544 research outputs found
Certification of open-source software : a role for formal methods?
Despiteitshugesuccessandincreasingincorporationincom- plex, industrial-strength applications, open source software, by the very nature of its open, unconventional, distributed development model, is hard to assess and certify in an effective, sound and independent way. This makes its use and integration within safety or security-critical systems, a risk. And, simultaneously an opportunity and a challenge for rigourous, mathematically based, methods which aim at pushing software analysis and development to the level of a mature engineering discipline. This paper discusses such a challenge and proposes a number of ways in which open source development may benefit from the whole patrimony of formal methods.L. S. Barbosa research was partially supported by the CROSS project, under contract PTDC/EIA-CCO/108995/2008
Towards a flexible and dynamic replication control for distributed real-time embedded systems with QoS interdependencies
Replication is a proven concept for increasing the availability of distributed systems. However, actively replicating
every software component in distributed embedded systems may not be a feasible approach. Not only the available
resources are often limited, but also the imposed overhead could significantly degrade the system's performance. The
paper proposes heuristics to dynamically determine which components to replicate based on their significance to the
system as a whole, its consequent number of passive replicas, and where to place those replicas in the network. The
results show that the proposed heuristics achieve a reasonably higher system's availability than static offline decisions
when lower replication ratios are imposed due to resource or cost limitations.
The paper introduces a novel approach to coordinate the activation of passive replicas in interdependent distributed
environments. The proposed distributed coordination model reduces the complexity of the needed interactions among
nodes and is faster to converge to a globally acceptable solution than a traditional centralised approach
Políticas de Copyright de Publicações Científicas em Repositórios Institucionais: O Caso do INESC TEC
A progressiva transformação das práticas científicas, impulsionada pelo desenvolvimento das novas Tecnologias de Informação e Comunicação (TIC), têm possibilitado aumentar o acesso à informação, caminhando gradualmente para uma abertura do ciclo de pesquisa. Isto permitirá resolver a longo prazo uma adversidade que se tem colocado aos investigadores, que passa pela existência de barreiras que limitam as condições de acesso, sejam estas geográficas ou financeiras. Apesar da produção científica ser dominada, maioritariamente, por grandes editoras comerciais, estando sujeita às regras por estas impostas, o Movimento do Acesso Aberto cuja primeira declaração pública, a Declaração de Budapeste (BOAI), é de 2002, vem propor alterações significativas que beneficiam os autores e os leitores. Este Movimento vem a ganhar importância em Portugal desde 2003, com a constituição do primeiro repositório institucional a nível nacional. Os repositórios institucionais surgiram como uma ferramenta de divulgação da produção científica de uma instituição, com o intuito de permitir abrir aos resultados da investigação, quer antes da publicação e do próprio processo de arbitragem (preprint), quer depois (postprint), e, consequentemente, aumentar a visibilidade do trabalho desenvolvido por um investigador e a respetiva instituição. O estudo apresentado, que passou por uma análise das políticas de copyright das publicações científicas mais relevantes do INESC TEC, permitiu não só perceber que as editoras adotam cada vez mais políticas que possibilitam o auto-arquivo das publicações em repositórios institucionais, como também que existe todo um trabalho de sensibilização a percorrer, não só para os investigadores, como para a instituição e toda a sociedade. A produção de um conjunto de recomendações, que passam pela implementação de uma política institucional que incentive o auto-arquivo das publicações desenvolvidas no âmbito institucional no repositório, serve como mote para uma maior valorização da produção científica do INESC TEC.The progressive transformation of scientific practices, driven by the development of new Information and Communication Technologies (ICT), which made it possible to increase access to information, gradually moving towards an opening of the research cycle. This opening makes it possible to resolve, in the long term, the adversity that has been placed on researchers, which involves the existence of barriers that limit access conditions, whether geographical or financial. Although large commercial publishers predominantly dominate scientific production and subject it to the rules imposed by them, the Open Access movement whose first public declaration, the Budapest Declaration (BOAI), was in 2002, proposes significant changes that benefit the authors and the readers. This Movement has gained importance in Portugal since 2003, with the constitution of the first institutional repository at the national level. Institutional repositories have emerged as a tool for disseminating the scientific production of an institution to open the results of the research, both before publication and the preprint process and postprint, increase the visibility of work done by an investigator and his or her institution. The present study, which underwent an analysis of the copyright policies of INESC TEC most relevant scientific publications, allowed not only to realize that publishers are increasingly adopting policies that make it possible to self-archive publications in institutional repositories, all the work of raising awareness, not only for researchers but also for the institution and the whole society. The production of a set of recommendations, which go through the implementation of an institutional policy that encourages the self-archiving of the publications developed in the institutional scope in the repository, serves as a motto for a greater appreciation of the scientific production of INESC TEC
Web services choreography testing using semantic service description
Web services have become popular due to their ability to integrate with and to interoperate heterogeneous applications. Several web services can be combined into a single application to meet the needs of users. In the course of web services selection, a web candidate service needs to conform to the behaviour of its client, and one way of ensuring this conformity is by testing the interaction between the web service and its user. The existing web services test approaches mainly focus on syntax-based web services description, whilst the semantic-based solutions mostly address composite process flow testing. The aim of this research is to provide an automated testing approach to support service selection during automatic web services composition using Web Service Modeling Ontology (WSMO). The research work began with understanding and analysing the existing test generation approaches for web services. Second, the weaknesses of the existing approaches were identified and addressed by utilizing the choreography transition rules of WSMO in an effort to generate a Finite State Machine (FSM). The FSM was then used to generate the working test cases. Third, a technique to generate an FSM from Abstract State Machine (ASM) was adapted to be used with WSMO. This thesis finally proposed a new testing model called the Choreography to Finite State Machine (C2FSM) to support the service selection of an automatic web service composition. It proposed new algorithms to automatically generate the test cases from the semantic description (WSMO choreography description). The proposed approach was then evaluated using the Amazon E-Commerce Web Service WSMO description. The quality of the test cases generated using the proposed approach was measured by assessing their mutation adequacy score. A total of 115 mutants were created based on 7 mutant operators. A mutation adequacy score of 0.713 was obtained. The experimental validation demonstrated a significant result in the sense that C2FSM provided an efficient and feasible solution. The result of this research could assist the service consumer agents in verifying the behaviour of the Web service in selecting appropriate services for web service composition
Integration of Virtual Programming Lab in a process of teaching programming EduScrum based
Programming teaching is a key factor for technological evolution. The efficient way to learn to program is by programming and hard training and thus feedback is a crucial factor in the success and flow of the process.
This work aims to analyse the potential use of VPL in the teaching process of programming in higher education. It also intends to verify whether, with VPL, it is possible to make students learning more effective and autonomous, with a reduction in the volume of assessment work by teachers. Experiments were carried out with the VPL, in the practical-laboratory classes of a curricular unit of initiation to programming in a higher education institution.
The results supported by the responses to surveys, point to the validity of the model
Multidisciplinary perspectives on Artificial Intelligence and the law
This open access book presents an interdisciplinary, multi-authored, edited collection of chapters on Artificial Intelligence (‘AI’) and the Law. AI technology has come to play a central role in the modern data economy. Through a combination of increased computing power, the growing availability of data and the advancement of algorithms, AI has now become an umbrella term for some of the most transformational technological breakthroughs of this age. The importance of AI stems from both the opportunities that it offers and the challenges that it entails. While AI applications hold the promise of economic growth and efficiency gains, they also create significant risks and uncertainty. The potential and perils of AI have thus come to dominate modern discussions of technology and ethics – and although AI was initially allowed to largely develop without guidelines or rules, few would deny that the law is set to play a fundamental role in shaping the future of AI. As the debate over AI is far from over, the need for rigorous analysis has never been greater. This book thus brings together contributors from different fields and backgrounds to explore how the law might provide answers to some of the most pressing questions raised by AI. An outcome of the Católica Research Centre for the Future of Law and its interdisciplinary working group on Law and Artificial Intelligence, it includes contributions by leading scholars in the fields of technology, ethics and the law.info:eu-repo/semantics/publishedVersio
A WSSL Implementation for Critical CyberPhysical Systems Applications
The advancements in wireless communication technologies have enabled unprecedented pervasiveness and ubiquity of Cyber-Physical Systems (CPS). Such technologies can now empower true Systems-of-Systems (SoS), which cooperate to achieve more complex and efficient functionalities, such as vehicle automation, industry, residential automation, and others. However, for CPS applications to become a reality and fulfill their potential, safety and security must be guaranteed, particularly in critical systems, since they rely heavily on open communication systems, prone to intentional and non-intentional interferences. To address these issues, in this work, we propose designing a Wireless Security and Safety Layer (WSSL) architecture to be implemented in critical CPS applications. WSSL increases the reliability of these critical communications by enabling the detection of communication errors. Otherwise, it increases the CPS security using a message signature process that uniquely identifies the sender. So, this work intends to present the WSSL architecture and its implementation over two different scenarios: over Message Queue Telemetry Transport (MQTT) protocol and inside a simulation environment for communication between Unmanned Aerial Vehicles (UAVs) and Ground Control Stations in case of Beyond Visual Line of Sight (BVLOS) applications. We aim to prove that the WSSL does not significantly increase the system payload and demonstrate its safety and security resources, allowing it to be used in any general or critical CPS.Os avanços nas tecnologias de comunicação sem fios permitiram uma omnipresença e ubiquidade sem precedentes dos Sistemas Ciber-Físicos (CPS). CPS são a combinação de um sistema físico, um sistema cibernético, e a sua rede de comunicação. Tais tecnologias podem agora capacitar verdadeiros Sistemas de Sistemas (SoS) que cooperam para alcançar funcionalidades mais complexas e eficientes, tais como automação de veículos, indústria, automação residencial, e outras. As aplicações CPS são baseadas num ambiente complexo, onde sistemas estão interligados e dispositivos interagem entre si em grande escala. Estas circunstâncias aumentam a superfície de ataque, e os desafios para garantir fiabilidade e segurança. Contudo, para que as aplicações CPS se tornem realidade e alcancem o seu potencial, a segurança do funcionamento e segurança contra intrusões devem ser garantidas, particularmente em sistemas críticos, uma vez que dependem fortemente de sistemas de comunicação abertos, propensos a interferências intencionais e não intencionais. Tais interferências podem ocasionar graves danos ao ambiente e riscos a integridade física e moral das pessoas envolvidas. Neste trabalho, propõe-se a concepção de uma arquitectura WSSL, a ser implementada em aplicações críticas de CPS, para abordar estas questões. Esta arquitectura aumenta a fiabilidade das comunicações críticas, permitindo a detecção de erros de comunicação. Além disso, aumenta a segurança dos CPS utilizando um processo de assinatura de mensagem que identifica de forma única o remetente, garantindo a integridade e autenticidade, pilares cruciais da cibersegurança. Assim, pretende-se apresentar a definição, arquitectura e a implementação da WSSL sobre um protocolo MQTT (do inglês Message Queue Telemetry Transport) para avaliação dos custos associados a sua implementação, e provar que esta não aumenta significativamente a carga útil do sistema. Também é pretendido avaliar seu comportamento e custos a partir da implementação em um ambiente simulado para comunicação entre veículos aéreos não tripulados e estações de controle terrestres . Por fim, deve-se avaliar se os seus recursos de segurança são eficientes na detecção de erros relativos a segurança do funcionamento ou a segurança contra intrusões, permitindo a sua utilização em qualquer CPS, seja ele um CPS crítico ou não.N/
Intergiciel d'intergiciels adaptable à base de Services, Composants et Aspects
Cette habilitation à diriger des recherches présente mes travaux sur le génie logiciel des intergiciels, domaine à la croisée de l’informatique répartie et du génie logiciel. L’intergiciel est la couche logicielle permettant de s’abstraire de l’hétérogénéité des technologies de l’informatique distribuée et de répondre aux besoins d’interopérabilité, de portabilité, d’adaptation et de séparation des préoccupations des applications réparties. Mes travaux ont été guidés par deux questions de recherche ouvertes : 1) quel est le paradigme de programmation le plus approprié pour les applications réparties ? 2) quelle est l’organisation la plus appropriée pour l’intergiciel ?La première partie présente une synthèse de mes travaux et contributions. Premièrement, mes travaux ont porté sur la transition des objets vers les composants CORBA donnant lieu à deux contributions majeures : le langage de script CorbaScript standardisé auprès de l’OMG et la plate-forme OpenCCM pour le développement, le déploiement, l’exécution et l’administration d’applications réparties à base de composants CORBA. Deuxièmement, je me suis intéressé à la conception de canevas intergiciels hautement adaptables. Ces travaux basés sur les composants réflexifs Fractal ont donné lieu à un cadre de programmation par attributs sur lequel trois canevas flexibles pour la gestion du transactionnel, le déploiement de systèmes distribués hétérogènes et les composants Java temps-réels ont été bâtis. Enfin, mes travaux ont porté sur la proposition du modèle Services Composants Aspects (SCA) et l’intergiciel d’intergiciels FraSCAti.La deuxième partie opère un zoom sur le projet FraSCAti. La contribution scientifique de ce projet est de proposer un intergiciel réflexif pour l’informatique orientée service combinant deux idées originales : la notion d’intergiciel d’intergiciels et le modèle Services Composants Aspects réflexif. Partant du constat qu’il n’existe pas d’intergiciel universel capable de couvrir l’ensemble des besoins de toutes les applications distribuées, le projet FraSCAti propose un canevas intergiciel extensible pour l’intégration et la composition élégante des intergiciels et technologies SOA existants, c’est-à-dire un intergiciel d’intergiciels. Le modèle SCA réflexif est quant à lui le mariage fécond du standard OASIS Service Component Architecture (SCA), du modèle de composants Fractal et de la programmation orientée aspects (AOP). Dans ce modèle, tout est composant réflexif permettant ainsi d’adapter dynamiquement aussi bien les applications métiers, l’intergiciel, les liaisons de communication réseau que les aspects non fonctionnels. Cette contribution a été appliquée sur l’orchestration de services à large échelle, la construction de systèmes de systèmes et une plate-forme distribuée multi-nuages. La dernière partie dresse un bilan des contributions et présente mes perspectives de recherche centrées sur le génie logiciel pour l’informatique en nuage (cloud computing)
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