The Internet of Things (IoT) is a fast-spreading technology that enables new types of services in several domains, such as transportation, health, and building automation. To exploit the potential of the IoT effectively, several challenges have to be tackled including the following ones. First, the proposed IoT visions provide a fragmented picture, leading to a lack of consensus about IoT systems and their constituents. A second set of challenges concerns the environment of IoT systems that is often dynamic and uncertain, e.g. devices can appear and be discovered at runtime as well as become suddenly unavailable. Additionally, the in- volvement of human users complicates the scene as people’s activities are not always predictable . The majority of existing approaches to en- gineer IoT systems rely on predefined processes to achieve users’ goals. Consequently, such systems have significant shortcomings in coping with dynamic and uncertain environments. To piece together the fragmented picture of IoT systems, we sys- tematically identified their characteristics by analyzing and synthesizing existing taxonomies. To address the challenges related to the IoT envir- onment and the involvement of human users, we used the concept of Emergent Configurations (ECs) to engineer IoT systems. An EC consists of a dynamic set of devices that cooperate temporarily to achieve a user goal. To realize this vision, we proposed novel approaches that enable users to achieve their goals by supporting the automated formation, en- actment, and self-adaptation of IoT systems. / <p>Note: The papers are not included in the fulltext online.</p><p>Paper I in dissertation as manuscript.</p>

O custo de serviços na Internet tem encorajado o uso de cache a nível de aplicação para suprir as demandas dos usuários e melhorar a escalabilidade e disponibilidade de aplicações. Cache a nível de aplicação, onde desenvolvedores manualmente controlam o conteúdo cacheado, tem sido adotada quando soluções tradicionais de cache não são capazes de atender aos requisitos de desempenho desejados. Apesar de sua crescente popularidade, este tipo de cache é tipicamente endereçado de maneira ad-hoc, uma vez que depende de detalhes específicos da aplicação para ser desenvolvida. Dessa forma, tal cache consiste em uma tarefa que requer tempo e esforço, além de ser altamente suscetível a erros. Esta dissertação avança o trabalho relacionado a cache a nível de aplicação provendo uma compreensão de seu estado de prática e automatizando a identificação de conteúdo cacheável, fornecendo assim suporte substancial aos desenvolvedores para o projeto, implementação e manutenção de soluções de caching. Mais especificamente, este trabalho apresenta três contribuições: a estruturação de conhecimento sobre caching derivado de um estudo qualitativo, um levantamento do estado da arte em abordagens de cache estáticas e adaptativas, e uma técnica que automatiza a difícil tarefa de identificar oportunidades de cache O estudo qualitativo, que envolveu a investigação de dez aplicações web (código aberto e comercial) com características diferentes, permitiu-nos determinar o estado de prática de cache a nível de aplicação, juntamente com orientações práticas aos desenvolvedores na forma de padrões e diretrizes. Com base nesses padrões e diretrizes derivados, também propomos uma abordagem para automatizar a identificação de métodos cacheáveis, que é geralmente realizado manualmente por desenvolvedores. Tal abordagem foi implementada como um framework, que pode ser integrado em aplicações web para identificar automaticamente oportunidades de cache em tempo de execução, com base na monitoração da execução do sistema e gerenciamento adaptativo das decisões de cache. Nós avaliamos a abordagem empiricamente com três aplicações web de código aberto, e os resultados indicam que a abordagem é capaz de identificar oportunidades de cache adequadas, melhorando o desempenho das aplicações em até 12,16%. / Latency and cost of Internet-based services are encouraging the use of application-level caching to continue satisfying users’ demands, and improve the scalability and availability of origin servers. Application-level caching, in which developers manually control cached content, has been adopted when traditional forms of caching are insufficient to meet such requirements. Despite its popularity, this level of caching is typically addressed in an adhoc way, given that it depends on specific details of the application. Furthermore, it forces application developers to reason about a crosscutting concern, which is unrelated to the application business logic. As a result, application-level caching is a time-consuming and error-prone task, becoming a common source of bugs. This dissertation advances work on application-level caching by providing an understanding of its state-of-practice and automating the decision regarding cacheable content, thus providing developers with substantial support to design, implement and maintain application-level caching solutions. More specifically, we provide three key contributions: structured knowledge derived from a qualitative study, a survey of the state-of-the-art on static and adaptive caching approaches, and a technique and framework that automate the challenging task of identifying cache opportunities The qualitative study, which involved the investigation of ten web applications (open-source and commercial) with different characteristics, allowed us to determine the state-of-practice of application-level caching, along with practical guidance to developers as patterns and guidelines to be followed. Based on such patterns and guidelines derived, we also propose an approach to automate the identification of cacheable methods, which is often manually done and is not supported by existing approaches to implement application-level caching. We implemented a caching framework that can be seamlessly integrated into web applications to automatically identify and cache opportunities at runtime, by monitoring system execution and adaptively managing caching decisions. We evaluated our approach empirically with three open-source web applications, and results indicate that we can identify adequate caching opportunities by improving application throughput up to 12.16%. Furthermore, our approach can prevent code tangling and raise the abstraction level of caching.

The overall contribution of this thesis is to propose an integrated approach for modeling and verifying the requirements of Self Adaptive Systems using Model Driven Engineering techniques. Model Driven Engineering is primarily concerned with reducing the gap between problem and software implementation domains through the use of technologies that support systematic transformation of problem level abstractions to software implementations. By using these techniques, we have bridged this gap through the use of models that describe complex systems at multiple levels of abstraction and through automated support for transforming and analyzing these models. We take requirements as input and divide it into Functional and Non Functional Requirements. We then use a process to identify those requirements that are adaptable and those that cannot be changed. We then introduce the concepts of Goal Oriented Requirements Engineering for modeling the requirements of Self Adaptive Systems, where Non Functional Requirements are expressed in the form of goals which is much more rich and complete in defining relations between requirements. We have identified some problems in the conventional methods of requirements modeling and properties verification using existing techniques, which do not take into account the adaptability features associated with Self Adaptive Systems. Our proposed approach takes into account these adaptable requirements and we provide various tools and processes that we developed for the requirements modeling and verification of Self Adaptive Systems. We validate our proposed approach by applying it on two different case studies in the domain of Self Adaptive Systems.

O custo de serviços na Internet tem encorajado o uso de cache a nível de aplicação para suprir as demandas dos usuários e melhorar a escalabilidade e disponibilidade de aplicações. Cache a nível de aplicação, onde desenvolvedores manualmente controlam o conteúdo cacheado, tem sido adotada quando soluções tradicionais de cache não são capazes de atender aos requisitos de desempenho desejados. Apesar de sua crescente popularidade, este tipo de cache é tipicamente endereçado de maneira ad-hoc, uma vez que depende de detalhes específicos da aplicação para ser desenvolvida. Dessa forma, tal cache consiste em uma tarefa que requer tempo e esforço, além de ser altamente suscetível a erros. Esta dissertação avança o trabalho relacionado a cache a nível de aplicação provendo uma compreensão de seu estado de prática e automatizando a identificação de conteúdo cacheável, fornecendo assim suporte substancial aos desenvolvedores para o projeto, implementação e manutenção de soluções de caching. Mais especificamente, este trabalho apresenta três contribuições: a estruturação de conhecimento sobre caching derivado de um estudo qualitativo, um levantamento do estado da arte em abordagens de cache estáticas e adaptativas, e uma técnica que automatiza a difícil tarefa de identificar oportunidades de cache O estudo qualitativo, que envolveu a investigação de dez aplicações web (código aberto e comercial) com características diferentes, permitiu-nos determinar o estado de prática de cache a nível de aplicação, juntamente com orientações práticas aos desenvolvedores na forma de padrões e diretrizes. Com base nesses padrões e diretrizes derivados, também propomos uma abordagem para automatizar a identificação de métodos cacheáveis, que é geralmente realizado manualmente por desenvolvedores. Tal abordagem foi implementada como um framework, que pode ser integrado em aplicações web para identificar automaticamente oportunidades de cache em tempo de execução, com base na monitoração da execução do sistema e gerenciamento adaptativo das decisões de cache. Nós avaliamos a abordagem empiricamente com três aplicações web de código aberto, e os resultados indicam que a abordagem é capaz de identificar oportunidades de cache adequadas, melhorando o desempenho das aplicações em até 12,16%. / Latency and cost of Internet-based services are encouraging the use of application-level caching to continue satisfying users’ demands, and improve the scalability and availability of origin servers. Application-level caching, in which developers manually control cached content, has been adopted when traditional forms of caching are insufficient to meet such requirements. Despite its popularity, this level of caching is typically addressed in an adhoc way, given that it depends on specific details of the application. Furthermore, it forces application developers to reason about a crosscutting concern, which is unrelated to the application business logic. As a result, application-level caching is a time-consuming and error-prone task, becoming a common source of bugs. This dissertation advances work on application-level caching by providing an understanding of its state-of-practice and automating the decision regarding cacheable content, thus providing developers with substantial support to design, implement and maintain application-level caching solutions. More specifically, we provide three key contributions: structured knowledge derived from a qualitative study, a survey of the state-of-the-art on static and adaptive caching approaches, and a technique and framework that automate the challenging task of identifying cache opportunities The qualitative study, which involved the investigation of ten web applications (open-source and commercial) with different characteristics, allowed us to determine the state-of-practice of application-level caching, along with practical guidance to developers as patterns and guidelines to be followed. Based on such patterns and guidelines derived, we also propose an approach to automate the identification of cacheable methods, which is often manually done and is not supported by existing approaches to implement application-level caching. We implemented a caching framework that can be seamlessly integrated into web applications to automatically identify and cache opportunities at runtime, by monitoring system execution and adaptively managing caching decisions. We evaluated our approach empirically with three open-source web applications, and results indicate that we can identify adequate caching opportunities by improving application throughput up to 12.16%. Furthermore, our approach can prevent code tangling and raise the abstraction level of caching.

O custo de serviços na Internet tem encorajado o uso de cache a nível de aplicação para suprir as demandas dos usuários e melhorar a escalabilidade e disponibilidade de aplicações. Cache a nível de aplicação, onde desenvolvedores manualmente controlam o conteúdo cacheado, tem sido adotada quando soluções tradicionais de cache não são capazes de atender aos requisitos de desempenho desejados. Apesar de sua crescente popularidade, este tipo de cache é tipicamente endereçado de maneira ad-hoc, uma vez que depende de detalhes específicos da aplicação para ser desenvolvida. Dessa forma, tal cache consiste em uma tarefa que requer tempo e esforço, além de ser altamente suscetível a erros. Esta dissertação avança o trabalho relacionado a cache a nível de aplicação provendo uma compreensão de seu estado de prática e automatizando a identificação de conteúdo cacheável, fornecendo assim suporte substancial aos desenvolvedores para o projeto, implementação e manutenção de soluções de caching. Mais especificamente, este trabalho apresenta três contribuições: a estruturação de conhecimento sobre caching derivado de um estudo qualitativo, um levantamento do estado da arte em abordagens de cache estáticas e adaptativas, e uma técnica que automatiza a difícil tarefa de identificar oportunidades de cache O estudo qualitativo, que envolveu a investigação de dez aplicações web (código aberto e comercial) com características diferentes, permitiu-nos determinar o estado de prática de cache a nível de aplicação, juntamente com orientações práticas aos desenvolvedores na forma de padrões e diretrizes. Com base nesses padrões e diretrizes derivados, também propomos uma abordagem para automatizar a identificação de métodos cacheáveis, que é geralmente realizado manualmente por desenvolvedores. Tal abordagem foi implementada como um framework, que pode ser integrado em aplicações web para identificar automaticamente oportunidades de cache em tempo de execução, com base na monitoração da execução do sistema e gerenciamento adaptativo das decisões de cache. Nós avaliamos a abordagem empiricamente com três aplicações web de código aberto, e os resultados indicam que a abordagem é capaz de identificar oportunidades de cache adequadas, melhorando o desempenho das aplicações em até 12,16%. / Latency and cost of Internet-based services are encouraging the use of application-level caching to continue satisfying users’ demands, and improve the scalability and availability of origin servers. Application-level caching, in which developers manually control cached content, has been adopted when traditional forms of caching are insufficient to meet such requirements. Despite its popularity, this level of caching is typically addressed in an adhoc way, given that it depends on specific details of the application. Furthermore, it forces application developers to reason about a crosscutting concern, which is unrelated to the application business logic. As a result, application-level caching is a time-consuming and error-prone task, becoming a common source of bugs. This dissertation advances work on application-level caching by providing an understanding of its state-of-practice and automating the decision regarding cacheable content, thus providing developers with substantial support to design, implement and maintain application-level caching solutions. More specifically, we provide three key contributions: structured knowledge derived from a qualitative study, a survey of the state-of-the-art on static and adaptive caching approaches, and a technique and framework that automate the challenging task of identifying cache opportunities The qualitative study, which involved the investigation of ten web applications (open-source and commercial) with different characteristics, allowed us to determine the state-of-practice of application-level caching, along with practical guidance to developers as patterns and guidelines to be followed. Based on such patterns and guidelines derived, we also propose an approach to automate the identification of cacheable methods, which is often manually done and is not supported by existing approaches to implement application-level caching. We implemented a caching framework that can be seamlessly integrated into web applications to automatically identify and cache opportunities at runtime, by monitoring system execution and adaptively managing caching decisions. We evaluated our approach empirically with three open-source web applications, and results indicate that we can identify adequate caching opportunities by improving application throughput up to 12.16%. Furthermore, our approach can prevent code tangling and raise the abstraction level of caching.

Disruption-Tolerant Networks (DTN) allow communication between devices that lack end-to-end connectivity. Even though the mobility of devices in a DTN is frequently dynamic, most proposed DTN protocols are not adaptive. This work presents an ongoing research project that aims to find out to which extent context-based adaptation may be useful to improve DTN performance. We are convinced that, in highly predictive networks, metadata exchange is a crucial factor in supporting routing decisions and recognize context changes. This paper summarizes the efforts we have made so far and presents the next steps we plan to take towards the design and implementation of an adaptive framework.

Routing in Disruption-Tolerant Networks has been researched for over 15 years. Several proposed algorithms exploit the predictive behavior of mobile devices in order to maximize a desired metric (e.g., delivery probability) and minimize waste of resources. However, even devices that follow a highly predictive mobility model might have its behavior temporarily altered due to external events such as accidents, natural conditions, mechanical failures, etc. Some routing approaches for predictive networks are not able to make use of the available knowledge to support the routing decision. Others are not able to adapt under context change. In this work, we present the initial phase of our research and the necessary steps towards an adaptive DTN protocol for challenging networks that is able to exploit available knowledge and adapt under context changes.:I. Introduction II. Challenging Networks III. Challenges Towards an Adaptive Framework IV. Framework Design and Implementation V. Conclusion

Orientador: Frank José Affonso / Resumo: O cenário atual de desenvolvimento de software tem revelado um uso crescente de aplicações baseadas em serviços. Em um ambiente de computação distribuída, monitorar a qualidade de serviços para que essa aplicação não apresente algum tipo de anomalia ou interrupção pode ser considerada uma tarefa vital. Para isso, é necessário prover meios para o desenvolvimento de sistemas baseados em serviços capazes de observar seu estado interno de execução e/ou contexto ao qual estão inseridos e reagir diante de mudanças ou algum tipo de imprevisibilidade. Aplicações orientadas a serviços que permitem adaptação em tempo de execução podem ser classificadas como Self-Apps (do inglês, Self-adaptive Service-oriented Applications). Em função da complexidade intrínseca a esse tipo de aplicação, o uso de frameworks tem se mostrado uma alternativa viável por aliviar a carga cognitiva de desenvolvimento, a qual envolve o conhecimento de diversas áreas de pesquisa. Motivado por esse cenário, durante a realização deste trabalho foi conduzida uma revisão da literatura que engloba a condução de um mapeamento sistemático e consultas complementares em bases nacionais de teses e dissertações. Essa revisão permitiu obter um panorama detalhado referente ao estágio atual da pesquisa, seus desafios e as perspectivas futuras sobre frameworks para Self-Apps. Embasado nos resultados dessa revisão, o objetivo deste trabalho é o desenvolvimento do framework DynaMS (do inglês, Dynamic Deployment, QoS Metrics and S... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The current software development scenario has shown a crescent usage of service-based applications. In a distributed computing environment, the monitoring of the service’s quality is a relevant task because aims to assure that it does not present any anomaly or interruption. To do so, it is necessary to provide means to develop service-based systems that are capable to observe their internal execution state and/or the context in which they are inserted and to react in face of changes or unforeseen circumstances. Service-oriented applications that are able to perform adaptation in runtime can be classified as Self-Apps (i.e., Self-adaptive Service-oriented Applications). Given the complexity involved in this type of application, the use of frameworks has been shown as a viable alternative to reduce the cognitive development load regarding the knowledge from different research areas. Motivated by this scenario, we conducted a literature review as a part of this work. This review includes a systematic mapping and complementary searches to national thesis and dissertations’ databases. This review provided us a detailed panorama about the current stage of research, its challenges and the future perspectives regarding frameworks for Self-Apps. Based on the results from this review, the purpose of this Master’s project is to present a framework called DynaMS (Dynamic Deployment, QoS Metrics and Semantic Search) to support the development of this type of application. In short, this f... (Complete abstract click electronic access below) / Mestre

Systematic Literature Reviews (SLR) are a powerful research tool to identify and select literature to answer a certain question. However, an approach to extract inherent analytical data in Systematic Literature Reviews’ multi-dimensional datasets was lacking. Previous Systematic Literature Review tools do not incorporate the capability of providing said analytical insight. Therefore, this thesis aims to provide a useful approach comprehending various algorithms and data treatment techniques to provide the user with analytical insight on their data that is not evident in the bare execution of a Systematic Literature Review. For this goal, a literature review has been conducted to find the most relevant techniques to extract data from multi-dimensional data sets and the aforementioned approach has been tested on a survey regarding Self-Adaptive Systems (SAS) using a web-application. As a result, we find out what are the most adequate techniques to incorporate into the approach this thesis will provide.

Le contexte de ce travail de recherche se situe dans le domaine du génie logiciel, et vise plus spécifiquement les systèmes auto-adaptatifs (Self Adaptive Systems, SAS). Le travail de recherche vise les tous premiers stades du cycle de vie du développement logiciel : la phase de spécification des exigences (Requirements Engineering). Nous nous concentrons sur la définition et la modélisation des exigences (Elicitation) ainsi que sur leur vérification. La contribution globale de cette thèse est de proposer une approche intégrée pour la modélisation et la vérification des exigences des SAS à l'aide de techniques d'ingénierie des modèles (Model Driven Engineering, MDE). Nous prenons les exigences en entrée de notre processus et les divisons en exigences fonctionnelles et non fonctionnelles. Ensuite, nous appliquons un processus pour identifier les exigences qui sont adaptables et celles qui sont invariantes. Les progrès récents dans les techniques basées sur les buts en Ingénierie des Exigences nous ont poussé à intégrer ces techniques dans notre approche. En (Goal Oriented Requirements Engineering, GORE), les (Non Functional Requirements, NFR) sont exprimées sous la forme de buts, ce qui est beaucoup plus riche et complet dans la définition des relations entre les exigences. Ici, les exigences invariantes sont capturées par le concept de buts fonctionnels et les exigences adaptables sont capturées par le concept des buts non fonctionnels. Nous avons identifié quelques problèmes dans les méthodes classiques de modélisation des exigences et la vérification des propriétés. Ces approches ne tiennent pas compte des caractéristiques d'adaptabilité associées avec les systèmes auto-adaptatifs. Afin de valider notre approche, nous avons modélisé les exigences de deux études de cas et vérifié les exigences d'une étude de cas. / The overall contribution of this thesis is to propose an integrated approach for modeling and verifying the requirements of Self Adaptive Systems using Model Driven Engineering techniques. Model Driven Engineering is primarily concerned with reducing the gap between problem and software implementation domains through the use of technologies that support systematic transformation of problem level abstractions to software implementations. By using these techniques, we have bridged this gap through the use of models that describe complex systems at multiple levels of abstraction and through automated support for transforming and analyzing these models. We take requirements as input and divide it into Functional and Non Functional Requirements. We then use a process to identify those requirements that are adaptable and those that cannot be changed. We then introduce the concepts of Goal Oriented Requirements Engineering for modeling the requirements of Self Adaptive Systems, where Non Functional Requirements are expressed in the form of goals which is much more rich and complete in defining relations between requirements. We have identified some problems in the conventional methods of requirements modeling and properties verification using existing techniques, which do not take into account the adaptability features associated with Self Adaptive Systems. Our proposed approach takes into account these adaptable requirements and we provide various tools and processes that we developed for the requirements modeling and verification of Self Adaptive Systems. We validate our proposed approach by applying it on two different case studies in the domain of Self Adaptive Systems.