Mohamed Hadj Kacem

Describing dynamic software architectures using an extended UML model

In this paper, we propose a new UML2.0 profile to describe the change of software architectures. The profile introduces a set of stereotypes for modeling the structural and the dynamic aspect as well as architectural constraints. We adapt the component diagrams metamodel on specific purposes by extending existing metaclasses. The adaptations are defined using stereotypes which are grouped in a profile. The profile offers to the architects an intuitive and complete way to specify the software architecture based on visual notations.

Antioxidant and anti-inflammatory effects of Ruta chalepensis L. extracts on LPS-stimulated RAW 264.7 cells

Ruta chalepensis L. is used in the traditional herbal treatment of various diseases. The aim of this work is to investigate the effect of different extracts of R. chalepensis L. on inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) gene expressions and their antioxidant capacity on murine RAW 264.7 macrophage challenged with lipopolysaccharide (LPS). In fact, this study shows that the ethanol and ethyl acetate extracts of R. chalepensis L. considerably decreased the nitric oxide (NO) production in murine RAW 264.7 macrophages stimulated with lipopolysaccharide. Thus, the treatment with both extracts significantly suppressed the levels of iNOS and COX-2 gene expressions through the inhibition of the nuclear factor-κB (NF-κB) activation. The preincubation of RAW 264.7 cells with various concentrations of ethanol and ethyl acetate extracts decreased the production of thiobarbituric acid-reactive substances (TBARS) in a dose-dependent manner. It also increased the activities of antioxidative enzymes, including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in LPS-stimulated macrophages, compared to those in the cells treated only with LPS. Besides, the 1H NMR spectra of both extracts have demonstrated the presence of aromatic signals, thus confirming the existence of phenolic compounds such as flavonoids and polyphenols. So, the ethanol and ethyl acetate extracts of R. chalepensis L. have been shown to possess enough antioxidant and anti-inflammatory activities to prevent LPS-induced oxidative stress and inflammation in RAW 264.7 macrophages.

An UML-based approach for validation of software architecture descriptions

UML became a standard for modeling distributed architectures. The development process produces models representing architecture according to different views and different abstraction levels. These models must be valid and coherent together, so the architecture description and its evolutions have to be logical and interpretable. This paper, proposes to define intra and inter profile validations rules enabling one to define the basic elements of each profile, to minimize the modeling errors and to ensure the architecture conformity to its meta-model.

Modeling and enforcing invariants of dynamic software architectures

In this paper, we propose an “end-to-end” approach that supports dynamic reconfiguration of software architectures taking advantage of graphical modeling, formal methods and aspect-oriented programming. There are three ingredients of the proposal. The specification end of the solution is covered by a new UML profile enabling to specify the desired architectural style (model), its invariants and the intended reconfiguration operations. In order to verify the consistency of the model and the preservation of the invariants after every reconfiguration, we automatically generate formal specifications in Z notation from the defined model. At the runtime enforcing end of the solution, we propose to encode the enforcement logic as aspect in the AspectJ language. The third important ingredient that makes our approach end-to-end is the automatic translation of formal specifications into aspect-based enforcement code.

A refinement-based approach for building valid SOA design patterns

Although design patterns have become increasingly popular, most of them are presented in an informal way, which can give rise to ambiguity and may lead to their incorrect usage. Patterns proposed by the SOA design pattern community are described with informal visual notations. Modelling SOA design patterns with a standard formal notation contributes to avoid misunderstanding by software architects and helps endowing design methods with refinement approaches for mastering system architectures complexity. In this paper, we present a formal refinement-based approach that aims, first, to model message-oriented SOA design patterns with the SoaML standard language, and second to formally specify these patterns at a high level of abstraction using the Event-B method. These two steps are performed before undertaking the effective coding of a design pattern providing correct by construction pattern-based software architectures. Our approach is experimented through an example we present in this paper. We implemented our approach under the Rodin platform, which we use to prove model consistency.

A multi-scale modelling perspective for SoS architectures

Software architectures for System of Systems (SoS) is an important research area. The design of an SoS can be organized around a set of architectural transformation models. In this paper, we propose a multi-scale modeling approach for SoS architecture description mastering the description details complexity. The proposed design approach is founded on SysML (System modeling language) notations and uses block diagrams. The diagrams are subject to vertical and horizontal transformations for refinement, since reaching a fine-grain description representing the necessary details. The intermediate models provide a description with a given abstraction that allow the validation to be conducted significantly while remaining tractable w.r.t. complexity. The validation scope can involve intrinsic properties ensuring the model correctness w.r.t. SysML description (eg. interface compatibility). An SoS architecture will provide these intrinsic properties, to have a precise model of the SoS architecture (its constituents and the connections between them). We adopt a rule-oriented description technique. The rules manage the refinement process as a model transformation between the coarse-grain and the fine-grain descriptions. We experimented our approach by a case study modeling an Integrated Air Defense (IAD) SoS using SysML models.

Building correct by construction SOA design patterns: modeling and refinement

Modeling SOA design patterns with a standard formal notation avoids misunderstanding by software architects and helps endow design methods with refinement approaches for mastering system architectures complexity. In this paper, we propose a formal architecture-centric approach that aims to model message-oriented SOA design patterns with the SoaML standard language. Pattern models are developed in a stepwise manner which are then automatically translated into Event-B specifications that can be proved using the Rodin theorem prover. These two steps are performed before undertaking the effective coding of a design pattern providing correct by construction solutions. Our approach is experimented through pattern examples.

Towards an approach for modeling and formalizing SOA design patterns with Event-B

This paper introduces a formal architecture-centric approach, which allows first to model message-oriented SOA design patterns with the SoaML standard language, and second to formally specify these patterns at a high level of abstraction using the Event-B method. These two steps are performed before undertaking the effective coding of a design pattern providing correct by construction pattern-based software architectures. We implement our approach under the Rodin platform which we use to prove model consistency.

Software Architectures: Multi-Scale Refinement

We propose a multi-scale modeling approach for complex software system architecture description. The multi-scale description may help to obtain meaningful granularities of these systems and to understand and master their complexity. This vision enables an architect designer to express constraints concerning different description levels, oriented to facilitate adaptability management. We define a correct-by-design approach that allows a given abstract architectural description to be refined into architecture models. We follow a progressive refinement process based on model transformations; it begins with a coarse-grain description and ends with a fine-grain description that specifies design details. The adaptability property management is performed through model transformation operations. The model transformation ensures the correctness of UML description, and the correctness of the modeled system. We experimented our approach with a use case that models a smart home system for the monitoring of elderly and disabled persons at home.

An Approach for SOA Design Patterns Composition

Software design patterns provide architects and developers with reusable software elements helping them to master building complex software systems. Nevertheless, presented in an informal way, software design patterns may give rise to ambiguity and may lead to their incorrect usage as well as incorrect compositions. We focus here on SOA design patterns composition and we propose a precise definition of the composition process with the semi-formal SoaML standard language. In this paper, we present an approach for composing SOA design patterns. The notion of patterns composition is defined based on two operators. The application of composition rules and the concretization of merging operators lead to the final description of the resulting compound pattern. Our approach covers both structural and behavioral features of composed patterns. To help non-specialists understanding the proposed approach, we illustrate it in details through the compound Service Broker pattern.