36 research outputs found
Distributed match-making
In many distributed computing environments, processes are concurrently executed by nodes in a store- and-forward communication network. Distributed control issues as diverse as name server, mutual exclusion, and replicated data management involve making matches between such processes. We propose a formal problem called distributed match-making as the generic paradigm. Algorithms for distributed match-making are developed and the complexity is investigated in terms of messages and in terms of storage needed. Lower bounds on the complexity of distributed match-making are established. Optimal algorithms, or nearly optimal algorithms, are given for particular network topologies
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Tree Machines: Architectures and Algorithms A Survey Paper
Recent advances in very large scale integrated (VLSI) circuit technology have lead to a surge in research aimed at finding new computer organizations that support a great deal of concurrency computer organizations based on tree structures appear well-suited to several kinds of parallel computations. In this paper we will discuss the performance of tree machines as well as Issues related to their implementation in VLSI. Examples of tree machines are presented, with an emphasis on the way the processing elements communicate in the machine. A taxonomy of tree algorithms based on a taxonomy of parallel algorithms proposed by Kung in 1979 is Introduced. Examples of tree algorithms are also given
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Linda, tuple spaces and its implementation on a network of Unix workstations
In this paper we outline an implementation of Linda on a network of Unix worksta颅tions. A literature survey was done to gain a better perspective on state of the art and to learn from the experiences of other implementations. The tuple space which is central to the Linda system is implemented as multiple segments distributed on different systems. The biggest challenge in implementing Linda is management of the tuple space. We outline a mechanism for creation and management of the distributed tuple space. Linda has been embedded in C with a partial support for the underlying datatypes of C. Results of some of the test routines run on the system along with some comparative timings are provided
Center for Space Microelectronics Technology 1988-1989 technical report
The 1988 to 1989 Technical Report of the JPL Center for Space Microelectronics Technology summarizes the technical accomplishments, publications, presentations, and patents of the center. Listed are 321 publications, 282 presentations, and 140 new technology reports and patents
[Research activities in applied mathematics, fluid mechanics, and computer science]
This report summarizes research conducted at the Institute for Computer Applications in Science and Engineering in applied mathematics, fluid mechanics, and computer science during the period April 1, 1995 through September 30, 1995
Distributed Simulation of High-Level Algebraic Petri Nets
In the field of Petri nets, simulation is an essential tool to validate and evaluate models. Conventional simulation techniques, designed for their use in sequential computers, are too slow if the system to simulate is large or complex. The aim of this work is to search for techniques to accelerate simulations exploiting the parallelism available in current, commercial multicomputers, and to use these techniques to study a class of Petri nets called high-level algebraic nets. These nets exploit the rich theory of algebraic specifications for high-level Petri nets: Petri nets gain a great deal of modelling power by representing dynamically changing items as structured tokens whereas algebraic specifications turned out to be an adequate and flexible instrument for handling structured items. In this work we focus on ECATNets (Extended Concurrent Algebraic Term Nets) whose most distinctive feature is their semantics which is defined in terms of rewriting logic. Nevertheless, ECATNets have two drawbacks: the occultation of the aspect of time and a bad exploitation of the parallelism inherent in the models. Three distributed simulation techniques have been considered: asynchronous conservative, asynchronous optimistic and synchronous. These algorithms have been implemented in a multicomputer environment: a network of workstations. The influence that factors such as the characteristics of the simulated models, the organisation of the simulators and the characteristics of the target multicomputer have in the performance of the simulations have been measured and characterised. It is concluded that synchronous distributed simulation techniques are not suitable for the considered kind of models, although they may provide good performance in other environments. Conservative and optimistic distributed simulation techniques perform well, specially if the model to simulate is complex or large - precisely the worst case for traditional, sequential simulators. This way, studies previously considered as unrealisable, due to their exceedingly high computational cost, can be performed in reasonable times. Additionally, the spectrum of possibilities of using multicomputers can be broadened to execute more than numeric applications
Multicast communications in distributed systems
PhD ThesisOne of the numerous results of recent developments in communication
networks and distributed systems has been an increased interest in the study
of applications and protocolsfor communications between multiple, as opposed
to single, entities such as processes and computers. For example, in replicated
file storage, a process attempts to store a file on several file servers, rather
than one. MUltiple entity communications, which allow one-to-many and
many-to-one communications, are known as multicast communications.
This thesis examines some of the ways in which the architectures of
computer networks and distributed systems can affect the design and
development of multicast communication applications and protocols.To assist
in this examination, the thesis presents three contributions. First, a set of
classification schemes are developed for use in the description and analysis of
various multicast communication strategies. Second, a general set of
multicast communication primitives are presented, unrelated to any specific
network or distributed system, yet efficiently implementable on a variety of
networks. Third, the primitives are used to obtain experimental results for a
study ofintranetwork and internetwork multicast communications.Postgraduate Scholarship, The Natural Sciences and Engineering Research Council of Canada:
Overseas Research Student Award:
the Committee of Vice-Chancellors and Principals of the Universities of the
Uni ted Kingdom
NASA University program management information system, FY 1993
The University Program Report, Fiscal Year 1993, provides current information and related statistics for 7682 grants/contracts/cooperative agreements active during the report period. NASA field centers and certain Headquarters program offices provide funds for those R&D activities in universities which contribute to the mission needs of that particular NASA element. This annual report is one means of documenting the NASA-university relationship, frequently denoted, collectively, as NASA's University Program
First International Conference on Ada (R) Programming Language Applications for the NASA Space Station, volume 2
Topics discussed include: reusability; mission critical issues; run time; expert systems; language issues; life cycle issues; software tools; and computers for Ada