Christian Attiogbé

Checking component composability

Component-Based Software Engineering (CBSE) is one of the approaches to master the development of large scale software. In this setting, the verification concern is still a challenge. The current work addresses the composability of components and their services. A component model (Kmelia) is introduced; an associated formalism, simple but expressive is introduced; it describes the services as extended LTSs and their structuring as components. The composability of components is defined on the basis of the composability of services. To ensure the correctness of component composition, we check that an assembly is possible via the checking of the composability of the linked services, and their behavioural compatibility. In order to mechanize our approach, the services and the components are translated into the Lotos formalism. Finally the Lotos CADP toolbox is used to perform experiments.

Integration of formal datatypes within state diagrams

In this paper, we present a generic approach to integrate datatypes expressed using formal specification languages within state diagrams. Our main motivations are (i) to be able to model dynamic aspects of complex systems with graphical user-friendly languages, and (ii) to be able to specify in a formal way and at a high abstraction level the datatypes pertaining to the static aspects of such systems. The dynamic aspects may be expressed using state diagrams (such as UML or SDL ones) and the static aspects may be expressed using either algebraic specifications or state oriented specifications (such as Z or B). Our approach introduces a flexible use of datatypes. It also may take into account different semantics for the state diagrams.

Composing components with shared services in the Kmelia model

The Kmelia abstract componentmodel is extended to allow the description of component compositions with multipart interactions leading to simultaneous communications between more than two services. Shared services are defined to explicitly control multipart interactions. Accordingly the communication actions of Kmelia are extended. The formal definitions of the Kmelia model, the composition of components via their services and their analysis are revisited to integrate the extension of the model. An example illustrates the need and the usage of shared services.

Specification of an access control system with a formalism combining CCS and CASL

Multi-formalism specifications are essential for the modelling of complex systems including different aspects such as data or concurrency. We advocate a formalism which combines the CCS process algebra with the CASL algebraic specification language. Formal foundations of this combination are presented following two steps, the syntax and the semantics. Our proposal is illustrated with a real size case study: an access control system to a set of buildings. With this concrete example, we aim at showing how our formalism proposal could be used to specify a comprehensive application.

Defining component protocols with service composition: illustration with the Kmelia model

We address in this article the description and usage of component protocols viewed as specific services. In addition to inter-component service composition, our Kmelia component model supports vertical structuring mechanisms that allow service composition inside a component. The structuring mechanisms (namely state annotation and transition annotation) are then used to describe protocols which are considered here as component usage guides. These structuring mechanisms are integrated in the support language of our component model and are implemented in our COSTO toolbox. We show how protocol analysis is performed in order to detect some inconsistencies that may be introduced by the component designers.

Formal framework for a generic combination of a process algebra with an algebraic specification language: an overview

In this paper, we suggest a formal framework as a basis for a genetic combination of formal languages. This makes it possible for the developer to specify the dynamic part of a system with a process algebra, and the static part with an algebraic specification language. The framework is based on a formal kernel composed of an abstract grammar describing the general form of the combination, and a global operational semantics giving the meaning of each language which can be built with our framework.

Using Assertions to Enhance the Correctness of Kmelia Components and their Assemblies

The Kmelia component model is an abstract formal component model based on services. It is dedicated to the specification and development of correct components. This work enriches the Kmelia language to allow the description of data, expressions and assertions when specifying components and services. The objective is to enable the use of assertions in Kmelia in order to support expressive service descriptions, to support client/supplier contracts with pre/post-conditions, and to enhance formal analysis of component-based systems. Assertions are used to perform analysis of services, component assemblies and service compositions. Additionally we enable the definition of virtual contexts for required services and the corresponding observable state space for the components which provide the services. We illustrate the work with the verification of consistency properties involving data at component and assembly levels.

Adaptation for Hierarchical Components and Services

Software coordination and adaptation are tightly related to modular software entities and access points. These entities (components or services) may be complex, dissimilar (various models) and designed at different granularity levels. In order to allow interoperability we need rich interface descriptions including service hierarchisation, flexible declarations and precise specifications. In this article we present a Hierarchical Behavioural interface description language that enables the structuring of services, their encapsulation and it also facilitates the use of component interfaces. We also investigate in this work the adaptation for Hierarchical Behavioural IDL. We recall various adaptation problems and we introduce modelling techniques and some solutions within hierarchical context considering precision of the interfaces, their layering and flexibility.

A Formal and Tool-Equipped Approach for the Integration of State Diagrams and Formal Datatypes

Separation of concerns or aspects is a way to deal with the increasing complexity of systems. The separate design of models for different aspects also promotes a better reusability level. However, an important issue is then to define means to integrate them into a global model. We present a formal and tool-equipped approach for the integration of dynamic models (behaviors expressed using state diagrams) and static models (formal data types) with the benefit to share advantages of both: graphical user-friendly models for behaviors, formal and abstract models for data types. Integration is achieved in a generic way so that it can deal with both different static specification languages (algebraic specifications, Z, B) and different dynamic specification semantics

A method to combine any process algebra with an algebraic specification language: the /spl pi/-calculus example

We introduce in (Salaun et al., 2001) the formal foundations to make a generic combination of one process algebra and one algebraic specification language possible. Furthermore, to strengthen the contribution of this work, a concrete illustration about an orders invoicing case study is detailed in (Salaun et al., 2001). In this paper, we especially focus on the addition of other languages; indeed in the initial work, we only consider a restricted number of process algebras: CCS, CSP, ACP, basic LOTOS. Therefore, we aim at formalizing the way to extend the previous combination. To achieve this goal, we present a method to enhance the syntax and semantics of the formal kernel introduced in (Salaun et al., 2001). These guidelines are illustrated with the /spl pi/-calculus.