网络中间件在分布式仿真系统中的应用

研究网络中间件问题中,为简化分布式仿真系统的开发,并使系统的健壮性、可扩展性、可用性更好,提出在分布式仿真系统中利用网络中间件的方法.对分布仿真系统的结构和工作流程进行分析,并阐述了网络中间件在系统中实现监测和控制的作用.其次,根据分布式仿真系统的工作原理和设计需求,阐述网络中间件在分布式仿真系统中的结构、模块设计和功能实现,并详细地论述了地址管理、指令执行、反馈消息及分析3个模块的工作机制.最后进行试验证明在网络中间件网络系统发展中的作用,为网络中间件开发提供有效参考.     

基于Java的分布式数据库中间件的研究

通过对分布式数据库系统中间件结构的研究,提出了一个基于Java 分布式数据库中间件的设计方法.本方法解决了分布式数据库开发中的复杂性问题.与以前的方法相比较,用该方法开发出来的分布式数据库维护方便、安全性高,具有高度的适应性、可升级性、可移植性及稳定性.     

Abstractions, Architecture, Mechanisms, and a Middleware for Networked Control

We focus on the mechanism half of the policy-mechanism divide for networked control systems, and address the issue of what are the appropriate abstractions and architecture to facilitate their development and deployment. We propose an abstraction of “virtual collocation” and its realization by the software infrastructure of middleware. Control applications are to be developed as a collection of software components that communicate with each other through the middleware, called Etherware. The middleware handles the complexities of network operation, such as addressing, start-up, configuration and interfaces, by encapsulating application components in “Shells” which mediate component interactions with the rest of the system. The middleware also provides mechanisms to alleviate the effects of uncertain delays and packet losses over wireless channels, component failures, and distributed clocks. This is done through externalization of component state, with primitives to capture and reuse it for component restarts, upgrades, and migration, and through services such as clock synchronization. We further propose an accompanying use of local temporal autonomy for reliability, and describe the implementation as well as some experimental results over a traffic control testbed.      

Networked Control Approach for Distributed Generation Systems

Microgrid has emerged as an answer to growing demand for distributed generation (DG) in power systems. It contains several DG units including microalternator, photovoltaic system and wind generation. It turns out that sustained operation relies on the stability of these constituent systems. In this paper, a microgrid consisting of microalternator and photovoltaic system is modeled as a networked control system of systems (SoS) subjected to packet dropouts and delays. Next, an observerbased controller is designed to stabilize the system in presence of the aforementioned communication constraints and simulation results are provided to support the control design methodology.      

Distributed Tracking Control for Networked Mechanical Systems

This paper investigates the distributed tracking control problems for a group of networked mechanical systems. We describe three scenarios that motivate these problems. Firstly, under the conditions that the desired time‐varying trajectory is available to a portion of the networked mechanical systems and that the available signals from the neighboring mechanical systems include the position and velocity information, a distributed tracking control strategy is proposed. Next, we remove the requirement for the neighboring mechanical system's velocity information and propose a control method so that the coupling signals among the networked mechanical systems can be only position information. In the third scenario, we assume that only positions are measured for each mechanical system. Distributed nonlinear observers are proposed to estimate the local mechanical system's velocity and acceleration. Based on the estimated states, the distributed controllers are designed to achieve the tracking control. Simulation results are provided to show the effectiveness of the proposed control laws.     

StarOSGi:一种OSGi分布式扩展中间件

随着应用范畴从单个结点扩展到普适计算、企业计算等分布式环境,OSGi技术需要提供对远程服务访问的支持。在保留其面向服务、动态性、轻量级等已有优点的前提下,如何为OSGi技术体系提供有效的分布式扩展,是研究者所面临的重要挑战。现有OSGi分布式扩展研究工作存在着对编程模型具有明显侵入性、不支持与非OSGi系统互操作等共性问题。以CORBA中间件技术为基础,以非侵入性、通用性和良好互操作性为目标,提出了基于CORBA的OSGi分布式扩展模型,进而基于CORBA动态调用和Java反射技术设计了一个支持OSGi分布式扩展的中间件StarOSGi。该中间件保持了OSGi原有面向服务的编程模型和轻量级特点,能够透明地将集中式的OSGi应用转变为分布式应用,并且支持OSGi应用与遗留CORBA应用的互操作,具有明显的性能优势。     

分布式安全中间件的研究与实现

中间件是目前开发分布式应用的主流技术，为了满足应用系统的安全需求，如何在中间件平台中提供安全服务成为必须解决的问题。针对网络安全问题的特点，本文在着重考虑系统互操作性、灵活性、可替换性和可成长性的基础上，提出了基于CORBA的开放式安全模型并介绍了StarBus平台的安全中间件的实现方案。     

基于虚拟共享内存中件的分布仿真平台构架方法研究

针对航空、航天分布试验与仿真系统对透明数据交互的需求,提出了应用虚拟共享内存中件构造分布仿真平台的方案,描述了虚拟共享内存中件的组成,功能、层次化结构与实现方式,介绍了应用虚拟共享内存中件构造分布仿真平台的方法。     

分布式实时系统的通信中间件设计与实现

面向汽车电子的分布式实时系统通信中间件,须处理大量周期通信或非周期通信事件,并对时间有着严格的限制,不能有效进行通信时刻控制。为此,参考AUTOSAR规范,从实时性保证与柔性配置管理角度出发,提出一种分布式实时应用的通信中间件。该通信中间件具有可重用性、可裁减性和可配置性,可应用于多种操作系统及硬件平台。通过通信中间件的运行示例分析,验证了该通信中间件的可行性。     

一种面向数字多媒体内容制作业务的分布式计算中间件

随着数字多媒体内容制作业务的增加,大数据量与运算密集的多任务计算越来越普遍.针对大规模用户在数字多媒体内容制作业务中对整合计算资源的迫切需求,本文设计与实现了一个面向数字多媒体内容制作业务的分布式计算中间件.该中间件自动的管理计算资源与计算任务,可以作为一个标准的组件应用于多种多媒体内容制作业务,通过复用该中间件,可以有效地简化分布式环境下实现多媒体内容制作业务的难度.该中间件已经被应用于一个多媒体内容制作平台,并实现了三个重要业务:集群渲染、特效合成、集群转码,有效地证明了该中间件的有效性.     

基于中间件的分布式多媒体系统

分析了分布式多媒体系统中异构产生的各种原因,提出了一种基于中间件技术的解决方法案,并介绍了一种定义和描述多媒体中间件的体系结构－－MSS及其应用。     

Distributed Database Designs and Computation Strategies for Networked Interactive Stimulations

In real-time interactive training and simulation systems, changes of the natural terrain surface and other objects are involved. Distributed geographical database and visual simulators are being built to meet the requirements of low cost and high efficiency. In this paper, four approaches for distributing terrain databases and simulation entities across loosely coupled networks of simulators are examined. An analytical model is developed, which can be used to quantitatively estimate the performance of a distributed system. An experimental simulation study is also conducted to validate the analytical method.     

消息中间件中的分布式监控管理子系统

对消息中间件进行监控管理可以提高其可用性、可靠性和通信效率。文章介绍了消息中间件分布式监控管理的一种设计方法及其体系架构，包括性能监控、消息拥塞和调度管理、历史性能统计分析及正确性测试等多种功能。     

Configurable Middleware for Distributed Real-Time Systems with Aperiodic and Periodic Tasks

Different distributed real-time systems (DRS) must handle aperiodic and periodic events under diverse sets of requirements. While existing middleware such as Real-Time CORBA has shown promise as a platform for distributed systems with time constraints, it lacks flexible configuration mechanisms needed to manage end-to-end timing easily for a wide range of different DRS with both aperiodic and periodic events. The primary contribution of this work is the design, implementation, and performance evaluation of the first configurable component middleware services for admission control and load balancing of aperiodic and periodic event handling in DRS. Empirical results demonstrate the need for, and the effectiveness of, our configurable component middleware approach in supporting different applications with aperiodic and periodic events, and providing a flexible software platform for DRS with end-to-end timing constraints.     

分布式数据服务中间件实现技术研究

数据服务中间件的主要功能包括数据位置的透明性，分布式数据查询，事务处理，异构数据源兼容等，以数据服务中间件的实现技术为核心，详细介绍了基于DCOM／COM＋技术的分布式通用数据服务中间件的功能及开发方法，并以企业的分布式数据管理为例，介绍了本分布式数据服务中间件的应用及特点，该分布式数据服务中间件可满足企业分布式查询，分布式计算等实际应用需求。     

网络化鱼雷控制系统仿真

传统的鱼雷研发过程需要昂贵的水下试验,数学建模与仿真为开展系统测试和验证提供了一种经济的方法;目前,越来越多的鱼雷电子控制部件采用CAN总线模块,这种基于CAN总线的系统有利于系统部件的更新和功能增加,并使不同任务的重构容易实现;论文提出了网络化鱼雷控制系统半实物仿真平台,描述了鱼雷控制系统网络化互联结构、总线协议和通信管理方法,并进行了控制系统仿真实验;仿真结果表明该仿真平台能够满足网络化鱼雷控制系统性能研究和仿真分析的需求。     

分布式网络控制系统的研究

综述了网络控制系统的出现背景、概念和特性,阐明了网络的应用给传统控制系统带来的益处及广阔的应用前景,分析了网络传输数据给网络控制系统带来的问题,并阐述了网络控制系统中不同于一般网络系统的通信问题,详细分析了近年来迅速发展的现场总线和以太网在分布式网络控制系统中的发展趋势。最后概述了网络控制系统当前的研究现状。指出将网络通信调度和系统控制结合起来,将基于假设的理论研究同基于实际对象的实验平台相结合,是未来的发展趋势。     

不确定型网络系统的分布式自适应跟踪控制器

文章针对带有不确定性的非线性网络系统设计了协调跟踪控制器, 使得follower实现了对仅部分信息可测且受干扰的动态leader的跟踪. 文章运用神经网络方法对follower动态进行建模, 提出了基于观测器的自适应控制策略, 并且通过Lyapunov理论证明, 在适当的网络拓扑条件和适当选择参数的前提下, 该网络系统可以达UUB (Cooperative Uniformly Ultimately Bounded). 最后, 文章给出仿真实例以验证所提算法的有效性.     

StarBus+: Distributed Object Middleware Practice for Internet Computing

In the past decade, the booming of Internet challenges the middleware in three aspects: quality of service, balance of changes and stabilization, and across-Internet integration. This paper presents our work on distributed object computing middleware technology for these challenges, as well as the research and development on StarBus , which is a CORBA standard-compliant middleware suite with the features such as object request broker supporting multi-* quality of service, component model, and integration with Web Service. This paper comprehensively presents the design and characteristics of StarBus , and demonstrates how StarBus is enhanced to address the challenges of Internet computing through three case studies: inter-enterprise integration over Internet, application evolution through dynamic reconfiguration, and great massive information system building. The paper also suggests some research directions which are important for Internet computing.