容错软件生成系统─FTSGS

在软件开发过程中采用避错设计、查错设计和容错设计技术是提高软件可靠性的基本途径。这里介绍了一种采用多个软件模块自动生成技术进行可靠性设计的系统。其主要功能是定义软件开发过程,指导、控制以使软件开发自动化。其目标是提供一个基于面向对象方法学的、高可靠性的软件开发平台。     

AADL软件容错系统建模与评估

提出了一种解决软件客错系统的可靠性评估方法,该方法基于AADL,对嵌入式软件系统进行建模,详细分析了软件系统内部各种构件的各种错误状态和其之间的错误传播,构建了AADL软件系统错误模型,并根据基本的转换规则将其转化为广义随机Petri网模型,使用现有工具对其进行了计算,从而实现了软件客错系统的可靠性评估;以航空交通控制(ATC)为应用场景进行实验.根据经验数据适当的假设了部分构件的失效率,收到了较好效果.     

网络应用软件监控系统的容错机制

对网络中的应用程序实施管理和监控已成为网管系统发展之必需。在对SNMP中MIB信息和协议数据单元扩充的基础上，设计并实现了面向应用软件的网络监控系统。文章重点阐述了容错机制的设计与实现。     

RTEMS嵌入式系统中的软件容错设计

为了提高嵌入式系统在恶劣环境下的可靠性,除了在硬件上采用诸如双机冷备份之类的容错方案外,在实时操作系统级提供软件容错处理功能既可以减小硬件资源开销,又可以在不影响系统工作效率的前提下明显提高系统的容错纠错能力.本文针对RTEMS实时操作系统缺乏软件容错支持功能的不足,在操作系统级设计了一套两级软件容错的方案,提高了嵌入式系统的可靠性.     

软件双冗余容错系统的容错能力和性能分析

双冗余是比较常用的冗余容错设计方法.软件双冗余容错系统通过冗余执行完成相同功能的两个软件副本,并检查它们的结果,根据两者结果是否一致来判断是否出现了错误.建立了软件双冗余容错系统的运行时模型,并引入了软件双冗余容错系统的容错能力的概念.根据该模型分析了单个软件副本的容错能力对软件双冗余容错系统的容错能力和性能的影响.分析结果显示,提高单个软件副本的容错能力不仅能够提高软件双冗余容错系统的容错能力,还能够提高系统的性能.但在极端情况下,双冗余容错系统的容错能力也可能会小于单个软件副本的容错能力.     

CAI软件自动生成系统

本课题是课件自动生成系统，用户通过交互式的描述产生中介语言，然后系统自动地将中介语言翻译成源代码，从而生成课件。     

FADEC系统软件非相似技术容错结构设计

随着航空发动机控制技术的发展,全权限数字电子控制（FADEC）系统的可靠性设计变得越来越重要;面对目前国内关于航空发动机高可靠性FADEC软件系统研究工作相对滞后的现状,针对硬件层基于相似余度技术,软件层基于非相似余度技术构成高可靠性FADEC系统的相关软件技术进行了研究;在提出FADEC系统软件非相似技术容错结构设计方案后,论文就此容错结构设计方案中的主要技术问题进行了研究。     

Fault tolerant processes

A process is said to be fault tolerant if the system provides proper service despite the failure of the process. For supporting fault-tolerant processes, measures have to be provided to recover messages lost due to the failure. One approach for recovering messages is to use message-logging techniques. In this paper, we present a model for message-logging based schemes to support fault-tolerant processes and develop conditions for proper message recovery in asynchronous systems. We show that requiring messages to be recovered in the same order as they were received before failure is a stricter requirement than necessary. We then propose a distributed scheme to support fault-tolerant processes that can also handle multiple process failures.Pankaj Jalote received the Bachelor of Technology degree in electrical engineering from the Indian Institute of Technology, Kanpur, India, in 1980, the M.S. degree in computer science from Pennsylvania State University, University Park, in 1982, and the Ph.D. degree in computer science from the University of Illinois at Urbana-Champaign in 1985. From August 1985 to July 1989 he was an Assistant Professor in the Department of Computer Science at the University of Maryland, College Park. Currently he is an Assistant Professor in the Department of Computer Science and Engineering at IIT Kanpur, India. His research interests include fault-tolerant computing, distributed systems, and software engineering.This work was supported in parts by the NSF grant DCI-8610337     

Fault tolerant mechanism design

We introduce the notion of fault tolerant mechanism design, which extends the standard game theoretic framework of mechanism design to allow for uncertainty about execution. Specifically, we define the problem of task allocation in which the private information of the agents is not only their costs of attempting the tasks but also their probabilities of failure. For several different instances of this setting we present both, positive results in the form of mechanisms that are incentive compatible, individually rational, and efficient, and negative results in the form of impossibility theorems.     

Fault tolerant Web Services

Zwass suggested that middleware and message service is one of the five fundamental technologies used to realize Electronic Commerce (EC). The Simple Object Access Protocol (SOAP) is recognized as a more promising middleware for EC applications among other leading candidates such as CORBA. Many recent polls reveal however that security and reliability issues are major concerns that discourage people from engaging in EC transactions. We notice that the fault-tolerance issue is somewhat neglected in the current standard, i.e., SOAP 1.2. We therefore propose a fault tolerant Web Services called fault tolerant SOAP or FT-SOAP through which Web Services can be built with higher resilience to failure. FT-SOAP is based on our previous experience with an object fault tolerant service (OFS) and OMG’s fault tolerant CORBA (FT-CORBA). There are many architectural differences between SOAP and CORBA. One of the major contributions of this work is to discuss the impact of these architectural differences on FT-SOAP design. Our experience shows that Web Services built on a SOAP framework enjoy higher flexibility compared to those built on CORBA. We also point out the limitations of the current feature sets of SOAP 1.2, e.g. the application of the intermediary. In addition, we examine two implementation approaches; namely, one based on the SOAP 1.2’s intermediary, and the other on Axis handler. We conclude that the intermediary approach is infeasible due to the backward compatibility issue. We believe our experience is valuable not only to the fault-tolerance community, but also to other communities as well, in particular, to those who are familiar with the CORBA platform.     

A case study in fault tolerant software

The addition of redundancy to data structures can be used to improve the ability of a software system to detect and correct errors, and to continue to operate according to its specifications. A case study is presented which indicates how such redundancy can be deployed and exploited at reasonable cost to improve software fault tolerance. Experimental results are reported for the small data base system considered.     

Fault tolerant algorithms for heat transfer problems

With the emergence of new massively parallel systems in the high performance computing area allowing scientific simulations to run on thousands of processors, the mean time between failures of large machines is decreasing from several weeks to a few minutes. The ability of hardware and software components to handle these singular events called process failures is therefore getting increasingly important. In order for a scientific code to continue despite a process failure, the application must be able to retrieve the lost data items. The recovery procedure after failures might be fairly straightforward for elliptic and linear hyperbolic problems. However, the reversibility in time for parabolic problems appears to be the most challenging part because it is an ill-posed problem. This paper focuses on new fault-tolerant numerical schemes for the time integration of parabolic problems. The new algorithm allows the application to recover from process failures and to reconstruct numerically the lost data of the failed process(es) avoiding the expensive roll-back operation required in most checkpoint/restart schemes. As a fault tolerant communication library, we use the fault tolerant message passing interface developed by the Innovative Computing Laboratory at the University of Tennessee. Experimental results show promising performances. Indeed, the three-dimensional parabolic benchmark code is able to recover and to keep on running after failures, adding only a very small penalty to the overall time of execution.     

Fault tolerant aggregation in heterogeneous sensor networks

Fault tolerance and scalability are important considerations in the design of sensor network applications. Data aggregation is an essential operation in sensor networks. Multiple techniques have been proposed recently to tackle the issues of scalability and fault tolerance of aggregation in sensor networks. In this article, we analyze the impact of using a few of the more reliable, though expensive, nodes–such as the Intel XScale–called microservers, in addition to the standard motes, on the fault tolerance and scalability of the aggregation algorithms in sensor networks. In particular, we propose a simple model that captures the essence of tree aggregation in such heterogeneous sensor networks. We validate this theoretical model with simulation results. We also study the effective impact on the sustainable probability of failure, and perform cost-benefit analysis. We also show how hybrid aggregation can be utilized instead of tree, to improve the performance of aggregation in heterogeneous sensor networks. We show that our work can be applied for effectively optimizing the use of expensive hardware while designing fault-tolerant, distributed sensor networks.