一种面向图的分布式软件动态配置和容错方法

提出一种新的方法，通过动态配置对基于组件的分布式软件的容错提供支持。此方法采用面向图的GOP编程模型，将整个分布式软件的体系结构用一张逻辑图来描述，系统的动态配置可以通过执行图上预定义的一组操作来完成。检测到故障或异常的时候实施这种动态配置能够支持系统的容错。文中描述了此方法的基本模型、系统结构和基于CORBA的原型实现。     

分布式软件动态配置环境可视化的研究与实现

研究了分布式软件开发配置模型OrbGOP的树形配置结构及可视化实现。基于图形编程技术,此模型通过建立构件到结点、构件互操作关系到结点连线的映射,将整个分布式软件的体系结构描述为一张树形逻辑图,用户通过执行图上预定义的一组操作就可以实现系统的动态配置,这使得动态配置工作简单有效,极大地减轻了软件维护的负担。     

基于事务的SMC动态演化容错机制

为提高“软件人”构件动态演化失败时的容错能力,提出一种基于事务的“软件人”构件动态演化容错机制。通过在“软件人”构件的管理外壳中扩展事务元接口,使“软件人”构件具备事务操作能力,定义演化失败时的事务处理流程;为支持“软件人”构件的分布式事务处理,提出一个轻量级的、支持“软件人”构件分布式动态配置的事务处理实现框架,为“软件人”构件动态演化失败时容错恢复的实施提供有效保障。     

基于模型的云应用动态配置框架

云应用是云计算技术在应用层的一种重要体现形式,通常由分布式异构组件构成,且组件相互依赖,配置参数众多。组件依赖导致配置参数间存在关联,使应用运行时弹性扩展难以确定组件实例的配置顺序并保证关联参数的一致性,导致应用扩展后的系统故障和服务不可用。针对这一问题,提出了一种基于模型的云应用动态自配置方法,实现运行时组件实例配置顺序的自动协调,保障配置参数的一致性,提高应用运行时弹性扩展的可靠性。首先提出一种部署配置模型STM(Service-based Topology Model),该模型采用声明式的方法刻画云应用的部署拓扑结构,并基于服务的方式描述组件信息,实现组件间关联关系的分离,涵盖运维部署、扩展、运行时服务状态的监测。 然后 基于该模型,提出了一个云应用动态自配置协议,其基于服务注册发现机制实现组件间强依赖关系的解耦,保证动态调整应用实例时组件配置变化的一致性,实现组件部署配置的并行化。基于上述方法实现了一个原型系统,通过对分布式应用BookStore-TPCW的部署配置和运行时弹性扩展来验证方法的有效性。     

分布式软件体系结构中组件依赖的描述

分布式软件的动态配置及软件体系结构中的一个重要问题是对组件依赖的理解和描述。该文采用的方法提供了精确描述组件交互的基础,展示了分布式系统组件间的拓扑关系,进而描述了软件体系结构。该方法还对组件测试提供了有力支持,它的突出优点是用一种方法来描述体系结构并支持软件测试。     

基于软件故障注入模型的容错软件可靠性评测

为了灵活准确地用故障注入技术对容错软件进行可靠性评测,通过对故障注入及容错软件可靠性评测的分析,采用分布式结构,提出了一个动态生成一静态存储一动态触发的故障注入模型,它将故障生成和故障触发分开在不同的机子上实现,从而在保证评测准确性的前提下,解决了故障需求复杂、故障生成困难及目标系统额外负载过大等问题,实现了一个较为理想的故障注入模型;最后,通过在航天某型号容错软件上的试验,证明了该模型的可行性。     

软件动态配置模型中的构件依赖描述

构件间的依赖关系是当前基于构件的分布式软件的研究热点之一.提出一种基于XML的描述构件间依赖的方法,并将该方法应用于一个动态配置分布式软件的模型中,成功地实现了构件的动态配置和部署,证明了该方法的可行性.     

一种支持动态管理的sea服务模型研究

为解决SCA和OSGi的结合在分布式环境下不能很好支持运行时组件模型动态管理的问题,在分析二者传 统结合方式的基础上,建立了一种基于OSGi的SC八月民务模型—DOSGi_ SCAo DOSGi_ SCA以分布式OSGi为基 础,构建了服务注册中心来管理本地服务和远程服务,实现了在分布式环境下支持运行时组件模型的动态管理。应用 实例表明,该模型实现了SCA和()SGi的优势互补,充分发挥了各自的优点,弥补了各自的不足。     

支持动态配置和抽象编程的软件体系结构描述

随着软件规模的不断增长和对软件安全性要求的提高,软件体系结构、动态配置和较高层次上的程序设计成为软件工程中的研究热点。目前在软件开发过程中用于这三者的技术是不同的,因此软件开发过程中各个阶段的表述方式不统一。该文提出一种面向图形的编程方法来解决该问题,该方法以一种统一的方式实现了基于组件的分布式系统的软件体系结构描述、动态配置和抽象编程。另外还给出一个简单的例子来说明该方法如何支持上述三个阶段中的对软件的描述。     

Contingencies-based reconfiguration of distributed factory automation

In this paper, we describe our experience using a Java-based platform to implement an emerging real-time distributed control model (IEC 61499). We provide a simple example of a control application that is distributed across two devices (Dallas Semiconductor TINI boards) and also investigate how this distributed implementation can be exploited to enhance the system's fault tolerance using a contingencies-based approach to reconfiguration.     

面向分布式图计算作业的容错技术研究综述

随着图数据规模的日益庞大和图计算作业的日益复杂,图计算的分布化成为必然趋势.然而图计算作业在运行过程中面临着分布式图计算系统内外各种来源的非确定性所带来的严峻的可靠性问题.本文首先分析了分布式图计算框架中不确定性因素和不同类型图计算作业的鲁棒性,并提出了基于成本、效率和质量三个维度的面向分布式图计算作业的容错技术评估框架,然后分别对分布式图计算的四种容错机制——基于检查点的容错、基于日志的容错、基于复制的容错、基于算法补偿的容错等机制结合国内外相关工作做了深入地分析、评估和比较.最后对未来的研究方向做了展望.     

Low complexity reconfiguration for real-time data-intensive service-oriented applications

Next generation distributed real-time systems will be complex high-performance environments containing applications with a flexible structure, integrating a large number of nodes of heterogeneous nature characterized by multiple and decoupled software units scattered all over the distributed environment; they are expected to offer data-intensive capabilities through merging the processing power of large numbers of nodes. These systems will have increased dynamic behavior by suffering frequent reconfigurations or state transitions resulting, among others, from the changing nature of the processed data. Handling the dynamics of these systems in real-time is a complex problem that requires to impose some bounds to the structure of the system to really achieve timely response not only during normal operation but also in the event of reconfigurations. In this paper, we present an approach to achieve real-time reconfiguration in distributed real-time service-based systems modeled as graphs. A reconfiguration requires to search for a new schedulable/valid solution or state from a complete system graph that contains all tentative solutions; each of these solutions will have undergo a schedulability analysis to determine if it is a valid solution; if the system graph is too complex, the overall time required for the schedulability check can be exponential with respect to the size of services and service implementations; this may lead to an unbounded reconfiguration time. In this paper, we present an approach to reduce the complexity of the system graphs so that a summarizing one that contains valid solutions is analyzed and not the complete system graph. We have implemented this mechanism inside the iLAND service reconfiguration and composition components to validate the proposed concepts and ideas; the reduction of the space of solutions with the presented approach is very high, which dramatically decreases the computation time of the reconfiguration process.     

Architecting and implementing distributed Web applications using the graph‐oriented approach

This paper presents a graph‐oriented framework, called WebGOP, for architecture modeling and programming of Web‐based distributed applications. WebGOP is based on the graph‐oriented programming (GOP) model, under which the components of a distributed program are configured as a logical graph and implemented using a set of operations defined over the graph. WebGOP reshapes GOP with a reflective object‐oriented design, which provides powerful architectural support in the World Wide Web environment. In WebGOP, the architecture graph is reified as an explicit object which itself is distributed over the network, providing a graph‐oriented context for the execution of distributed applications. The programmer can specialize the type of graph to represent a particular architecture style tailored for an application. WebGOP also has built‐in support for flexible and dynamic architectures, including both planned and unplanned dynamic reconfiguration of distributed applications. We describe the WebGOP framework, a prototypical implementation of the framework on top of SOAP, and a performance evaluation of the prototype. The prototype demonstrated the feasibility of our approach. Results of the performance evaluation showed that the overhead introduced by WebGOP over SOAP is reasonable and acceptable. Copyright © 2003 John Wiley & Sons, Ltd.     

Supporting Cost-Effective Fault Tolerance in Distributed Message-Passing Applications with File Operations

In this paper we present an approach to reliable distributed computing, which incorporates fault tolerance into applications at low cost, in terms of both run-time performance and programming effort required to construct reliable application software. In our model fault tolerance is based on distributed consistent checkpointing and rollback-recovery integrated with a user-level reliable transmission protocol. By employing novel techniques 8and algorithms, our approach is distinguished from other consistent checkpointing schemes by the following features: first, minimum communication overhead for constructing a consistent distributed checkpoint and catching messages in transit during checkpointing; second, tolerance to message losses due to site failures or unreliable non-FIFO networks; and third, efficient checkpointing and recovery of persistent state, i.e., user files. Based on the model, a software library prototype called Libra has been implemented for supporting fault tolerance in distributed message-passing applications with file operations. The library provides an easy to use programming interface including message-passing and file I/O primitives, which hides the complexity of both fault-tolerant network communications and checkpointing and recovering user files from the application level. Experience with a number of long-running distributed applications shows that Libra can provide fault tolerance in a cost-effective manner.     

Reconfiguring fault-tolerant two-dimensional array architectures

Circuit complexities reduce overall reliability and mean-time-between-failure rates of today's very large processing arrays. Our integrated, three-level hierarchy of reconfiguration methods provides reasonable levels of fault tolerance for such systems. Operating in a completely distributed fashion, the hierarchy does not require that any components be fault free. It significantly improves array reliability by using a combination of transient fault rollback techniques and local and global reconfiguration algorithms     

TMR计算机系统FT-HIT的冗余管理技术

ＦＴ－ＨＩＴ是自行研制的３模冗余（ＴＭＲ）航天容错计算机系统，系统通过硬件冗余和主要由软件实现容错的冗余管理模式实现系统的容错性能。其冗余管理主要包括：故障检测、故障屏蔽、故障隔离、系统重构与故障恢复等功能     

Reconfigurable distributed control using smart peripheral elements

Increasingly, there is a move towards in-built intelligence for sensors and actuators in order to integrate these “smart” peripheral elements as part of a distributed control system. The utilisation of local intelligence to provide local fault detection and fault tolerance allows the incorporation of new variables into the structure of the system. The proposed approach is to integrate this information into the structure of the control law. Thus, the main goal is to integrate a decision-making procedure between peripheral elements and different control strategies. The reconfiguration of the control law, based upon local health measures, is decided by this procedure.