Methods and opportunities for rejuvenation in aging distributed software systems

In this paper we describe several methods for detecting the need for software rejuvenation in mission critical systems that are subjected to worm infection, and introduce new software rejuvenation algorithms. We evaluate these algorithms’ effectiveness using both simulation studies and analytic modeling, by assessing the probability of mission success. The system under study emulates a Mobile Ad-Hoc Network (MANET) of processing nodes. Our analysis determined that some of our rejuvenation algorithms are quite effective in maintaining a high probability of mission success while the system is under explicit attack by a worm infection.     

双抗衰系统协同工作模型

"软件衰退"现象在软件系统中普遍存在,利用"软件抗衰"技术可以在软件出现衰退时提高系统性能,针对基于MIDAS三层架构系统结构的特殊性,提出一种双抗衰系统工作模型分布在中间层应用服务器和数据库服务器端协同工作,可以应对三层架构系统部分或整体出现衰退,采用应用级或系统级恢复,提高系统整体的性能,同时也保障了数据的完整性、安全性.     

基于软件再生理论的分布式自适应性能监控系统设计

软件再生理论认为,计算系统运行过程中的系统资源损耗是影响系统性能的主要因素。设计一个性能监控系统,通过采集和分析资源使用情况,适时释放被损耗的资源可以有效保证系统的持续高性能。监控系统采用C/S模式以减轻监控端的负载,保证监控端的轻量级,同时实现对监控端的异步监控;基于自组织映射网络对数据的分析,实现对监控端监控参数的自适应调节;提供多种数学模型对系统性能变化进行分析和预测;设计了简单有效的决策方法支持系统的重启控制;最后通过实验证明自适应采集策略有效减少了数据采集和传输量,保证了监控端的轻量级、低负载,尽可能地降低了监控系统本身对被监控系统的影响。     

卫星地面站系统软件抗衰策略研究

卫星被越来越广泛地应用到军事侦察、资源勘探、气象预报、电视转播、通讯等重要领域,所以卫星地面站系统比普通的软件系统对安全性、可靠性、抗毁性、错误检测和恢复等有更高的要求。卫星系统高度的实时性要求卫星地面站软件系统是不允许失效的。但是软件系统存在软件老化现象,导致软件失效,为了对抗软件老化,采用了一种针对卫星地面站软件系统抗衰的微重启策略,可缩短应用系统的平均恢复时间（MTTR）,提高系统的可靠性,可以为卫星测轨和定轨提供精确的原始卫星观测数据,对改善卫星测轨和定轨的精度具有重要的现实意义和应用价值。     

基于检查点和Rejuvenation的软件运行模型分析

近来的研究表明,长时间运行的通信软件往往存在老化现象。为防止软件老化引起的突发性系统停机,提高系统的可靠性,人们提出了一种预防性的软件容错策略,称为rejuvenation。由于它的过程复杂,总的停机成本仍然是可观的。检查点是一种轻量级的软件容错策略,其成本远小于rejuvenation的成本。该文通过合理结合rejuvenation和检查点技术,实现了降低总的系统停机成本的目的。文中给出了系统的Petri网模型,并结合实例进行了分析。     

Analysis of service availability for time-triggered rejuvenation policies

In this paper we investigate the effect of three time-triggered system rejuvenation policies on service availability using a queuing model. The model is formulated as an extended stochastic Petri net using a variety of distributions for times between state changes. We define a metric for steady-state service availability and derive how it can be estimated from the models in a hybrid approach combining simulation and analytical reasoning. We further analyze time-to-failure of systems with rejuvenation. Experiments show that the optimal rejuvenation interval as well as the achievable service availability improvement depend significantly on system utilization. The experiments also show that service availability can deviate significantly from steady-state system availability. For low utilization all rejuvenation policies perform well. For medium utilization, one policy is significantly inferior to the other two, while for high utilization, no rejuvenation should be performed at all.     

DNA计算在软件抗衰技术中的应用研究

针对软件系统中进程间控制、调用及数据访问的关系,分析了进程间的耦合程度,给出了判定进程间重启相关度方法和系统重启树的构建规则,并结合DNA计算的原理和特性,给出了判定进程间重启相关度DNA计算模型,并初步制定了重启实施策略,为实现智能化细粒度软件抗衰提供支持.     

自恢复容错系统的模型和分析

容错系统不仅会产生硬件故障,而且连续长时间的运行,系统的性能还会逐渐下降或失效,即老化现象。本文综合考虑容错系统中的硬件故障和老化现象,提出了将传统的冗余策略和软件抗衰策略相结合,并给出了该系统的时间颜色Petri网(ti med-CPN)模型,并结合实例进行了分析。     

Fuzzy inference system for software product family process evaluation

When developing multiple products within a common application domain, systematic use of a software product family process can yield increased productivity in cost, quality, effort and schedule. Such a process provides the means for the reuse of software assets which can considerably reduce the development time and the cost of software products. A comprehensive strategy for the evaluating the maturity of a software product family process is needed due to growing popularity of this concept in the software industry. In this paper, we propose a five-level maturity scale for software product family process. We also present a fuzzy inference system for evaluating maturity of software product family process using the proposed maturity scale. This research is aimed at establishing a comprehensive and unified strategy for process evaluation of a software product family. Such a process evaluation strategy will enable an organization to discover and monitor the strengths and weaknesses of the various activities performed during development of multiple products within a common application domain.     

Framework for evaluation and selection of the software packages: A hybrid knowledge based system approach

Evaluation and selection of the software packages is complicated and time consuming decision making process. Selection of inappropriate software package can turn out to be costly and adversely affects business processes and functioning of the organization. In this paper we describe (i) generic methodology for software selection, (ii) software evaluation criteria, and (iii) hybrid knowledge based system (HKBS) approach to assist decision makers in evaluation and selection of the software packages. The proposed HKBS approach employs an integrated rule based and case based reasoning techniques. Rule based reasoning is used to capture user needs of the software package and formulate a problem case. Case based reasoning is used to retrieve and compare candidate software packages with the user needs of the package. This paper also evaluates and compares HKBS approach with the widely used existing software evaluation techniques such as analytic hierarchy process (AHP) and weighted scoring method (WSM).     

The evaluation of software systems' structure using quantitative software metrics

The design and analysis of the structure of software systems has typically been based on purely qualitative grounds. In this paper we report on our positive experience with a set of quantitative measures of software structure. These metrics, based on the number of possible paths of information flow through a given component, were used to evaluate the design and implementation of a software system (the UNIX operating system kernel) which exhibits the interconnectivity of components typical of large-scale software systems. Several examples are presented which show the power of this technique in locating a variety of both design and implementation defects. Suggested repairs, which agree with the commonly accepted principles of structured design and programming, are presented. The effect of these alterations on the structure of the system and the quantitative measurements of that structure lead to a convincing validation of the utility of information flow metrics.     

Survey of reliability and availability prediction methods from the viewpoint of software architecture

Many future software systems will be distributed across a network, extensively providing different kinds of services for their users. These systems must be highly reliable and provide services when required. Reliability and availability must be engineered into software from the onset of its development, and potential problems must be detected in the early stages, when it is easier and less expensive to implement modifications. The software architecture design phase is the first stage of software development in which it is possible to evaluate how well the quality requirements are being met. For this reason, a method is needed for analyzing software architecture with respect to reliability and availability. In this paper, we define a framework for comparing reliability and availability analysis methods from the viewpoint of software architecture. Our contribution is the comparison of the existing analysis methods and techniques that can be used for reliability and availability prediction at the architectural level. The objective is to discover which methods are suitable for the reliability and availability prediction of today’s complex systems, what are the shortcomings of the methods, and which research activities need to be conducted in order to overcome these identified shortcomings. The comparison reveals that none of the existing methods entirely fulfill the requirements that are defined in the framework. The comparison framework also defines the characteristics required of new reliability and availability analysis methods. Additionally, the framework is a valuable tool for selecting the best suitable method for architecture analysis. Furthermore, the framework can be extended and used for other evaluation methods as well.     

Availability Analysis of Application Servers Using Software Rejuvenation and Virtualization

Demands on software reliability and availability have increased tremendously due to the nature of present day applications. We focus on the aspect of software for the high availability of application servers since the unavailability of servers more often originates from software faults rather than hardware faults. The software rejuvenation technique has been widely used to avoid the occurrence of unplanned failures, mainly due to the phenomena of software aging or caused by transient failures. In this paper, first we present a new way of using the virtual machine based software rejuvenation named VMSR to offer high availability for application server systems. Second we model a single physical server which is used to host multiple virtual machines (VMs) with the VMSR framework using stochastic modeling and evaluate it through both numerical analysis and SHARPE (Symbolic Hierarchical Automated Reliability and Performance Evaluator) tool simulation. This VMSR model is very general and can capture application server characteristics, failure behavior, and performability measures. Our results demonstrate that VMSR approach is a practical way to ensure uninterrupted availability and to optimize performance for aging applications. This research was supported by the Korea Research Foundation Grant funded by the Korean Government (MOEHRD) under Grant No. KRF2007-210-D00006.     

An experimental evaluation of capture-recapture in software inspections

The use of capture-recapture to estimate the residual faults in a software artifact has evolved as a promising method. However, the assumptions needed to make the estimates are not completely fulfilled in software development, leading to an underestimation of the residual fault content. Therefore, a method employing a filtering technique with an experience factor to improve the estimate of the residual faults is proposed in this paper. An experimental study of the capture-recapture method with this correction method has been conducted. It is concluded that the correction method improves the capture-recapture estimate of the number of residual defects in the inspected document.     

炼油企业蒸汽动力系统优化运营软件设计与开发

简要介绍了开发的软件的核心功能,采用面向对象技术,使用统一建模语言对炼油企业蒸汽动力系统优化运营软件系统进行了分析和设计。用例图描述了软件系统的功能需求、序列图初步分析了系统核心功能的实现过程。在需求分析的基础上进行了系统的数据模型设计,主要包括公用数据模型,装置数据模型和物流数据模型。最后采用C#语言开发了软件系统SPSOpti,并给出了应用实例,为企业节省了相当可观的经济效益。     

地检质谱仪上位机软件系统的设计与实现

设计并实现了质谱仪上位机软件系统,可完成对质谱仪的状态信息接收、各项重要参数的监测与实时设定。软件能够在试验时通过串口发送控制命令来实时控制质谱仪的状态,也可通过串口采集质谱仪的相关参数及实时数据,并在数据采集后提供数据处理、分析和特定格式谱图保存功能。     

软件网络升级嵌入式系统的研究

介绍软件网络升级嵌入式系统。硬件主要采用C8051F020单片机及RTL8019AS网络芯片设计,软件采用Cx51单片机高级语言编程,网络协议选择通用的TCP/IP协议。介绍了此嵌入式系统硬件和软件的设计方法,并详述了嵌入式系统实现远程软件升级的原理。     

一种提高集群系统可用性的方法及其应用

文中将一种预防性的容错方法——软件再生引入集群系统中，分析两种软件老化模型，提出了对应的软件再生策略，最后在Web集群服务器中实现。从实验结果可以看出软件再生技术较好地提高了集群系统的软件容错性能和系统可用性。     

Empirical evaluation of a decision support model for adopting software product line engineering

ContextThe software product line engineering (SPLE) community has provided several different approaches for assessing the feasibility of SPLE adoption and selecting transition strategies. These approaches usually include many rules and guidelines which are very often implicit or scattered over different publications. Hence, for the practitioners it is not always easy to select and use these rules to support the decision making process. Even in case the rules are known, the lack of automated support for storing and executing the rules seriously impedes the decision making process.ObjectiveWe aim to evaluate the impact of a decision support system (DSS) on decision-making in SPLE adoption. In alignment with this goal, we provide a decision support model (DSM) and the corresponding DSS.MethodFirst, we apply a systematic literature review (SLR) on the existing primary studies that discuss and present approaches for analyzing the feasibility of SPLE adoption and transition strategies. Second, based on the data extraction and synthesis activities of the SLR, the required questions and rules are derived and implemented in the DSS. Third, for validation of the approach we conduct multiple case studies.ResultsIn the course of the SLR, 31 primary studies were identified from which we could construct 25 aspects, 39 questions and 312 rules. We have developed the DSS tool Transit-PL that embodies these elements.ConclusionsThe multiple case study validation showed that the adoption of the developed DSS tool is justified to support the decision making process in SPLE adoption.     

计算机测控系统的故障分析以及抗干扰技术研究

针对计算机测控系统实际运行中故障问题,从软硬件可靠性与系统运行环境的角度分析了故障产生的原因,提出来了相应的抗干扰措施.抗干扰技术与系统可靠性是计算机测控系统开发不可忽视的两个重要内容,常用的抗干扰技术主要有硬件抗干扰和软件抗干扰.软件抗干扰措施是硬件抗干扰措施的一个补充和延伸,运用得法可以显著提高计算机测控系统的可靠...