International audience

The vision of 6G goes beyond incremental improvements in network performance, representing a paradigm shift toward a programmable, intelligent “network of networks.” In this context, digital twins (DTs) emerge as key enabling technologies for 6G, providing virtual replicas of physical, virtual, and logical infrastructures. The capabilities of 6G, such as ultra-high-speed transmission, massive connectivity, and integration with Artificial Intelligence, are essential for enabling accurate, real-time, and synchronized DTs. However, developing DT systems poses significant challenges, including integrating heterogeneous data sources, ensuring real-time synchronization, and ensuring interoperability across distributed environments. This article presents MidDiTS, a middleware solution that supports the modeling, synchronization, and management of DT systems. MidDiTS provides a comprehensive set of services, including physical entity connection, model and instance management, data ingestion, API integration, and device management. By abstracting away system complexities and promoting interoperability, MidDiTS enables developers to focus on higher-level business logic and accelerates the development of robust, synchronized DT systems for next-generation networked environments. We validated MidDiTS in a 6G-based scenario, demonstrating significant improvements in timeliness, reliability, and operational stability. The results highlight the role of advanced network capabilities in sustaining real-time DT synchronization and confirm the suitability of MidDiTS for supporting DT systems under next-generation network conditions.

Abstract Modern systems are increasingly connected and more integrated with other existing systems, giving rise to systems‐of‐systems (SoS). An SoS consists of a set of independent, heterogeneous systems that interact to provide new functionalities and accomplish global missions through emergent behavior manifested at runtime. The distinctive characteristics of SoS, when contrasted to traditional systems, pose significant research challenges within software engineering. These challenges motivate the need for a paradigm shift and the exploration of novel approaches for designing, developing, deploying, and evolving these systems. The International Workshop on Software Engineering for Systems‐of‐Systems (SESoS) series started in 2013 to fill a gap in scientific forums addressing SoS from the software engineering perspective, becoming the first venue for this purpose. This article presents a study aimed at outlining the evolution and future trajectory of software engineering for SoS based on the examination of 57 papers spanning the 11 editions of the SESoS workshop (2013–2023). The study combined scoping review and scientometric analysis methods to categorize and analyze the research contributions concerning temporal and geographic distribution, topics of interest, research methodologies employed, application domains, and research impact. Based on such a comprehensive overview, this article discusses current and future directions in software engineering for SoS.

Abstract A multi‐tenant microservice architecture involving components with asynchronous interactions and batch jobs requires efficient strategies for managing asynchronous workloads. This article addresses this issue in the context of a leading company developing tax software solutions for many national and multi‐national corporations in Brazil. A critical process provided by the company's cloud‐based solutions encompasses tax integration, which includes coordinating complex tax calculation tasks and needs to be supported by asynchronous operations using a message broker to guarantee order correctness. We explored and implemented two approaches for managing asynchronous workloads related to tax integration within a multi‐tenant microservice architecture in the company's context: (i) a polling‐based approach that employs a queue as a distributed lock (DL) and (ii) a push‐based approach named single active consumer (SAC) that relies on the message broker's logic to deliver messages. These approaches aim to achieve efficient resource allocation when dealing with a growing number of container replicas and tenants. In this article, we evaluate the correctness and performance of the DL and SAC approaches to shed light on how asynchronous workloads impact the management of multi‐tenant microservice architectures from delivery and deployment perspectives.

In the last years, Internet of Things (IoT) platforms have been designed to provide IoT applications with various services such as device discovery, context management, and data filtering. The lack of standardization has led each IoT platform to propose its own abstractions, APIs, and data models. As a consequence, programming interactions between an IoT consuming application and an IoT platform is time-consuming, is error prone, and depends on the developers’ level of knowledge about the IoT platform. To address these issues, this article introduces IoTvar , a middleware library deployed on the IoT consumer application that manages all its interactions with IoT platforms. IoTvar relies on declaring variables automatically mapped to sensors whose values are transparently updated with sensor observations through proxies on the client side. This article presents the IoTvar architecture and shows how it has been integrated into the FIWARE, OM2M, and muDEBS platforms. We also report the results of experiments performed to evaluate IoTvar, showing that it reduces the effort required to declare and manage IoT variables and has no considerable impact on CPU, memory, and energy consumption.

Academia and industry have recently acknowledged the many benefits of architecting with microservices. Nonethe-less, adopting a microservice architecture does not immediately guarantee the achievements promised by such an architectural style. A crucial architectural decision is why and where multi-tenancy should be adopted in microservice architectures. This paper presents a multi-tenant microservice architecture conceived to meet the requirements of a company to serve multiple customer applications (tenants). By reporting the migration and modern-ization of a monolith legacy architecture towards microservices, this paper discusses how a multi-tenant microservice architecture could benefit scalability, management, and third-party system integration. This paper also presents empirical results of a scalability evaluation to assess the adoption of multi-tenancy in the proposed architecture and quantify its impact on the system's performance.

Ever since the commercial offerings of the Cloud started appearing in 2006, the landscape of cloud computing has been undergoing remarkable changes with the emergence of many different types of service offerings, developer productivity enhancement tools, and new application classes as well as the manifestation of cloud functionality closer to the user at the edge. The notion of utility computing, however, has remained constant throughout its evolution, which means that cloud users always seek to save costs of leasing cloud resources while maximizing their use. On the other hand, cloud providers try to maximize their profits while assuring service-level objectives of the cloud-hosted applications and keeping operational costs low. All these outcomes require systematic and sound cloud engineering principles. The aim of this paper is to highlight the importance of cloud engineering, survey the landscape of best practices in cloud engineering and its evolution, discuss many of the existing cloud engineering advances, and identify both the inherent technical challenges and research opportunities for the future of cloud computing in general and cloud engineering in particular.

Missions represent a key concern in the development of Systems-of-Systems (SoS) since they are related to both capabilities of constituent systems and interactions among these systems that contribute to the accomplishment of global goals of the SoS. In a mission-oriented approach to design software-intensive SoS, the activity towards the concretization of the mission model is its refinement to an architectural model. This paper addresses this synergetic relationship between mission and architectural models. As main contribution, we introduce a model-based refinement process supported by model-to-model transformations intended to apply mission models represented in mKAOS, a language to model missions, for automatically generating architecture descriptions in SosADL, a formal language to describe SoS software architectures.

Nowadays, complex software-intensive systems have resulted from the integration of heterogeneous independent systems, thus leading to a new class of systems called Systems-of-Systems (SoS). As in any system, SoS architectures have been regarded as an important element for determining their success. However, the state of the art reveals shortcomings that contribute to compromise the quality of these systems, as their inherent characteristics (such as emergent behavior and evolutionary development) are often not properly addressed. In this context, this PhD research aims at investigating how SoS software architectures can be used to model and evolve these systems. As main contribution, an architecture-centric approach for developing software-intensive SoS with focus on the formal specification and dynamic reconfiguration of their architectures is proposed. Such an approach mainly intends to contribute to fill some of the relevant existing gaps regarding the development of software-intensive SoS driven by their software architectures.

Dynamic software architectures are those that describe how components and connectors can be created, interconnected, and/or removed during system execution. Most existing architecture description languages (ADLs) provide a limited support to expressively describe these architectures and entail architectural mismatches and inconsistencies between architecture and implementation due to their decoupling from implementation. In this paper, we introduce the dynamic reconfiguration support provided by π-ADL, a formal, well-founded theoretically language for describing dynamic software architectures under structural and behavioral viewpoints. π-ADL provides architectural-level primitives for specifying programmed dynamic reconfigurations, i.e., Foreseen changes described at design time and triggered at runtime. In addition, π-ADL allows enacting dynamic reconfiguration by means of: (i) an exogenous approach, in which it is possible to control all elements of the software architectures and to apply the changes on the whole structure, and (ii) an endogenous approach, in which the architectural elements can manage dynamic reconfiguration actions. Furthermore, π-ADL is integrated with the Go programming language, thus enabling to automatically generate implementation code from architectural descriptions, thus tackling the existing gap between them. We hereby use a real-world flood monitoring system as an illustrative example of how to describe dynamic software architectures in π-ADL and automatically generate source code in Go.

Adaptation is an important concern in cloud-based applications composed of services provided by different cloud providers since cloud services can suffer from Quality of Services(QoS) fluctuations. Other conditions that can also trigger an adaptation process at runtime are the unavailability of services or the violation of user-defined policies. Moreover, the detection and reaction on such changes must be done in an autonomic way, without the need of user intervention. This paper presents a dynamic adaptation approach for multi-cloud applications supported by a Branch-and-Bound (B&B) algorithm in order to optimize the adaptation process itself when selecting the services to be deployed within the application. Computational experiments comparing the B&B algorithm with another algorithm that evaluates all possible configurations for adapting an application showed that the B&B algorithm is faster than the previous version. This new algorithm brings benefits to the scalability of the adaptation process, which can deal with large configurations of multi-cloud applications composed by a plethora of cloud services.

The Internet of Things (IoT) has emerged as a paradigm in which smart things actively collaborate among them and with other physical and virtual objects available in the Web in order to perform high-level tasks. IoT environments are typically characterized by a high degree of heterogeneity, thus encompassing devices with different capabilities, functionalities, and network protocols. In such a scenario, it is necessary to provide abstractions for physical devices and services to applications and end-users, as well as means to manage the interoperability between such heterogeneous elements. In this context, we introduce EcoDiF (Web Ecosystem of Physical Devices), a Web-based platform for integrating heterogeneous physical devices with applications and users in order to provide services to support real-time data control, visualization, processing, and storage. In this paper, we present the main features of EcoDiF and detail its architecture and implementation, which is based on well-known Web technologies such as HTTP, REST, EEML, and EMML. Furthermore, we present a preliminary evaluation of an EcoDiF prototype through proof-of-concept applications from different domains as well as a performance analysis of the platform.

Software systems have become increasingly large and complex, often resulting from the integration of several operationally independent systems, thus leading to a new class of systems called Systems-of-Systems (SoS). Moreover, SoS have currently become essentially software-dependent systems, thus arising the Software-intensive Systems-of-Systems (SiSoS). However, in spite of their relevance, there is a lack of a common understanding of what exactly SiSoS are, their characteristics and types, as well as other elements that surround them. In this context, the main contribution of this work is to provide a conceptual model that provides a comprehensive understanding about them. For this purpose, we have extended the ISO/IEC/IEEE 42010 International Standard by considering related studies and previous taxonomies about SoS. In order to illustrate the use of our model, two software-intensive systems were analyzed and discussed. By establishing a common understanding about SiSoS, results achieved until now have showed us that this model can provide an important support to the research on SiSoS and, as a consequence, it can contribute to the development of these systems.

With the advance of the Cloud Computing paradigm, new challenges in terms of models, tools, and techniques to support developers to design, build and deploy complex software systems that make full use of the cloud technology arise. In the heterogeneous scenario of this new paradigm, the development of applications using cloud services becomes hard, and the software product lines (SPL) approach is potentially promising for this context since specificities of the cloud platforms, such as services heterogeneity, pricing model, and other aspects can be catered as variabilities to core features. In this perspective, this paper (i) proposes a seamless adaptation of the SPL-based development to include important features of cloud-based applications, and (ii) reports the experience of developing HW-CSPL, a SPL for the Health Watcher (HW) System, which allows citizens to register complaints and consult information regarding the public health system of a city. Several functionalities of this system were implemented using different Cloud Computing platforms, and run time specificities of this application deployed on the cloud were analyzed, as well as other information such as change impact and pricing.

Ubiquitous environments still suffer from low availability given that any device may fail and it is hard to replace a failed element. In this paper we present AdaptUbiFlow (Adaptive Ubiquitous Workflow), an OpenCOPI´s element that aims to increase the availability of an ubiquitous system. When a device fails, AdaptUbiFlow supports the automatic reconfiguration of the system replacing the failed device (or service) by an equivalent one, this makes the system fault-tolerant without the need of any manual intervention. The replacing of a device/service is chosen taking into account not only the QoS and QoC (Quality of Context) provided but also the application's execution flow to ensure that the best adaptation option will be chosen. AdaptUbiFlow evaluation showed encouraging results.