needed is a behavioral model of the component, at the input and output interface levels. This paper introduces the notion of behavioral points of view and an associated graphical notation, SyncClass, to represent such a model. The underlying semantics of SyncClass makes it possible to automatically verify component assembly, either for individual components or for a whole system.