Le contexte de cette thèse est à l’intersection des contextes des grilles de calculs, des nouvelles technologies du Web ainsi que des Clouds et des services à la demande. Depuis leur avènement au cours des années 90, les plates-formes distribuées, plus précisément les systèmes de grilles de calcul (Grid Computing), n’ont pas cessé d’évoluer permettant ainsi de susciter multiple efforts de recherche. Les grilles de PCs ont été proposées comme une alternative aux super-calculateurs par la fédération des milliers d’ordinateurs de bureau. Les détails de la mise en oeuvre d’une telle architecture de grille, en termes de mécanismes de mutualisation des ressources, restent très difficile à cerner. Parallèlement, le Web a complètement modifié notre façon d’accéder à l’information. Le Web est maintenant une composante essentielle de notre quotidien. Les équipements ont, à leur tour, évolué d’ordinateurs de bureau ou ordinateurs portables aux tablettes, lecteurs multimédias, consoles de jeux, smartphones, ou NetPCs. Cette évolution exige d’adapter et de repenser les applications/intergiciels de grille de PCs qui ont été développés ces dernières années. Notre contribution se résume dans la réalisation d’un intergiciel de grille de PCs que nous avons appelé RedisDG. Dans son fonctionnement, RedisDG reste similaire à la plupart des intergiciels de grilles de calcul, c’est-à-dire qu’il est capable d’exécuter des applications sous forme de «sacs de tâches» dans un environnement distribué, assurer le monitoring des noeuds, valider et certifier les résultats. L’innovation de RedisDG, réside dans l’intégration de la modélisation et la vérification formelles dans sa phase de conception, ce qui est non conventionnel mais très pertinent dans notre domaine. Notre approche consiste à repenser les grilles de PCs à partir d’une réflexion et d’un cadre formel permettant de les développer, de manière rigoureuse et de mieux maîtriser les évolutions technologiques à venir. / The context of this work is at the intersection of grid computing, the new Web technologies and the Clouds and services on demand contexts. Desktop Grid have been proposed as an alternative to supercomputers by the federation of thousands of desktops. The details of the implementation of such an architecture, in terms of resource sharing mechanisms, remain very hard. Meanwhile, the Web has completely changed the way we access information. The equipment, in turn, have evolved from desktops or laptops to tablets, smartphones or NetPCs. Our approach is to rethink Desktop Grids from a reflexion and a formal framework to develop them rigorously and better control future technological developments. We have reconsidered the interactions between the traditional components of a Desktop Grid based on the Web technology, and given birth to RedisDG, a new Desktop Grid middelware capable to operate on small devices, ie smartphones, tablets like the more traditional devicves (PCs). Our system is entirely based on the publish-subscribe paradigm. RedisDG is developped with Python and uses Redis as advanced key-value cache and store.

In this study a comparison of the publish-subscribe communication protocols OPS, MQTT and DDS were conducted. The implementation used for DDS was fastDDS and the client library Paho Eclipse MQTT C++ was used for MQTT with the broker implementation Eclipse Mosquitto. The goal was to see which out of these protocols performs best in a peer-to-peer communication scenario when it comes to latency and throughput with varying payload size. Two experiments were carried out. The first experiment measures the round-trip-time of a message and is realized by a ping-pong application. The latency was then calculated by taking half of the round-trip-time. The second experiment was publishing messages from one client and being retrieved by another and counting the amount of messages being retrieved in one second. To get bytes per second the payload size was multiplied by the amount of messages retrieved by the subscriber. The result of the first experiment showed that OPS with the underlying transport protocol TCP had the most favorable result. For the second experiment OPS with UDP as the transport protocol had the highest throughput in most cases however for the highest payload used in the experiment fastDDS with UDP had the highest throughput. However, the results gave substantial differences between the protocols in regards to throughput which indicate that the configuration might not be optimal for a fair comparison. Further research of this is recommended before making a final conclusion in regards to the overall results. / I denna studie genomfördes en jämförelse av kommunikationsprotokollen OPS, MQTT och DDS. Implementeringen som användes för DDS var fastDDS och klientbiblioteket Paho Eclipse MQTT C++ användes för MQTT med Eclipse Mosquitto som broker. Målet var att se vilket av dessa protokoll som fungerar bäst i ett peer-to-peer-kommunikationsscenario när det gäller fördröjningstid och throughput med varierande payloadstorlek. Två experiment utfördes. Det första experimentet mäter round-trip-time för ett meddelande och realiseras av en ping-pong-applikation. Fördröjningstiden beräknades sedan genom att ta hälften av round-trip-time. Det andra experimentet var att publicera meddelanden från en klient och mottas av en annan och räkna mängden meddelanden som mottas på en sekund. För att få byte per sekund multiplicerades payload storleken med mängden meddelanden som togs emot av prenumeranten. Resultatet av det första experimentet visade att OPS med det underliggande transportprotokollet TCP hade det mest gynnsamma resultatet. För det andra experimentet hade OPS med UDP som transportprotokoll den högsta throughput i de flesta fall, men för den största payloadstorleken som användes i experimentet hade fastDDS med UDP den högsta. Resultaten gav dock betydande skillnader mellan protokollen när det gäller throughput som indikerar att konfigurationen kanske inte är optimal för en rättvis jämförelse. Ytterligare forskning om detta rekommenderas för att utreda orsaken till dessa skillnader och därefter kunna skapa konfigurationer som ger rättvisa förutsättningar för en optimal jämförelse.

Today, virtually every company world-wide is connected to the Internet. This wide-spread connectivity has given rise to sophisticated, targeted, Internet-based attacks. For example, between 2012 and 2013 security researchers counted an average of about 74 targeted attacks per day. These attacks are motivated by economical, financial, or political interests and commonly referred to as “Advanced Persistent Threat (APT)” attacks. Unfortunately, many of these attacks are successful and the adversaries manage to steal important data or disrupt vital services. Victims are preferably companies from vital industries, such as banks, defense contractors, or power plants. Given that these industries are well-protected, often employing a team of security specialists, the question is: How can these attacks be so successful? Researchers have identified several properties of APT attacks which make them so efficient. First, they are adaptable. This means that they can change the way they attack and the tools they use for this purpose at any given moment in time. Second, they conceal their actions and communication by using encryption, for example. This renders many defense systems useless as they assume complete access to the actual communication content. Third, their actions are stealthy — either by keeping communication to the bare minimum or by mimicking legitimate users. This makes them “fly below the radar” of defense systems which check for anomalous communication. And finally, with the goal to increase their impact or monetisation prospects, their attacks are targeted against several companies from the same industry. Since months can pass between the first attack, its detection, and comprehensive analysis, it is often too late to deploy appropriate counter-measures at businesses peers. Instead, it is much more likely that they have already been attacked successfully. This thesis tries to answer the question whether the last property (industry-wide attacks) can be used to detect such attacks. It presents the design, implementation and evaluation of a community-based intrusion detection system, capable of protecting businesses at industry-scale. The contributions of this thesis are as follows. First, it presents a novel algorithm for community detection which can detect an industry (e.g., energy, financial, or defense industries) in Internet communication. Second, it demonstrates the design, implementation, and evaluation of a distributed graph mining engine that is able to scale with the throughput of the input data while maintaining an end-to-end latency for updates in the range of a few milliseconds. Third, it illustrates the usage of this engine to detect APT attacks against industries by analyzing IP flow information from an Internet service provider. Finally, it introduces a detection algorithm- and input-agnostic intrusion detection engine which supports not only intrusion detection on IP flow but any other intrusion detection algorithm and data-source as well.

Made available in DSpace on 2016-08-17T14:53:29Z (GMT). No. of bitstreams: 1 DISSERTACAO Dejailson Nascimento Pinheiro.pdf: 1433962 bytes, checksum: 4173dad207f09fa2033a834f86a5d4b7 (MD5) Previous issue date: 2014-08-06 / Mobile Social Networks (MSNs) are social structures in which members relate in groups and interaction is accomplished through information and communication technologies using portable devices and wireless network technologies. Healthcare is one among the many possible areas of RSMs application. The MobileHealthNet project, developed in partnership by UFMA and PUC-Rio, aims to develop a middleware that allows access to social networks and facilitate the development of collaborative services targeting the health domain, the exchange of experiences and communication between patients and health professionals, as well as a better management of health resources by government agencies. An important aspect in the development of the MobileHealthNet middleware is the infrastructure necessary for the gathering, distribution and processing of context data. In this master thesis we propose a software infrastructure incorporated to the MobileHealthNet middleware that allows the specification, acquisition, validation and distribution of context data, considering quality requirements, making them available to context-aware applications. The distribution of context data is based on a data-centric the publish/subscribe model, using the OMG-DDS specification. / Redes Sociais Móveis (RSMs) são estruturas sociais em que seus membros relacionam-se em grupos e a interação é realizada através de tecnologias de informação e comunicação utilizando dispositivos portáteis com acesso a tecnologias de rede sem fio. Entre os muitos domínios de aplicação das RSMs, temos a área da saúde. O projeto MobileHealthNet, desenvolvido em parceria pela UFMA e PUC-Rio, tem por objetivo desenvolver um middleware que permita o acesso às redes sociais e facilite o desenvolvimento de serviços colaborativos para o setor da saúde, a troca de experiências e a comunicação entre pacientes e profissionais da saúde, além de uma melhor gestão dos recursos da saúde por órgãos governamentais. Um aspecto importante no desenvolvimento do middleware proposto pelo projeto MobileHealthNet é a infraestrutura necessária para a coleta, distribuição e processamento de dados de contexto. Neste trabalho de mestrado é proposta uma infraestrutura de software incorporada ao middleware MobileHealthNet que permite a especificação, obtenção, validação e distribuição de dados de contexto, considerando requisitos de qualidade, tornando-os disponíveis a aplicações sensíveis ao contexto. A distribuição dos dados de contexto é baseado no modelo publish/subscribe centrado em dados, utilizando-se a especificação OMG-DDS.

Today, virtually every company world-wide is connected to the Internet. This wide-spread connectivity has given rise to sophisticated, targeted, Internet-based attacks. For example, between 2012 and 2013 security researchers counted an average of about 74 targeted attacks per day. These attacks are motivated by economical, financial, or political interests and commonly referred to as “Advanced Persistent Threat (APT)” attacks. Unfortunately, many of these attacks are successful and the adversaries manage to steal important data or disrupt vital services. Victims are preferably companies from vital industries, such as banks, defense contractors, or power plants. Given that these industries are well-protected, often employing a team of security specialists, the question is: How can these attacks be so successful? Researchers have identified several properties of APT attacks which make them so efficient. First, they are adaptable. This means that they can change the way they attack and the tools they use for this purpose at any given moment in time. Second, they conceal their actions and communication by using encryption, for example. This renders many defense systems useless as they assume complete access to the actual communication content. Third, their actions are stealthy — either by keeping communication to the bare minimum or by mimicking legitimate users. This makes them “fly below the radar” of defense systems which check for anomalous communication. And finally, with the goal to increase their impact or monetisation prospects, their attacks are targeted against several companies from the same industry. Since months can pass between the first attack, its detection, and comprehensive analysis, it is often too late to deploy appropriate counter-measures at businesses peers. Instead, it is much more likely that they have already been attacked successfully. This thesis tries to answer the question whether the last property (industry-wide attacks) can be used to detect such attacks. It presents the design, implementation and evaluation of a community-based intrusion detection system, capable of protecting businesses at industry-scale. The contributions of this thesis are as follows. First, it presents a novel algorithm for community detection which can detect an industry (e.g., energy, financial, or defense industries) in Internet communication. Second, it demonstrates the design, implementation, and evaluation of a distributed graph mining engine that is able to scale with the throughput of the input data while maintaining an end-to-end latency for updates in the range of a few milliseconds. Third, it illustrates the usage of this engine to detect APT attacks against industries by analyzing IP flow information from an Internet service provider. Finally, it introduces a detection algorithm- and input-agnostic intrusion detection engine which supports not only intrusion detection on IP flow but any other intrusion detection algorithm and data-source as well.

Just as packet switched networks constituted a major breakthrough in our perception of the information exchange in computer networks so have the decoupling properties of publish/subscribe systems revolutionized the way we look at networking in the context of large scale distributed systems. The decoupling of the components of publish/subscribe systems in time, space and synchronization has created an appealing platform for the asynchronous information exchange among anonymous information producers and consumers. Moreover, the content-based nature of publish/subscribe systems provides a great degree of flexibility and expressiveness as far as construction of data flows is considered. However, a number of challenges and not yet addressed issued still exists in the area of the publish/subscribe systems. One active area of research is directed toward the problem of the efficient content delivery in the content-based publish/subscribe networks. Routing of the information based on the information itself, instead of the explicit source and destination addresses poses challenges as far as efficiency and processing times are concerned. Simultaneously, due to their decoupled nature, publish/subscribe systems introduce new challenges with respect to issues related to dependability and fail-awareness. This thesis seeks to advance the field of research in both directions. First it shows the design and implementation of routing algorithms based on the end-to-end systems design principle. Proposed routing algorithms obsolete the need to perform content-based routing within the publish/subscribe network, pushing this task to the edge of the system. Moreover, this thesis presents a fail-aware approach towards construction of the content-based publish/subscribe system along with its application to the creation of the soft state publish/subscribe system. A soft state publish/subscribe system exposes the self stabilizing behavior as far as transient timing, link and node failures are concerned. The result of this thesis is a family of the XSiena content-based publish/subscribe systems, implementing the proposed concepts and algorithms. The family of the XSiena content-based publish/subscribe systems has been a subject to rigorous evaluation, which confirms the claims made in this thesis.

Content-based publish-subscribe is emerging as a communication paradigm able to meet the demands of highly dynamic distributed applications, such as those made popular by mobile computing and peer-to-peer networks. Nevertheless, the available systems implementing this communication model are still unable to cope efficiently with dynamic changes to the topology of their distributed dispatching infrastructure. This hampers their applicability in the aforementioned scenarios. This thesis addresses this problem and presents a complete approach to the reconfiguration of content-based publish-subscribe systems. In Part I, it proposes a layered architecture for reconfigurable publish-subscribe middleware consisting of an overlay, a routing, and an event-recovery layer. This architecture allows the same routing components to operate in different types of dynamic network environments, by exploiting different underlying overlays. Part II addresses the routing layer with new protocols to manage the recon- figuration of the routing information enabling the correct delivery of events to subscribers. When the overlay changes as a result of nodes joining or leaving the network or as a result of mobility, this information is updated so that routing can adapt to the new environment. Our protocols manage to achieve this with as little overhead as possible. Part III addresses the overlay layer and proposes two novel approaches for building and maintaining a connected topology in highly dynamic network sce- narios. The protocols we present achieve this goal, while managing node degree and keeping reconfigurations localized when possible. These properties allow our overlay managers to be applied not only in the context of publish-subscribe mid- dleware but also as enabling technologies for other communication paradigms like application-level multicast. Finally, the thesis integrates the overlay and routing layers into a single frame- work and evaluates their combined performance both in wired and in wireless scenarios. Results show that the optimizations provided by our routing reconfig- uration protocols allow the middleware to achieve very good performance in such networks. Moreover, they highlight that our overlay layer is able to optimize this performance even further, significantly reducing the network traffic generated by the routing layer. The protocols presented in this thesis are implemented in the REDS middle- ware framework developed at Politecnico di Milano. Their use enables REDS to operate efficiently in dynamic network scenarios ranging from large-scale peer-to- peer to mobile ad hoc networks.

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2018-02-22T12:31:13Z No. of bitstreams: 1 Euclides Palma Paim_.pdf: 2529933 bytes, checksum: 9c867ad7f5950b65e99f49343f096e8e (MD5) / Made available in DSpace on 2018-02-22T12:31:13Z (GMT). No. of bitstreams: 1 Euclides Palma Paim_.pdf: 2529933 bytes, checksum: 9c867ad7f5950b65e99f49343f096e8e (MD5) Previous issue date: 2017-10-31 / Nenhuma / Imagens médicas são usadas diariamente para apoio ao diagnóstico em diferentes áreas da Radiologia no mundo todo. Essas imagens seguem uma padronização internacional definida pela ISO 12052, conhecida como padrão DICOM (Digital Imaging and Communications in Medicine). Cada instituição que reivindica conformidade com esta norma, possui seus próprios serviços de armazenamento, sistemas de visualização e processamento específicos para esses dados. No entanto, há uma grande necessidade de que essas imagens sejam analisadas por diferentes especialistas, a fim de que cada caso possa ser discutido de forma ampla, na busca do melhor tratamento para cada patologia. A indisponibilidade de dados em tempo real para a avaliação médica especializada impacta direta e profundamente no sucesso terapêutico. O modelo de computação em nuvem tem as características necessárias para garantir que estas imagens se encontrem ao alcance dos profissionais mais recomendados para cada caso, aptos a oferecer o melhor atendimento. A grande quantidade de recursos disponíveis em nuvem, para lidar com esses dados de forma escalável, facilita a criação de uma infraestrutura para apoio ao diagnóstico à distância através de recursos de Telemedicina. Tomando como base o paradigma computacional Publicar/Assinar, podemos estabelecer comunicação em tempo real para solucionar situações no campo da saúde, como comunicação entre hospitais ou clínicas e entre médicos, enfermeiros e especialistas envolvidos no diagnóstico. Em ambientes clínicos que lidam com transmissão massiva de imagens em alta resolução no padrão DICOM, bem como em ambientes com problemas de desempenho de rede, transmitir essas imagens em tempo hábil, armazenar e disponibilizar de forma segura é um problema sem solução espontânea. Dessa forma esse trabalho propõe uma arquitetura baseada em nuvem computacional, para coletar, comprimir, armazenar e recuperar dados utilizando o paradigma Publicar/Assinar e dois níveis de escalabilidade. O modelo PS2DICOM é estabelecido como um middleware que oferece recursos de infraestrutura na camada IaaS (Infrastructure as a Service), apoiando as tarefas de transmissão e armazenamento de arquivos dentro do padrão DICOM. O sistema oferece compactação dos dados com diferentes intensidades, conforme largura de banda disponível. O modelo PS2DICOM conta ainda com dois níveis de balanceamento de carga e com a elasticidade reativa oferecida pela infraestrutura. A pesquisa contribui ao apresentar uma arquitetura eficaz para otimizar tarefas de rede, capaz de ser adotada como solução ao desenvolver aplicações voltadas para nuvens computacionais aplicadas a saúde em futuras situações reais. A arquitetura foi testada utilizando um protótipo com módulos distintos, desenvolvidos para cada serviço específico oferecido e mostrou-se eficiente como solução para os problemas em questão. Seus detalhes são descritos nos capítulos seguintes, bem como sua implementação, que corrobora a viabilidade do modelo. / Medical images are used daily to support diagnosis in different areas of Radiology throughout the world. These images follow an international standardization defined by ISO 12052, known as DICOM (Digital Imaging and Communications in Medicine) standard. Each institution that claims compliance with this standard has its own storage services, visualization and processing systems specific to that data. However, there is a great need for these images to be analyzed by different specialists, so that each case can be discussed in a broad way, in the search for the best treatment for each pathology. The unavailability of real-time data for specialized medical evaluation has a direct and profound impact on therapeutic success. The cloud computing model has the necessary characteristics to ensure that these images are within the reach of the professionals most recommended for each case, able to offer the best service. The large amount of resources available in the cloud to handle this data in a scalable way facilitates the creation of an infrastructure to support remote diagnosis through Telemedicine resources. Based on the computational paradigm Publish/Subscribe, we can establish real-time communication to solve situations in the field of health, such as communication between hospitals or clinics and between doctors, nurses and experts involved in the diagnosis. In clinical environments that deal with massive transmission of high resolution images in the DICOM standard, as well as in environments with network performance problems, transmitting these images in a timely manner, storing and making them available securely is a problem without a spontaneous solution. In this way, this work proposes a computational cloud-based architecture to collect, compress, store and retrieve data using the Publish/Subscribe paradigm and two levels of scalability. The PS2DICOM model is established as a middleware that provides infrastructure resources in the IaaS (Infrastructure as a Service) layer, supporting the tasks of transmitting and storing files within the DICOM standard. The system offers data compression with different intensities, depending on available bandwidth. The PS2DICOM model also has two levels of load balancing and the reactive elasticity offered by the infrastructure. The research contributes to presenting an efficient architecture to optimize network tasks, capable of being adopted as a solution when developing applications focused on computational clouds applied to health in future real situations. The architecture was tested using a prototype with distinct modules, developed for each specific service offered and proved to be efficient as a solution to the problems in question. Its details are described in the following chapters, as well as its implementation, which corroborates the viability of the model.

<p>Validerat; 20101217 (root)</p>

The dream of weaving technology into our everyday fabric of life is recently being made possible by advances in ubiquitous computing and sensor technologies. Countless sensors of various sizes have made their way into everyday commercial applications. Many projects aim to explore new ways to utilize these new technologies to aid and interact with the general population. Context-aware systems use available context information to assist users automatically, without explicit user input. By inferring user intent and configuring the system proactively for each user, context-aware systems are an integral part of achieving user-friendly ubiquitous computing environments. <br /><br /> A common issue with building a distributed context-aware system is the need to develop a supporting infrastructure providing features such as storage, distributed messaging, and security, before the real work on processing context information can be done. This thesis proposes a coordination framework that provides an effective common foundation for context-aware systems. The separation between the context-processing logic component and the underlying supporting foundation allows researchers to focus their energy at the context-processing part of the system, instead of spending their time re-inventing the supporting infrastructure. <br /><br /> As part of an ongoing project, Impress, the framework uses the open standard, Jabber, as its communication protocol. The Publish-Subscribe (pubsub) extension to Jabber provides interesting features that match those needed by a context-aware system. The main contribution of this thesis is the design and implementation of a coordination framework, called the Impress Context Store, that provides an effective common foundation for context-aware systems. The separation between the context-processing logic and the underlying supporting foundation allows researchers to focus their energy at the context-processing part of the system, instead of spending their time re-inventing the supporting infrastructure.