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。     

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.     

基于组件的分布式软件的动态配置和容错

论文提出一种结构化新方法,它能通过动态配置支持基于组件的分布式软件的容错。采用面向图形的编程模型,基于组件的分布式软件的软件体系结构可用一个逻辑图来表示,该逻辑图可以精化为一个明确的对象并分布到网络中,软件的动态配置通过执行定义在图上的一系列操作来实现,发生错误时通过动态重配置软件来支持容错。论文描述了该方法的基本模型、系统结构及其在CORBA上的实现原型。     

面向图形的构件依赖关系的描述方法

对CORBA分布式应用中构件间依赖关系的描述和依赖关系的动态更新进行了较详细的分析.在此基础上提出了一种面向图形的构件间依赖关系的描述方法,该方法把基于CORBA的分布式应用的体系结构视为一张逻辑图,在图上预定义一组操作,这有助于构件间依赖关系的描述和应用系统的动态配置.同时在CORBA之上实现了一个原型,概括地介绍了实现方法.     

Visual programming support for graph‐oriented parallel/distributed processing

GOP is a graph‐oriented programming model which aims at providing high‐level abstractions for configuring and programming cooperative parallel processes. With GOP, the programmer can configure the logical structure of a parallel/distributed program by constructing a logical graph to represent the communication and synchronization between the local programs in a distributed processing environment. This paper describes a visual programming environment, called VisualGOP, for the design, coding, and execution of GOP programs. VisualGOP applies visual techniques to provide the programmer with automated and intelligent assistance throughout the program design and construction process. It provides a graphical interface with support for interactive graph drawing and editing, visual programming functions and automation facilities for program mapping and execution. VisualGOP is a generic programming environment independent of programming languages and platforms. GOP programs constructed under VisualGOP can run in heterogeneous parallel/distributed systems. Copyright © 2005 John Wiley & Sons, Ltd.     

High-level abstractions for message-passing parallel programming

Large-scale scientific and engineering computation problems are usually complex and consequently the development of parallel programs for solving these problems is a difficult task. In this paper, we describe the graph-oriented programming (GOP) model and environment for building and evaluating parallel applications. The GOP model provides higher level abstractions for message-passing parallel programming and the software environment offers tools which can ease programmers for parallelizing, writing, and deploying scientific and engineering computing applications. We discuss the motivations and various issues in developing the model and the software environment, present the design of the system architecture and the components, and describe the evaluation of the environment implemented on top of MPI with a sample parallel scientific application program. With the support of the high-level abstractions provided by the proposed GOP environment, programming of parallel applications on various parallel architectures can be greatly simplified.     

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。     

A CORBA Based QOS Support for Distributed Multimedia Applications

Advance object oriented computing platform such as the Common Object Request Broker Architecture (CORBA) provides a conducive and standardized framework for the development of distributed applications. Most of the off-the-shelf CORBA are implemented over legacy network transports and distributed processing platforms such as TCP/IP and RPC. They are not suitable for real-time applications due to their high processing overheads, and lack of features and mechanisms in supporting quality of service both at the network level and at the end-host level. To overcome this limitation we have designed and implemented a CORBA-based Real Time Stream Service (RTSS) that allows real-time streams to be managed through the CORBA channel but by-passing the heavy CORBA protocol stacks. RTSS aims to achieve an integrated QOS framework that incorporates both host scheduling and end-to-end network-level QOS to better support the processing of distributed multimedia applications over ATM networks. For host scheduling, a novel scheme of frequency-based scheduling mechanism has been proposed to cope with dynamic CPU load condition. The scheme has been implemented for a stand-alone host and will be extended to the networked environment. At the network-level QOS, RTSS provides object-oriented application programming interfaces (APIs) which guarantee end-to-end QOS when operating directly over ATM adaptation layers. The benefits of RTSS for the development of real-time multimedia distributed applications are demonstrated through a number of experiments.     

基于CORBA的分布式应用程序的性能优化

CORBA是构建异构的分布式应用的首选规范，但由于CORBA规范自身对性能优化方面考虑的不足，因此CORBA应用程序普遍存在运行效率低的问题，该文结合CORBA体系结构特点和CORBA规范，给出一些在开发CORBA应用的过程中可采取的优化策略。     

构件间依赖关系的形式化图形原语描述方法

目前,基于构件的软件系统的研究越来越引起人们的重视.提出了一种基于图形的构件间依赖关系的描述方法,并对CORBA分布式应用中构件间依赖关系的描述和依赖关系的动态更新进行了较详细的分析.在CORBA上实现了一个原型,从而实现了基于CORBA的分布式应用的动态配置.     

一种图形化的CORBA体系结构描述方法

随着软件技术的发展,对于软件体系结构的研究越来越引起人们的重视。本文对CORBA分布式软件体系结构的描述需求和组件之间的依赖关系进行了较详细的分析,在此基础上提出了一种基于图形的软件体系结构描述方法,该方法把基于CORBA的分布式应用的软件体系结构视为一张逻辑图,在图上预定义一组操作,有助于CORBA应用的程序设计和维护。本文还在CORBA之上实现了一个原型,概括地介绍了具体的实现途径。     

CORBA与Web服务的比较与集成

CORBA作为成熟的分布式计算标准，主要用来构造企业内部事务紧急的应用，Web Services是近年来提出的一种新的面向服务的体系结构，主要用来开发基于Internet的服务。针对CORBA在Internet环境下数据共享和应用集成的局限性，提出了CORBA与Web Services集成的方案，设计了集成网关并研究了集成中的关键问题：接口映射转换、消息类型转换和CORBA对象的动态调用。     

一个集成了COM和CORBA的脚本语言

提出了一个集成了COM和COTBA两种分布式对象系统的简单脚本语言——GSCRSIPT,该语言使用自动化编程接口和动态调用接口来分别操纵在网络中的COM和COTBA对象。GSCRIPT是平台独立的,同一GSCRIPT程序可以在多种操作系统和硬件平台上运行,同时,也详细介绍了GSCRIPT解释器的体系结构和提供事件服务的方法,它们也是GSCRIPT实现平台钎立性的途径。     

基于CORBA的分布式MVC软件体系结构

MVC作为一种经典的软件模式,在界面程序设计和B/S系统中得到广泛应用,但对于分布式实时交互应用而言,其高效性和可扩展性等仍有待提高。本文深入分析了MVC软件模式的结构特点,提出一种基于CORBA的分布式MVC软件体系结构SEV。SEV将动态数据处理从模型中分离出来,并采用CORBA分布对象机制提高系统可扩展性,为面向分布式实时交互式系统的设计提供了高效可扩展的软件参考模型。     

A dynamic platform for run-time adaptation

We present a middleware platform for assembling pervasive applications that demand fault-tolerance and adaptivity in distributed, dynamic environments. Unlike typical adaptive middleware approaches, in which sophisticated component model semantics are embedded into an existing, underlying platform (e.g., CORBA, COM, EJB), we propose a platform that imposes minimal constraints for greater flexibility. Such a tradeoff is advantageous when the platform is targeted by automatic code generators that inherently enforce correctness by construction.Applications are written as simple, single-threaded programs that assemble and monitor a set of distributed components. The approach decomposes applications into two distinct layers: (1) a distributed network of interconnected modules performing computations, and (2) constructor logic that assembles that network via a simple block-diagram construction API. The constructor logic subsequently monitors the configured system via a stream of high-level events, such as notifications of resource availability or failures, and consequently provides a convenient, centralized location for reconfiguration and debugging. The component network is optimized for performance, while the construction API is optimized for ease of assembly. Microbenchmarks indicate that our runtime incurs minimal overhead.In addition to describing the programming model, platform implementation, and a variety of pervasive applications built using our system, this paper also extends our previous work with a thorough analysis of remote objects and tracking techniques, new contributions in distributed component liveness-monitoring approaches, and expanded microbenchmarks.     

一种基于CORBA的分布式全文检索系统设计

海量信息的全文检索是人类获取信息的重要手段之一,而网络海量信息的检索使传统的全文检索技术面临新的挑战。如何改善检索系统的结构,提高检索系统的性能和效率,以加快检索速度,成为一个值得研究的课题。公用对象请求代理体系CORBA技术的出现为这一课题提供了一个有效的解决方法。该文在对WEB计算方式和CORBA体系进行详细讨论的基础上,结合实际课题的研究,给出了一种基于CORBA技术的分布式全文检索系统架构设计。     

CORBA负载平衡的研究

一、引言作为分布式计算的一个重要规范—CORBA,其主要目标是解决面向对象的异构应用之间的互操作问题,并提供了分布式计算所需的多项服务。ORB是CORBA平台的核心,它用于屏蔽与底层平台有关的细节,使开发者可以集中精力去解决与应用相关的问     

基于CORBA的网络管理的若干关键问题研究

1 基于CORBA的网络管理体系结构网络管理的含义如图1的USE-CASE图示意。基于CORBA的网络管理利用了CORBA的分布对象模型和互操作机制,通过CORBA中间件来屏蔽掉各种被管理资源的异构性。基于CORBA的网络管理体系结构的一般结构如图2示意,CORBA服务在网络管理系统和被管理系统之间作为中间件,通过ORB进行通讯。CORBA应用于网络管理的目     

A graphical development and debugging environment for parallel programs

To provide high-level graphical support for PVM (Parallel Virtual Machine) based program development, a complex programming environment (GRADE) is being developed. GRADE currently provides tools to construct, execute, debug, monitor and visualize message-passing parallel programs. It offers a high-level graphical programming abstraction mechanism to construct parallel applications by introducing a new graphical language called GRAPNEL. GRADE also provides the programmer with the same graphical user interface during the program design and debugging stages. A distributed debugging engine (DDBG) assists the user in debugging GRAPNEL programs on distributed memory computer architectures. Tape/PVM and PROVE support the performance monitoring and visualization of parallel programs developed in the GRADE environment.