La collaboration en temps réel est un cas spécial de collaboration où les utilisateurs travaillent sur le même élément simultanément et sont au courant des modifications des autres utilisateurs en temps réel. Les données distribuées doivent rester disponibles et consistant tout en étant répartis sur plusieurs systèmes physiques. "Strong Consistency" est une approche qui crée un ordre total des opérations en utilisant des mécanismes tel que le "locking". Cependant, cela introduit un "bottleneck". Ces dix dernières années, les algorithmes de concurrence ont été étudiés dans le but de garder la convergence de tous les replicas sans utiliser de "locking" ni de synchronisation. "Operational Trans- formation" et "Conflict-free Replicated Data Types (CRDT)" sont utilisés dans ce but. Cependant, la complexité de ces stratégies les rend compliquées à intégrer dans des logicielles conséquents, comme les éditeurs de modèles, spécialement pour des data structures complexes comme les graphes. Les implémentations actuelles intègrent seulement des data linéaires tel que le texte. Dans ce mémoire, nous présentons CollabServer, un framework pour construire des environnements de collaboration. Il a une implémentation de CRDTs pour des data structures complexes tel que les graphes et donne la possibilité de construire ses propres data structures. / Real-time collaboration is a special case of collaboration where users work on the same artefact simultaneously and are aware of each other’s changes in real-time. Shared data should remain available and consistent while dealing with its physically distributed aspect. Strong Consistency is one approach that enforces a total order of operations using mechanisms, such as locking. This however introduces a bottleneck. In the last decade, algorithms for concurrency control have been studied to keep convergence of all replicas without locking or synchronization. Operational Transformation and Conflict free Replicated Data Types (CRDT) are widely used to achieve this purpose. However, the complexity of these strategies makes it hard to integrate in large software, such as modeling editors, especially for complex data types like graphs. Current implementations only integrate linear data, such as text. In this thesis, we present CollabServer, a framework to build collaborative environments. It features a CRDTs implementation for complex data types such as graphs and gives possibility to build other data structures.

Data warehouses (DWs) have traditionally been loaded with data at regular time intervals, e.g., monthly, weekly, or daily, using fast bulk loading techniques. Recently, the trend is to insert all (or only some) new source data very quickly into DWs, called near-realtime DWs (right-time DWs). This is done using regular INSERT statements, resulting in too low insert speeds. There is thus a great need for a solution that makes inserted data available quickly, while still providing bulk-load insert speeds. This paper presents RiTE ('Right-Time ETL'), a middleware system that provides exactly that. A data producer (ETL) can insert data that becomes available to data consumers on demand. RiTE includes an innovative main-memory based catalyst that provides fast storage and offers concurrency control. A number of policies controlling the bulk movement of data based on user requirements for persistency, availability, freshness, etc. are supported. The system works transparently to both producer and consumers. The system is integrated with an open source DBMS, and experiments show that it provides 'the best of both worlds', i.e., INSERT-like data availability, but with bulk-load speeds (up to 10 times faster).

The last decade has seen the transition from single-core processors to multi-cores and many-cores. This move has by and large shifted the responsibility from chip manufacturers to programmers to keep up with ever-increasing expectations on performance. In the single-core era, improvements in hardware capacity could immediately be leveraged by an application: faster machine - faster program. In the age of the multi-cores, this is no longer the case. Programs must be written in specific ways to utilize available parallel hardware resources. Programming language support for concurrent and parallel programming is poor in most popular object-oriented programming languages. Shared memory, threads and locks is the most common concurrency model provided. Threads and locks are hard to understand, error-prone and inflexible; they break encapsulation - the very foundation of the object-oriented approach. This makes it hard to break large complex problems into smaller pieces which can be solved independently and composed to make a whole. Ubiquitous parallelism and object-orientation, seemingly, do not match. Actors, or active objects, have been proposed as a concurrency model better fit for object-oriented programming than threads and locks. Asynchronous message passing between actors each with a logical thread of control preserves encapsulation as objects themselves decide when messages are executed. Unfortunately most implementations of active objects do not prevent sharing of mutable objects across actors. Sharing, whether on purpose or by accident, exposes objects to multiple threads of control, destroying object encapsulation. In this thesis we show techniques for compiler-enforced isolation of active objects, while allowing sharing and zero-copy communication of mutable data in the cases where it is safe to do so. We also show how the same techniques that enforce isolation can be utilized internal to an active object to allow data race-free parallel message processing and data race-free structured parallel computations. This overcomes the coarse-grained nature of active object parallelism without compromising safety. / UPMARC

With data volumes increasing at a high rate and the emergence of highly scalable infrastructures (cloud computing, petascale computing), distributed management of data becomes a crucial issue that faces many challenges. This thesis brings several contributions in order to address such challenges. First, it proposes a set of principles for designing highly scalable distributed storage systems that are optimized for heavy data access concurrency. In particular, it highlights the potentially large benefits of using versioning in this context. Second, based on these principles, it introduces a series of distributed data and metadata management algorithms that enable a high throughput under concurrency. Third, it shows how to efficiently implement these algorithms in practice, dealing with key issues such as high-performance parallel transfers, efficient maintainance of distributed data structures, fault tolerance, etc. These results are used to build BlobSeer, an experimental prototype that is used to demonstrate both the theoretical benefits of the approach in synthetic benchmarks, as well as the practical benefits in real-life, applicative scenarios: as a storage backend for MapReduce applications, as a storage backend for deployment and snapshotting of virtual machine images in clouds, as a quality-of-service enabled data storage service for cloud applications. Extensive experimentations on the Grid'5000 testbed show that BlobSeer remains scalable and sustains a high throughput even under heavy access concurrency, outperforming by a large margin several state-of-art approaches.

Introduction: Sexually Transmitted Diseases, including HIV/AIDS, continue to be a major burden in the United States. Sexual partnering behaviors contribute to the spread of STDs. Sexual concurrency has been shown to exponentially increase STD prevalence in populations. Serial monogamy with short periods between sexual partners also introduces risk. Methods: We identified sexually active men and women from the 2006-2010 National Survey of Family Growth (NSFG) and used sub sets for each particular study. Sexual partnering was defined as being concurrent, serially monogamous or monogamous in the previous year. Polytomous logistic regression models were developed to evaluate the associations between age of sexual debut among adult men, age of menarche and discordant heterosexual identity and behavior among all women and sexual partnering patterns. Descriptive, mediation, subpopulation and stratified analyses were also conducted. Results: Sexual debut < 15 and 15-17 years was associated with concurrency (adjusted odds ratio (aOR)<15: 2.19; 95% Confidence Interval (CI): 1.36-3.55; aOR 15-17: 1.69; 95% CI: 1.04-2.75). This association was mediated by lifetime number of partners (further adjusted for lifetime partners: OR<15: 1.26; 95% CI: 0.74-2.22; OR15-17: 1.13; 95% CI: 0.67-1.92). Age of menarche was not associated with subsequent concurrent sexual partnering (adjusted odds ratio (aOR)early: 1.09; 95% Confidence Interval (CI): 0.57-2.09; aORaverage: 1.13; 95% CI: 0.64-1.99) or serial monogamy (aORearly: 0.75; 95% CI: 0.41-1.38; aORaverage: 0.71; 95% CI: 0.39-1.29). A subanalysis among currently unmarried women did not alter this relationship. Heterosexually discordant women who had both male and female partners in the previous year were 5.5 times as likely to report having a concurrent relationship (95% CI: 2.77-11.09) and 2.43 times as likely to report engaging in serially monogamous relationships (95% CI: 1.19-4.97) with their male partners than concordant women. Conclusions: Sexual partnering behaviors are potentially modifiable and reducing risky partnerships will contribute to a decrease in STD acquisition and transmission. Our findings have important implications. Clinically, they support the provision of comprehensive services, regardless of sexual identity. For policy, they confirm the need for early, inclusive and thorough sexual and reproductive health programming for our youth, in particular focusing on the benefits of lifetime partner reduction.

This thesis provides a specification theory with strong algebraic and compositionality properties, allowing for the systematic construction of new components out of existing ones, while ensuring that given properties continue to hold at each stage of system development. The theory shares similarities with the interface automata of de Alfaro and Henzinger, but is linear-time in the style of Dill's trace theory, and is endowed with a richer collection of operators. Components are assumed to communicate with one another by synchronisation of input and output actions, with the component specifying the allowed sequences of interactions between itself and the environment. When the environment produces an interaction that the component is unwilling to receive, a communication mismatch occurs, which can correspond to run-time error or underspecification. These are modelled uniformly as inconsistencies. A linear-time refinement preorder corresponding to substitutivity preserves the absence of inconsistency under all environments, allowing for the safe replacement of components at run-time. To build complex systems, a range of compositional operators are introduced, including parallel composition, logical conjunction and disjunction, hiding, and quotient. These can be used to examine the structural behaviour of a system, combine independently developed requirements, abstract behaviour, and incrementally synthesise missing components, respectively. It is shown that parallel composition is monotonic under refinement, conjunction and disjunction correspond to the meet and join operations on the refinement preorder, and quotient is the adjoint of parallel composition. Full abstraction results are presented for the equivalence defined as mutual refinement, a consequence of the refinement being the weakest preorder capturing substitutivity. Extensions of the specification theory with progress-sensitivity (ensuring that refinement cannot introduce quiescence) and real-time constraints on when interactions may and may not occur are also presented. These theories are further complemented by assume-guarantee frameworks for supporting component-based reasoning, where contracts (characterising sets of components) separate the assumptions placed on the environment from the guarantees provided by the components. By defining the compositional operators directly on contracts, sound and complete assume-guarantee rules are formulated that preserve both safety and progress. Examples drawn from distributed systems are used to demonstrate how these rules can be used for mechanically deriving component-based designs.

Les serveurs Internet sont des logiciels particuliers. Ils doivent répondre aux demandes d'un grand nombre de clients distants, supporter leur évolution et être robustes car ils ne s'arrêtent jamais. Les modèles de concurrence permettent d'entrelacer les traitements d'un grand nombre de clients. Aucun consensus ne se dégage sur un meilleur modèle. Pour s'abstraire du modèle de concurrence, je propose un modèle de développement de serveurs Internet. Les outils de vérification formelle permettent d'accroître la sûreté des logiciels mais il est nécessaire de leur fournir un modèle simple du logiciel. Le modèle de développement que je propose est utilisé pour générer le serveur et son modèle formel. Le décodage d'une requête cliente dépend du modèle de concurrence. Je propose d'utiliser un générateur d'analyseur syntaxique qui s'abstrait de ce problème et automatise le développement du décodage / Internet servers are software with specific features. Indeed, they answer request of wide and distant clients, support the customer evolution and be robust because they never stop. The concurrency models allow to interleave the statements of wide customers. No general agreement frees on a better model. To abstract himself from the concurrency model, I propose a development model of Internet servers. Model checkers allow to increase the software safety. But, it is necessary to provide a simple model of software to check it. I propose to use my development model of servers in order to genrate ther server automatically and its formal model. Finally as the request parsing depends on the concurrency model, I propose to use Tatoo, a parser generator. Tatoo abstracts himself from this dependency and automates the development of parsing

O uso de Web Services tem aberto novas possibilidades de desenvolvimento de software, entre elas a composição de serviços. A composição de serviços apresenta novas questões no ambiente computacional, entre elas a execução integral, garantindo consistência e contemplando o controle de concorrência. O workflow é um conjunto de tarefas e interações organizadas de modo que forneça uma funcionalidade ao sistema, provendo a automatização de processos complexos, através da composição de serviços. Tal composição deve ser executada de forma transacional, processando as operações com consistência. A execução de workflows oriundos de domínios diferentes, faz com que os serviços que estão sendo utilizados, não possuam ciência do contexto da execução, podendo gerar atendimentos que não sejam justos, causando situações de deadlock e de starvation. Este trabalho apresenta estratégias para a execução de workflows em domínios distintos, que requisitam múltiplos serviços de um mesmo conjunto, sem a necessidade de um coordenador central, de forma transacional. O atendimento a requisição contempla uma política justa na utilização do recurso que impede a ocorrência de deadlock ou de starvation para os workflows em execução. Os experimentos realizados neste trabalho mostram que o sistema desenvolvido, aplicando as estratégias propostas, executa as composições de serviços de maneira transacional, atendendo as requisições com justiça, livre de deadlock e starvation, mantendo o sistema independente e autônomo. / Web Services are increasing software development possibilities, among then service composition. Service composition introduces new issues on computational environment, such as the whole service execution, ensuring consistency and concurrency control. Workflow is a set of organized tasks and interactions in order to provide functionality to the system, automating complex process through composition service. Such composition must be performed by transactional support, performing operations consistently. The workflow execution from different domain clients sharing the same composition make these clients ignore the execution context. It may cause inconsistencies, from unfair attendance to deadlock or starvation. This work depicts strategies for workflow execution from different domains, requesting multiple services from the same composition, without a centralized coordinator, in transactional way. The request attendance contains a fair policy for resource usage and consumption to avoid deadlock and starvation. Applying the proposed strategy on the experiments performed in this work, it confirms that the developed system executes service composition with transactional support, avoiding deadlock or starvation, keeping the whole system autonomous and independent.

Sistemas multi-agentes devem oferecer recursos suficientes para que seus agentes possam interagir de maneira satisfatória e atingir seus objetivos. Um exemplo de recurso é um conjunto de dados armazenados em algum tipo de mecanismo de persistência, como um sistema gerenciador de banco de dados. O acesso a dados deve ser possível mesmo que eles estejam distribuídos, fato inclusive que também caracteriza os sistemas multi-agentes. Assim, este trabalho apresenta um sistema chamado DASE cujo objetivo é prover a agentes o acesso a dados distribuídos de forma simples e transparente, ou seja, independentemente da complexidade que o ambiente dos agentes possui e das peculiaridades do Sistema de Banco de Dados Distribuído. O DASE suporta qualquer Sistema Gerenciador de Banco de Dados, seja ele centralizado ou distribuído, desde que o mesmo esteja em conformidade com o JDBC. Além disso, oferece recursos importantes como controle de concorrência, suporte a ambientes de dados simultâneos e uso de sentenças de acesso a dados pré-definidas e parametrizadas. Todos os aspectos mais importantes analisados durante o projeto deste sistema estão descritos neste trabalho, evidenciando e justificando o porquê de cada decisão que certamente refletiram no funcionamento e comportamento do DASE. O sistema foi implementado de acordo com o seu projeto, resultando em uma versão funcional e estável, o que foi comprovado através de seu uso em um projeto que envolvia sistemas multiagentes e controle de tráfego aéreo. Além disso, alguns testes de análise de desempenho considerando cenários variados foram realizados. / Multi-agent systems must offer the needed resources to allow their agents to interact and to reach their goals. An example of resource is a set of data stored in any kind of resource manager, such as a database management system. Data access must be possible even if the data is distributed, characteristic that is also present in multi-agent systems. Thus, this work describes a system whose objective is to provide to agents distributed data access in a simple and transparent way, in other words, hiding the agent environment and complexities related to distributed database systems. DASE supports any database management system, centralized or distributed, in compliance with JDBC (Java Database Connectivity). In addition it offers important features, such as concurrency control, simultaneous data environments and stored SQL sentences. All challenges and important aspects overcome in order to design and implement DASE are described, explaining and justifying every decision that in some way had a participation to form DASE set of functions and behavior. The system was implemented following its design, resulting in a functional and stable version, what could be verified through its adoption in a project based on multiagent systems and air traffic control systems. In addition, a plenty of performance tests were done regarding different scenarios.

[pt] O objetivo deste trabalho é defender o resgate do conceito de co-rotinas como uma construção de controle poderosa e conveniente, que pode substituir tanto continuações de primeira classe como threads com um conceito único e mais simples. Para suprir a ausência de uma definição precisa e adequada para o conceito de co-rotinas, propomos um novo sistema de classificação, e introduzimos o conceito de co- rotinas completas, para o qual provemos uma definição formal, baseada em uma semântica operacional. Demonstramos a seguir a equivalência de poder expressivo entre co-rotinas completas simétricas e assimétricas e entre co-rotinas completas e continuações one-shot tradicionais e parciais, discutindo as vantagens de corotinas completas assimétricas em relação a co-rotinas simétricas e continuações de primeira classe. Finalmente, analizamos os benefícios e desvantagens associados aos diversos modelos de concorrência, justificando a adoção de modelos alternativos a multithreading e o oferecimento de co-rotinas como uma construção básica de concorrência, adequada à implementação desses modelos. / [en] The purpose of this work is to defend the revival of coroutines as a powerful and convenient control construct, which can replace both firstclass continuations and threads with a single and simpler concept. In order to provide an adequate and precise definition of the concept of coroutines, we propose a new classifying system, and introduce the concept of complete coroutines, for which we provide a formal definition based on an operational semantics. We then demostrate that complete symmetric coroutines and complete asymmetric coroutines have equivalent expressive power, as well as complete coroutines and one-shot traditional and partial continuations. We also discuss the advantages of using complete asymmetric coroutines instead of symmetric coroutines or first-class continuations. Finally, we analyse the benefits and problems associated with different concurrency models, and argue in favor of the replacement of multithreading with alternative concurrency models and the provision of coroutines as a basic concurrency construct, adequate for the implementation of these alternative models.