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Biblioteca Digital do IPB (53.442 recursos)

A Biblioteca Digital do IPB, tem por objectivo divulgar e permitir o livre acesso à produção científica produzida pela comunidade académica, promovendo a integração, partilha e a visibilidade da informação científica e garantindo a preservação da memória intelectual do Instituto Politécnico de Bragança.

DIC - EC - Artigos em Actas de Conferências Indexadas

Mostrando recursos 1 - 20 de 25

  1. A uniform resource identifier scheme for SNMP

    Lopes, Rui Pedro; Oliveira, José Luís
    One of the World Wide Web characteristics, besides its omnipresence in computer systems, is the adoption of a universal user interface that is used to access several different services that were previously accessed individually by independent applications. The Internet resources started to be identified by URI schemes, a text string with specific syntax and grammar. Although existing for several services such as http, ftp, gopher and news, these identifiers are not used to identify SNMP resources. This paper proposes an URI scheme for identifying SNMP resources and presents some practical scenarios where the existence of such compact and complete identifying...

  2. A uniform resource identifier scheme for SNMP

    Lopes, Rui Pedro; Oliveira, José Luís
    One of the World Wide Web characteristics, besides its omnipresence in computer systems, is the adoption of a universal user interface that is used to access several different services that were previously accessed individually by independent applications. The Internet resources started to be identified by URI schemes, a text string with specific syntax and grammar. Although existing for several services such as http, ftp, gopher and news, these identifiers are not used to identify SNMP resources. This paper proposes an URI scheme for identifying SNMP resources and presents some practical scenarios where the existence of such compact and complete identifying...

  3. Policy-based network management in an integrated mobile network

    Oliveira, José Luís; Gonçalves, Pedro; Dziunikowski, W.; Wszolek, J.; Rasmussen, S.; Lopes, Rui Pedro; Roque, Vitor
    Through the seamless integration of different kinds of technologies, services and terminals, and with the expected offered bandwidth, the next generation networks will put a new set of challenges related to operation and management. In this paper we present a Policy-based Network Management System that is being developed inside the Daidalos IST project.

  4. Policy-based network management in an integrated mobile network

    Oliveira, José Luís; Gonçalves, Pedro; Dziunikowski, W.; Wszolek, J.; Rasmussen, S.; Lopes, Rui Pedro; Roque, Vitor
    Through the seamless integration of different kinds of technologies, services and terminals, and with the expected offered bandwidth, the next generation networks will put a new set of challenges related to operation and management. In this paper we present a Policy-based Network Management System that is being developed inside the Daidalos IST project.

  5. Multi-management schemes for MAF platforms

    Lopes, Rui Pedro
    Due to the crescent complexity of networks and systems, network management solutions are being pushed towards more distributed and cooperative models. Several specifications promoted by the IETF DISMAN charter already allow strong distribution of management tasks. Unfortunately, they are not adequate to achieve cooperative models. According to recent research, mobile agents provide a good platform to back cooperative models but several lacks are still identified - interoperability between different platforms and SNMP integration. Based on Mobile Agent Facility specification from the OMG, we propose a MIB to better integrate mobile agent models into SNMP frameworks and a GUI tool to...

  6. A multi-protocol architecture for SNMP entities

    Lopes, Rui Pedro; Oliveira, José Luís
    Crescent requirements on the network management area, droved by the successive increase on networks size, internetworking complexity and time-constraint services deployment, impose the omnipresence of technicians and tools. The universality of the interfaces, both for the manager and for the agent sides, is essential to support these requirements. This paper presents a middleware architecture for the development of agents that can be transparently mapped into different management protocol stacks.

  7. Maintenance behaviour-based prediction system using data mining

    Bastos, Pedro; Lopes, Rui Pedro; Pires, L.C.M.; Pedrosa, Tiago
    In the last years we have assisted to several and deep changes in industrial manufacturing. Induced by the need of increasing efficiency, bigger flexibility, better quality and lower costs, it became more complex. The complexity of this new scenario has caused big pressure under enterprises production systems and consequently in its maintenance systems. Manufacturing systems recognize high level costs due equipment breakdown, motivated by the time spent to repair, which corresponds to no production time and scrapyard, and also money spent in repair actions. Usually, enterprises do not share data produced from their maintenance interventions. This investigation intends to create an organizational architecture that...

  8. ToCL: a thread oriented communication library to interface VIA and GM protocols

    Alves, Albano; Pina, António; Rufino, José; Exposto, José
    In this paper we present ToCL a thread oriented communication library specially designed to fully exploit multithreading in a multi-networked cluster environment. ToCL provides a basic set of primitives to handle zero-copy message passing between application threads spread among cluster nodes. Large messages are fragmented and sent to remote threads as single messages using multiple low-level communication subsystems. The current implementation supports both Myrinet through GM and Gigabit Ethernet through VIA but we plan to extend it to other communication subsystems.

  9. pCoR - a protoype for resource oriented computing

    Pina, António; Oliveira, Vitor; Moreira, Cecília; Alves, Albano
    In this paper we present CoR a resource oriented computing model that address the question of how to integrate user-level fine-grained multithreading, communication and coordination into a cluster of symmetrical multiprocessor computers. To support the design of complex distributed application using the proposed paradigm we built pCoR a run-time system which has new areas that represents extensions to the strict shared memory and message passing models supported by other platforms: remote operations, dynamic domains, communication ports, multithreading management, shared memory, replication and partition are some of its distinguished features. In addition, it provides a thread-safe transport communication layer to take advantage...

  10. High performance multithreaded message passing on a myrinet cluster

    Alves, Albano; Pina, António; Rufino, José; Exposto, José
    The main purpose of this paper is to present the impact of pCoR thread level message passing facilities on applications running in a Myrinet cluster. To exploit Myrinet technology we use the GM library, which provides a limited number of ports as abstractions to name communication end-points. pCoR communication layer multiplexes GM ports by using a dispatcher thread to handle messages to/from a large number of communication entities (working threads). Our approach combines polling operations executed bymultiple threads to avoid unnecessary context switching; a simple mechanism is used to engage working threads into the polling scheme. We aim to reduce the total...

  11. Scalable multithreading in a low latency myrinet cluster

    Alves, Albano; Pina, António; Rufino, José; Exposto, José
    In this paper we present some implementation details of a programming model – pCoR – that combines primitives to launch remote processes and threads with communication over Myrinet.B asically, we present the efforts we have made to achieve high performance communication among threads of parallel/distributed applications. The expected advantages of multiple threads launched across a low latency cluster of SMP workstations are emphasized with a graphical application that manages huge maps consisting of several JPEG images.

  12. Pedestrians behavior simulation in real 3D environments

    Deusdado, Leonel; Belo, Orlando; Fernandes, António Ramires
    Massive virtual models are one of the most computer graphics pieces required on the Internet especially the ones that simulate three-dimensional urban scenarios. Additionally, the integration of “artificial life” components in these environments, demanding for a virtualization of life involving the static geometry, pioneer in computer games research. This clearly reveals a growing interest for various kinds of analysis in several areas of activity. In this scenario “virtual public facilities” had captured a lot of attention and research efforts when used to simulate and act without certain human constraints that we can find easily in real world. Integrating both Artificial...

  13. Path planning for complex 3D multilevel environments

    Deusdado, Leonel; Fernandes, António Ramires; Belo, Orlando
    The continuous development of graphics hardware is contributing to the creation of 3D virtual worlds with high level of detail, from models of large urban areas, to complete infrastructures, such as residential buildings, stadiums, industrial settings or archaeological sites, to name just a few. Adding virtual humans or avatars adds an extra touch to the visualization providing an enhanced perception of the spaces, namely adding a sense of scale, and enabling simulations of crowds. Path planning for crowds in a meaningful way is still an open research field, particularly when it involves an unknown polygonal 3D world. Extracting the potential...

  14. Evaluating applications performance in a multi-networked cluster

    Alves, Albano; Pina, António; Rufino, José; Exposto, José
    Traditionally, a cluster is defined as a collection of homogeneous nodes interconnected by a single high performance communication technology. However, in some cases, cluster nodes may be organized into several partitions – subclusters – internally interconnected by one or more selected SAN technologies. In order to constitute a multi-networked cluster, sub-clusters must share a common SAN technology or a bridge facility must be used. In this paper we show how RoCL – a lightweight user-level communication library designed to support multi-threading in a multi-networked environment – manages to exploit such cluster organization. Performance evaluation results obtained by using two partitions of...

  15. Mapping application-level components into hierarchical systems resources

    Alves, Albano; Pina, António; Rufino, José; Exposto, José
    The appropriate organization of application components and their right mapping into physical resources is fundamental to fully exploit cutting edge technologies especially when hierarchical architectures are used. We present a new approach to combine application modelling with resource management. The proposed programming model allows the mixing of message-passing and global memory facilities and integrates them with the high-level abstractions provided for specifying and organizing application components and resources. The methodologies and tools we had designed pave the way to build complex systems through the use of cooperative applications, executed simultaneously, involving multiple users, thus extending the MPMD model.

  16. Deploying applications in Multi-SAN SMP clusters

    Alves, Albano; Pina, António; Rufino, José; Exposto, José
    The effective exploitation of multi-SAN SMP clusters and the use of generic clusters to support complex information systems require new approaches. On the one hand, multi-SAN SMP clusters introduce another level of parallelism which is not addressed by conventional programming models that assume a homogeneous cluster. On the other hand, traditional parallel programming environments are mainly used to run scientific computations, using all available resources, and therefore applications made of multiple components, sharing cluster resources or being restricted to a particular cluster partition, are not supported. We present an approach to integrate the representation of physical resources, the modelling of applications...

  17. Deploying applications in Multi-SAN SMP clusters

    Alves, Albano; Pina, António; Rufino, José; Exposto, José
    The effective exploitation of multi-SAN SMP clusters and the use of generic clusters to support complex information systems require new approaches. On the one hand, multi-SAN SMP clusters introduce another level of parallelism which is not addressed by conventional programming models that assume a homogeneous cluster. On the other hand, traditional parallel programming environments are mainly used to run scientific computations, using all available resources, and therefore applications made of multiple components, sharing cluster resources or being restricted to a particular cluster partition, are not supported. We present an approach to integrate the representation of physical resources, the modelling of applications...

  18. meμ: unifying application modeling and cluster exploitation

    Alves, Albano; Pina, António; Rufino, José; Exposto, José
    The increasing complexity of high-demand long-running applications has faced programmers with the need to take into account both development hardness and execution time. meu provides the flexibility to control the amount of computational and communication power being used in order to maximize resources utilization and to deliver high performance. In this paper we focus on the aspects of the paradigm that go beyond traditional message passing approaches, promoting the idea that by raising the abstraction level of programming models, programmers will make better use of the available resources with clear impact on both productivity and performance. We introduce the resource as the abstraction...

  19. Fully heuristic timetabling driven by students' feedback on availability

    Sousa, Filipe; Alves, Albano
    The optimal schedule of lectures and exams is critical in higher education institutions. But it is a very time consuming task for those who are in charge of planning academic activities. For this reason, a considerable attention has been devoted to automated timetabling. Because timetabling solutions are highly dependent on the way institutions are organized, it is common that each institution develops its own platform. At the Instituto Politécnico de Bragança we have evaluated several existent solutions but we have concluded that no particular solution fulfills the totality of our requirements. That leads us to the development of a new platform in order to handle all...

  20. Shortcut routing for chord graphs in the domus hash space

    Rufino, José; Pina, António; Alves, Albano; Exposto, José
    We present and evaluate shortcut routing algorithms for Chord graphs in the hash space, specifically developed to accelerate distributed lookups in the Distributed Hash Tables (DHTs) of the Domus framework. The algorithms explore our findings about the relation of exponential and euclidean distances in Chord graphs, in conjunction with the availability, in each DHT node, of multiple routing tables of the underlying Chord graph. The outcome are routing decisions capable of achieving average distances as low as 40% of those offered by Chord’s conventional routing method. Moreover, the supplemental computational effort to take the shortcut routing decisions is sufficiently low...

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