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proceedings of the 15th annual conference on Computer Science

作者： Sang Hyuk Son Department of Computer Science University of Virginia Charlottesville Virginia

ISBN: (纸本)9780897912181

We are investigating the problem of ensuring global consistency in the context of distributed database systems. Our current research effort concentrates on theoretical study of reliability mechanisms such as algorithm design and performance characterization. In addition, we are building a testbed for evaluating different reliability mechanisms through detailed simulation and actual *** is the key factor in improving the availability of distributed database systems. A major restriction in using replication is that replicated copies must behave like a single copy. We have developed algorithms for replication control using tokens [2, 5]. The next step of our research in this direction would be to evaluate different partial operation policies which are critical in maintaining the correctness and achieving the high availability of distributed database systems. Two alternatives are possible when a partition occurs: pessimistic and optimistic. Neither of the two alternatives is superior to the other. Higher availability achieved by an optimistic approach may be penalized during recovery from partition failures, by backing out committed transactions which violate consistency *** if the replication and concurrency control mechanisms are correct and maintain the consistency of the database, the failures of hardware and/or software at the processing site and communication network may destroy the consistency of the database. In order to cope with failures, distributed database systems.must provide recovery mechanisms. The goal of checkpointing is to save database states on a separate secure device so that the database can be recovered when errors and failures occur. A checkpointing mechanism which does not interfere with the transaction processing in distributed environment is highly desirable for many applications, where restricting transaction activity during checkpointing is not feasible. Our earlier research has resulted in the developme

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Robustness testing of a distributed simulation backplane

Robustness testing of a distributed simulation backplane

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International symposium on software reliability Engineering (ISSRE)

作者： K. Fernsler P. Koopman RS6000 Graphics Development IBM Corporation Austin TX USA Institute for Complex Engineered Systems & Department of Electrical and Computer Engineering Carnegie Mellon University Pittsburgh PA USA

Creating robust software requires not only careful specification and implementation, but also quantitative measurement. This paper describes Ballista exception handling testing of the High Level Architecture RunTime Infrastructure (HLA RTI). The RTI is a standard distributed simulation system intended to provide completely robust exception handling, yet implementations have normalized robustness failure rates as high as 10%. Non-robust testing responses include exception handler crashes, segmentation violations, "unknown" exceptions, and task hangs. Other issues include different robustness failure modes across ports to two operating systems. and mandatory client machine rebooting after a particular RTl failure. Testing the RTI led to scalable extensions of the Ballista architecture for handling exception-based error reporting models, testing object-oriented software structures (including call-backs, pass by reference, and constructors), and operating in a state-rich, distributed system environment. These results demonstrate that robustness testing can provide useful feedback to high-quality software development processes, and can be applied to domains well beyond the previous work on testing operating systems.

关键词： Robustness Backplanes Vehicle crash testing software testing System testing Object oriented modeling Computer architecture Operating systems software measurement Runtime

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Primary-shadow consistency issues in the DRB scheme and the recovery time bound

Primary-shadow consistency issues in the DRB scheme and the ...

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International symposium on software reliability Engineering (ISSRE)

作者： K.H. Kim L. Bacellar C. Subbaraman Department of Electrical & Computer Engineering University of California Irvine CA USA

The distributed recovery block (DRB) scheme is an approach for realizing both hardware and software fault tolerance in real time distributed and parallel computer systems. We point out that in order for the DRB scheme to yield a high fault coverage and a low recovery time bound, some important consistency requirements must be satisfied by the replicated application tasks in a DRB computing station. Newly identified approaches for meeting the consistency requirements, which involve, among other things, integration of network surveillance and reconfiguration (NSR) techniques with the DRB scheme, are presented. The paper then presents an analysis of the recovery time bound of the DRB scheme. The analysis is based on a modular structured concrete implementation model of the DRB scheme for local area network (LAN) based distributed computer systems. which is called the DRB/T LAN scheme and incorporates an NSR scheme and the newly identified consistency ensuring mechanisms. Finally, we consider approaches for applying the DRB scheme to new types of application computation segments that were not considered before and then discuss approaches for meeting the consistency requirements in such DRB stations. These approaches broaden the application range of the DRB scheme significantly.

关键词： Local area networks distributed computing Application software Hardware Fault tolerant systems Real time systems Concurrent computing Surveillance Concrete Computer networks

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The ADNET Communications System: Inter-Process Communication in a Fault Tolerant Local Area Network

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IFAC proceedings Volumes 1983年第18期16卷 233-238页

作者： W.L. Lakin M.R. Moulding Procurement Executive Ministry of Defence Admiralty Surface Weapons Establishment Portsmouth Hants UK Division of Electrical and Electronic Engineering The Hatfield Polytechnic Hatfield Herts UK

An experimental local area network (ADNET) has been developed at the Admiralty Surface Weapons Establishment (ASWE) to investigate the use of a distributed computer architecture for shipborne command and control systems. The ADNET Communications System provides the means by which software processes distributed throughout the network can communicate. At the hardware level it uses the ASWE Serial Highway. This is a polled multi-drop bus which employs hardware redundancy to achieve high reliability. Both broadcast and point-to-point intercomputer message transfers are supported and a high level of error detection and correction is provided. The software of the communications system provides protocols which eliminate the need for a fixed connectively within the network. This allows the applications software to be dynamically reconfigurable and leads to the provision of fault tolerant functions for the network. The ASWE Serial Highway is described together with the software and protocols of the communications system. In addition, the use of the protocols by fault tolerant functions is illustrated by examining the operation of the ASWE distributed database Management System (ADDAM).

关键词： Communications computers applications communications control applications computer applications computer hardware computer interfaces computer software data handling multiprocessing systems parallel processing system failure and recovery

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Action models: a reliability modeling formalism for fault-tolerant distributed computing systems

Action models: a reliability modeling formalism for fault-to...

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International Computer Performance and Dependability symposium

作者： A.P.A. van Moorsel Distributed Software Research Department Bell Laboratories Research Lucent Technologies Murray Hill NJ USA

Modern-day computing system design and development is characterized by increasing system complexity and ever shortening time to market. For modeling techniques to be deployed successfully, they must conveniently deal with complex system models, and must be quick and easy to use by non-specialists. In this paper we introduce "action models", a modeling formalism that tries to achieve the above goals for reliability evaluation of fault-tolerant distributed computing systems. including both software and hardware in the analysis. The metric of interest in action models is the job success probability, and we will argue why the traditional availability metric is insufficient for the evaluation of fault-tolerant distributed systems. We formally specify action models, and introduce path-based solution algorithms to deal with the potential solution complexity of created models. In addition, we show several examples of action models, and use a preliminary tool implementation to obtain reliability results for a reliable clustered computing platform.

关键词： Fault tolerant systems distributed computing Time to market Fault trees Stochastic systems Petri nets Telecommunication switching Hardware Availability Clustering algorithms

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MEADEP and its applications in evaluating dependability for air traffic control systems

MEADEP and its applications in evaluating dependability for ...

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Annual symposium on reliability and Maintainability (RAMS)

作者： Dong Tang M. Hecht J. Handal L. Czekalski SoHaR Inc.orporated Beverly Hills USA Federal Aviation Administration Washington D.C. DC USA

MEADEP (measure dependability) is a user-friendly dependability evaluation tool for measurement-based analysis of computing systems.including both hardware and software. Features of MEADEP are: a data processor for converting data in various formats (records with a number of fields stored in a commercial database format) to the MEADEP format, a statistical analysis module for graphical data presentation and parameter estimation, a graphical modeling interface for constructing reliability block and Markov diagrams, and a model solution module for availability/reliability calculation with graphical parametric analysis. Use of the tool on failure data from measurements can provide quantitative assessments of dependability for critical systems. while greatly reducing requirements for specialized skills in data processing, analysis, and modeling from the user. MEADEP has been applied to evaluate dependability for several air traffic control systems.(ATC) and results produced by MEADEP have provided valuable feedback to the program management of these critical systems.

关键词： software measurement Application software Hardware software tools Spatial databases Statistical analysis Parameter estimation Availability Data processing Data analysis

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distributed FILE MANAGER FOR THE TRW EXPERIMENTAL DEVELOPMENT SYSTEM.

Annual Proceedings - Reliability Physics (Symposium)

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Annual proceedings - reliability Physics (symposium) 1979年 322-336页

作者： Danforth, Scott

Since 1976, the Computer Engineering Section at TRW has been using Concurrent Pascal in its multiple-minicomputer signal processing facility for research into the software engineering of special purpose locally distributed systems. In such systems. the particular operating system support required at any processor can be quite specific, removing the necessity for use of typical vendor-supplied general purpose operating systems. Intercomputer link drivers, file systems. graphics packages, and performance monitors are examples of typical services. To these, a simple distributed file manager (DFM) has been added which maintains three possible levels of access control for a file distributed redundantly over any number of machines. The particular services or application code interfaces into the DFM which were decided upon, the operation of the manager and its representation as a collection of Concurrent Pascal system types, and the method of monitoring its performance are discussed.

关键词： Computer networks

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Calculating worst-case execution times of transactions in databases for event-driven, hard real-time embedded systems

Calculating worst-case execution times of transactions in da...

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International symposium on database Engineering and Applications (IDEAS)

作者： A. Munnich G. Farber Institute for Real-Time Computer Systems Technische Universität München Munich Germany

In embedded real-time systems.the use of databases increases, particularly to ensure the quality of data and to simplify the development of software. Especially for safety-critical applications one must guarantee in advance by suitable verification-algorithms that all deadlines hold in all possible cases of use. The worst-case execution time of transactions is an essential input of those algorithms. Therefore, we present here a method to calculate these times for non-distributed, main memory databases in event-driven, embedded hard real-time systems. We use the very powerful means of event-streams and event-dependency-matrices for a detailed description of the embedding environment and an application model to specify the necessary information about the application itself.

关键词： Transaction databases Real time systems Embedded system Embedded computing Embedded software software quality Application software Concurrent computing Humans Production

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A simulation model of adaptive protocols in distributed computing systems.with mobile hosts

A simulation model of adaptive protocols in distributed comp...

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Annual symposium on Simulation

作者： S.J. Lai A. Zaslavsky G.M. Martin Department of Computer Technology Monash University Melbourne Australia

Simulation is a scientific method which is largely dominated by computers and has allowed the testing and assessment of many models before actual implementation. The paper proposes an approach to construction of a simulation that models the behaviour of an adaptive queuing protocol (AQP). AQP was developed for database applications on mobile computers in a distributed multidatabase environment but can also be used in many other areas including distributed operating systems. By constructing the simulation model it is possible to both prove that it can be implemented, and at the same time study its expected behaviour in a mobile computing environment. The results of the simulation are analysed and discussed.< >

关键词： Computational modeling Protocols distributed computing Mobile computing Computer simulation Testing distributed databases Application software Computer applications Operating systems

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Protecting mobile code

Protecting mobile code

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International symposium on software reliability Engineering (ISSRE)

作者： T. Sander International Computer Science Institute Berkeley CA USA

There are at least two major security challenges in mobile code distributed systems. First hosts have to be protected from potentially malicious actions of mobile code they are executing. Many techniques are known which address this problem. Second mobile agents themselves have to be protected against malicious hosts. Satisfactory ways to deal with the second problem are necessary features for many of the (security-sensitive) tasks mobile agent (MA) systems.are envisioned for, e.g., in e-commerce applications where a shopping agent is sent out on the Internet, vendors have a high incentive in tampering with these agents. The key point is is that the originator of the agent needs to have sound guarantees that the results an agent brings back are correct. Why else should he send out the agent in the first place?.

关键词： Cryptography Mobile agents Internet software protection Computer security Electrical capacitance tomography IP networks Data security Application software databases

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