The quantification of distributed Data Base (DDB) reliability is needed for the DDB design phase and for the comparative evaluation of the effectiveness of various data distribution strategies. A method based on a Mar...
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The quantification of distributed Data Base (DDB) reliability is needed for the DDB design phase and for the comparative evaluation of the effectiveness of various data distribution strategies. A method based on a Markov model is outlined to evaluate the transition probabilities from a functioning system to a faulty one and viceversa. The method consists of two steps: first is the computation of the transition rate matrix of the DDB with Kronecker algebra, which is used then to calculate the probabilities of the different possible states of the DDB;the second is an algorithm to calculate the structure vector related to a given transaction of the DDB.
An implementation of a reliable remote procedure call (RPC) mechanism for obtaining remote services is described. The reliability issues are discussed together with how they have been dealt with. The performance of th...
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An implementation of a reliable remote procedure call (RPC) mechanism for obtaining remote services is described. The reliability issues are discussed together with how they have been dealt with. The performance of the remote call mechanism is compared with that of local calls. The remote call mechanism is shown to be an efficient tool for distributed programming.
An approach is presented for maintaining high availability in a replicated database system with a failure-prone communications network. The status of the network is assumed to change dynamically, making the detection ...
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ISBN:
(纸本)0818607378
An approach is presented for maintaining high availability in a replicated database system with a failure-prone communications network. The status of the network is assumed to change dynamically, making the detection of partitions infeasible. The approach is based on restricting the data items transactions can access and on special requirements placed on update propagation.
In this paper the authors present fault-tolerant softwarereliability models based on component reliabilities. Two methods for estimating component reliabilities and the associated variances are given along with an ap...
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ISBN:
(纸本)0818605014
In this paper the authors present fault-tolerant softwarereliability models based on component reliabilities. Two methods for estimating component reliabilities and the associated variances are given along with an approach for calculating the system reliability estimate variance. The derived models are used as a basis for discussing trade-offs between the two dominate fault-tolerant software strategies, Recovery Blocks and N-Version Programming.
Many proposals have been made for structuring distributed programs. This paper looks at one such proposal, the one embedded in the Argus programming language and system. The paper provides a discussion of decisions ma...
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ISBN:
(纸本)0818605014
Many proposals have been made for structuring distributed programs. This paper looks at one such proposal, the one embedded in the Argus programming language and system. The paper provides a discussion of decisions made in the two major areas of process structure and communication, and compares the chosen structures with alternatives. The paper emphasizes the rationale for decisions and the issues that must be considered in making such decisions.
We present a technique that uses coverage measures in reliability estimation for fault tolerant programs, particularly N-version software. This technique exploits both coverage and time measures collected during testi...
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ISBN:
(纸本)0818681780
We present a technique that uses coverage measures in reliability estimation for fault tolerant programs, particularly N-version software. This technique exploits both coverage and time measures collected during testing phases for the individual program versions and the N-version software system for reliability prediction. The application of this technique on the single-version software was presented in our previous research. In this paper we Extend this technique and apply it on the N-version programs. The results obtained from the experiment conducted on an industrial project demonstrate that our technique significantly reduces the hazard of reliability overestimation for both single-version and multi-version fault tolerant softwaresystems.
This paper describes the requirements and attributes of the Experimental distributed Processing Facility (EDPF). The EDPF will provide a flexible and dynamically reconfigurable distributed environment that will be use...
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ISBN:
(纸本)0818605014
This paper describes the requirements and attributes of the Experimental distributed Processing Facility (EDPF). The EDPF will provide a flexible and dynamically reconfigurable distributed environment that will be used to address generic distributed processing issues as applied to the needs of the future battlefield. Survivability and reliability are the key issues under investigation. The EDPF will integrate the requirements for standard hardware and software. This facility will focus on loosely coupled nodes over newly developed (e. g. , fiber optics) or transitional communications media. All designs and implementations performed on the EDPF will use the Ada programming language. The EDPF will be used in a laboratory environment where system performance analysis can be performed on various distributed processing models. The EDPF will be capable of being deployed in a field environment for future tactical demonstrations.
One of the key concepts available in many object-based programming languages is that of type inheritence, which permits new object types to be refined out of existing object types. It is shown how this concept can be ...
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ISBN:
(纸本)0818607378
One of the key concepts available in many object-based programming languages is that of type inheritence, which permits new object types to be refined out of existing object types. It is shown how this concept can be utilized to introduce recoverability into a system. A multilevel object-based recovery model is used that allows recoverable objects to be constructed out of recoverable and unrecoverable objects. Simple examples are used to illustrate the ideas and to demonstrate the suitability of the approach. These results are relevant to the development of distributedsystems.supportng atomic actions and recoverable objects.
A discussion is presented of access control in a heterogeneous distributeddatabase management system (DDBMS) built by integrating existing DBMSs at the nodes of a network. Often complicating the implementation of acc...
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ISBN:
(纸本)0818607378
A discussion is presented of access control in a heterogeneous distributeddatabase management system (DDBMS) built by integrating existing DBMSs at the nodes of a network. Often complicating the implementation of access control is the requirement in a heterogeneous DDBMS for site autonomy;the local DBMS at each site maintains control of the data stored at that site. Each local DBMS decides for itself if a user may access the data it manages. The problems raised by this issue are examined, and a solution is proposed.
In a large, parallel, real-time system, high, continuous levels of performance and reliability can be achieved only if the system's dynamics are taken into account. One solution is offered by construction of an ad...
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ISBN:
(纸本)0818607378
In a large, parallel, real-time system, high, continuous levels of performance and reliability can be achieved only if the system's dynamics are taken into account. One solution is offered by construction of an adaptive system that can change its structure, both offline and during operation, to maintain reliable performance in response to arriving data on failures, request latencies, utilization, etc. Construction of such a system requires: (1) an explicit representation of its components, their interactions, and the allowable adaptations of both;and (2) algorithms and mechanisms that plan and carry out adaptations. A representation consisting of entities and relationships is presented. This representation describes the requirements of functionality, performance, and reliability imposed on the system, and the state information relevant for adaptations of a sample real-time application executing on a shared-memory multiprocessor. A distributed, dynamic adaptation algorithm for the assignment/scheduling of software components on processors is presented in order to demonstrate the feasibility of dynamic software adaptations.
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