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 Operational Semantics Dedicated to the Coordination of Cooperating Agents

Abstract. This paper presents a contribution towards rigourous reasoning about coordinating agents. First, it defines formal models for coordination and coordinating agents. These models enable to specify the relations between the concepts of: plan, plan proposal and resource allocation, on the one hand, and concepts of: knowledge, belief and capability, on the other hand. Second, it provides a structured coordination language enabling to specify primitives, protocols and processes of coordination. This language is defined by a precise syntax, and it is formally interpreted using a transition system leading to an operational semantics for coordinating agents

Assessing the performance of a serological point-of-care test in measuring detectable antibodies against SARS-CoV-2

This study investigated the performance of a rapid point-of-care antibody test, the BioMedomics COVID-19 IgM/IgG Rapid Test, in comparison with a high-quality, validated, laboratory-based platform, the Roche Elecsys Anti-SARS-CoV-2 assay. Serological testing was conducted on 709 individuals. Concordance metrics were estimated. Logistic regression was used to assess associations with seropositivity. SARS-CoV-2 seroprevalence was 63.5% (450/709; 95% CI 59.8%-67.0%) using the BioMedomics assay and 71.9% (510/709; 95% CI 68.5%-75.2%) using the Elecsys assay. There were 60 discordant results between the two assays, all of which were seropositive in the Elecsys assay, but seronegative in the BioMedomics assay. Overall, positive, and negative percent agreements between the two assays were 91.5% (95% CI 89.2%-93.5%), 88.2% (95% CI 85.1%-90.9%), and 100% (95% CI 98.2%-100%), respectively, with a Cohen’s kappa of 0.81 (95% CI 0.78–0.84). Excluding specimens with lower (Elecsys) antibody titers, the agreement improved with overall, positive, and negative percent concordance of 94.4% (95% CI 92.3%-96.1%), 91.8% (95% CI 88.8%-94.3%), and 100% (95% CI 98.2%-100%), respectively, and a Cohen’s kappa of 0.88 (95% CI 0.85–0.90). Logistic regression confirmed better agreement with higher antibody titers. The BioMedomics COVID-19 IgM/IgG Rapid Test demonstrated good performance in measuring detectable antibodies against SARS-CoV-2, supporting the utility of such rapid point-of-care serological testing to guide the public health responses and vaccine prioritization. © 2022 Coyle et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

SARS-CoV-2 seroprevalence in the urban population of Qatar: An analysis of antibody testing on a sample of 112,941 individuals

ABSTRACTBackgroundQatar has experienced a large SARS-CoV-2 epidemic. Our first objective was to assess the proportion of the urban population that has been infected with SARS-CoV-2, by measuring the prevalence of detectable antibodies. Our second objective was to identify predictors for infection and for having higher antibody titers.MethodsResidual blood specimens from individuals receiving routine and other clinical care between May 12-September 9, 2020 were tested for anti-SARS-CoV-2 antibodies. Associations with seropositivity and higher antibody titers were identified through regression analyses. Probability weights were applied in deriving the epidemiological measures.ResultsWe tested 112,941 individuals (∼10% of Qatar’s urban population), of whom 51.6% were men and 66.0% were 20-49 years of age. Seropositivity was 13.3% (95% CI: 13.1-13.6%) and was significantly associated with sex, age, nationality, clinical-care type, and testing date. The proportion with higher antibody titers varied by age, nationality, clinical-care type, and testing date. There was a strong correlation between higher antibody titers and seroprevalence in each nationality, with a Pearson correlation coefficient of 0.85 (95% CI: 0.47-0.96), suggesting that higher antibody titers may indicate repeated exposure to the virus. The percentage of antibody-positive persons with prior PCR-confirmed diagnosis was 47.1% (95% CI: 46.1-48.2%), severity rate was 3.9% (95% CI: 3.7-4.2%), criticality rate was 1.3% (95% CI: 1.1-1.4%), and fatality rate was 0.3% (95% CI: 0.2-0.3%).ConclusionsFewer than two in every 10 individuals in Qatar’s urban population had detectable antibodies against SARS-CoV-2 between May 12-September 9, 2020, suggesting that this population is still far from the herd immunity threshold and at risk from a subsequent epidemic wave.</jats:sec

Modélisation des applications distribuées à architecture dynamique : Conception et Validation

The Adaptability of networked service-oriented systems is necessary to guarantee the continuity of services under changing infrastructure constraints and evolving user requirements. The architectural and the behavioural dynamic reconfigurations constitute the two acting categories allowing adaptability of such software systems to be managed.We propose to support the architectural reconfiguration-based adaptation and we propose a UML-based approach for describing, validating and checking dynamic software architectures. We elaborate a new UML profile associated with three meta-models that we define in order to describe (i) different architectural styles, (ii) their dynamic instances together with the associated reconfiguration operations, and (iii) their reconfiguration protocol. Our approach supports describing the architectural constraints that should be preserved during architecture evolving. The proposed approach supports automatic validation through a set of rules we define and implement for ensuring the correctness of the models w.r.t. the meta-models. These models are automatically transformed into Z specifications. This allows designers to prove, by elaborating Z theorems, the consistency of the defined architectural styles and the conformity of the associated instances and their transformation rules. We define a Design Process, called X, allowing guiding and assisting the architects to model the dynamic software architectures. The X Design Process is partially based on the MDA approach and 2TUP Process. Our design process is based on PIM and PSM parts. The proposed design process uses an iterative and incremental development approach and it is architecture-centric. A software environment supporting the different features of this approach has been developed and integrated as a plug-in in the open-source FUJABA tool. The plug-in is available at URL: http://www.laas.fr/~khalil/TOOLS/X.zip.Nos travaux de recherche consistent à apporter des solutions de modélisation conformément à l'approche MDA. Nos recherches consistent à fournir des solutions permettant de guider et d'assister les activités de modélisation des architectures logicielles. Il s'agit principalement de proposer une démarche de conception orientée modèle permettant de décrire l'architecture logicielle en tenant compte de trois aspects : le style architectural, les opérations de reconfiguration et le protocole de reconfiguration.Nous proposons des notations visuelles permettant de décrire de façon compatible avec UML 2.0 l'architecture logicielle. La technique de description que nous adoptons est orientée règles, basée sur les théories de transformation de graphe, permettant, ainsi, de décrire la dynamique structurelle.Nous proposons une extension d'UML 2.0 par un nouveau profil formé de trois méta-modèles. Nous proposons aussi une approche de validation basée sur des règles intra-modèle et des règles inter-modèles. Nous adoptons également une approche de vérification. Cette approche permet, dans une première étape, une transformation automatique du style architectural et de chaque opération de reconfiguration vers le langage Z. Elle permet dans une deuxième étape, de vérifier la consistance du style architectural et la conformité de l'évolution d'une architecture vis-à-vis de son style architectural. Nous utilisons le système de preuve Z/EVES. Finalement, nous proposons une démarche de modélisation des architectures logicielles dynamiques, appelée X, permettant de décrire les différentes étapes pour modéliser l'architecture logicielle. La démarche proposée est inspirée de la méthode MDA et 2TUP.Le profil et la démarche X que nous avons proposés ont fait l'objet d'une implémentation et d'une intégration, sous forme de plug-in java, dans l'atelier d'aide à la conception FUJABA. Le plug-in implémenté est disponible sur l'URL : http://www.laas.fr/~khalil/TOOLS/X.zip

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 dy-namic 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 pro-file offers to the architects an intuitive and complete way to specify the software architecture based on visual notations. Categories and Subject Descriptor

An Approach for Modeling and Formalizing SOA Design Patterns

11 pagesInternational audienceAlthough design patterns has 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. Modeling 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 architecture-centric 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 patternbased 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

Towards an Approach for Modeling and Formalizing SOA Design Patterns with Event-B

International audienceThis 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

Modeling and refinement SOA design patterns with Event-B method

20 pagesUsing design patterns has become increasingly popular. Most design patterns are proposed in an informal way, which can give rise to ambiguity and may lead to incorrect usage. Patterns, proposed by the SOA design pattern community, are described with an appropriate notation. So they require modeling with a standard notation and then formalization. In this paper, we propose a formal architecture-centric 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 language. These two steps are performed before undertaking the effective coding of a design pattern providing correct by design solutions. 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

Towards an Approach for Modeling and Formalizing SOA Design Patterns with Event-B

International audienceThis 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