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Uma abordagem de predição da dinâmica comportamental de processos para prover autonomia a ambientes distribuídos; An approach to provide autonomy to distributed environments by predicting the dynamics of process behavior

Dodonov, Evgueni
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 01/07/2009 Português
Relevância na Pesquisa
56.08%
A evolução de sistemas distribuídos resultou em aumento significativo de complexidade para manutenção e gerenciamento, tornando pouco eficientes técnicas convencionais baseadas em intervenções manuais. Isso motivou pesquisas que deram origem ao paradigma de computação autônoma (Autonomic Computing), que provê aspectos de auto-configuração, auto-recuperação, auto-otimização e auto-proteção a fim de tornar sistemas auto-gerenciáveis. Nesse contexto, esta tese teve como objetivo prover autonomia a ambientes distribuídos, sem a necessidade de mudar o paradigma de programação e as aplicações de usuários. Para isso, propôs-se uma abordagem que emprega técnicas para compreensão e predição de dinâmicas comportamentais de processos, utilizando abordagens de sistemas dinâmicos, inteligência artificial e teoria do caos. Os estudos realizados no decorrer desta pesquisa demonstraram que, ao predizer padrões comportamentais, pode-se otimizar diversos aspectos de computação distribuída, suportando tomadas de decisão autônomas pelos ambientes. Para validar a abordagem proposta, foi desenvolvida uma política de escalonamento distribuído, denominada PredRoute, a qual utiliza o conhecimento sobre o comportamento de processos para otimizar...

Controle de acesso para sistemas distribuídos.; Access control for distributed systems.

Souza, Marcos Tork
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 22/11/2010 Português
Relevância na Pesquisa
66.05%
A implementação de arcabouços de controle de acesso para sistemas distribuídos é dificultada pelas características próprias desta classe de ambientes, demandando modificações tanto na arquitetura do arcabouço quanto no modelo de política de controle de acesso usualmente empregados em arquiteturas não distribuídas. Este trabalho tenciona sanar ou mitigar estas dificuldades formalizando os requisitos desta classe de ambientes em duas frentes distintas (arquitetura e modelo de política de acesso) e analisando o impacto que uma exerce sobre a outra. Duas conclusões fundamentais são suportadas por esta análise: a necessidade do arcabouço ser construído na forma de um sistema distribuído, e que embora um modelo de política de fato possa ser escolhido, a especificação deste precisará ser modificada de forma a se adaptar às características específicas do ambiente. O arcabouço DRBAC (Distributed Role Based Access Control) foi desenvolvido sobre uma arquitetura distribuída e aplica o modelo de política de controle de acesso baseado em papéis. A arquitetura foi obtida a partir da expansão da arquitetura de referência de ferramentas de controle de acesso e a especificação do modelo foi desenvolvida a partir da especificação padronizada pelo NIST (National Institute Of Standards and Technology). A validação do trabalho é levada a termo por meio de uma série de experimentos realizados sobre a implementação de uma prova de conceito deste arcabouço.; The creation of frameworks for access control in distributed systems is made difficult by this class of systems own characteristics...

AFIDS : arquitetura para injeção de falhas em sistemas distribuídos; AFIDS - architecture for fault injection in distributed systems

Sotoma, Irineu
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
Português
Relevância na Pesquisa
66.08%
Sistemas distribuídos já são de amplo uso atualmente e seu crescimento tende a se acentuar devido a popularização da Internet. Cada vez mais computadores se interligam e trocam informações entre si. Nestes sistemas, requerimentos como confiabilidade, disponibilidade e desempenho são de fundamental importância para a satisfação do usuário. Estes requerimentos podem ser atendidos aproveitando-se da redundância já existente com as maquinas interligadas. Mas para atingir os requisitos de confiabilidade e disponibilidade, protocolos tolerantes a falhas devem ser construídos. Tolerância a falhas visa continuar a fornecer o serviço de algum protocolo, aplicação ou sistema a despeito da ocorrência de falhas durante a sua execução. Tolerância a falhas pode ser implementada por hardware ou por software através de mascaramento ou recuperação de falhas. Recentemente, a injeção de falhas implementada por software tem sido um dos principais métodos utilizados para validar protocolos tolerantes a falhas em sistemas distribuídos, e muitas ferramentas tem sido construídas. Contudo, não ha nenhuma biblioteca de classes orientada a objetos para auxiliar novos pesquisadores na construção da sua própria ferramenta de injeção de falhas. Este trabalho apresenta uma proposta de uma arquitetura orientada a objetos escrita em C++ para sistemas operacionais UNIX usando sockets...

Trix : um sistema operacional multiprocessado para transputers, com gerencia distribuida de processos; Trix, a transputer based multiprocessor operating system, with distributed process management

Pasin, Marcelo
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
Português
Relevância na Pesquisa
56.07%
O trabalho em torno do sistema TRIX visa desenvolver um sistema operacional multiprocessado experimental, para servir de base a futuros trabalhos de pesquisa em sistemas operacionais e processamento paralelo. Como características essenciais do sistema tem-se simplicidade, desempenho e compatibilidade com UNIX. Com o sistema operando em vários processadores, pode-se fazer experiências de muitos tipos em processamento paralelo, como por exemplo, ensaios de distribuição de carga, avaliações de desempenho, implementação de linguagens paralelas ou distribuídas, ,bancos de dados, sistemas dedicados, etc. Ao construir o sistema TRIX, decidiu-se usar o código fonte de um sistema já pronto e funcionando, para encurtar o tempo de desenvolvimento. Optou-se pelo MINIX, que é um sistema bem estruturado, dividido em camadas de processos seqüenciais que se comunicam por troca de mensagens. Mais que isso, 0 MEND( a compatível com o UNIX versão 7 e o seu c6digo fonte pode ser usado para fins acadêmicos sem ferir o seu Copyright. Foi necessário porem dotar o MINIX de características distribuídas, para o controle de uma arquitetura multiprocessada. projeto e implementação destas características é o assunto deste trabalho. Inicialmente são avaliados os sistemas operacionais multiprocessados encontrados na literatura...

Monitoramento on-line em sistemas distribuídos : mecanismo hierárquico para coleta de dados; On-line monitoring of distributed systems: a hierarchical mechanism for data collection

Tesser, Rafael Keller
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
Português
Relevância na Pesquisa
66.04%
Este trabalho propõe um modelo hierárquico para coleta de dados de monitoramento em sistemas distribuídos. Seu objetivo é proporcionar a análise on-line do comportamento de sistemas e programas distribuídos. O meio escolhido para realizar essa análise foi a visualização. Inicialmente é apresentada uma contextualização sobre monitoramento de sistemas distribuídos. Também são abordados aspectos específicos ao monitoramento de Grid. Após, é analisado um conjunto de ferramentas de monitoramento. Então tem-se a apresentação do modelo proposto. Esse é composto por coletores locais, por uma hierarquia de agregadores e por clientes. É utilizado o modelo push de transmissão de dados e há um mecanismo de subscrição aos coletores. Foi implementado um protótipo do modelo de coleta proposto, que foi utilizado na implementação de um protótipo de ferramenta de monitoramento on-line. Nessa, os dados coletados são fornecidos ao DIMVisual, que é um modelo de integração de dados para visualização. Para visualização, o protótipo utiliza a ferramenta TRIVA, que recebe os dados integrados como entrada. Essa ferramenta foi modificada para gerar uma visualização que é atualizada de maneira on-line. Também foram realizados experimentos para avaliar o tempo necessário para enviar mensagens com diferentes hierarquias e configurações dos coletores. Além disso...

Atomic Broadcast and Quorum-based Replication in Asynchronous Crash-Recovery Distributed Systems

Rodrigues, Luís; Raynal, Michel
Fonte: Department of Informatics, University of Lisbon Publicador: Department of Informatics, University of Lisbon
Tipo: Relatório
Publicado em /01/1999 Português
Relevância na Pesquisa
65.92%
This paper describes a solution to the Atomic Broadcast problem in asynchronous distributed systems in which processes can crash and recover. Our solution is based on a transformation of any Consensus algorithm into an Atomic Broadcast algorithm. Thus, our work can benefit from recent results in the study of the Consensus problem in the crash-recovery model. The paper also shows how to extend the Atomic Broadcast primitive to support the implementation of Quorum-based replica management in crash-recovery systems. The proposed technique makes a bridge between established results on Weighted Voting and recent results on the Consensus problem.

HPC: A Model of Structure and Change in Distributed Systems

LeBlanc, Thomas J. ; Friedberg, Stuart A. (1958 - )
Fonte: University of Rochester. Computer Science Department. Publicador: University of Rochester. Computer Science Department.
Tipo: Relatório
Português
Relevância na Pesquisa
66.04%
Distributed systems must provide certain fundamental facilities including communication, protection, resource management, reliability, and process (computation) abstraction. Current designs for distributed systems tend to focus on only one of these issues; support for multiprocess structures has been especially neglected. The HPC model, an object-oriented model of interprocess relationships for distributed systems, addresses all of these fundamental services. The major novelties of HPC lie in the extension of the process abstraction to collections of processes and the provision of a rich set of structuring mechanisms for distributed computations. An important aspect of the model is that it results in the ability to maintain and exploit execution context for managing processes in a distributed computation. In this paper we describe the HPC model, show how the model can be used to build system-level services, and discuss the implementation of an HPC kernel.

Engineering security into distributed systems: a survey of methodologies

Uzunov, A.; Fernandez, E.; Falkner, K.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em //2012 Português
Relevância na Pesquisa
65.96%
Rapid technological advances in recent years have precipitated a general shift towards software distribution as a central computing paradigm. This has been accompanied by a corresponding increase in the dangers of security breaches, often causing security attributes to become an inhibiting factor for use and adoption. Despite the acknowledged importance of security, especially in the context of open and collaborative environments, there is a growing gap in the survey literature relating to systematic approaches (methodologies) for engineering secure distributed systems. In this paper, we attempt to fill the aforementioned gap by surveying and critically analyzing the state-of-the-art in security methodologies based on some form of abstract modeling (i.e. model-based methodologies) for, or applicable to, distributed systems. Our detailed reviews can be seen as a step towards increasing awareness and appreciation of a range of methodologies, allowing researchers and industry stakeholders to gain a comprehensive view of the field and make informed decisions. Following the comprehensive survey we propose a number of criteria reflecting the characteristics security methodologies should possess to be adopted in real-life industry scenarios...

Engineering security methodologies for distributed systems.

Uzunov, Anton Victor
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2014 Português
Relevância na Pesquisa
66.07%
Over the last decade, researchers and practitioners have increasingly come to acknowledge that the introduction of security into software systems – especially complex, distributed systems – should proceed by means of a structured, systematic approach, combining principles from both software and security engineering. Such systematic approaches, particularly those implying some sort of process aligned with the development life-cycle, are termed security methodologies. While there are numerous methodologies in the literature, each with its own peculiar advantages and disadvantages, making it more or less suitable for a given set of project situations, none can lay claim to being universal, i.e. able to take into account all system-specific attributes, all technologies, all skill levels, and – in general – to be applicable to all project situations. In other words, the literature does not currently present developers with an “ideal” methodology (in an absolute sense); and, indeed, such a requirement would be infeasible, since “ideal” must necessarily be interpreted with respect to a given situation – encompassing system types, technologies, skillsets and whatever other qualities are seen as desirable. The problem facing the area is thus not so much the construction of “bigger and better” methodologies with novel or interesting features – i.e. (unattainably) ideal methodologies in an absolute sense – but the construction of (attainably) ideal methodologies for particular project situations. This thesis proposes a comprehensive solution to the latter problem by developing a conceptual “toolkit” for engineering security methodologies...

Eine Systemumgebung zur Erstellung paralleler C++ Programme und deren Ausführung in heterogenen verteilten Systemen; A System Environment for the Creation of Parallel C++ Programs and their Execution in Heterogeneous Distributed Systems

Blochinger, Wolfgang
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
Português
Relevância na Pesquisa
66.03%
Diese Arbeit behandelt die Realisierung und die Anwendung der Systemumgebung DOTS (Distributed Object-Oriented Threads System) zur Erstellung paralleler C++ Programme. DOTS verwirklicht insbesondere spezielle Anforderungen zur Parallelisierung von Algorithmen aus dem Bereich des symbolischen Rechnens. Die effiziente Parallelisierung der sich typischerweise rasch fortentwickelnden sequentiellen Verfahren des symbolischen Rechnens wird durch das von DOTS realisierte parallele Programmiermodell des strikten Multithreading im besonderem Maße unterstützt. Die hohe Abstraktionsebene dieses Modells gewährleistet die weitgehende Übernahme der sequentiellen Entwicklungsmethodik und ermöglicht somit die schnelle und einfache Erstellung paralleler Programme ausgehend von einer sequentiellen Codebasis. Das Programmiermodell ist durch eine kompakte Programmierschnittstelle mit vollständig orthogonal verwendbaren Primitiven verwirklicht. Die Behandlung des oftmals anzutreffenden hohen Grads an Nichtdeterminismus der parallelisierten Programme wird durch die Integration spezieller Primitive in das Programmiermodell des strikten Multithreading von DOTS berücksichtigt. DOTS wurde zur Erstellung paralleler C++ Programme entwickelt, die in heterogenen verteilten Systemen ausgeführt werden können. Die Laufzeitumgebung von DOTS integriert ein breites Spektrum von Rechnerarchitekturen und Betriebssystemen (Microsoft Windows PCs...

Integración de un modelo de tiempo real en middleware configurable para sistemas distribuidos; Integrating a real-time model in configurable middleware for distributed systems

Pérez Tijero, Héctor
Fonte: Universidad de Cantabria Publicador: Universidad de Cantabria
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
66.06%
This thesis describes the integration of the end-to-end flow real-time model, which is defined in the MARTE (Modeling and Analysis of Real-Time and Embedded Systems) standard, into distribution middleware, as it can facilitate the development process of distributed real-time systems based on the Model-Driven Engineering (MDE) paradigm. The study focuses on how distribution standards and their implementations guarantee the real-time behaviour of these kinds of applications, thus providing a set of features required to develop analyzable distributed real-time systems. The standards studied are RT-CORBA (Real-Time Common Object Request Broker Architecture), the DSA (Distributed Systems Annex) of Ada, and DDS (Data Distribution Service for real-time systems). The features analysed will contribute to the definition of the endpoints pattern, a new proposal that, when integrated with distribution middleware, enables the use of MDE and schedulability analysis techniques more easily. This thesis also presents a distributed real-time platform supporting different distribution standards, and scheduling policies, and several examples or case studies to validate the features and usability of the endpoints pattern. In addition, this thesis deals with the use of the end-to-end flow model in high-integrity systems by adapting the endpoints pattern to the Ravenscar profile...

On the Convergence of the Holistic Analysis for EDF Distributed Systems

Díaz de Cerio Urain, Unai; Uribe, Juan P.; González Harbour, Michael; Palencia Gutiérrez, José Carlos
Fonte: Universidade de Cantabria Publicador: Universidade de Cantabria
Tipo: info:eu-repo/semantics/workingPaper; submittedVersion
Português
Relevância na Pesquisa
66.05%
Dynamic scheduling techniques, and EDF (Earliest Deadline First) in particular, have demonstrated their ability to increase the schedulability of real time systems compared to fixed-priority scheduling. In distributed systems, the scheduling policies of the processing nodes tend to be the same as in stand-alone systems and, although few EDF networks exist, it is foreseen that dynamic scheduling will gradually develop into real-time networks. There are some response time analysis techniques for EDF scheduled distributed systems, mostly derived from the holistic analysis developed by Spuri. The convergence of the holistic analysis in context of EDF distributed systems with shared resources had not been studied until now. There is a circular dependency between tasks’ release jitter values, response times and preemption level ceilings of shared resources. In this paper we present an extension of Spuri’s algorithm and we demonstrate that its iterative formulas are non-decreasing, even in the presence of shared resources. This result enables us to assert that the new algorithm converges towards a solution for the response times of the tasks and messages in a distributed system.

Scheduling Real-Time Jobs in Distributed Systems - Simulation and Performance Analysis

Stavrinides, Georgios L.; Karatza, Helen D.
Fonte: Universidade Carlos III de Madrid Publicador: Universidade Carlos III de Madrid
Tipo: info:eu-repo/semantics/publishedVersion; info:eu-repo/semantics/bookPart; info:eu-repo/semantics/conferenceObject
Publicado em /11/2014 Português
Relevância na Pesquisa
65.98%
One of the major challenges in ultrascale systems is the effective scheduling of complex jobs within strict timing constraints. The distributed and heterogeneous system resources constitute another critical issue that must be addressed by the employed scheduling strategy. In this paper, we investigate by simulation the performance of various policies for the scheduling of real-time directed acyclic graphs in a heterogeneous distributed environment. We apply bin packing techniques during the processor selection phase of the scheduling process, in order to utilize schedule gaps and thus enhance existing list scheduling methods. The simulation results show that the proposed policies outperform all of the other examined algorithms.; The work presented in this paper has been partially supported by EU under the COST program Action IC1305, “Network for Sustainable Ultrascale Computing (NESUS)”.; Proceedings of: First International Workshop on Sustainable Ultrascale Computing Systems (NESUS 2014). Porto (Portugal), August 27-28, 2014.

Distributed Estimation of a class of Nonlinear Systems

Park, Derek Heungyoul
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
56.1%
This thesis proposes a distributed observer design for a class of nonlinear systems that arise in the application of model reduction techniques. Distributed observer design techniques have been proposed in the literature to address estimation problems over sensor networks. In large complex sensor networks, an efficient technique that minimizes the extent of the required communication is highly desirable. This is especially true when sensors have problems caused by physical limitations that result in incorrect information at the local level affecting the estimation of states globally. To address this problem, scalable algorithms for a suitable distributed observer have been developed. Most algorithms are focussed on large linear dynamical systems and they are not directly generalizable to nonlinear systems. In this thesis, scalable algorithms for distributed observers are proposed for a class of large scale observable nonlinear system. Distributed systems models multi-agent systems in which each agents attempts to accomplish local tasks. In order to achieve global objectives, there should be agreement regarding some commonly known variables that depend on the state of all agents. These variables are called consensus states. Once identified...

Performance collaborative, distributed systems engineering (CDSE) : lessons learned from CDSE enterprises; Performance CDSE : lessons learned from CDSE enterprises

Utter, Darlene Ann
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 291 p.
Português
Relevância na Pesquisa
65.99%
The United States aerospace and defense budgets are shrinking, resources are scarce and requirements are more demanding: aerospace and defense enterprises are expected to deliver a more capable product in less time and with fewer resources. To achieve this tough mission, the enterprises that comprise the United States aerospace and defense industries must form strategic partnerships and collaborations to utilize their respective resources, knowledge, and expertise to meet their customers' needs. Collaboration, be it between competing companies or within different divisions of the same company, is necessary for the survival of each company and the defense industry. In the past. United States aerospace and defense company relationships consisted mostly of a prime contractor. with sub-contractors providing a specific hardware or software subsystem. as specified by the prime contractor. Today, aerospace and defense company relationships are moving more toward that of "partners" where the previous supplier or sub-contractor for hardware or software subsystems is now sharing in the overall system design and engineering efforts.; (cont.) Since the partner companies and intra-company divisions are still geographically distributed throughout the United States...

Introduction to Distributed Systems

Thampi, Sabu M.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 23/11/2009 Português
Relevância na Pesquisa
56.07%
Computing has passed through many transformations since the birth of the first computing machines. Developments in technology have resulted in the availability of fast and inexpensive processors, and progresses in communication technology have resulted in the availability of lucrative and highly proficient computer networks. Among these, the centralized networks have one component that is shared by users all the time. All resources are accessible, but there is a single point of control as well as a single point of failure. The integration of computer and networking technologies gave birth to new paradigm of computing called distributed computing in the late 1970s. Distributed computing has changed the face of computing and offered quick and precise solutions for a variety of complex problems for different fields. Nowadays, we are fully engrossed by the information age, and expending more time communicating and gathering information through the Internet. The Internet keeps on progressing along more than a few magnitudes, abiding end systems increasingly to communicate in more and more different ways. Over the years, several methods have evolved to enable these developments, ranging from simplistic data sharing to advanced systems supporting a multitude of services. This article provides an overview of distributed computing systems. The definition...

Modular RADAR: An Immune System Inspired Search and Response Strategy for Distributed Systems

Banerjee, Soumya; Moses, Melanie
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 17/06/2010 Português
Relevância na Pesquisa
56.1%
The Natural Immune System (NIS) is a distributed system that solves challenging search and response problems while operating under constraints imposed by physical space and resource availability. Remarkably, NIS search and response times do not scale appreciably with the physical size of the animal in which its search is conducted. Many distributed systems are engineered to solve analogous problems, and the NIS demonstrates how such engineered systems can achieve desirable scalability. We hypothesize that the architecture of the NIS, composed of a hierarchical decentralized detection network of lymph nodes (LN) facilitates efficient search and response. A sub-modular architecture in which LN numbers and size both scale with organism size is shown to efficiently balance tradeoffs between local antigen detection and global antibody production, leading to nearly scale-invariant detection and response. We characterize the tradeoffs as balancing local and global communication and show that similar tradeoffs exist in distributed systems like LN inspired artificial immune system (AIS) applications and peer-to-peer (P2P) systems. Taking inspiration from the architecture of the NIS, we propose a modular RADAR (Robust Adaptive Decentralized search with Automated Response) strategy for distributed systems. We demonstrate how two existing distributed systems (a LN inspired multi-robot control application and a P2P system) can be improved by a modular RADAR strategy. Such a sub-modular architecture is shown to balance the tradeoffs between local communication (within artificial LNs and P2P clusters) and global communication (between artificial LNs and P2P clusters)...

An Approach to Modularization of Distributed Systems

Minsky, Naftaly
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 24/09/2013 Português
Relevância na Pesquisa
56.09%
Modularization is an important architectural principle underlying many types of complex systems. It tends to tame the complexity of systems, to facilitate their management, and to enhance their flexibility with respect to evolution. In software, modularization has been practiced and studied thoroughly in local, i.e. non-distributed systems. But very little attention has been paid so far to modularization in distributed systems. This is, in part, because distributed systems are inherently modularized, in the sense that the internals of each component of such a system is inaccessible to other components, thus satisfying the Parnas hiding principle. It is, however, the thesis of this paper that there is much to be gained by being able to treat groups of distributed components as modules, called here distributed modules. And that besides the conventional hiding principle, distributed modularization should provide additional capabilities, which rarely, if ever, figure in conventional modularized systems. These capabilities include, but are not limited to: the ability to impose constraints on which kind of messages can be sent from a given distributed-module to its outside; and the ability to create AOP-like crosscutting modules. This paper introduces a model of modular distributed system...

On a Framework for Complex and ad hoc Event Management over Distributed Systems

Vargas-Solar,Genoveva; Bucciol,Paolo; Collet,Christine
Fonte: Instituto Politécnico Nacional, Centro de Innovación y Desarrollo Tecnológico en Cómputo Publicador: Instituto Politécnico Nacional, Centro de Innovación y Desarrollo Tecnológico en Cómputo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2010 Português
Relevância na Pesquisa
66.02%
Internet-based communications have amazingly evolved in recent years. As a consequence, the number - and complexity - of distributed systems which provide access to services and applications has dramatically increased. As long as these services have been extended to support an increasing number of communication media (voice, audio, video, ...) and systems, ad hoc communication protocols and methodologies have been designed and developed. Given the autonomy of available services and applications, distributed systems generally rely on event-based communications for integrating these resources. However, a general model for the management of event-based communications, suitable for complex and ad hoc event processing as well as for the generic publish/subscribe messaging paradigm, is still missing. This paper presents a general and flexible event detection and processing framework which can be adapted based on specific requirements and situations. Within the framework, the main aspects of event management over distributed systems are treated, such as event definition, detection, production, notification and history management. Other aspects such as event composition, are also discussed. The goal of the paper is to provide a common paradigm for event-based communications...

Modular Visualization of Distributed Systems

Guevara S.,Gustavo A.; Desell,Travis; LaPorte,Jason; Varela,Carlos A.
Fonte: CLEI Electronic Journal Publicador: CLEI Electronic Journal
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2011 Português
Relevância na Pesquisa
66.04%
Abstract. Effective visualization is critical to developing, analyzing, and optimizing distributed systems. We have developed OverView, a tool for online/offline distributed systems visualization, that enables modular layout mechanisms, so that different distributed system high-level programming abstractions such as actors or processes can be visualized in intuitive ways. OverView uses by default a hierarchical concentric layout that distinguishes entities from containers allowing migration patterns triggered by adaptive middleware to be visualized. In this paper, we develop a force-directed layout strategy that connects entities according to their communication patterns in order to directly exhibit the application communication topologies. In force-directed visualization, entities’ locations are encoded with different colors to illustrate load balancing. We compare these layouts using quantitative metrics including communication to entity ratio, applied on common distributed application topologies. We conclude that modular visualization is necessary to effectively visualize distributed systems since no one layout is best for all applications.