11,079 research outputs found
A Taxonomy of Data Grids for Distributed Data Sharing, Management and Processing
Data Grids have been adopted as the platform for scientific communities that
need to share, access, transport, process and manage large data collections
distributed worldwide. They combine high-end computing technologies with
high-performance networking and wide-area storage management techniques. In
this paper, we discuss the key concepts behind Data Grids and compare them with
other data sharing and distribution paradigms such as content delivery
networks, peer-to-peer networks and distributed databases. We then provide
comprehensive taxonomies that cover various aspects of architecture, data
transportation, data replication and resource allocation and scheduling.
Finally, we map the proposed taxonomy to various Data Grid systems not only to
validate the taxonomy but also to identify areas for future exploration.
Through this taxonomy, we aim to categorise existing systems to better
understand their goals and their methodology. This would help evaluate their
applicability for solving similar problems. This taxonomy also provides a "gap
analysis" of this area through which researchers can potentially identify new
issues for investigation. Finally, we hope that the proposed taxonomy and
mapping also helps to provide an easy way for new practitioners to understand
this complex area of research.Comment: 46 pages, 16 figures, Technical Repor
A Literature Survey of Cooperative Caching in Content Distribution Networks
Content distribution networks (CDNs) which serve to deliver web objects
(e.g., documents, applications, music and video, etc.) have seen tremendous
growth since its emergence. To minimize the retrieving delay experienced by a
user with a request for a web object, caching strategies are often applied -
contents are replicated at edges of the network which is closer to the user
such that the network distance between the user and the object is reduced. In
this literature survey, evolution of caching is studied. A recent research
paper [15] in the field of large-scale caching for CDN was chosen to be the
anchor paper which serves as a guide to the topic. Research studies after and
relevant to the anchor paper are also analyzed to better evaluate the
statements and results of the anchor paper and more importantly, to obtain an
unbiased view of the large scale collaborate caching systems as a whole.Comment: 5 pages, 5 figure
Kompics: a message-passing component model for building distributed systems
The Kompics component model and programming framework was designedto simplify the development of increasingly complex distributed systems. Systems built with Kompics leverage multi-core machines out of the box and they can be dynamically reconfigured to support hot software upgrades. A simulation framework enables deterministic debugging and reproducible performance evaluation of unmodified Kompics distributed systems.
We describe the component model and show how to program and compose event-based distributed systems. We present the architectural patterns and abstractions that Kompics facilitates and we highlight a case study of a complex
distributed middleware that we have built with Kompics. We show how our approach enables systematic development and evaluation of large-scale and dynamic distributed systems
Modelação e simulação de equipamentos de rede para Indústria 4.0
Currently, the industrial sector has increasingly opted for digital technologies
in order to automate all its processes. This development comes from
notions like Industry 4.0 that redefines the way these systems are designed.
Structurally, all the components of these systems are connected in a complex
network known as the Industrial Internet of Things. Certain requirements
arise from this concept regarding industrial communication networks. Among
them, the need to ensure real-time communications, as well as support for
dynamic resource management, are extremely relevant. Several research
lines pursued to develop network technologies capable of meeting such
requirements. One of these protocols is the Hard Real-Time Ethernet Switch
(HaRTES), an Ethernet switch with support for real-time communications and
dynamic resource management, requirements imposed by Industry 4.0.
The process of designing and implementing industrial networks can,
however, be quite time consuming and costly. These aspects impose
limitations on testing large networks, whose level of complexity is higher and
requires the usage of more hardware. The utilization of network simulators
stems from the necessity to overcome such restrictions and provide tools to
facilitate the development of new protocols and evaluation of communications
networks.
In the scope of this dissertation a HaRTES switch model was developed
in the OMNeT++ simulation environment. In order to demonstrate a
solution that can be employed in industrial real-time networks, this dissertation
presents the fundamental aspects of the implemented model as well as a set
of experiments that compare it with an existing laboratory prototype, with the
objective of validating its implementation.Atualmente o setor industrial tem vindo cada vez mais a optar por tecnologias
digitais de forma a automatizar todos os seus processos. Este desenvolvimento
surge de noções como Indústria 4.0, que redefine o modo de como
estes sistemas são projetados. Estruturalmente, todos os componentes
destes sistemas encontram-se conectados numa rede complexa conhecida
como Internet Industrial das Coisas. Certos requisitos advêm deste conceito,
no que toca às redes de comunicação industriais, entre os quais se destacam
a necessidade de garantir comunicações tempo-real bem como suporte a
uma gestão dinâmica dos recursos, os quais são de extrema importância.
Várias linhas de investigação procuraram desenvolver tecnologias de rede
capazes de satisfazer tais exigências. Uma destas soluções é o "Hard
Real-Time Ethernet Switch" (HaRTES), um switch Ethernet com suporte a
comunicações de tempo-real e gestão dinâmica de Qualidade-de-Serviço
(QoS), requisitos impostos pela Indústria 4.0.
O processo de projeto e implementação de redes industriais pode, no
entanto, ser bastante moroso e dispendioso. Tais aspetos impõem limitações
no teste de redes de largas dimensões, cujo nível de complexidade é
mais elevado e requer o uso de mais hardware. Os simuladores de redes
permitem atenuar o impacto de tais limitações, disponibilizando ferramentas
que facilitam o desenvolvimento de novos protocolos e a avaliação de redes
de comunicações.
No âmbito desta dissertação desenvolveu-se um modelo do switch HaRTES
no ambiente de simulação OMNeT++. Com um objetivo de demonstrar uma
solução que possa ser utilizada em redes de tempo-real industriais, esta
dissertação apresenta os aspetos fundamentais do modelo implementado
bem como um conjunto de experiências que o comparam com um protótipo
laboratorial já existente, no âmbito da sua validação.Mestrado em Engenharia Eletrónica e Telecomunicaçõe
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