<p>During the last years the need for real-time database services has increased due to the growing number of data-intensive applications needing to enforce real-time constraints. The COMponent-based Embedded real-Time database (COMET) is a real-time database developed to meet these demands. COMET is developed using the AspeCtual COmponent-based Real-time system Development (ACCORD) design method, and consists of a number of components and aspects, which can be composed into a number of different configurations depending on system demands, e.g., Quality of Service (QoS) management can be used in unpredictable environments. </p><p>In embedded systems with requirementson high up-time it may not be possible to temporarily shut down the system for reconfiguration. Instead it is desirable to enable dynamic reconfiguration of the system, exchanging components during run-time. This in turn sets demands on the feedback control of the system to adjust to these new conditions, since a new time variant system has been created. </p><p>This thesis project implements improvements in COMET to create a more stable database suitable for further development. A mechanism for dynamic reconfiguration of COMET is implemented, thus, enabling components and aspects to be swapped during run-time. Adaptive feedback control algorithms are also implemented in order to better adjust to workload variations and database reconfiguration.</p>

Aspect-oriented middleware is a promising technology for the realisation of dynamic reconfiguration in heterogeneous distributed systems. However, like other dynamic reconfiguration approaches, AO-middleware-based reconfiguration requires that the consistency of the system is maintained across reconfigurations. AO-middleware-based reconfiguration is an ongoing research topic and several consistency approaches have been proposed. However, most of these approaches tend to be targeted at specific contexts, whereas for distributed systems it is crucial to cover a wide range of operating conditions. In this paper we propose an approach that offers distributed, dynamic reconfiguration in a consistent manner, and features a flexible framework-based consistency management approach to cover a wide range of operating conditions. We evaluate our approach by investigating the configurability and transparency of our approach and also quantify the performance overheads of the associated consistency mechanisms.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-08-13T20:41:07Z No. of bitstreams: 1 LUIZ BRUNELLI - TESE PPGEE 2005..pdf: 3761170 bytes, checksum: e05b83824a2a7e6d3aca6ea19daf1396 (MD5) / Made available in DSpace on 2018-08-13T20:41:07Z (GMT). No. of bitstreams: 1 LUIZ BRUNELLI - TESE PPGEE 2005..pdf: 3761170 bytes, checksum: e05b83824a2a7e6d3aca6ea19daf1396 (MD5) Previous issue date: 2005-02 / CNPq / Nesta tese descreve-se uma nova solução para o tratamento da complexidade das interconexões entre os elementos de processamento das redes neuronais artificiais (RNAs). Ela possibilita implementar RNAs em hardware, de tecnologia digital, com um número maior de neurônios do que se faz atualmente. As RNAs têm sido usadas como solução em vários problemas complexos. Em alguns destes problemas faz-se necesário a sua implementação em hardware. Vários s˜ao os compromissos que devem ser satisfeitos durante o projeto e implementa¸c˜ao das RNAs, dentre eles o das interconexões entre os neurônios. Atualmente encontram-se implementações neuronais utilizando circuitos integrados especificamente desenvolvidos para uma dada arquitetura de rede neuronal e também o uso de circuitos integrados configurados pelo usuário. Dentre estes circuitos existem os FPGAs reconfigur´aveis dinamicamente (DR-FPGAs) que podem ter suas características alteradas durante a sua opera¸c˜ao, sem sofrer interrupções em seu funcionamento normal. Estes dispositivos têm sido utilizados na implementação de RNAs. Propõe-se uma solução para o problema das interconexões entre os neurônios artificiais utilizando os DR-FPGAs e uma nova forma de computação: as Figuras de Execução (F.E.). As F.E. permitem teoricamente reduzir o impacto das interconexões através da eliminação do transporte de dados via barramento, além de outras vantagens e desvantagens durante o processamento da computação. As F.E. não parecem estar restritas apenas as aplicações de RNAs. Elas podem ser utilizadas pela computação reconfigurável em problemas massivamente paralelos e/ou que necessitem trocar informações entre os vários elementos de processamento do sistema. / In this thesis a new solution for the treatment of the complexity in the interconnections among the processing elements of the artificial neural networks (ANNs) is described. It enables realize ANNs digital hardware implementation with a larger number of neurons than does nowadays. The ANNs have been used as a solution in various complex problems. Some of these problems require hardware implementation. A lot of constraints must be satisfied during the project flow of the implementations of ANNs, such as the neural interconnections. Nowadays, neural implementations are done using integrated circuits, specifically developed for a given neural network architecture or integrated circuits configured by the user. Among these circuits exist the dynamically reconfigured FPGAs (DR-FPGAs) which can have their characteristics changed during operation without suffering interruptions in their execution. These devices have been usedforANNimplementations. Itpresentsaproposaltosolvethe interconnection problem for artificial neurons using DR-FPGAs in a new computational way: the Execution Patterns1 (EPs). The EPs allow, theoretically, to reduce the influence of interconnections through the removal of data transport via busses, besides other advantages and disadvantages. TheEPsdoesnotseemtoberestrictedonlytoANNapplications. They can be used by reconfigurable computation in massive parallel problems and/or problems that demand information exchange among the various elements in a processing system.

[pt] Ao mesmo tempo em que sistemas de processamento de fluxo de dados devem prover serviços de análise e manipulação de dados ininterruptamente (disponibilidade 24x7), eles comumente também precisam lidar com mudanças em seus ambientes de execução (e.g., alterar a topologia da rede) e nos requisitos que eles devem cumprir (e.g., adição de novas funções de processamento dos fluxos de dados). Por um lado, reconfiguração dinâmica de software (i.e., a capacidade de substituir parte do software em tempo de execução) é uma característica desejável. Por outro lado, sistemas de fluxo de dados podem sofrer com a interrupção e sobrecarga causada pela reconfiguração. Por conta da necessidade de reconfigurar (i.e., evoluir) o sistema ao mesmo tempo em que o sistema não pode ser interrompido (i.e., bloqueado), reconfiguração consistente e não bloqueante é ainda considerada um problema em aberto na literatura. Esta tese apresenta e valida uma abordagem não quiescente para reconfiguração dinâmica de software que preserva a consistência de sistemas de fluxo de dados distribuídos. A abordagem proposta permite que o sistema seja reconfigurado gradual e suavemente, sem precisar interromper o processamento do fluxo de dados ou atingir a quiescência. A avaliação indica que a abordagem proposta realiza reconfiguração distribuída consistentemente e tem um impacto desprezível sobre a diminuição na disponibilidade e no desempenho do sistema. Além disto, a implementação da abordagem proposta teve um desempenho melhor em todos os testes comparativos. / [en] While many data stream systems have to provide continuous (24x7) services with no acceptable downtime, they also have to cope with changes in their execution environments and in the requirements that they must comply (e.g., moving from on-premises architecture to a cloud system, changing the network technology, adding new functionality or modifying existing parts). On one hand, dynamic software reconfiguration (i.e., the capability of evolving on the fly) is a desirable feature. On the other hand, stream systems may suffer from the disruption and overhead caused by the reconfiguration. Due to the necessity of reconfiguring (i.e., evolving) the system whilst the system must not be disrupted (i.e., blocked), consistent and non-disruptive reconfiguration is still considered an open problem. This thesis presents and validates a non-quiescent approach for dynamic software reconfiguration that preserves the consistency of distributed data stream processing systems. Unlike many works that require the system to reach a safe state (e.g., quiescence) before performing a reconfiguration, the proposed approach enables the system to smoothly evolve (i.e., be reconfigured) in a non-disruptive way without reaching quiescence. The evaluation indicates that the proposed approach supports consistent distributed reconfiguration and has negligible impact on availability and performance. Furthermore, the implementation of the proposed approach showed better performance results in all experiments than the quiescent approach and Upstart.

Les domaines de recherche actuels, tels que l'informatique ubiquitaire et l'informatique en nuage (cloud computing), considèrent que ces environnements d’exécution sont en changement continue. Les applications dynamiques, où les composants peuvent être ajoutés et supprimés pendant l'exécution, permettent à un logiciel de s'adapter et de s'ajuster à l'évolution des environnements, et de tenir compte de l’évolution du logiciel. Malheureusement, les applications dynamiques soulèvent des questions de conception et de développement qui n'ont pas encore été pleinement explorées.Dans cette thèse, nous montrons que le dynamisme est une préoccupation transversale qui rompt avec un grand nombre d’hypothèses que les développeurs d’applications classiques sont autorisés à prendre. Le dynamisme affecte profondément la conception et développement de logiciels. S'il n'est pas manipulé correctement, le dynamisme peut « silencieusement » corrompre l'application. De plus, l'écriture d'applications dynamiques est complexe et sujette à erreur. Et compte tenu du niveau de complexité et de l’impact du dynamisme sur le processus du développement, le logiciel ne peut pas devenir dynamique sans (de large) modification et le dynamisme ne peut pas être totalement transparent (bien que beaucoup de celui-ci peut souvent être externalisées ou automatisées).Ce travail a pour but d’offrir à l’architecte logiciel le contrôle sur le niveau, la nature et la granularité du dynamisme qui est nécessaire dans les applications dynamiques. Cela permet aux architectes et aux développeurs de choisir les zones de l'application où les efforts de programmation des composants dynamiques seront investis, en évitant le coût et la complexité de rendre tous les composants dynamiques. L'idée est de permettre aux architectes de déterminer l'équilibre entre les efforts à fournir et le niveau de dynamisme requis pour les besoins de l'application. / Current areas of research, such as ubiquitous and cloud computing, consider execution environments to be in a constant state of change. Dynamic applications—where components can be added, removed and substituted during execution—allow software to adapt and adjust to changing environments, and to accommodate evolving features. Unfortunately, dynamic applications raise design and development issues that have yet to be fully addressed. In this dissertation we show that dynamism is a crosscutting concern that breaks many of the assumptions that developers are otherwise allowed to make in classic applications. Dynamism deeply impacts software design and development. If not handled correctly, dynamism can silently corrupt the application. Furthermore, writing dynamic applications is complex and error-prone, and given the level of complexity and the impact dynamism has on the development process, software cannot become dynamic without (extensive) modification and dynamism cannot be entirely transparent (although much of it may often be externalized or automated). This work focuses on giving the software architect control over the level, the nature and the granularity of dynamism that is required in dynamic applications. This allows architects and developers to choose where the efforts of programming dynamic components are best spent, avoiding the cost and complexity of making all components dynamic. The idea is to allow architects to determine the balance between the efforts spent and the level of dynamism required for the application's needs. At design-time we perform an impact analysis using the architect's requirements for dynamism. This serves to identify components that can be corrupted by dynamism and to—at the architect's disposition—render selected components resilient to dynamism. The application becomes a well-defined mix of dynamic areas, where components are expected to change at runtime, and static areas that are protected from dynamism and where programming is simpler and less restrictive. At runtime, our framework ensures the application remains consistent—even after unexpected dynamic events—by computing and removing potentially corrupt components. The framework attempts to recover quickly from dynamism and to minimize the impact of dynamism on the application. Our work builds on recent Software Engineering and Middleware technologies—namely, OSGi, iPOJO and APAM—that provide basic mechanisms to handle dynamism, such as dependency injection, late-binding, service availability notifications, deployment, lifecycle and dependency management. Our approach, implemented in the Robusta prototype, extends and complements these technologies by providing design and development-time support, and enforcing application execution consistency in the face of dynamism.

Made available in DSpace on 2016-08-17T14:53:27Z (GMT). No. of bitstreams: 1 Marcio Augusto Sekeff.pdf: 1014650 bytes, checksum: 620b3ce1069bc8032552ed7d6cbf8d41 (MD5) Previous issue date: 2007-12-14 / Modern computing environments are characterized by a high degree of dynamism that, along with the heterogeneity of computational devices and communication infrastructure, demand the development of a new range of applications that must be able to self-adapt dynamically and transparently according to changes in its execution environment. A computational grid is an example of a modern environment where it is common to notice a high variation on resource availability, node instability, variations on load distribution, and heterogeneity of computational devices and network technology. Another example is mobile computing, where the great diversity of computational devices, wireless network dynamism, limitations regarding available resources (such as, battery power) and mobility require the software to able to adapt to environmental changes. This paper presents the Adapta framework, a reflective middleware that provides the means to develop self-adaptive distributed applications, separating the business code from the one responsible for adaptation. Adapta also provides a runtime execution environment that monitors computational resources and noticies application components about the occurrence of important events that should trigger reconfiguration actions. Adapta provides a XML based reconfiguration language that defines how the application must adapt in response to environmental changes. Statements of the reconfiguration language can also be applied at runtime, which allows to dynamically change the reconfiguration mechanism itself. / Sistemas computacionais modernos são caracterizados por um alto grau de dinamismo que, junto com a heterogeneidade dos dispositivos computacionais e da infraestrutura de comunicação, requerem o desenvolvimento de um novo grupo de aplicações capazes de se auto-adaptar dinamica e transparentemente de acordo com mudanças em seu ambiente de execução. Um exemplo destes ambientes é o compreendido por grade computacionais, onde é comum observar alta variabilidade na disponibilidade de recursos, instabilidade de nós, variações no balanceamento de carga e heterogeneidade dos dispositivos computacionais e tecnologia de rede. Outro example são os ambientes de computação móvel, nos quais a grande diversidade de dispositivos computacionais, o dinamismo das redes sem fio, as limitações na disponibilidade de recursos (por exemplo, bateria) e a questão da mobilidade exigem a habilidade do software de se adaptar a mudan ças do ambiente. Este trabalho apresenta o arcabouço Adapta, um middleware reflexivo que provê os meios para desenvolver aplicações distribuídas auto-adaptativas, separando as regras de negócio do código responsável pela adaptação. Adapta também consiste em um sistema em execução que monitora recursos computacionais e notifica componentes da aplicações da importância de eventos que devem disparar ações de reconfiguração. O Adapta define uma linguagem de reconfiguração baseada em XML através da qual é possível especificar como a aplicação deve se adaptar em resposta a mudanças ambientais. Sentenças desta linguagem de reconfiguração podem ser aplicadas em tempo de execução, o que permite alterar dinamicamente o próprio mecanismo de reconfiguração.

During the last years the need for real-time database services has increased due to the growing number of data-intensive applications needing to enforce real-time constraints. The COMponent-based Embedded real-Time database (COMET) is a real-time database developed to meet these demands. COMET is developed using the AspeCtual COmponent-based Real-time system Development (ACCORD) design method, and consists of a number of components and aspects, which can be composed into a number of different configurations depending on system demands, e.g., Quality of Service (QoS) management can be used in unpredictable environments. In embedded systems with requirementson high up-time it may not be possible to temporarily shut down the system for reconfiguration. Instead it is desirable to enable dynamic reconfiguration of the system, exchanging components during run-time. This in turn sets demands on the feedback control of the system to adjust to these new conditions, since a new time variant system has been created. This thesis project implements improvements in COMET to create a more stable database suitable for further development. A mechanism for dynamic reconfiguration of COMET is implemented, thus, enabling components and aspects to be swapped during run-time. Adaptive feedback control algorithms are also implemented in order to better adjust to workload variations and database reconfiguration.

Les capacités d'auto-reconfiguration des architectures FPGA modernes ouvrent la voie à des applications dynamiques capables d'adapter leur fonctionnement pour répondre à des évènements ponctuels. Les flots de reconfiguration des architectures commerciales sont aujourd'hui aboutis mais limités par des contraintes inhérentes à la complexité de ces circuits. Dans cette thèse, plusieurs contributions sont avancées afin de proposer une architecture FPGA reconfigurable permettant le placement dynamique de tâches matérielles. Dans un premier temps, une représentation intermédiaire des données de configuration de ces tâches, indépendante de leur positionnement final, est présentée. Cette représentation permet notamment d'atteindre des taux de compression allant jusqu'à 11x par rapport à la représentation brute d'une tâche. Un flot de conception basé sur des outils de l'état de l'art accompagne cette représentation et génère des tâches relogeables à partir d'une description haut-niveau. Ensuite, le comportement en ligne de ce mécanisme est étudié. Deux algorithmes permettant le décodage de ces tâches et la génération en temps-réel des données de configuration propres à l'architectures son décrits. Par ailleurs, une amélioration du réseau d'interconnexion d'une architecture FPGA est proposée pour accroître la flexibilité du placement de tâches hétérogènes, avec une augmentation de 10% en moyenne du délai du chemin critique. Enfin, une alternative programmable aux mémoires de configuration de ces circuits est étudiée pour faciliter leur reconfiguration partielle. / The self-reconfiguration capabilities of modern FPGA architectures pave the way for dynamic applications able to adapt to transient events. The CAD flows of modern architectures are nowadays mature but limited by the constraints induced by the complexity of FPGA circuits. In this thesis, multiple contributions are developed to propose an FPGA architecture supporting the dynamic placement of hardware tasks. First, an intermediate representation of these tasks configuration data, independent from their final position, is presented. This representation allows to compress the task data up to 11x with regard to its conventional raw counterpart. An accompanying CAD flow, based on state-of-the-art tools, is proposed to generate relocatable tasks from a high-level description. Then, the online behavior of this mechanism is studied. Two algorithms allowing to decode and create in real-time the conventional bit-stream are described. In addition, an enhancement of the FPGA interconnection network is proposedto increase the placement flexibility of heterogeneous tasks, at the cost of a 10% increase in average of the critical path delay. Eventually, a configurable substitute to the configuration memory found in FPGAs is studied to ease their partial reconfiguration.

L’informatique en nuage, au travers de son modèle en couche et de l’accès à ses services à la demande, a bouleversé la façon de gérer les infrastructures (IaaS) et la manière de produire les logiciels (SaaS). Grâce à l’élasticité de l’infrastructure, la quantité de ressource peut être ajustée automatiquement en fonction de la demande afin de satisfaire un certain niveau de qualité de service (QoS) aux clients tout en minimisant les coûts d’exploitation sous-jacents. Le modèle d’élasticité actuel qui consiste à ajuster les ressources IaaS au travers de services de dimensionnement automatique basiques montre ses limites en termes de réactivité et de granularité d’adaptation. De plus, bien qu’étant une caractéristique cruciale de l’informatique en nuage, l’élasticité est à ce jour pauvrement outillée empêchant ainsi les différents acteurs du Cloud de jouir pleinement de ses bienfaits. Dans ce travail de thèse, nous proposons d’étendre leconcept d’élasticité aux couches hautes du nuage, et plus précisément au niveau du SaaS. Nous présentons ainsi le nouveau concept d’élasticité logicielle que nous définissons comme la capacité d’un logiciel à s’adapter, idéalement de manière autonome, pour répondre aux changements de la demande et/ou aux limitations de l’élasticité des ressources de l’infrastructure. Il s’agit alors d’envisager l’élasticité de manière transverse et multi-couche en considérant l’adaptation des ressources Cloud au sens large. Pour ce faire, nous présentons un modèle pour la gestion autonome de l’élasticité multi-couche et le Framework ElaStuff associé. Dans le but d’outiller et d’industrialiser le processus de gestion de l’élasticité, nous proposons l’outil de surveillance perCEPtion basé sur le traitement des événements complexes et permettant à l’administrateur de mettre en place une observation avancée du système Cloud. De plus, un langage dédié à l’élasticité multi-couche nommé ElaScript est proposé pour exprimer simplement et efficacement des plans de reconfiguration orchestrant les actions d’élasticité de différents niveaux. Enfin, notre proposition d’étendre l’élasticité aux couches hautes du Cloud, et plus particulièrement au niveau SaaS, est validée expérimentalement selon plusieurs points devue (QoS, énergie, réactivité et précision du passage à l’échelle,etc.). / Cloud computing, through its layered model and access to its on-demand services, has changed the way of managing the infrastructures (IaaS) and how to produce software (SaaS). With the advent of IaaS elasticity, the amount of resources can be automatically adjusted according to the demand to satisfy a certain level of quality of service (QoS) to customers while minimizing underlying operating costs. The current elasticity model is based on adjusting the IaaS resources through basic autoscaling services, which reaches to its limit in terms of responsiveness and adaptation granularity. Although it is an essential feature for Cloud computing, elasticity remains poorly equipped which prevents the various actors of the Cloud to really enjoy its benefits. In this thesis, we propose to extend the concept of elasticity to higher layers of the cloud, and more precisely to the SaaS level. Then, we present the new concept of software elasticity by defining the ability of the software to adapt, ideally in an autonomous way, to cope with workload changes and/or limitations of IaaS elasticity. This predicament brings the consideration of Cloud elasticity in a multi-layer way through the adaptation of all kind of Cloud resources. To this end, we present a model for the autonomic management of multi-layer elasticity and the associated framework ElaStuff. In order to equip and industrialize the elasticity management process, we propose the perCEPtion monitoring tool, based on complex event processing, which enables the administrators to set up an advanced observation of the Cloud system. In addition, we propose a domain specific language (DSL) for the multi-layer elasticity, called ElaScript, which allows to simply and effectively express reconfiguration plans orchestrating the different levels of elasticity actions. Finally, our proposal to extend the Cloud elasticity to higher layers, particularly to SaaS,is validated experimentally from several perspectives (QoS,energy, responsiveness and accuracy of the scaling, etc.).

Drawing on multiple theoretical lenses, this research studies continuous transformation, or ‘morphing’, of a business process resource network (BPRN). The aim is to further our understanding of continuous organisational change at the lowest levels of analysis within an organisation: that is, at the resource level, and that resource’s relationships to other resources as they exist within a BPRN. Data was gathered from a single, in depth case study. Analysis was achieved by means of mapping BPRN evolution using ‘temporal bracketing’, ‘visual’ and ‘narrative’ approaches (Langley, 1999). The analysis revealed two mechanisms that appear to govern microstate morphing: bond strength and stakeholder expectation. In addition, four factors emerged as important: environmental turbulence, timing and timeliness of changes, concurrency of changes, and enduring business logic. An emergent model of microstate morphing which acknowledges the importance of socio-materiality in actor network morphogenesis (ANM) is presented. This study shows how effective relationships and configuration of resources within the BPRN can be achieved to facilitate timely, purposeful morphing. Five propositions are offered from the emergent ANM model. Specifically, these relate to the conditional operating parameters and the identified generative mechanisms for continuous organisational transformation within the BPRN. Implications for practice are significant. A heuristic discussion guide containing a series of questions framed around the ANM model to highlight the challenges of microstate morphing for practitioners is proposed. Two routes for future research are suggested: replication studies, and quantifying BPRN change in relation to an organisation’s environment using a ii survey instrument and inferential statistical analysis based on the ANM model features and propositions.