Ahmed Hadj Kacem

• PhD
• Professor (Full) at Faculty of Economics and management of Sfax

The Internet of Things (IoT) aims to interconnect the physical world with the digital world, presenting complex challenges that require accurate models to ensure implementation accuracy and minimize errors. In this paper, we propose a general approach for modeling, specifying, and verifying Internet of Things architectures using the Unified Modelin...

Developing Internet of Things systems without the benefit of a standard is a difficult process. In this regard, we propose to describe Internet of Things systems using a UML meta-model. It is critical to ensure that no ambiguity, incompleteness, or misunderstanding exists in the Internet of Things systems that instantiate the meta-model. To do this...

The Internet of Things (IoT) is a rapidly growing technology trend that seeks to bridge the gap between the physical and digital worlds. Given the complexity of IoT systems, design patterns are essential to overcome recurring problems. However, IoT design patterns must be modeled as valid mathematical entities to avoid implementation errors and amb...

With the speed rise of heterogeneous Blockchain (BC) platforms, interoperability became a critical area of research barrer for a variety of use cases, ranging from supply chain to healthcare. Consequently, a number of BC interoperability solutions were proposed to overcome these issues. One of these is Bifröst, a notary-based BC interoperability Ap...

In the blockchain environment, smart contracts are computer programs that run on the blockchain platform. However, the development of smart contracts is a major challenge for developers, since blockchain platforms are still evolving. Owing to the inherited nature of blockchain, developing smart contracts without introducing vulnerabilities is not a...

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 mad...

Cyber-physical systems (CPS) are characterized with their concurrency, heterogeneity and time sensitivity. In this context, it is crucial to have self-adaptive CPS systems in order to manage changing in their internal and external environment and supporting new requirements. Also, CPS systems are known with their restricted connectivity, and conseq...

Regular physical activity improves strength and fitness for all age groups including older adults. It allows them to feel better and to have a good mental and physical health state. As he gets older, every older adult will inevitably experience the deterioration of his toughness and his functional abilities. The sedentary lifestyle of older adults...

Statistics say that there will be 25 billion devices interconnected to the Internet by the end of 2021. This explosive growth of connected objects has led us to the advent of a promising technology that can satisfy this need known as the Internet of Things (IoT). IoT enables digitalization around the world, but it also increases the challenges for...

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 pr...

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 th...

Today software systems are very complex and changing. Therefore, preserving their functionality and the quality of their service seems to be a difficult. Consequently, the concept of self-adaptation was introduced to handle the problem of the increasing complexity and dynamism of modern software systems. In this context, researchers have been study...

Being physically active is enjoyable and safe for all age groups including for the older adults. In fact, regular physical activity improves fitness, strength and feeling better. Each person will inevitably experience the deterioration of his functional abilities as he gets older, and the sedentary behavior represents the greatest risk having a gre...

A large number of annotation systems in e-health domain have been implemented in the literature. Several factors distinguish these systems from one another. In fact, each of these systems is based on a separate paradigm, resulting in a disorganized and unstructured vision. As part of our research, we attempted to categorize them based on the functi...

IoT systems are required to manage themselves to changes regarding their internal and external contexts. So, adaptability is a very important aspect in IoT software systems. The MAPE (Monitoring, Analysis, Planning, Execution) control loop model, inspired from the autonomic nervous system, has been identified as a crucial element for realizing self...

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 con...

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 soundne...

In recent years, Educational Recommender Systems (ERSs) have attracted great attention as a solution towards addressing the problem of information overload in e-learning environments and providing relevant recommendations to online learners. These systems play a key role in helping learners to find educational resources relevant and pertinent to th...

After the deployment of a Wireless Sensor Network (WSN), we may need to update or even change the algorithm running in the sensors. WSNs are often deployed on a large scale which makes the manual update of the running algorithms impractical. Moreover, for some WSNs, sensors are physically inaccessible like sensors deployed in harsh environments mak...

The annotation practice is an almost daily activity used by healthcare professionals (PHC) to analyze patients' records, collaborate, share knowledge, and communicate. These annotations are generated within a healthcare cycle. Similarly, this cycle represents the life cycle of annotations in the patient record. The exponential increase in the numbe...

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 al...

This paper presents a model-based graphical tool for supporting multiscale modeling of software architectures. The implemented solution is based on a rule-oriented iterative modeling process ensuring transition from a coarse-grained description to a fine-grained description. The rules manage the refinement between scales and are applied with respec...

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.

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 observat...

Multi-tenant service composition has become a common delivery model for business processes in cloud computing. To dynamically support the workload tenant variation, elasticity holds the promise of ensuring the quality of service (QoS) of the business process by providing the involved service instances at a low cost. However, integrating both of mul...

A network paradigm called the Software-Defined Network (SDN) has recently been introduced. The idea of SDN is to separate the control logic from forwarding devices to enable a centralized control platform. However, SDN is still a distributed and asynchronous system: events can be triggered by any network entity, while messages and packets are prone...

A Wireless Sensor Network (WSN) is composed of sensors that communicate together in a distributed way to supervise the environment. The energy consumption is an important performance measure for a WSN that spurs the development of energy-efficient distributed algorithms for WSNs. In this field, we focus on a specific type of distributed algorithms...

Engineering self-adaptive systems using a standard or a guide is a challenging task. In this context, we propose using a set of MAPE (Monitor-Analyze-Plan-Execute) patterns for modeling self-adaptive systems. Ensuring that there is no ambiguity, incompleteness and misunderstanding of self-adaptive systems that instantiate MAPE patterns is very cruc...

This book constitutes the revised selected papers from the 14th International Conference on Risks and Security of Internet and Systems, CRiSIS 2019, held in Hammamet, Tunisia, in October 2019. The 20 full papers and 4 short papers presented in this volume were carefully reviewed and selected from 64 submissions. They cover diverse research themes...

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. Inde...

Dynamic workflow applications are increasingly used in many enterprises to satisfy the variable enterprise requirements. Cloud computing has gained a particular attention to run these applications. However, due to lack of formal description of the resource perspective, the behavior of Cloud resource allocation cannot be correctly managed. This pape...

The widespread adoption of multi-tenancy in the Software as a Service delivery model triggers several data protection issues that could decrease the tenants’ trustworthiness. In this context, accountability can be used to strengthen the trust of tenants in the cloud through providing the reassurance of the processing of personal data hosted in the...

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...

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...

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 We...

A Wireless Sensor Network (WSN) is an important wireless technology that is widely used in the Internet of things and that has wide variety of applications. In fact, a WSN consists of independent sensors, communicating with each other in a distributed way to monitor the environment. In this network, most of the existing distributed algorithms are d...

The efforts to computerize the medical record of a patient began in 1990. In the documents of this record, the healthcare professional practices the annotation activity. Most medical annotation systems are made to perform a specific task. As a result, we have dozens of medical annotation system that we sneak a fragmented image in the absence of gen...

Cyber-physical systems (CPS) represent an emerging type of distributed systems that integrate a multitude of physical elements and software applications into large networks of interconnected components. Ensuring that such systems meet their timing requirements is essential, especially with time-sensitive applications. To deal with this, suitable wa...

Geo-distributed big-data processing has recently received much attention since it ensures large-scale and geographically distributed data processing, using Hadoop or Spark, in an efficient, fault-tolerant and reliable manner. The objective of this work is to propose a new geo-distributed MapReduce-based framework and algorithm for federated cloud p...

In this paper, we focus on maintaining a forest of spanning trees in dynamic networks. In fact, we propose an approach based on two levels for specifying and proving distributed algorithms in a forest. The first level allows us to control the dynamic structure of the network by triggering a maintenance operation when the forest is altered. To do so...

Context: Architecture constraints are specifications of conditions to which an architecture model must adhere in order to satisfy an architecture decision imposed by a given design principle. These constraints can be specified with predicate languages like OCL at design time and checked on design artifacts. Objective: Many works in the literature s...

Provisioning the MapReduce data-intensive applications across geo-distributed cloud federation is a key rationale behind the cost effectiveness and performance improvement. The objective of this paper is to maximize the profit for service providers by minimizing costs and penalty. This work proposes a fully distributed scheduling algorithm to proce...

Specifying correct software-intensive Systems of Systems architectures is a challenging research direction requiring new modeling abstractions and techniques. For this purpose, we provide a refinement-based approach for multi-scale description of software architectures. We define an incremental process starting from a coarse-grained description, an...

In Service Oriented Architecture (SOA), many feature modeling approaches of Service Provider (SP) have been proposed, notably: the two widely used service contracts WSDL and WADL. By studying these approaches, we found that they suffer from several problems, notably: they only work for specific communication technologies (e.g., SOAP or REST) and th...

Self-adaptive systems are able to change their own behavior whenever the software or hardware is not accomplishing what it was intended to do. In this context, the MAPE (Monitoring, Analysis, Planning, Execution) control loop model has been identified as crucial element for realizing self-adaptation in software systems. Complex self-adaptive system...

The design and the proof of correctness of distributed algorithms in dynamic networks are difficult tasks. These networks are characterized by frequent topology changes due to unpredictable appearance and disappearance of mobile devices and/or communication links. In this paper, we propose a correct-by-construction approach for specifying and provi...

Self-adaptive systems are able to modify their behaviour and/or structure to deal with their continuously changing environment and internal dynamics. Adaptive systems are generally more difficult to design, specify and verify owing to their high complexity. Ensuring the correctness of the system adaptation logic is very crucial. This correctness al...

In dynamic distributed systems, the topology of networks changes over time which makes difficult the design and much harder the proof of distributed algorithms. These unavoidable changes of the topology make the election and the maintenance of the elected leader a complex task. The maintaining problem is not considered in a static context. To encod...

Software Design Patterns provide architects and developers with reusable software elements helping them to master building complex software systems. In real applications, problems are complex and their solutions can be represented by compound patterns that require the combination and reuse of two or more design patterns. In this paper, we propose a...

We propose a multi-scale methodology for complex software systems using the model transformation techniques. The methodol- ogy provides a correct by design approach for the description of multi-scale architectures. It is founded on a rule-oriented iterative modeling process ensuring transition from a coarse-grained description to a fine-grained des...

Finding maximal and maximum cliques are well-known problems in the graph theory. They have different applications in several fields such as the analysis of social network, bioinformatics and graph coloring. They have attracted the interest of the research community. The main goal of this paper is to present a comprehensive review of the existing ap...

Modeling correct software-intensive Systems of Systems architectures is a challenging research direction that can be mastered by providing appropriate modeling abstractions. For this purpose, we provide an iterative modeling solution for a multi-scale description of software architectures. We provide a visual notation extending the graphical UML no...

The first obstacle to the realization of research on cloud computing is the development of an appropriate research platform. Although commercial clouds are realistic as platforms of research, they are not always practical due to the financial cost and time required by experiments. Also, it is difficult to achieve the evaluation of some critical sce...

Cloud computing has received an increasing attention in the past years thanks to its new model of resources provisioning. One well-known challenge in this context is to make an appropriate decision when mapping tasks to resources considering multiple objectives that are often contradictory. This problem has become more complex, mainly for workflow...

The enumeration problem addresses a collection of important algorithmic issues related to distributed computations. Among existing solutions, we are interested on the seminal algorithm of Mazurkiewicz, based on local computations. Our paper contributes to the design of a correct-by-construction enumeration algorithm. The main idea relies upon the d...

Modeling correct software-intensive Systems of Systems architectures is a challenging research direction that can be mastered by providing modeling abstractions. For this purpose, we provide an iterative modeling solution for a multi-scale description of software architectures. We provide a visual notation extending the graphical UML notations to r...

The problem of constructing and maintaining a spanning tree in dynamic networks is important in distributed systems. Trees are essential structures in various communication protocols such as information broadcasting, routing, etc. In a distributed computing environment, the solution of this problem has many practical motivations. To make designing...

Architecture constraints are components of design documentation. They enable designers to enforce rules that architecture descriptions should respect. Many systems make it possible to associate constraints to models at design stage but very few enable their association to code at implementation stage. When possible, this is done manually, which is...

Researchers in distance education are interested in observing and modelling of learner's personality profile, and adapting their learning experiences accordingly. When learners read and interact with their reading materials, they do unselfconscious activities like annotation which may be key feature of their personalities. Annotation activity requi...

In Service Oriented Architecture (SOA), service contracts are widely used for designing and developing the features (e.g., services and capabilities) of Service Providers (SPs). Two of the most widely used traditional service contracts in SOA are: WSDL and WADL. We identify that these service contracts suffer from several problems, like: they only...