O desenvolvimento de sistemas de ensino a distância (EaD) adaptativos vêm sendo o alvo de pesquisa nos últimos anos, porém uma das carências mais importantes é que estes sistemas não possuem dados suficientes que descrevam o aluno, de modo a realizar a adaptação adequada. Uma das grandes dificuldades no processo é a aquisição desses dados. Normalmente para a realização de um curso em um sistema de EaD na Web, o aluno, entre outras atividades, deve cadastrar-se no sistema e informar seus dados pessoais. Alguns sistemas possuem mecanismos para descoberta das preferências do aluno, seu estilo de aprendizagem ou estilo cognitivo, visando oferecer um ensino personalizado. Porém, se este mesmo aluno se matricular em outro curso que utilize outro sistema de EaD na Web, todas essas informações não são repassadas de um sistema para o outro e acabam sendo informadas ou descobertas novamente. Portanto, os sistemas não colaboram entre si no sentido de tornar as informações sobre os alunos mais completas. Quanto mais variada for a informação que os sistemas tiverem sobre os alunos, o modelo do aluno em cada sistema estará mais completo e, conseqüentemente, a adaptabilidade do conteúdo ao seu perfil, mais eficiente. O objetivo principal desta tese é solucionar a problemática associada ao gerenciamento de dados contidos no modelo de aluno quando compartilhadas entre vários ambientes de ensino a distância (EaD). Como solução, esta tese propõe o modelo LPEM (Learner Profile Exchange Model) que define as estratégias que regem o compartilhamento de dados de modelos de aluno entre diversos sistemas. O diferencial do modelo está no uso de uma ontologia (OntoLearner), baseada em padrões, para a troca de dados. A especificação da ontologia OntoLearner também consiste em uma contribuição da tese, e pode ser utilizada no contexto de qualquer sistema desse mesmo domínio. Um subconjunto relativo as principais funcionalidades do modelo foi implementado, para isso também foi definida nesta tese a especificação física do modelo, que oferece as funcionalidades do modelo na forma de Web services. Uma arquitetura orientada a serviços também é descrita na tese e serve de referencia para implementação do modelo LPEM. O protótipo serviu de indicativo para comprovar que a solução proposta é possível de ser implementada, gerando os resultados esperados quanto ao compartilhamento dos dados. / The development of adaptive systems has been the target of some research works over the last years. However, an important lack to be considered is that these systems do not have enough information about the student in order to provide an adequate adaptation. One of the most important drawbacks for this lack is the difficulty of acquiring such information. New learners of an e-learning system are normally required to update their personal information before proceeding in one of the offered courses. Some systems are able to adapt its course content presentation using some techniques that discover the learner’s preferences, level of previous knowledge, and cognitive style. However, this important information about learners is not shared among different e-learning systems. This forces the learner to fill cumbersome forms in each new system, and also forces each new systems to analyze and process new learner’s behavioral information. By consequence, current systems do not collaborate with each other in order to enrich the information related to users of different e-learning systems. Considering these problems, the main objective of this thesis is to address the problem of data management within the learner’s model when data are shared among different e-learning systems. In this thesis we propose the LPEM (Learner Profile Exchange Model) model, which defines the strategies to share the learner’s data model among the different systems. The main contribution of the proposed model is the use of an ontology, named OntoLearner, which is based on standards for data exchange. The ontology OntoLerarner is a contribution as well, since it has been developed for LPEM but can be used by any other system in this domain. A subset of the main functionalities of the proposed model was implemented. For that purpose, the physical model was defined in order to provide a functionalities model for Web Services. The prototype shows that the proposed solution can be implemented, generating the results expected for data sharing.

A disseminação dos dispositivos embarcados por diferentes domínios de aplicação torna necessário que a interação entre eles dispense ao máximo a intervenção humana. Diversos protocolos e tecnologias foram criados para a atingir este objetivo. Uma destas tecnologias é o Device Profile for Web Services (DPWS), que tem tido relativa aceitação tanto em ambientes industriais quanto residenciais. A expressividade e flexibilidade do DPWS tem permitido integrar dispositivos com recursos reduzidos diretamente com os sistema de gerenciamento das organizações. Com a diversidade dos dispositivos disponíveis e o crescimento das aplicações de redes sem fio, torna-se importante que os dados possam ser protegidos para manter a sua integridade e sigilo. Em aplicações como controle de processos, aquisição de dados estratégicos, medição de consumo de energia, entre outras, os prejuízos causados por interferências indevidas justificam a aplicação de estratégias de proteção dos dados, mesmo com o custo que elas podem gerar. Neste trabalho, são estudados os impactos da união da flexibilidade e expressividade do DPWS com a criptografia e compressão, fornecendo subsídios para que seja avaliado o custo de cada combinação destas soluções para definir quais níveis de proteção e otimização são mais adequados a cada cenário em que o DPWS possa ser aplicado. Ao fim do estudo realizado, demonstra-se o custo da criptografia na proteção dos dados, avaliando-se diferentes suítes de cifragem nas quais os algoritmos RC4 e o AES se mostram como opções viáveis em ambientes embarcados apesar do custo inerente ao processo de criptografia. Outro ponto importante é a comprovação estatística de que a compressão dos dados propicia um ganho de desempenho com redução de banda ocupada capaz de compensar o custo computacional da sua aplicação. Estas análises comprovam que o uso do tráfego seguro não pode ser aplicado a todos os casos devido às suas exigências de recursos. Em certas aplicações é possível achar um ponto intermediário onde se garanta apenas a autenticidade dos dados, deixando a criptografia completa para os casos mais críticos. Por fim, a conclusão à qual se chega é que o DPWS pode ser um substituto para as opções atuais de gerenciamento, sobre as quais tem como principal vantagem a capacidade de crescer em representatividade e complexidade de acordo com os recursos computacionais disponíveis. / The growth of use of embedded devices in several application domains makes necessary the reduction of human interaction for the devices control and has motivated the development of new technologies to achieve this goal. The Device Profile for Web Services (DPWS) is one of such technologies. It has been adopted on both industrial and home applications due to its flexibility, scalability and interoperability that allows the direct integration between deeply embedded devices and enterprise management systems. The remote device management requires a high level of data protection that could guarantee the integrity and confidentiality needed by industrial applications. In applications such as process control, strategic data acquisition, power consumption measurement, the possible harm caused by undue interference justify the use of data protection strategies despite the increasing of cost added by security technologies. This paper presents the results of a statistically proven study on the security layer applications of DPWS embedded devices using compressed data. The main objective of this work is to provide the background required to DPWS secure devices design, estimating the impact of many combinations of compression and security algorithms such as gzip, RC4 and AES. It proves that these technologies fit in embedded devices applications when data security is a strong requirement. Additionally, it is shown that performance degradation caused by data compression is compensated by the reduction of the amount of data to be encrypted. Best results were obtained when the compressed data fit in one Ethernet packet. Finally, is concluded that DPWS can replace the current alternatives to process management, having the advantages of scalability direct connection between deeply embedded devices and enterprise management systems.

Este projeto de mestrado aborda a utilização de recursos daWeb Semântica na seleção de informações sobre Web Services no registro UDDI (Universal Description, Discovery, and Integration). Esse registro possui a limitação de apenas armazenar informações funcionais de Web Services. As informações não funcionais que incluem as informações de qualidade de serviço (QoS - Quality of Service) não são contempladas e dessa forma dificulta a escolha do melhor serviço pelos clientes. Neste projeto, a representação da base de conhecimento com informações sobre os provedores, clientes, acordos, serviços e a qualidade dos serviços prestados foi feita por meio de uma ontologia. Essa ontologia é utilizada pelo módulo UDOnt-Q (Universal Discovery with Ontology and QoS) que foi projetado para servir de plataforma para algoritmos de busca e composição de serviços com qualidade. Embora a utilização de semântica possa ser empregada para a composição e automatização de serviços, o foco deste trabalho é a garantia de qualidade de serviço em Web Services. Os algoritmos desenvolvidos empregam recursos da Web Semântica para classificar e selecionar os Web Services adequados de acordo com as informações de qualidade que estão armazenados na ontologia. O módulo e os algoritmos foram submetidos a avaliações de desempenho que revelaram problemas de desempenho com relação a abordagem adotada durante o processo de inferência da ontologia. Tal processo é utilizado para a classificação das informações dos elementos presentes na ontologia. Contudo, uma vez que as informações foram inferidas, o processo de busca e seleção de serviços comprovou a viabilidade de utilização do módulo e de um dos seus algoritmos de seleção / This master project addresses the use of Semantic Web resources in the selection of information about Web Services in UDDI registry (Universal Description, Discovery, and Integration). This registry has the limitation of only storing functional information of Web Services. The nonfunctional information that includes the quality of service information (QoS - Quality of Service) is not covered and thus it is complicate to choose the best service for customers. In this project, the representation of the knowledge base with information about the providers, customers, agreements, services and quality of services has been made through an ontology. This ontology is used by the module UDOnt-Q (Universal Discovery with Ontology and QoS) that was designed to serve as a platform for search algorithms and composition of services with quality. Although the use of semantics can be adopted for the composition and automation of services, the focus of this work is to guarantee quality of service in Web Services. The developed algorithms employ SemanticWeb resources to classify and select the appropriate Web Services according to the quality information that is stored in the ontology. The module and the algorithms have been subjected to performance evaluations that revealed performance problems in relation to the approach taken during the ontology inference process. This process is used for classification of information of the elements present in the ontology. However, since the information was inferred, the process of search and selection services proved the viability of using the module and one of its selection algorithms

Tese de Mestrado Integrado. Engenharia Informática e Computação. Faculdade de Engenharia. Universidade do Porto. 2012

Our society increasingly relies on the Internet for common services like online banking, shopping, and socializing. Many of these services heavily depend on secure end-to-end transactions to transfer personal, financial, or other sensitive information. At the core of ensuring secure transactions are the TLS/SSL protocol and the ``trust'' relationships between all involved partners. In this thesis we passively monitor the HTTPS traffic between a campus network and the Internet, and characterize the certificate usage and trust relationships in this complex landscape. By comparing our observations against known vulnerabilities and problems, we provide an overview of the actual security that typical Internet users (such as the people on campus) experience. Our measurements cover both mobile and stationary users, consider the involved trust relationships, and provide insights into how the HTTPS protocol is used and the weaknesses observed in practice.

Service-Oriented Architecture (SOA) represents an emerging architectural approach that is able to tackle challenges in the contemporary service-based economy, in which the global market revenues are shifting from the manufacture of traditional off-the-shelf products to the provision of diversified services that suffice for customers’ needs. In such a service-based economy, one can envisage an entirely “service-oriented” world, where a massive number of distributed services with different natures and capabilities are provided by various professionals around the world. Problems arise when business applications demand desirable services through different sources and providers that are appropriate for their own benefits and preferences. Therefore, it can be very challenging to design an SOA infrastructure that enables users to exploit this great level of service heterogeneity and quantity. One of the key issues in service-oriented architecture is to achieve efficient service discovery and loosely-coupled service distribution while maintaining a satisfactory degree of scalability, usability, and Web consistency. This thesis deals with SOA infrastructure-level design and implementation issues. It approaches this SOA infrastructure within the scope of Web services, which capture an important, and perhaps the best, ‘realisation’ of SOA. It investigates and formulates how public Web services distributed across the World Wide Web can be augmented by a software platform that enables scalable, user-centred,semantic-enabled, and integration-oriented service retrieval, selection, and matching. The primary goal of this thesis is thus to propose a conceptual framework of an enhanced SOA infrastructure with regard to service distribution and discovery. / It also aims to design and implement a platform (PWSP), by means of which a large number of public Web services on the Web can be distributed based on service demands, retrieved based on service descriptions, selected based on service qualities, and matched based on service messages in a user-centred, scalable, and Web-consistent manner without augmenting existing Web services standards.

Abstract not available

Service-oriented architectures (SOA), and in particular Web services, have quickly become a popular technology to connect applications both within and across enterprise boundaries. However, as services are increasingly used to implement critical functionality, security has become an important concern impeding the widespread adoption of SOA. Trust negotiation is an approach to access control that may be applied in scenarios where service requesters are often unknown in advance, such as for services available via the public Internet. Rather than relying on requesters' identities, trust negotiation makes access decisions based on the level of trust established between the requester and the provider in a negotiation, during which the parties exchange credentials, which are signed assertions that describe some attributes of the owner. However, managing the evolution of trust negotiation policies is a difficult problem that has not been sufficiently addressed to date. Access control policies have a lifecycle, and they are revised based on applicable business policies. Additionally, because a trust relationship established in a trust negotiation may be long lasting, their evolution must also be managed. Simply allowing a negotiation to continue according to an old policy may be undesirable, especially if new important constraints have been added. In this thesis, we introduce a model-driven trust negotiation framework for service-oriented applications. The framework employs a model for trust negotiation, based on state machines, that allows automated generation of the control structures necessary to enforce trust negotiation policies from the visual model of the policy. Our policy model also supports lifecycle management. We provide sets of operations to modify policies and to manage ongoing negotiations, and operators for identifying and managing impacts of changes to trust negotiation policies on ongoing trust negotiations. The framework presented in the thesis has been implemented in the Trust-Serv prototype, which leverages industry specifications such as WS-Security and WS-Trust to offer a container-centric mechanism for deploying trust negotiation that is transparent to the services being protected.

Web services are increasingly gaining acceptance as a framework for facilitating application-to-application interactions within and across enterprises. It is commonly accepted that a service description should include not only the interface, but also the business protocol supported by the service. The present work focuses on the formalization of the important category of protocols that include time-related constraints (called timed protocols), and the impact of time on compatibility and replaceability analysis. We formalized the following timing constraints: CInvoke constraints define time windows of availability while MInvoke constraints define expirations deadlines. We extended techniques for compatibility and replaceability analysis between timed protocols by using a semantic-preserving mapping between timed protocols and timed automata, leading to the novel class of protocol timed automata (PTA). Specifically, PTA exhibit silent transitions that cannot be removed in general, yet they are closed under complementation, making every type of compatibility or replaceability analysis decidable. Finally, we implemented our approach in the context of a larger project called ServiceMosaic, a model-driven framework for web service life-cycle management.

<p>In silico experiments in the field of bioinformatics generate large amounts of data since most of the tasks are done in an exploratory fashion. Workflows are one of the many tools used by scientists to model complex tasks.The interoperability of data generated from these tools plays an important role in improving the efficiency of such tools and also in verifying results from other experiments.We aim to compare workflow systems by integrating bioinformatics data in Vistrails and Taverna. We also look at how the two systems use the open provenance model that has been developed to bring provenance interoperability. We developed web services to perform similar functions of some workflows in Vistrails. With the services we were able to perform most of the tasks we planned using both systems. Differences in how lists of items are processed in the two systems results in differences in how workflows are composed in the two systems. In Taverna there is implicit iteration and Vistrails requires the use of additional modules to perform iteration.There are also differences in the execution times of workflows using web services, with workflows in Taverna taking longer than their counterparts in Vistrails. There are some similarities in the execution pattern of workflows if same workflow is invokedmultiple times, with the first invocation taking longer time than the subsequent ones.</p>