Medical Cyber-Physical Systems (MCPS) play an increasingly critical role in smart healthcare environments. However, the integration of these systems with opaque AI models introduces significant challenges in terms of transparency, traceability, and verifiability. To address these issues, we propose ExMCPS - a model-driven framework that combines ModelBased Systems Engineering (MBSE), Explainable Artificial Intelligence (XAI), and formal modeling techniques to design MCPS that are both explainable and verifiable throughout their lifecycle. We also present a methodological pipeline and an evaluation plan to clarify the applicability of our approach.

Deep Neural Networks (DNN) have recently driven a revolution in various fields of Artificial Intelligence (AI), especially in Deep Learning (DL). However, they remain difficult to design, implement, verify, adapt, and reuse. To address these challenges, this paper introduces DNN-SL, a Domain-Specific Modeling Language (DSML) designed specifically for modeling and verifying DNN architectures. Our approach combines Model-Driven Engineering (MDE) with formal methods to define a multi-layer framework consisting of a DSML definition layer, an MDE implementation layer, and a Maude-based formal semantics layer. This architecture enables DNN models to automatically be translated into formal Maude specifications, thus facilitating the verification of properties including robustness and interpretability. By combining intuitive modeling with formal rigor, our solution simplifies the development of reliable and accessible DL, even for non-experts.

In the era of Big Data, where data are continuously and exponentially generated, secure collection of massive volumes of data is essential for enabling effective analysis using advanced techniques such as machine learning. These methods facilitate extracting meaningful insights from structured, semi-structured, or unstructured data generated by websites, devices, and sensors at high velocities. Securing this data, analyzed by modern machine learning techniques (e.g., linear regression) and subjected to continuous streams, presents a significant challenge due to its volume and diverse formats. Traditional security and privacy methods prove inadequate in addressing these complex challenges. As a result, the security and efficiency issue for big data collection still deserves research. This paper proposes a secure mechanism for big data collection offering an unprecedented opportunity for predictive analysis and decision-making for improved security performance and efficiency. Differential confidentiality emerges as a promising solution for business data and confidential data collection. The collected big data is stored securely using DiffPrivLib. The discussion and performance evaluation results show the security and efficiency of the proposed secure mechanism. With the implementation of differential confidentiality on the collected data, the results of the data analysis presented an accuracy of 0.91 which shows a very important efficiency of the system to classify correctly the instances.

Artificial intelligence has transformed the automotive industry, giving rise to safer and more comfortable semi-autonomous vehicles. This review evaluates the critical role of recommendation systems in the development of autonomous driving and compares them to advanced driver assistance systems (ADAS). These systems go above and beyond typical ADAS by providing personalized driving experiences, enhancing route planning based on real-time data, and enhancing driver comfort and safety through proactive actions. The main objective of this review is to critically analyze and explain different approaches to recommendation systems for autonomous vehicles based on their algorithms, data sources, strengths, and weaknesses. This review focuses specifically on the role of personalization technologies in adapting the driver assistant to his or her individual preferences and vehicle environment data. Our analysis highlights key challenges and opportunities for future research, including addressing data limitations and evaluating system performance in complex real-world scenarios.

Abstract In our research, we established a medical annotation model in the form of an ontology in an effort to ensure data interchange amongst medical annotation systems. We employ the “patient partner” approach to involve the patient in the medical annotative activity. In fact, the patient will be able to register, annotate, and comprehend the comments made in his medical file utilizing this new paradigm.

Abstract In the literature, a wide number of annotation systems in the e-health sector have been implemented. These systems are distinguished by a number of aspects. In fact, each of these systems is based on a different paradigm, resulting in a jumbled and confused vision. The purpose of this study is to categorize medical annotation systems in order to provide a standardized overview. To accomplish this, we combed through twenty years’ worth of scientific literature on annotation systems. Then, we utilized five filters to determine which systems would proceed to the classification phase. The following filters have been chosen: accessible, free, web-based or stand-alone, easily installable, functional, availability of documentation. The classification step is performed on systems that evaluate “true” for all of these filters. This classification is based on three modules: the publication module, the general information module and the functional module. This research gave us the chance to draw attention to the issues that healthcare professionals may face when using these systems in their regular work.

Abstract The coronavirus known as COVID-19 is the topic of the hour all over the world. This virus has invaded the world with its invariants, which are characterized by their rapid spread. COVID-19 has impacted the health of people and the economy of countries. For that, laboratories, researchers, and doctors are in a race against time to find a cure for this pandemic. To combat this virus, cutting-edge technologies such as artificial intelligence, cloud computing, and big data have been put in place. In our work, we use Internet of Things (IoT) technology. The use of IoT in an efficient way can lead to detecting infected people and avoiding being contaminated. In this paper, we are interested in the remote medical monitoring of patients who have tested positive for COVID-19. We propose a meta-modeling technique to model the IoT architecture. Then we implement two IoT solutions that permit the remote medical monitoring of patients infected with COVID-19 and the respect of social distancing by instantiating correct models that conform to the proposed meta-model in order to mitigate the COVID-19 outbreak.

Summary Modeling and specifying correct software systems is a challenging task that can be supported by providing appropriate modeling abstractions. This article proposes an approach for graphical multiscale modeling of such systems using model transformation techniques. The approach is founded on a guided rule‐based iterative modeling process ensuring controlled transition from a coarse‐grained description to a fine‐grained description. It provides also user‐friendly graphical descriptions by extension of UML notations, hence preserving the common practices from software architectures design. The iterative design process is supported by a set of model transformation rules. The rules manage the refinement process (by adding or removing subsystems or by adding or removing details on a given subsystem) as a model transformation. Our approach is supported by a rule‐based generator that implements the automatic transformation of UML diagrams into Event‐B specifications allowing formal verification of their correctness properties, and relieving software architects of mastering formal techniques. To experiment and validate our approach, we consider a case study dedicated to the smart cities.

Summary Wireless sensor networks (WSNs) are composed of sensors exchanging the information that they collect from the environment. The use of a scheduler offers an efficient solution to eliminate information redundancy and possible collisions in this network. A scheduler is responsible for choosing the sensors to exchange information at each step of the algorithm's execution. This article presents a WSN handshake algorithm (WSN‐HS) scheduling the communications between every two sensors safely in an exclusive mode. Our WSN‐HS is energy‐efficient. It tries to elaborate communications between sensors with the minimum of messages and thus with the minimum of energy consumption. In addition, our algorithm is fault‐tolerant to sensors' disappearance. Hence, when a sensor runs out of energy, the other sensors in the network will not be blocked and they will continue executing the distributed algorithm. We compare and evaluate our algorithm with another handshake algorithm. The results of the simulation done with two examples of distributed algorithms show that our algorithm significantly minimizes the energy consumption in the WSN. Moreover, in this article, we detail the analysis that emphasizes the efficiency of our WSN‐HS algorithm.

Abstract The architecture of distributed systems is subject to certain failures: component failure, downed connections etc. These failures come from the dynamicity and complexity of these systems. As a solution to cure this weakness, adaptation plans can be added. However, the main difficulty of self‐adaptation emerges while considering the soundness of the adaptation and preservation of stylistic constraints of the system. The MeidyaCoM ‐ Policy , an architecture‐centric approach for modelling and checking repair policies to guarantee the success of the adaptation, is presented. This approach is a solution for applying self‐healing. A new unified modelling language (UML) profile that provides a visual notation for modelling repair policies is proposed to automatically transform UML models to Z notation using transformation rules coded in eXtensible styles language transformation (XSLT) language. These specifications are implemented under the Z/EVES theorem prover to prove specification soundness and consistency to guarantee the success of the adaptation. MeidyaCoM ‐ Policy applies to all architectural styles. It is instantiated for the publish/subscribe style and illustrated with a case study. An outline of the developed software environment is provided.

Aging often involves a significant change in roles and social positions. The greatest health risk for seniors is the adoption of a sedentary lifestyle that causes isolation, depression, and many diseases. However, convincing an older adult to regularly do physical activities is not generally a simple mission. This paper proposes a personalized and contextualized persuasion system to promote physical activities for older adults. In fact, our approach considers the personal and health profile of the older adult. It also considers different context parameters (context-awareness). This intelligence is guaranteed thanks to the use of the semantic modeling and reasoning, which from different types of information would be able to decide the best moment to trigger notifications from our persuasive system to the participating older adults.

The annotation practice is an almost daily activity; it is used by healthcare professionals (PHC) to analyze, collaborate, share knowledge and communicate, between them, information present in the healthcare record of patients. These annotations are created in a healthcare cycle that consists of: diagnosis, treatment, advice, follow-up and observation. Due to an exponential increase in the number of medical annotation systems that are used by different categories of health professionals, we are faced with a problem of lack of organization of medical annotation systems developed on the basis of formal criteria. As a result, we have a fragmented image of these annotations tools which make the mission of choice of an annotation system by a PHC, in a well-defined context (biology, radiology…) and according to their needs to the functionalities offered by these tools, are difficult. In this article we present a classification of thirty annotation tools developed by industry and academia based on 5 generic criteria. We conclude this survey paper with model proposition.

With the advent of the web 2.0, user-centric, consumers are increasingly becoming producers of information. He can express his opinions on the monetary exchange of goods, services and information through annotations. An annotation takes many different forms and is used for many different functions. This annotative activity is carried out by systems specially developed to annotate the products or services of an online commerce web site. In the literature, many tools have been developed to annotate various products and services. In this article, we present a classification of thirty annotation tools developed by industry and academia. This organization of annotation tools is built on the basis of functionalities that they offer. From this classification, we present our observations and the limits of these systems.

Summary Modeling Cyber‐physical systems (CPS) is a challenging step that requires a lot of background from both the cyber and physical fields. However, there is a lack of studies in the existing literature that discuss the state of the art in modeling CPS or explore the research gaps in this area. In this paper, we survey existing approaches to modeling CPS. We focus on studying the considered CPS properties. Based on this study, we classify these properties and discuss their importance in different application domains. Moreover, research directions are presented to address key challenges in the specification of CPS models.

Today, developing self-adaptive systems is very challenging due to their increasing complexity and dynamism. Consequently, ensuring the correctness of their behavior is a difficult task. In this paper, we present a survey of the different existing approaches proposing the formal verification of self-adaptive systems. To that aim, we discuss several related works in the field. Then, we present a taxonomy of these researches based on some criteria. After that, we present a rich discussion and a comparison between the different existing works. Finally, we identify some perspectives and challenges which can enhance the formal verification of self-adaptive systems.

Cyber‐physical systems (CPSs) are characterized by a multitude of physical and software. Particularly time‐related properties are of paramount importance and they can impact the behaviour of these systems. Designing and verifying CPS while tackling time‐related and physical properties are very important steps in the CPS life cycle development. Indeed, it is necessary to capture and characterize the different features and their dependencies with time through expressive models. Then, these models must be verified to prove their correctness. Existing process modelling languages such as business process modelling notation (BPMN) has been widely used to model business processes. However, BPMN lacks several features for modelling rich CPS processes such as those related to time and physical properties. In this study, the authors propose a verification framework for collaborative time‐aware CPS processes. In this context, they propose to extend BPMN to support the various CPS concepts and properties. Based on this extension, they propose a consistency verification approach, which aims to verify that the time‐related and physical properties associated with each process do not give rise to conflicts. Finally, they propose a compatibility verification approach, which aims to verify that the set of involved CPS processes form consistent inter‐CPS processes.

During the learning process, learners' activities are numerous and especially varied. This diversification is important to both educational plans and psychological plans. Thus, learner can choose to read, write, listen, discuss, experiment, or annotate various resources to achieve his learning goals. Among these activities, we focus in our research on the annotative activity of learner because annotation practice is very common and omnipresent. While reading, learner usually uses comments, highlights, circles sections and posts it to annotate the consulted resources. So, we propose an approach of recommendation of web services from the learner's annotative activity to assist him in his learning activates. This process of recommendation is based on two preparatory phases: the phase of modelling learner's personality profile through analysis of annotation digital traces in learning environment realized through a profile constructor module and the phase of discovery of web services which can meet the goals of annotations made by learner via the web service discovery module. The evaluation of these two main modules (web service discovery module and profile constructor module) through empirical studies realized on groups of learners based on the Student's t-test showed significant results.

Distributed algorithms have become a rapidly growing field of research due to the advances of the network technologies. However, they are very difficult to implement correctly because they must meet many requirements. In this paper, we follow the guidelines of systematic literature reviews to provide a survey of the existing works ensuring the formal verification of distributed algorithms in static and dynamic networks. Then, we develop a taxonomy of these solutions based on some criteria. Also, a discussion on each criterion is shown with a focus on constraints, requirements and challenges. Finally, we identify some recommendations and open research areas which can motivate the development of more efficient solutions. So, throughout this present paper, we provide information for researchers and developers to understand the contributions and challenges of the existing solutions to pave the way for enhancing their reliability.

Nowdays, Cloud computing has gained a particular attention to run dynamic workflow applications. Nevertheless, due to lack of formal description of the resource perspective in dynamic workflows, the behavior of Cloud resource allocation cannot be correctly managed. In this paper, we aim at formally verifying the correctness of dynamic workflow changes in a Cloud environment using the Event-B method. More precisely, we propose a formal model which aims to preserve the correctness of workflow properties at both design time and runtime. We have considered properties related to control flow and resource perspectives.

Managing and processing BigData in geo-distributed datacenters gain much attention in recent years. Despite the increasing attention on this topic, most efforts have been focused on user-centric solutions, and unfortunately much less on the difficulties encountered by Cloud providers to improve their profits. Highly efficient framework for geo-distributed BigData processing in cloud federation environment is a crucial solution to maximize profit of the cloud providers. The objective of this paper is to maximize the profit for cloud providers by minimizing costs and penalty. This work proposes to transfer compute (computations) to geo-distributed data and outsourcing only the desired data to idles resources of federated clouds in order to minimize job costs; and proposes a jobs reordering dynamic approach to minimize the penalties costs. The performance evaluation proves that our proposed algorithm can maximize profit, reduce the MapReduce jobs costs and improve utilization of clusters resources.

Self-adaptive systems are able to adjust au-tonomously their behavior when the software or hardware is not accomplishing what it is intended to do. The MAPE control loop, based on the following components: Monitor, Analyze, Plan and Execute, is a prominent approach for realizing adaptation. Engineering complex self-adaptive systems needs the use of several architectural patterns in a composed form in their designs. In this paper, we focus on modeling compound MAPE patterns for decentralized control in self-adaptive systems and defining formally the composition process using the Event-B method. The composition of design patterns is illustrated by the composition of the master/slave and the coordinated control patterns.

The aim of this work is to propose a distributed algorithm, encoded by the local computations model, for computing maximal cliques in dynamic networks.This model provides an abstraction which simplifies the design and the proof of distributed algorithms.To guarantee the correctness of our algorithm, we use the Event-B formal method, which supports a refinement based incremental development using the RODIN platform.

Cloud computing has gained tremendous attention by provisioning resources and Multi-Tenant Business Process (MTBP) as a service. To dynamically support the workload demand variation, elasticity holds the promise of ensuring the Quality of Service (QoS) of the MTBP by providing the required involved service instances while keeping a low cost for the service providers. However, involved services invocation is constrained by hard timing constraints and the service provider is subject to pay penalty costs if services are not correctly executed. This problem is more complex when dealing with time-dependent elasticity mechanisms that can change according to the execution time. Unlike the static mechanism, which has been studied in the existing approaches, time-dependent elasticity mechanisms are insufficiently taken into consideration. In this paper, we propose a novel stochastic optimization approach considering the time-dependent of elastic MTBP. This approach aims at offering a method that assists service providers to find the optimal pricing strategy for involved services used by process under uncertain parameters. The implementation using a real workload shows the elasticity performance of the MTBP which is demonstrated by experimental results.

Wireless Sensor Networks (WSNs) are widely used in critical applications (health-care, transport, volcanic eruption monitoring, etc.). Any design error in WSN algorithms can be harmful for the human's life. Therefore, we should be sure that WSN algorithms work correctly from the very first design stages. In this paper, we propose a new approach combining local computations models and refinement to prove correctness of distributed algorithms for WSNs. We use the formal method Event-B to apply refinement. In fact, local computations models provide abstract description of computations which can be easily specified with Event-B. We illustrate our approach by an example of distributed algorithm for WSN.

This article describes how Web services play an important role in several fields such as e-commerce and e-health. As the number of Web services is increasing rapidly, finding the best Web service according to users' requirements becomes more challenging. The traditional method of Web service discovery is based on keyword match. Due to this, many Web services which are most relevant to the user request are left undiscoverable. Some other emergent approaches are based on semantics to improve the quality of the discovered Web services in terms of relevance and satisfaction of user's need. In this paper, the authors present a survey of existing semantic Web services discovery approaches giving priority to relevant ones. Furthermore, this paper provides a critical and comparative analysis of the studied approaches and stands out major challenges to be addressed to substantially enhance the semantic Web service discovery.

Today, cloud computing has become a promising paradigm that aims at delivering computing resources and services on demand. The adoption of these services has been rapidly increasing. One of the main issues in this context is how to evaluate the ability of cloud systems to provide the desired services while respecting the QoS constraints. Experimentation in a real environment is a hard problem. In fact, the financial cost and the time required are very high. Also, the experiments are not repeatable, because a number of variables that are not under control of the tester may affect experimental results. Therefore, using simulation frameworks to evaluate cloud applications is preferred. This paper presents a survey of the existing simulation tools in cloud computing. It provides also a critical and comparative analysis of the studied tools. Finally, it stands out a major challenge to be addressed for further research.

Dynamic networks are characterized by frequent topology changes due to the unpredictable appearance and disappearance of mobile devices and/or communication links. In this paper, we propose a correct-by-construction approach for proving distributed algorithms in a forest of spanning trees. Our approach consists in two phases. The first one aims to control the dynamic structure of the network by triggering a maintenance operation when the forest is altered. To do so, we develop a formal pattern using the Event-B method which is based on an existing model for building and maintaining a spanning forest in dynamic networks. The second phase of our approach deals with distributed algorithms which can be applied to spanning trees. We illustrate our pattern through an example of a leader election algorithm. The proof statistics show that our solution can save efforts on specifying as well as proving the correctness of distributed algorithms in a forest of spanning trees.

Self-adaptive systems are able to manage themselves autonomously. A common approach to engineer these systems is to use the MAPE control loop based on these four steps: Monitoring, Analysis, Planning, and Execution. Existing research pays little attention to the modeling of self-adaptive systems with multiple MAPE control loops, and is lacking in considering the formal specification and verification of temporal constraints in such systems. In this paper, we present a new approach for modeling self-adaptive systems with multiple MAPE control loops and we present a set of time patterns for self-adaptive systems. We illustrate our approach by modeling and verifying a time critical forest fire detection system that exhibits a self-adaptive behavior.

High Performance Computing (HPC) has seen prodigious growth over the past few years and fault tolerance solutions have been incorporated into HPC systems. The most commonly used technique for fault tolerance in HPC is checkpointing. Processes achieve fault tolerance by saving local checkpoint periodically during execution. When a failure occurs, the previously saved global checkpoint can be used to restart the computation from an intermediate state. Quasi-Synchronous Checkpointing (QSC) is attractive because it allows finding consistent global checkpoints without an extra message overhead. QSC algorithms are classified into: Strictly Z-Path Free, Z-Path Free and Z-Cycle Free. Z-paths and Z-cycles are undesirable patterns that can give rise to inconsistent system states. QSC algorithms are often evaluated with regard to performance, generally through simulation. However, few works have been designed to validate their correctness. Our approach validates if a QSC algorithm is correct by modeling its execution into a graph and then verifying over this graph if the algorithm is exempt from undesirable patterns. QSC is based on the Happened-Before Relation (HBR) introduced by Lamport. One main problem linked to the HBR is the combinatorial state explosion. Nevertheless, for a HPC system modeled with a HBR graph, the computational cost for the identification of such patterns becomes prohibitively high. In this paper, we define a set of transformation rules oriented towards the detection of the undesirable patterns over a graph derived from the causal order set abstraction (CAOS) which is equivalent to a HBR graph, but it drastically reduces the statespace of a system.

Accountability provides effective means for data protection in the cloud. On the provider's side, it consists in accepting to take responsibility for the users' data protection and governance in light of explicit agreements between them. Accountability is guaranteed through multiple measures ranging from preventive controls, violation detection, and analysis to compensatory and rectification measures. All the mentioned measures rely on proof concepts using forensic evidences. On the other hand, one of the properties making cloud popular is the multi-tenancy which reduces services costs and maximize resource usage. Therefore, it is important for a forensic evidence to support multi-tenancy. For this purpose, we propose a model-based approach which provides a description of multi-tenant aware evidence. We also define an algorithm for the definition of evidences from recorded transactions (a.k.a., event logs) between tenants and multi-tenant services. Furthermore, we propose a middleware layer on which we apply our approach to evaluate, through different scenarios, its efficiency.

Cyber-physical systems (CPS) enable the development of complex real-world applications through the integration of computational and physical processes. The resulting processes are usually constrained by hard timing and physical requirements. These requirements are of paramount importance and must be handled at the different steps of the CPS process life cycle: from modeling until execution. Business Process Modeling Notation (BPMN) enables us to model processes in general. Even if BPMN provides a rich notation to cater for relevant features of process modeling, its capabilities are limited to capturing specific CPS processes properties, particularly physical and temporal properties. On the other hand, it is necessary to verify these properties to ensure that CPS can operate in a provably correct manner. In this paper, we focus on the problem of modeling and verifying CPS processes according to physical and temporal properties. To do so, we first propose to extend BPMN to handle specific CPS processes. Based on this extension, we propose a verification approach which relies on a constraint satisfaction model to check the consistency of the considered properties.

Modeling is one of the most important topics in the area of Cyber-Physical Systems (CPS). By using BPMN4CPS [1], a designer can model CPS and their temporal properties as a set of collaborative and communicating processes organized in three parts: a cyber part, a controller part, and a physical part. However, the designer might specify a faulty combination of properties that can cause temporal violations. To address this problem and to check the consistency of the given properties, our tool automatically translates a CPS process model to a constraint satisfaction model. In this paper, we illustrate how to implement the BPMN4CPS approach and we demonstrate the capabilities of our tool.

The resources provisioning for workflow applications has become one of the most difficult challenges in the cloud. It consists in taking an appropriate decision when mapping tasks to resources while meeting QoS requirements. The need to modify workflows while they are being executed has become a major requirement to deal with unusual situations and evolution. Therefore, it is necessary to implement a provisioning policy which takes into account dynamic changes of workflow, while satisfying some performance criteria defined by the user. Simulation tools are an efficient solution to evaluate the performance of cloud applications. They offer a free environment that can mimic the behavior of a real cloud environment. Nevertheless, existing simulators are based on static application models. In this paper, we introduce CloudSim4DWf, which extends the existing CloudSim simulator with a new resource provisioning policy for dynamic workflows. The different experiments that we present show the efficiency of our tool.

Docker is the most popular open-source software for managing software containers. Docker is widely used in the industry and is becoming the de-facto standard. In this paper, we tackle the issue of bringing Docker into the Linked Open Data Cloud to enhance docker images descriptions and search. We first present the construction of the ontology that describes Docker images. This ontology is interconnected with DBPedia and reuses SIOC and prov vocabularies. We then describe the automated process that automatically extracts data from the Docker Hub Registry to populate the aforementioned ontology. We also present a Web platform that provides a SPARQL endpoint as well as analytical insights into the dataset.

Web services have become an industrial standard offering interoperability among various platforms. With their proliferation, it is becoming increasingly difficult to find a web service that satisfies one's requirements. Yet, discovering the most relevant ones is a key solution to benefit from the large number of web services available nowadays on the Internet. This paper presents a practical tool - called rMatcher - to measure the similarity of semantic web services in order to suggest to its user the best ones meeting his requirements. The tool has been developed and experimented on semantic web services described using the OWL-S language.

Cyber-physical systems (CPS) are a set of physical entities controlled by software systems to reach a specific goal under temporal and physical resource constraints. Existing research pays little attention to the modeling of CPS at the business process layer, and is lacking in considering the temporal dimension. In this paper, we present a set of time patterns applied to the cyber and physical elements of CPS processes. We model this process using a directed graph with associated time and time-dependent constraints.

Distributed algorithms are designed to run on interconnected autonomous computing entities for achieving a common task: each entity executes asynchronously the same code and interacts locally with its immediate neighbours. It is widely agreed that the lack of knowledge of the global state makes termination detection one of the most important and complex problems in distributed computing. By relying on refinement, we prove that an algorithm computing a spanning tree with Local Termination Detection (each entity is able to determine only its own termination condition), can be reused and adapted in order to compute the same algorithm with Global Termination Detection (at least one entity is aware that the entire computation is achieved in the network). The main idea relies upon specifying a combination of a well known algorithm namely SSP and the spanning tree algorithm, following a top/down approach. This paper is a starting point towards a general framework for enhancing termination detection property of distributed algorithms and reusing their proofs.

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.

Self-adaptive systems are able to modify their behavior and/or structure to deal with their continuously changing environment and internal dynamics. MAPE control loops, based on these four steps: Monitoring, Analysis, Planning, and Execution, have been identified as crucial elements in realizing self-adaptation of software systems. Adaptive systems are generally more difficult to design, specify and verify due to their high complexity. Ensuring the correctness of the system's adaptation logic is very crucial. In this paper, we propose a refinement approach that aims first to model step-by-step self-adaptive systems based on MAPE control loop. Second, our approach aims to formally specify self-adaptive systems at a high level of abstraction using the Event-B method. This formal specification provides a way to verify several properties for self-adaptive systems such as safety, reachability and temporal constraints. We illustrate our approach by verifying the fire detection system that exhibits a self-adaptive behavior.

Self-adaptive systems adapt their own behavior autonomously in order to control the satisfaction of their requirements under changing environmental conditions. MAPE (Monitor, Analyze, Plan and Execute) control loops have been used as important models for realizing self-adaptation. Adaptive systems are generally more difficult to design, specify and verify due to their high complexity. In this paper, we propose a formal refinement approach that aims first to model self-adaptive systems based on MAPE control loop. Second, our approach aims to formally specify self-adaptive systems at a high level of abstraction using the Event-B method providing correct by construction software. This formal specification provides a way to verify correctness of self-adaptive systems regarding a number of criteria. We provide a software tool (as an Eclipse plug-in) that supports designers in their architectural choices by defining a set of patterns describing the different ways of organizing MAPE loops, such as Master/Slave, coordinated control and hierarchical control. We illustrate our approach within a marine monitoring environment case study for validation purpose.

Proving the correctness of distributed algorithms in dynamic networks is a hard task due to the time complexity and the highly dynamic behavior. In the literature, the existing solutions lack a consensus about their developments and their proofs. Moreover, the proofs which have been presented are done manually. In this paper, we propose a reuse based approach for specifying and proving distributed algorithms in dynamic networks. It consists in developing a formal pattern using Event-B method, based on refinement techniques. The proposed pattern allows to handle topological events in dynamic networks and to characterize the concept of time. Our solution relies on evolving graphs as a powerful model to record the evolution of a network topology. To illustrate it, we present an example of a distributed counting algorithm. The proof statistics related to the development of the pattern and the algorithm show the efficiency of our solution.

Modeling is one of the most important topics in the domain of Cyber-Physical Systems (CPS). In the field of process modelling, Business Process Modeling and Notation (BPMN) is the most used standard. However, BPMN remains limited to cater for the specific characteristics and properties of CPS such as real world properties. In this paper, we propose BPMN4CPS, which provides a set of extensions for BPMN to properly and accurately model CPS processes. In order to illustrate the applicability of BPMN4CPS, we present a case study of an ambulance drone system.

As the number of web services is increasing, finding the best service according to the users' requirements becomes a challenging task. Traditional method of web services discovery is based on keyword match. Due to this, many web services which are most relevant to the user request are left undiscoverable. Some other emergent approaches for discovering web services are based on semantics which improves the quality of the discovered web services in terms of relevance and satisfaction of user's need. In this paper, we briefly discuss the challenges facing semantic web services discovery and present different approaches for this process. We present also our proposed algorithm that aims to help users in the process of selection of the most appropriate semantic web service.

Combining the Service Oriented Architecture (SOA) and Software Product Line (SPL) paradigms is an emerging research area that has gained a considerable interest in recent years. We observe that the approaches proposed in the literature address mostly the variability modeling of Service Providers (SPs) (e.g., developing and composing SPs). However, handling the variability of Service Consumers (SCs) and how to interrelate the variability of SCs and SPs have not been studied. In this paper, our objective is to carry out an in-depth and rigorous study that addresses these issues. We propose a new model-based, top-down, formal and end-to-end SOA approach based on the Multiple SPLs (MSPL) paradigm. The main idea is to develop an MSPL composed of two dependent SPLs for SP and SC in order to generate customized, valid and consistent SPs and SCs. We propose that the variability of each SPL is managed by a Feature Model (FM). In order to ensure the consistency between these two SPLs and in particular between their FMs, we define the automated analysis update operator based on formal propositional logical techniques. We developed a tool that implements all the required steps of our approach and we demonstrate its efficiency in a practical case study.

This Editorial [1] was originally published bearing the title “Towards the optimal synchronization granularity for dynamic scheduling of pipelined computations on heterogeneous computing systems” which was taken from another article's title [2] due to a production error. The title is now corrected above, and in the Editorial itself. We apologize for this error.

Service composition is fundamental in the SOA paradigm. It is oriented to build complex applications from smaller components. The design of composing service-based applications is mainly carried out throughout two composition techniques namely choreography and orchestration. Although these two composition models are different in nature, they are complementary. Choreography presents an abstract description of protocols. It offers a top view of the management rules which govern the interactions between the services involved in a decentralized application. On the other hand, orchestration provides details of the executable process at single peers which are necessary for the implementation of choreography. In this context, one open research problem, is the correct transformation of choreography specifications to orchestration specifications since orchestration provides more details to choreography specification. The choreography transformation has been the subject of several research works. Nevertheless, the existing works have considered that the choreography, on which their transformations are based, is correct by default. So, they have not sought to verify whether it is free of any error or not. Actually, due to the message passing nature of web services interaction, many subtle errors can occur. So, it is crucial to implement a checking process oriented to identify eventual incompatibilities that may arise. For this purpose, we present a formal verification approach based on the SPIN model-checker. The approach automatically transforms WS-CDL choreography specifications to Promela code for verification purposes. We verify non-functional properties that are expressed with linear temporal logic.

Workflow technologies have become an efficient mean for the development of different applications. One well known challenge for executing workflows on cloud computing is the resources provisioning. The latter consists in making an appropriate decision when mapping tasks to resources considering multiple objectives that are often contradictory. The problem of resources provisioning for workflow applications in the cloud has been widely studied in the literature. However, the existing works didn't consider the change in workflow instances at runtime. This functionality has become a major requirement to deal with unusual situations and evolutions. In this paper, we present a first step towards the resources provisioning for a dynamic workflow in the cloud. In fact, we propose a provisioning algorithm which takes into account some constraints. After that, we extend it in order to support the dynamic changes of workflow. Our algorithm is evaluated using CloudSim simulator. The different experiments that we present show the efficiency of our approach in terms of financial execution cost and overhead.

One of the most important issues in dynamic networks is to prove the correctness of distributed algorithms. This issue has been widely studied in the literature. Nevertheless, we note a lack of consensus about the development and proof of these algorithms. Moreover, the proofs which have been presented are usually done manually. In this paper, we introduce a formal pattern based on evolving graphs which allows to record the dynamic behavior of a network topology. To specify the proposed pattern, we use the Event-B formal method which supports a refinement-based incremental development using RODIN platform.

In a dynamic network topological events can occur at any time, and no stable periods can be assumed. To make designing distributed algorithms easier, we model these latter with a local computation model. The implementation of a local computation model using message passing communication model has given rise to various problems. Among these we can mention the use of a great amount of communication and computation resources. In order to solve these problems, we propose another implementation of rewriting systems using mobile agents. We present then, using local computations, a framework for describing distributed algorithms for mobile agents in a dynamic network. We make use of the high level encoding of these algorithms as transition rules. The main advantage of this uniform and formal approach is the proof correctness of distributed algorithms. We illustrate this approach by giving an example of distributed computation of a hierarchical spanning tree by mobile agents in a dynamic network.

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. In this paper we focus on SOA design patterns composition and we propose a rigorous composition method based on two steps. Firstly, we outline a precise definition of the composition process with the semi-formal SoaML standard language. Secondly, we outline a formal composition process using Event-B method. Our approach covers both structural and behavioral features of composed patterns.

Many annotation systems proposed in the learning domain suffer from an under-exploitation of the annotation's semantics at the level of the assistance presented to the learner during his annotative activity. Thus, these tools offer the same classic features to its users, such as management, search, sharing and storage of annotations. In this paper, we propose a new annotation system which differs in its novel features. The system tries to assist the learner via web services during his learning activities. Therefore, from a user's annotation, our application is able to interpret a goal implicitly expressed and tries to discover and invoke a web service that can meet this annotation's objective. This tool is based on an annotation model composed of an ontology and pattern annotation. The evaluation of the developed annotation system using Student's t-test confirmed that the learners are more motivated to annotate with our annotation tool than other systems.

The researchers in education are interested to observing and modelling the learner, and adapting their learning experience accordingly. When learners read and interact actively with their reading materials, they do unselfconscious activities like annotation practices which can be key feature to their personalities. Annotation practices require the reader to be active with the document, to think critically and to make specific annotations in the margins of the text. In this paper we propose modeling learner's personality by referring to their annotations. The experiments show the significant role of annotation activity to reflect certain learner' personality traits.

Workflow applications are an enabling technology for coordinating the activities of an enterprise. The resources provisioning for these applications is one of the most difficult challenges in the cloud. It consists in making an appropriate decision when mapping tasks to resources while satisfying QoS requirements. Current resources provisioning approaches in the cloud consider only static workflows and ignore the need to change workflow instances at runtime. This functionality is an essential requirement to deal with unusual situations and evolutions. In this paper, we propose a novel resources provisioning approach which considers the dynamic changes of workflows. The proposed approach introduces an algorithm which determines the assignment of tasks to the appropriate cloud resources. After that, we extend it in order to support the dynamic changes of workflows. Our algorithm is evaluated using CloudSim simulator. The experimental results which we present illustrate the efficiency of our approach in term of financial execution cost.

Distributed systems have undergone a very fast evolution in the last years. Large-scale distributed systems have become an integral part of everyday life with the development of new large-scale applications, consisting of thousands of computers and supporting millions of users. Examples include global Internet services, cloud computing systems, "big data" analytic platforms, peer-to-peer systems, wireless sensor networks and so on. The recent research addresses questions related to the way of how to design, build, operate and maintain large-scale distributed systems. Another question associated to it is how to represent and ensure causal dependencies in such systems in a optimal way. Causal dependencies have been established according to the Happened-Before Relation (HBR), which was introduced by Lamport. The HBR establishes a strict partial order among the events in a system, and therefore, one main problem linked to it is the combinatorial state explosion. To attack this problem the Causal Order Set Abstraction (CAOS) theory arises. CAOS attains the optimal representation at the set level of the causal dependencies of events in a distributed system. In this paper, we propose a mechanism based on the HBR and the Immediate Dependency Relation to automatically model any large-scale distributed system execution into the CAOS form. The resultant CAOS model, expressed in the form of a graph, drastically reduce the state-space of a system. In general, the resultant CAOS graph can be used for different purposes, such as for the design of more efficient algorithms, validation, verification, and/or the debugging of the existing ones, among others. In this paper, we illustrate how the CAOS graph can be used for validation purposes. The mechanism is implemented in C++. The results of its execution shows the viability to support large-scale systems.

Service-oriented architectures (SOA) are hugely adopted. Within the SOA, service composition is fundamental. The design of composing service-based applications is mainly carried out throughout two composition techniques namely choreography and orchestration. Although these two composition models are different in nature, they are complementary. Choreography presents an abstract description of protocols. It offers a top view of the management rules which govern the interactions between the services involved in a decentralized application. On the other hand, orchestration provides details of the executable process at single peers which are necessary for the implementation of choreography. In this context, one open research problem, is the correct transformation of choreography specifications to orchestration specifications since orchestration provides more details to choreography specification. The choreography transformation has been the subject of several research works. Nevertheless, the existing works have considered that the choreography, on which their transformations are based, is correct by default. So, it is crucial to implement a checking process oriented to identify eventual incompatibilities that may arise. For this purpose, we present a formal verification approach based on the SPIN model-checker. The approach automatically transforms WS-CDL choreography specifications to Promela code for verification purposes. We verify non-functional properties that are expressed with linear temporal logic.

In this paper, we propose a new approach for modeling compound SOA design patterns. The goal is to easily building and allowing the mass customization of compound design patterns. In this regard, we have used the paradigm of Software Product Line (SPL). The SPL development is realized through several tasks. In this work, the elaboration of the variability model, in particular the cardinality-based feature model, has been considered. We propose to compose this model with three related layers. Thus, it will be easy to interpret and to understand. The first layer expresses the existing dependencies and constraints between design patterns. Thus, only valid compound design patterns can be obtained. The second one illustrates the functional requirements. The third one shows the non-functional constraints.

Software as a Service (SaaS) is a delivery model in which software resources are accessed remotely by users. Multi-tenancy is one of key properties of SaaS to achieve higher profit margin by leveraging the economies of scale. This feature empowered by virtualization comes several new complexities introduced related to the area of accountability. For this purpose, we tackle the problem of integrating multi-tenancy in cloud services accountability and determine crucial issues that can be solved. To do this, we propose a multitenant services monitoring approach that keeps monitoring service execution at runtime and detecting privacy violations. This approach is based on multitenant accountability patterns for integrating multi-tenancy architecture and expressing rules that are enforced using AOP. Furthermore, we propose a middleware layer for implementing our approach into conventional cloud architecture. The performed evaluation proves the flexibility and the efficiency of our approach for services based applications in the cloud computing.

Elasticity is an essential property of cloud computing. It helps service providers to efficiently exploit cloud resources and reduce servicing costs. Therefore, the multitenant business processes are long-running and they are concurrently accessed by dynamic requests from tenants. However, ensuring business process elasticity at the infrastructure and the platform levels may only result in significant resources waste due to the partner services autonomy and variability. For this purpose, we tackle the problem of handling elasticity at the process and services levels to scale-out and scale-in their service instances whenever possible. To do this, we propose an auto-scaling approach to hold the promise of ensuring the elasticity of the multitenant business process. This research is based on service patterns for integrating multi-tenancy architecture and making ecisions on the execution of the elasticity mechanisms. Furthermore, we encapsulate our approach into a middleware layer (Middleware as a Service) between the application layer and the platform layer in the cloud architecture. Provided experimental evaluations show that our approach is efficient for ensuring elasticity under various workloads variation of the business process in cloud computing.

As a piece of software continues to evolve, it inevitably becomes more complicated and harder to understand, maintain, reuse, evolve and improve. Software architecture has emerged as a solution to these issues particularly for complex systems. Having a correct software architecture is critical to the success of the design and the development of a system. In order to design a correct software architecture the concept of architectural styles is used. In this paper, we propose SOA-CoM, a formal approach for the correct modeling of service oriented architectural styles. We specify a set of communication Schemas that define SOA structural and interaction properties. These Schemas are modeled as UML graphs. In order to reuse them and to build the style, we define composition rules that can be applied to them. A software architect can then extend the designed style with non-functional properties (NFP) using extension rules. To ensure design correctness, we specify these communication Schemas using the formal language ASL (ArchWare Style Language). All specifications are implemented and checked using the ASL Toolkit.

International audience

Medical information systems are in perpetual evolution which makes them different from each other in each hospital. These different systems compose a heterogeneous, distributed system with high complexity. Thus interoperability of medical information systems is one of the main challenges of the IT society. Semantic interoperability in healthcare is especially important when all the varying types of data need to interact. A lot of works tried to solve even partially this problem of interoperability. This paper highlights the most relevant of them and presents a comparative study between new technologies and research trends to resolve heterogeneity issues of medical information systems.

Due to the lack of knowledge of the global state and the non determinism in the execution of the processes, distributed algorithms are considered to be very complex to design and to prove. However, it becomes crucial to guarantee that these algorithms run as designed. Modularization mechanism in formal development provides a simple way to manage this complexity. In this paper, we rely on the modularization mechanism of the Event-B method and on local computations model to propose a reuse based approach for modelling classes of distributed algorithms. The proposed approach consists in developing a formal pattern defined as a set of proved logical entities called modules. These modules are developed separately and, when needed, can be incorporated and instantiated in a given system development. Such a mechanism can save efforts on modelling and proving the computation steps in distributed algorithms.

Autonomic Computing Systems are oriented to prevent the human intervention and to enable distributed systems to manage themselves. One of their challenges is the efficient monitoring at runtime oriented to collect information from which the system can automatically repair itself in case of failure. Quasi-Synchronous Check pointing is a well-known technique, which allows processes to recover in spite of failures. Based on this technique, several check pointing algorithms have been developed. According to the checkpoint properties detected and ensured, they are classified into: Strictly Z-Path Free (SZPF), Z-Path Free (ZPF) and Z-Cycle Free (ZCF). In the literature, the simulation has been the method adopted for the performance evaluation of check pointing algorithms. However, few works have been designed to validate their correctness. In this paper, we propose a validation approach based on graph transformation oriented to automatically detect the previous mentioned check pointing properties. To achieve this, we take the vector clocks resulting from the algorithm execution, and we model it into a causal graph. Then, we design and use transformation rules oriented to verify if in such a causal graph, the algorithm is exempt from non desirable patterns, such as Z-paths or Z-cycles, according to the case.

Various models of learner’s annotative activity have been proposed in E-learning domain. This models which try to conceptualize the annotations of learner are used as basis of many annotations systems. In this article, we propose a new formal model of learner’s annotations dedicated to Web services invocation. This conceptual model, composed of ontology and pattern of annotation, tries to present the learner’s annotative activity as a means of invocation of appropriate Web services. Therefore, from a learner’s annotation we interpret a goal implicitly expressed and we try to discover and invoke a Web service which can meet the annotation’s object and consequently assist the learner in his learning activities.

Correction added

Needless to say, distributed algorithms are usually hard to design mush harder to prove and to use in real distributed systems. In these systems, local computations theory has proved its power to formalize and prove in an intuitive way distributed algorithms. This paper uses this formalism to present solutions to the election problem in several network topologies using mobile agents at the design and the implementation levels. We formalized the proposed solutions in the local computations model using transition systems [11]. This facilitates the proof of the proposed solutions using the mathematical tool-box provided by the local computation theory. Using mobile agents, the proposed solutions get rid of synchronization and do not need continuous use of all machines computational resources. Proposed solutions are also simulated within the VISIDIA [3] platform.

Security in mobile agent systems is twofold: protection of mobile agents and protection of agent execution system. Indeed, the proposed solutions for the security of distributed systems arenpsilat sufficient. Moreover, therepsilas no solution which treats the different concerns of security in the mobile agent systems. To achieve this goal, we use formal foundations which provide a rigorous reasoning about security of mobile agent systems. We propose in this paper a formal framework for the security in mobile agent systems which consists of three basic frameworks. The specification framework proposes, explicitly, a generic definition of security policies that may be enhanced by several concepts related to one or more security models. For illustration, we present a security policy enhancement based on the concepts of the RBAC model. Inevitably, we associate to the specification framework a verification framework which checks the consistency of the proposed specifications as well as the consistency intra-policy. In response to the dynamic changes of security requirements in mobile agent systems, we propose a third framework for the reconfiguration of policies.

Architectural style constitutes a mean to put in practice design approaches based on pattern refinement, adaptation and reuse. Our objective is to support such approaches. In this work, we focus on real-life architectural styles and more particularly on the event-based style. We provide a set of basic styles and we describe a formal approach to specify them and to compose them to generate more complex patterns. In this way, we help the architect to design correct and elaborated architectural styles that can serve as a starting point for a more correct and successful refinement process.

Summary form only given. This paper proposes a formal definition of a conceptual model for mobile agent systems. This works constitute a part of a general research project aiming at defining a generic interaction model that covers the different facets of the cooperative activity among mobile agent based systems. We propose a framework for the specification of interaction mechanisms among mobile agent systems. Doing so, and using the Z notation, we bring closer the concepts describing a mobile agent systems and the cooperative activity while integrating them with the concepts related to the agent migration. The syntax and the semantic of proposed specifications have been checked using the Z-EVES tool.

Summary form only given. This paper presents a formal approach where we adopt a formal specification language which allows us to cover individual agent aspects (knowledge, goals, roles, ...) as well as collective aspects of a multiagent application in terms of coordination protocols, organization structure and planning activities. In this context, we propose a methodology based on stepwise refinements allowing to develop a design specification starting from an abstract requirements specification. We illustrate our approach by developing a multiagent solution for the pursuit problem.