Space filling curves (SFCs) are proximity preserving linearizations of multidimensional data. they are frequently used for parallel domain decomposition in scientific computing applications where interactions occur be...
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the Replica Placement Problem (RPP) aims at selecting the nodes for duplicating data objects in order to optimize their access. Even though a lot of work already exists on RPP, the issue of implementing the resulting ...
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ISBN:
(纸本)9780889866386
the Replica Placement Problem (RPP) aims at selecting the nodes for duplicating data objects in order to optimize their access. Even though a lot of work already exists on RPP, the issue of implementing the resulting allocation scheme is typically overlooked. In this paper we introduce the Replica Transfer Scheduling Problem (RTSP), briefly stated as: given a network of servers with limited storage capacitv, a set of data objects and two replication schemes x(old) and X-new, find a schedule of object transfers and deletions for implementing X-old based on X-old with minimum communication cost. Given that this problem is NP-complete, we introduce several different heuristics to solve it, and evaluate them via simulations.
Both web services framework and peer-to-peer networks provide a discovery process, but as current P2P systems focus more on the discovery of content in the form of common files (possibly associated with metadata), a c...
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ISBN:
(纸本)9780889867048
Both web services framework and peer-to-peer networks provide a discovery process, but as current P2P systems focus more on the discovery of content in the form of common files (possibly associated with metadata), a centralized UDDI registry serves content in the form of metadata describing web services. thus, the intersection between P2P and Web services is clear, so that it recently gained lots of interest: there is the need of finding a way to exploit the high potential of web services without paying in terms of scalability or single-point-of-failures. Our aim in this paper is two-fold: on the one hand, we want to present a high level protocol for the addressing and the discovery of web services that is totally decentralized and based on a structured P2P topology. On the other hand, we introduce a way to solve the exact match key-based routing problem, that afflicts structured P2P systems. this model guarantees that all addressed web services will be discovered in a logarithmic number of hops, as it is based on a distributed Hash Table. One of the key innovation is the possibility of customizing the categorization of web services using tags, which are becoming very common in the so called Web 2.0.
the Multi-Level computing Architecture (MLCA) is a novel parallel System-on-a-Chip architecture targeted for multimedia applications. It features a top level controller that automatically extracts task level paralleli...
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ISBN:
(纸本)9780889866386
the Multi-Level computing Architecture (MLCA) is a novel parallel System-on-a-Chip architecture targeted for multimedia applications. It features a top level controller that automatically extracts task level parallelism using techniques similar to how instruction level parallelism is extracted by superscalar processors. this allows the MLCA to support a simple programming model that is similar to sequential programming. In order to assist programmers to easily and efficiently port multimedia applications to the MLCA programming model, a compilation environment is designed. this compilation environment enhances parallelism in MLCA programs by applying three simple code transformations that are based on known compiler optimizations. In this paper, we describe the MLCA architecture, its programming model, its compilation environment and an evaluation of its performance. Our experimental evaluation withthree real multimedia applications and an MLCA simulator shows that the MLCA is a viable architecture and scaling speedups can be obtained using the compilation environment with little programmer effort.
Finding the expectation of the maximum execution time among parallel processors is crucial in parallel performance evaluation. Unfortunately, current analytical methods for maximum mean calculation cannot be applied t...
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High performance and reliability are critical requirements for real time systems. Efficient scheduling that assigns tasks of an application to suitable processors in these systems is necessary for achieving high perfo...
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Group mutual exclusion is a naturel problem, formulated by Joung, that generalize the classical mutual exclusion problem. In group mutual exclusion a process requests a"session" before entering its critical ...
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distributed object-oriented middleware technologies have been adopted for ubiquitous communicating real-time and embedded systems. Although Java plays an important role in building distributed object-oriented middlewa...
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ISBN:
(纸本)9780889866386
distributed object-oriented middleware technologies have been adopted for ubiquitous communicating real-time and embedded systems. Although Java plays an important role in building distributed object-oriented middleware because of its portability and productivity, it is not popularto real-time system developers because it is slow and hard to keep real-timeness due to garbage collection. this paper presents a novel memory classification and measurement approach for modem programming language such as Java to analyze the memory utilization of middleware technologies in order to improve them for embedded systems using limited computing resource. We classified Java memory into four categories such as static, quasi-static, quasi-dynamic and dynamic, and show how to measure the size of each memory. Intensive case studies using popular Java middleware technologies such as Web Services, CORBA, RMI and HORB revealed that reducing the use of dynamic memory has contributed far more to the efficiency and performance than reducing the use of quasi-static and quasi-dynamic memory.
We describe a highly scalable algorithm for secure system evolution in an infrastructure for widely distributed Byzantine fault-tolerant applications. To maintain high availability, the system and its applications evo...
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ISBN:
(纸本)9780889866386
We describe a highly scalable algorithm for secure system evolution in an infrastructure for widely distributed Byzantine fault-tolerant applications. To maintain high availability, the system and its applications evolve on-line, providing uninterrupted service during installation of upgrades. Installations are made to appear atomic with respect to other installations and application execution steps. Our algorithm guarantees safe installation despite Byzantine faulty replicas and replica groups. An initial phase prepares replica groups for an upgrade, while a second phase triggers the installation of the upgrade by gossip among groups. A simple but novel scheme using secret sharing and Byzantine quorums prevents faulty replicas and replica groups from disrupting or maliciously exploiting installations. Installation message complexity and computational complexity grow linearly withthe number of replicas.
Passive testing is a technique suitable for continuous, non-intrusive, autonomous testing of qualitative behavioural properties (correctness) of a deployed distributed system. A real passive tester has to face observa...
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ISBN:
(纸本)9780889866379
Passive testing is a technique suitable for continuous, non-intrusive, autonomous testing of qualitative behavioural properties (correctness) of a deployed distributed system. A real passive tester has to face observational uncertainty, which may lead to false verdicts. We submit the novel idea of a self-tuned passive tester, which is able to adapt to a priori unknown, and possibly changing delays in communication channels. We propose the structure and algorithms of a passive tester that "tunes itself" basing solely on its own, locally issued verdicts. this seemingly counter-intuitive principle is shown by simulation to be viable and effective.
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