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1990 ACM Symposium on Communications Architectures and Protocols, SIGCOMM 1990

作者： Liang, L. Neufeld, G.W. Chanson, S.T. Distributed Systems Research Group Department of Computer Science University of British Columbia VancouverBCV6TlW5 Canada

ISBN: (纸本)0897914058

This paper generalizes group communications into nested groups for the internet environment. By using a name graph model, two problems in nested group name resolution are identified - resolution loops and resolution duplications. Existing approaches of solving these problems are surveyed and their shortcomings analyzed. The research contribution of this paper is the design and analysis of an algorithm which uses statically saved topology information of the name graph to detect and handle resolution and duplication loops at the time when group membership and/or group structure change. While preserving some necessary properties of loops, the algorithm transforms the name graph into one which avoids resolution loops and controls duplications. The communication complexity of the algorithm has an upper bound of O(lAl) in the worst case, where IAl is the number of arcs in the name graph. © 1990 ACM.

关键词： Topology

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The algebraic specification language LOTOS: An industrial experience

The algebraic specification language LOTOS: An industrial ex...

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1990 ACM SIGSOFT International Workshop on Formal Methods in Software Development, IWFMSD 1990

作者： Logrippo, Luigi Melanchuk, Tim Du Wors, Robert J. University of Ottawa Computer Science Department Protocols Research Group OttawaONKIN 9B4 Canada Advanced Development Group Gandalf Data Ltd. 130 Colonnade Rd. S. NepeanONK2E 7J5 Canada Connected Systems Group 61 Reaney Court KanataONK2K 1W7 Canada

ISBN: (纸本)0897914155

The ISO specification language LOTOS is presented, together with the results of a project involving the evaluation of its usefulness in an industrial environment. LOTOS is a mixture of concepts taken from CCS and CSP, along with an algebraic abstract data type formalism. The language was used by Gandalf to develop a formal specification of an existing protocol, part of a distributed data PBX. The effort concentrated on the specification of two aspects of the protocol: the top level system architecture, and the call management phase. It is shown how the unique features of LOTOS were found to be useful for expressing these aspects. The results of the project were positive, and further use of LOTOS is planned within Gandalf. © 1990 ACM.

关键词： Specification languages

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THE COMMAND SUPPORT AT-SEA EXPERIMENT

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NAVAL ENGINEERS JOURNAL 1990年第3期102卷 25-36页

作者： BUSCHER, DJ SUNDAY, DM David J. Buscher:is an electrical engineer on the Principal Professional Staff of the Fleet Systems Department of The Johns Hopkins University Applied Physics Laboratory. He earned his BS degree in electrical engineering from Villanova University in 1967 an MSEE degree from the University of Maryland in 1972 and an MS degree in technical management from The Johns Hopkins University in 1985. He was the lead engineer on the Command Support At-Sea Experiment Project. He started his career in 1967 with the U.S. Army Harry Diamond Laboratory working on computer and communications projects. During this time he worked in Vietnam with the United States Army Vietnam Science Advisor Office. Since joining JHU/APL in 1978 he has worked on a variety of projects associated with computer graphics hospital patient information systems computer networks autonomous underwater vehicles and satellite communications. He is currently assistant group supervisor of the Computer Systems Group. Daniel M. Sunday:is a mathematician on the Principal Professional Staff of the Fleet Systems Department of The Johns Hopkins University Applied Physics Laboratory. He earned his Ph.D. in mathematics from the University of Minnesota in 1971 and did postdoctoral research on neural networks at the University of California at Berkeley. Since joining JHU/APL in 1980 Dr. Sunday has worked as a designer and developer of software systems with emphasis on medical imaging interactive graphics natural language interfaces and software standards. He was the network designer for the Headquarters Integrated Office System (HIOS) Network for the Army at the Pentagon. He is currently the lead software engineer on the Command Support At-Sea Experiment Project.

The Command Support At-Sea Experiment (CS@SE) provides experimental advanced graphics display systems consisting of large screen color displays and operator console color displays in the combat information center (CIC) of an Aegis cruiser and in the tactical flag command center (TFCC) of an aircraft carrier. CS@SE systems are designed to prototype potential command support capabilities in an at-sea environment to validate and refine requirements for planned production system upgrades. These systems use sophisticated color graphics techniques to provide real-time tactical displays that improve the availability of information to an operator by reducing clutter through the use of color, area fill, transparen overlays and intensity coding of track symbols. Interfaces wen developed with the Aegis Display System (ADS), Shipboarc Gridlock System with Auto-correlation (SGS/AC), Flag Dats Display System (FDDS) and Tomahawk Engagement Planning and Exercise Evaluation System (TEPEE) that provided the data for the presentation of a tactical display. Display elements included both real-time and over-the-horizon (OTH) surface track data, velocity leaders, tags, uncertainty ellipses, and history trails. The display also included filled land masses, country boundaries, commercial airways, cities, graphics overlays (i.e., operational areas), weapon system missile performance contours, and engagement plans. This paper describes the experiment, its installation and integration into the shipboard environments of an Aegis cruiser (USS Leyte Gulf ) and an aircraft carrier (USS America , its usage by the ships companies and embarked staffs, and the experiment result! and findings. Key conclusions of the experiment are: 1 Advanced graphics color displays can significantly enhance the ability of the warfighter to assimilate a complex tactical display. 2 Both ships reported a requirement for a correlated OTH and real-time track display with the ability to clearly differentiate the two types

关键词： computer Graphics

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computer-SYSTEM ARCHITECTURE CONCEPTS FOR FUTURE COMBAT systems

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NAVAL ENGINEERS JOURNAL 1990年第3期102卷 43-62页

作者： ZITZMAN, LH FALATKO, SM PAPACH, JL Dr. Lewis H. Zitzman:is the group supervisor of the Advanced Systems Design Group Fleet Systems Department The Johns Hopkins University Applied Physics Laboratory (JHU/APL). He has been employed at JHU/APL since 1972 performing applied research in computer science and in investigating and applying advanced computer technologies to Navy shipboard systems. He is currently chairman of Aegis Computer Architecture Data Bus and Fiber Optics Working Group from which many concepts for this paper were generated. Dr. Zitzman received his B.S. degree in physics from Brigham Young University in 1963 and his M.S. and Ph.D. degrees in physics from the University of Illinois in 1967 and 1972 respectively. Stephen M. Falatko:was a senior engineering analyst in the Combat Systems Engineering Department Comptek Research Incorporated for the majority of this effort. He is currently employed at ManTech Services Corporation. During his eight-year career first at The Johns Hopkins University Applied Physics Laboratory and currently with ManTech Mr. Falatko's work has centered around the development of requirements and specifications for future Navy systems and the application of advanced technology to Navy command and control systems. He is a member of both the Computer Architecture Fiber Optics and Data Bus Working Group and the Aegis Fiber Optics Working Group. Mr. Falatko received his B.S. degree in aerospace engineering with high distinction from the University of Virginia in 1982 and his M.S. degree in applied physics from The Johns Hopkins University in 1985. Mr. Falatko is a member of Tau Beta Pi Sigma Gamma Tau the American Society of Naval Engineers and the U.S. Naval Institute. Janet L. Papach:is a section leader and senior engineering analyst in the Combat Systems Engineering Department Comptek Research Incorporated. She has ten years' experience as an analyst supporting NavSea Spa War and the U.S. Department of State. She currently participates in working group efforts under Aegis Combat System Doctrin

This paper sets forth computer systems architecture concepts for the combat system of the 2010–2030 timeframe that satisfy the needs of the next generation of surface combatants. It builds upon the current Aegis computer systems architecture, expanding that architecture while preserving, and adhering to, the Aegis fundamental principle of thorough systems engineering, dedicated to maintaining a well integrated, highly reliable, and easily operable combat system. The implementation of these proposed computer systems concepts in a coherent architecture would support the future battle force capable combat system and allow the expansion necessary to accommodate evolutionary changes in both the threat environment and the technology then available to effectively counter that threat. Changes to the current Aegis computer architecture must be carefully and effectively managed such that the fleet will retain its combat readiness capability at all times. This paper describes a possible transition approach for evolving the current Aegis computer architecture to a general architecture for the future. The proposed computer systems architecture concepts encompass the use of combinations of physically distributed, microprocessor-based computers, collocated with the equipment they support or embedded within the equipment itself. They draw heavily on widely used and available industry standards, including instruction set architectures (ISAs), backplane busses, microprocessors, computer programming languages and development environments, and local area networks (LANs). In this proposal, LANs, based on fiber optics, will provide the interconnection to support system expandability, redundancy, and higher data throughput rates. A system of cross connected LANs will support a high level of combat system integration, spanning the major warfare areas, and will facilitate the coordination and development of a coherent multi-warfare tactical picture supporting the future combatant command st

关键词： computer Architecture

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THE GEMINI REPLICATED-FILE SYSTEM TESTBED

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INFORMATION scienceS 1989年第2期48卷 119-134页

作者： BURKHARD, WA MARTIN, BE PARIS, JF Computer Systems Research Group Department of Computer Science and Engineering University of California San Diego La Jolla California 9209 U.S.A

The Gemini system is a replicated-file testbed facility designed for local area networks and is built using ordinary host unix machines. Gemini was designed to test empirically consistency and recovery schemes for replicated files in a distributed environment. A principle objective is to protect files against a fixed number of host and network failures while maintaining consistent data. Gemini replicated files are implemented as several copies of ordinary files that reside on distinct hosts. We present the Gemini system testbed design and discuss three consistency and recovery schemes: voting with witnesses, dynamic voting, and semisynchronous voting. Empirical and analytic performance results are presented.

关键词： Database systems

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Regeneration protocols for replicated objects

Regeneration protocols for replicated objects

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International Conference on Data Engineering

作者： D.D.E. Long J.-F. Paris Computer Systems Research Group Department of Computer Science and Engineering University of California San Diego CA USA

The read and write availabilities of replicated data managed by the regeneration algorithm, a replica control protocol based on file regeneration, are evaluated, and two regeneration protocols are presented that overcome some of its limitations. The first protocol combines regeneration and the available copy approach to improve availability of replicated data. The second combines regeneration and the dynamic voting approach to guarantee data consistency in the presence of network partitions while maintaining a high availability. Expressions for the availabilities of replicated data managed by both protocols are derived and found to improve significantly on the availability achieved using extant consistency protocols.< >

关键词： Access protocols Availability Partitioning algorithms computer science Voting computer network management Local area networks Data engineering Reliability engineering Fault tolerant systems

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SEMIAUTOMATIC IMPLEMENTATION OF PROTOCOLS USING AN ESTELLE-C COMPILER

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IEEE TRANSACTIONS ON SOFTWARE ENGINEERING 1988年第3期14卷 384-393页

作者： VUONG, ST LAU, AC CHAN, RI Distributed System Research Group Department of Computer Science University of British Columbia Vancouver B.C. V6T 1W5 Canada

The basic ideas underlying an Estelle-C compiler, which accepts an Estelle protocol specification and produces a protocol implementation in C, are presented. The implementation of the ISO (International Organization for Standardization) class-2 transparent protocol, using the semiautomatic approach, is discussed. A manual implementation of the protocol is performed and compared to the semiautomatic implementation. The semiautomatic approach to protocol implementation offers several advantages over the conventional manual one, including correctness and modularity in protocol implementation code, conformance to the specification, and reduction in implementation time. Finally, ongoing development of a new Estelle-C compiler is presented.

关键词： Specifications accuracy class Modularity Protocol specification compilers ISO

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A realistic evaluation of consistency algorithms for replicated files 21

A realistic evaluation of consistency algorithms for replica...

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21st Annual Symposium on Simulation, ANSS 1988

作者： Pâris, Jehan-François Long, Darrell D.E. Glockner, Alexander Computer Systems Research Group Department of Computer Science and Engineering University of California San Diego San DiegoCA92093 United States

ISBN: (纸本)0818608455

Data are often replicated in distributed systems to protect them against site failures and network malfunctions. When this is the case, an access policy must be chosen to insure that a consistent view of the data is always presented. Voting protocols guarantee consistency of replicated data in the presence of any scenario involving non-Byzantine site failures and network partitions. While Static Majority Consensus Voting protocols use static quorums, Dynamic Voting protocols, like Dynamic Voting and Lexicographic Dynamic Voting, dynamically adjust quorums to changes in the status of the network of sites holding the copies. The availabilities of replicated data managed by these three protocols are compared using a simulation model with realistic parameters. Dynamic Voting is found to perform better than Majority Consensus Voting for all files having more than three copies while Lexicographic Dynamic Voting performs much better than the two other protocols for all eleven configurations under study.

关键词： Discrete event simulation

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The object library for parallel simulation (OLPS) 88

The object library for parallel simulation (OLPS)

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Proceedings of the 20th conference on Winter simulation

作者： Marc Abrams Distributed Systems Group Department of Computer Science Stanford University Stanford CA

ISBN: (纸本)9780911801422

The Object Library for Parallel Simulation (OLPS) is a set of C++ objects from which a parallel, discrete event simulation or simulation language can be built and run on multiprocessor workstations. OLPS provides a common interface to the simulation programmer for several parallel simulation algorithms, including implementations of the Chandy-Misra and Time-Warp algorithms. OLPS also provides instrumentation to compare the performance of each parallel algorithm on the same simulation problem. The system currently runs on the V distributed system on the DEC Firefly.

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Efficient dynamic voting algorithms

Efficient dynamic voting algorithms

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International Conference on Data Engineering

作者： J.-F. Paris D.D.E. Long Computer Systems Research Group Department of Computer Science and Engineering University of California San Diego CA USA

Two novel dynamic voting algorithms are proposed. One, called optimistic dynamic voting, operates on possibly out-of-date information, which greatly increases the efficiency of the algorithm and simplifies its implementation. The other, called topological dynamic voting, explicitly takes into account the topology of the network on which the copies reside to increase the availability of the replicated data. The authors compare availabilities of replicated data managed by both algorithms with those of data managed by existing voting protocols using a simulation model with realistic parameters. Optimistic dynamic voting is found to perform as well as the best existing voting algorithms while topological dynamic voting performs much better than all other voting algorithms when two or more copies reside in the same nonpartitionable group.< >

关键词： Voting Heuristic algorithms Partitioning algorithms Availability Protocols Network topology computer networks computer science Data engineering Fault tolerant systems

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