Optimal distribution of a hierarchy of network management agents

In this paper, we consider several mathematical and algorithmic problems which arise naturally in the optimal deployment of modern network management systems. Specifically, we will consider the problem of minimizing the total communication costs within an architecture consisting of a distributed hierarchy of cooperating intelligent agents. We consider several communication cost models, and describe provable optimal schemes for distributing agents among machines in each of these models.     

Distributed sensor fault diagnosis in a class of interconnected nonlinear uncertain systems

In this paper, a distributed sensor fault detection and isolation (FDI) method is developed for a class of interconnected nonlinear uncertain systems. In the distributed FDI architecture, a FDI component is designed for each subsystem in the interconnected system. For each subsystem, its corresponding local FDI component is designed by utilizing local measurements and certain communicated information from neighboring FDI components associated with subsystems that are directly interconnected to the particular subsystem under consideration. Under certain assumptions, adaptive thresholds for distributed sensor fault detection and isolation in each subsystem are derived, ensuring robustness with respect to interactions among subsystems and system modeling uncertainty. Moreover, the fault detectability condition is rigorously investigated, characterizing the class of sensor faults in each subsystem that is detectable by the proposed distributed FDI method. Additionally, the stability and learning capability of the distributed adaptive fault isolation estimators is established. A simulation example of interconnected inverted pendulums mounted on carts is used to illustrate the effectiveness of the distributed FDI method.     

通用的分布对象服务访问框架的设计与实现

本文分析了分布对象系统的开放特性，以及由此而产生的分布式应用中服务对象的访问与管理问题；介绍了分布对象管理结构OMA和CorbaScript脚本语言。在此基础之上，详述了如何采用CorbaScript，基于OMA结构实现一个通用的分布对象服务访问框架。     

Distributed fault diagnosis in a class of interconnected nonlinear uncertain systems

In this article, a distributed fault detection and isolation (FDI) method is developed for a class of interconnected nonlinear uncertain systems. In the distributed FDI architecture, a FDI component is designed for each subsystem in the interconnected system. For each subsystem, its corresponding local FDI component is designed by utilising local measurements and certain communicated information from neighbouring FDI components associated with subsystems that are directly interconnected to the particular subsystem under consideration. Under certain assumptions, adaptive thresholds for distributed FDI in each subsystem are derived, ensuring robustness with respect to interactions among subsystems and system modelling uncertainty. Moreover, the fault detectability and isolability conditions are rigorously investigated, characterising the class of faults in each subsystem that are detectable and isolable by the proposed distributed FDI method. Additionally, the stability and learning capability of the local adaptive fault isolation estimators designed for each subsystem is established. A simulation example of interconnected inverted pendulums mounted on carts is used to illustrate the effectiveness of the method.     

A unified frame work for discrete event systems

Early fault detection and isolation minimize cost and processing time of industrial systems. The main purpose of this paper is to introduce a novel delta-marking idea to design a generalized interpreted Petri net-based fault detection and isolation scheme (IPN-based diagnoser) for all PN models. This idea overcomes the event detectability problem that restricts the performance of the conventional dignosers to certain types of Petri net model. Furthermore, a unified framework for a discrete event system that comprises a PN-based model, a PN-based supervisor, and a PN-based diagnoser of a process under consideration, is built in this paper. In addition, this paper addresses some issues for industrial systems modeling and supervision. A rapid thermal process (RTP) is used as an industrial process to test the proposed unified framework after revising its PN-model. This scheme is not only developed for RTPs, but also can be employed for industrial processes with certain modifications depending on the nature of their structures. Simulation results have confirmed the effectiveness of the proposed unified framework.     

基于环型结构的分布式入侵检测系统的设计与实现

分析了目前的分布式入侵检测系统的特点和协作方式,提出了一种基于环型结构分布式入侵检测系统模型和令牌控制机制。论述了环型结构的分布式入侵检测系统的体系结构和功能框架,引入了优先响应和事件可信度的思想,给出了基于环型结构的分布式入侵检测协作算法,解决了目前分布式入侵检测系统中各系统结构复杂、负载不均衡等缺陷。     

Observer-based fault detection and isolation filter design for linear time-invariant systems

In this paper we consider a model-based fault detection and isolation problem for linear time-invariant dynamic systems subject to faults and disturbances. We use a state observer scheme that cancels the system dynamics and defines a residual vector signal that is sensitive only to faults and disturbances. We then design a stable fault detection and isolation filter such that the ?_∞-norm of the transfer matrix function from disturbances to the residual is minimised (for fault detection) subject to the constraint that the transfer matrix function from faults to residual is equal to a pre-assigned diagonal transfer matrix (for isolation of possibly simultaneous occurring faults). Our solution is given in the form of linear matrix inequalities using state-space techniques, as well as a model matching problem using matrix factorisation techniques. A numerical example is given to illustrate the efficiency of the fault detection and isolation filter.     

Modeling and Tracking of Transaction Flow Dynamics for Fault Detection in Complex Systems

With the prevalence of Internet services and the increase of their complexity, there is a growing need to improve their operational reliability and availability. While a large amount of monitoring data can be collected from systems for fault analysis, it is hard to correlate this data effectively across distributed systems and observation time. In this paper, we analyze the mass characteristics of user requests and propose a novel approach to model and track transaction flow dynamics for fault detection in complex information systems. We measure the flow intensity at multiple checkpoints inside the system and apply system identification methods to model transaction flow dynamics between these measurements. With the learned analytical models, a model-based fault detection and isolation method is applied to track the flow dynamics in real time for fault detection. We also propose an algorithm to automatically search and validate the dynamic relationship between randomly selected monitoring points. Our algorithm enables systems to have self-cognition capability for system management. Our approach is tested in a real system with a list of injected faults. Experimental results demonstrate the effectiveness of our approach and algorithms     

社区管理系统技术架构

为了构建松耦合、易扩展的分布式社区管理系统,提出了基于SOA的社区管理系统分层架构.为实现该分层架构,将轻量级Java EE框架S2SH应用于SOA技术架构中,构建了基于S2SH的SOA架构,给出了该架构的工作流程,并将该架构应用到社区管理系统的设计中.     

基于环型结构的分布式入侵检测系统的设计与实现*

分析了目前的分布式入侵检测系统的特点和协作方式,提出了一种基于环型结构分布式入侵检测系统模型和令牌控制机制。论述了环型结构的分布式入侵检测系统的体系结构和功能框架,引入了优先响应和事件可信度的思想,给出了基于环型结构的分布式入侵检测协作算法,解决了目前分布式入侵检测系统中各系统结构复杂、负载不均衡等缺陷。     

Analysis of mobile agents in network fault management

Network domains have become more and more advanced in terms of their size, complexity and the level of heterogeneity. Comprehensive fault management is the most significant challenge in network management. Fault management can help increase the availability of the network by quickly identifying the faults and then, proactively, start the recovery process. Current centralized configured network management systems suffer from problems such as insufficient scalability, availability and flexibility as networks become more distributed. Mobile agents (MAs), with integral intelligence, can present a reasonable new technology that will help to achieve distributed management, several researchers have embraced these approaches. In this paper, we introduce a general analytical model for network management client/server (CS) and MA paradigms. We express how to build up an analytical framework, which can be used to quantitatively assess the performances of the MA and CS paradigms under different scenarios. We present some numerical and experimental results that demonstrate the applicability of our proposed framework, which will be based on a combination of MA and CS schemes called Adaptive Intelligent Mobile Agent.     

Analyzing the effectiveness of fault-management architectures in layered distributed systems

Fault management infrastructure in distributed systems includes manager processes and agents with various kinds of interactions for monitoring and surveillance of the status of the application software and hardware. The system architecture now includes these additional components and interactions, and they affect the system availability. This paper describes an architecture model called MAMA (Model for Availability Management Architecture) with an architecture definition language MAMA-dl for the combination of the application and management parts, and its analysis. The analysis extends the Fault Tolerant Layered Queueing Model to account for propagation of knowledge of the system state in the management sub-architecture. The model is demonstrated on a problem of placement of manager tasks in a system.     

Fault-Management in P2P-MPI

We present in this paper a study on fault management in a grid middleware. The middleware is our home-grown software called P2P-MPI. This framework is MPJ compliant, allows users to execute message passing parallel programs, and its objective is to support environments using commodity hardware. Hence, running programs is failure prone and a particular attention must be paid to fault management. The fault management covers two issues: fault-tolerance and fault detection. Fault-tolerance deals with the program execution: P2P-MPI provides a transparent fault tolerance facility based on replication of computations. Fault detection concerns the monitoring of the program execution by the system. The monitoring is done through a distributed set of modules called failure detectors. The contribution of this paper is twofold. The first contribution is the evaluation of the failure probability of an application depending on the replication degree. The failure probability depends on the execution length, and we propose a model to evaluate the duration of a replicated parallel program. Then, we give an expression of the replication degree required to keep the failure probability of an execution under a given threshold. The second contribution is a study of the advantages and drawbacks of several fault detection systems found in the literature. The criteria of our evaluation are the reliability of the failure detection service and the failure detection speed. We retain the binary round-robin protocol for its failure detection speed, and we propose a variant of this protocol which is more reliable than the application execution in any case. Experiments involving of up to 256 processes, carried out on Grid’5000, show that the real detection times closely match the predictions.     

分布式信任管理体系结构研究与实现

近年来研究者着重于信任管理模型的研究,如何把信任管理模型集成到分布式应用系统中,需要深入探讨。在分析现有的信任管理体系结构基础上,结合面向服务的体系结构(SOA)和信任管理模型的固有特性,提出了分布式应用环境中的信任管理模型体系结构。同时,提出了基于相对熵的推荐信息过滤方法。在多代理仿真平台RePast上,实现了提出的体系结构和推荐信息过滤方法,并与其他推荐信息过滤方法进行了比较。     

面向分布式流体系结构的多副本积极容错技术

随着互联网环境下计算系统规模的不断扩大,分布式流体系结构的可靠性问题面临着严峻的挑战。以多模冗余容错技术为基础,针对软错误提出了一种面向分布式流体系结构的多副本积极容错技术TREFT,利用三个程序副本进行高效的检错与纠错。在分布式流体系结构原型系统上的实验结果表明,该技术能有效提高系统的可靠性,具有较低的容错成本,平均增加10.77%的容错开销。     

Distributed fault detection and isolation scheme for abrupt and incipient faults in a class of nonlinear systems

This note developed a distributed fault detection and isolation scheme for a class of large-scale systems in discrete-time framework. The unstructured modeling uncertainty and abrupt and incipient faults are considered in this scheme. By using overlapping decompositions, the large-scale system is decomposed into a set of subsystems which are monitored by a network of local fault detectors (LFDs) and local fault isolation estimators (LFIEs). Specially, the LFIEs, corresponding the faults affecting the common components among different subsystems, may reach a cooperative (or consensus) isolation decision, based on the fact that they can exchange some knowledge about the local information of system by suitable communication links. As a result, for these LFIEs, the capability of isolating faults may be improved. Moreover, the derivation of rigorous analytical results for the detectability and isolability properties of the proposed scheme is given. Simulation results are provided to show the effectiveness of the presented scheme.     

分布式入侵检测框架

现有的网络安全系统往往功能比较单一,难以完成网络系统的整体防护要求,难以保证可靠地提供所需的业务,难以保证业务信息的安全可靠.因此,提出了一个分布式入侵检测框架DIDF,将防火墙、入侵检测和安全事件响应结合起来,实现了一个以管理为核心,具有防范、检测和响应能力的综合安全体系.     

Splitting GSM schemas: A framework for outsourcing of declarative artifact systems

Case Management is emerging as an important paradigm for Business Process Management. The Guard-Stage-Milestone (GSM) model is a recent case management approach that substantially influences OMG׳s emerging Case Management Modeling Notation standard. We study the problem of outsourcing part of a GSM schema to another party, and develop a formal framework that supports splitting and outsourcing of GSM schemas. One element of the framework focuses on restructuring the GSM schema to facilitate outsourcing while preserving the semantics of the original schema; the second focuses on locking protocols that define how the distributed parties should operate. Additionally, the framework allows parties to keep local parts of their GSM subschema private without affecting the outcomes of the global execution. The rules restructuring developed here enables a crisp separation of concerns, which allows reuse of existing GSM (and thus Case Management) engines for executing the subschemas. Both elements of the framework are formally proven correct.     

Detection,isolation and handling of actuator faults in distributed model predictive control systems

In this work, we focus on monitoring and reconfiguration of distributed model predictive control systems applied to general nonlinear processes in the presence of control actuator faults. Specifically, we consider nonlinear process systems controlled with a distributed control scheme in which two Lyapunov-based model predictive controllers manipulate two different sets of control inputs and coordinate their actions to achieve the desired closed-loop stability and performance specifications. To deal with control actuator faults which may reduce the ability of the distributed control system to stabilize the process, a model-based fault detection and isolation and fault-tolerant control system which detects and isolates actuator faults and determines how to reconfigure the distributed control system to handle the actuator faults while maintaining closed-loop stability is designed. A detailed mathematical analysis is carried out to determine precise conditions for the stabilizability of the fault detection and isolation and fault-tolerant control system. A chemical process example, consisting of two continuous stirred tank reactors and a flash tank separator with a recycle stream and involving stabilization of an unstable steady-state, is used to demonstrate the approach.