Distributed systems are largely present and deployed in recent applications. Several systems have common basic requirements, which motivates to adapt reusable solutions for each family of systems. In this paper, we focus on distributed systems designed for large-scale applications requiring a high degree of Reliability and Dynamicity (ReDy distributed systems). We propose a basic architecture for this family of systems and a design solution to guarantee the scalability of the system, the fault tolerance, and a highly dynamic membership management. The studied systems range from hybrid architecture, on which we combine centralized and decentralized solutions.

IoT systems are known for being complex, heterogeneous, distributed, resources constrained, integrating probably moving devices or services in a highly dynamic environment. This is a non exhaustive set of characteristics that an IoT system should satisfy. Designing an IoT system according to a given architecture in order to satisfy a set of required characteristics is a priority in order to meet principal requirements of the system according to the specific application field. In this paper, we give an overview of main existing categories of IoT architectures. We identify principally software IoT architecture, hardware IoT architecture, and general IoT architecture. Based on this study, we propose an end-to-end IoT architecture designed according to a five layered model. We propose a summary of different enabling technologies presented according to the end-to-end architecture. We finally exhibit main challenges of IoT systems that can be raised at different contexts and applications.

-Internet of Things (IoT) faces different architectural challenges to meet the large scale application issues, the heterogeneity, and the self-adaptivity.Many IoT applications require a dynamic construction of the system and should ensure a high degree of reliability. I. INTRODUCTIONInternet of Things (IoT) is the next wave of digital transformation: many objects that surround us will be connected. Sensors, actuators, and computing units will form networks for different applications. Those applications may concern home and personal uses, enterprises uses, public utilities, or transportation. The IoT is already ready for some specific uses as the majority of personal uses and some enterprise uses. Today, different challenges are still open. In particular architectural challenges to meet the large scale application issues, the heterogeneity, and the self-adaptivity of complex systems. A large part of current work of the IoT architecture have been inherited from the wireless sensor networks background [4]. Other architectures should be investigated for different application domains [5]. Many IoT applications require a dynamic construction of the system and should ensure a high degree of reliability. For this end, we propose the ReDy distributed systems for Reliable and Dynamic distributed systems [1]. Those systems are designed using the ReDy architecture. The ReDy architecture is a reusable solution for a large spectrum of distributed systems. Our solution integrates two important requirements that are common to the concerned systems. The first one is to design the system in a highly dynamic environment, i.e, components can continuously join and leave the system network. The second requirement is about fault tolerance. The designed system should have a high resistance to faults, which permit to preserve the overall behavior of the system even in the presence of faulty components. A large family of systems needs to guarantee the above requirements. Besides proposing a common architecture for those systems, our solution gives general rules that should be respected and implemented during the design phase so as to construct reliable and dynamic distributed systems.As application samples we have: large scale wireless sensor networks, deploy and forget networks, self-adaptive systems of systems, critical infrastructure monitoring, smart grid and household metering, autonomous vehicles, heterogeneous systems with interaction between other sub-networks, smart traffic, intelligent transportation and logistics [5].We take the advantage of the formal methods, witch are a particular kind of mathematically based techniques for the specification and verification, to model the ReDy architecture and to validate complicated behaviors. The use of formal method allows us to ensure a good level of reliability and robustness of our proposed design.Formalizing our system using a formal model let us to express the behavior of the system in an unambiguous way: the formal specification expresses a unique semantic. In addition to...

Smart Grid introduces intelligent infrastructure to the existing power grid. Energy production is no longer confined just to large power plants, but is becoming geographically distributed on small renewable energy plants that can inject electricity directly into the grid. IoT proposes a good solution to connect the producers to the consumers and to propose a reactive balancing of power production and consumption. The ReDy architecture, which is intended for IoT applications, provides a base to implement a scalable, reliable, and dynamic IoT network ready to meet Smart Grid needs. The different producers and consumers represent nodes of a decentralized network managed with a dynamic membership management algorithm. Each node is a centralized sub-network composed of one gateway making decisions and several sensors and actuators.

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