分布式系统

This paper adopts stepwise in-depth and refinement method to make analysis of technologies about current dynamic distributed architecture and pointed compares the advantage and weakness of kinds of techniques. At the same time the paper studies the dynamic distributed computing technology. On basis of before-mentioned technology, the paper applies the new 00-based dynamic distributed architecture technology and theory to developing and implementing the remote education subject-base system.

本论文采用逐步深入、求精的研究方法，对目前的动态分布式系统结构的各种技术进行分析，并具有针对性的比较了各种技术的优缺点，同时研究了动态分布式计算技术，在此基础上应用基于面向对象技术的新的动态分布式系统结构技术和思想来开发实现了远程教育题库系统。

In addition, all these core modules conformably used the ACE interface while using thread operations, UDP communication, timer and other APIs closely related to the operating system, which improved the portability of code and solved the problem of cross-platform development of distributed system. Reliability guarantee layer and resource management module completed object-oriented interface design by using OMG's IDL language, which ensured the openness of the distributed system.

另外，所有核心模块在使用到线程操作、UDP通信和定时器等与操作系统密切相关的API时，统一使用了ACE的接口，提高了代码的可移植性，解决了分布式系统的跨平台开发问题；可靠性保证层和资源管理模块使用OMG的IDL语言完成面向对象的接口设计，保证了分布式系统的开放性。

Along with the extensive application of distributed system, distributed database system has become an important field of information processing.

近年来，随着分布式系统的广泛应用，分布式数据库已成为信息处理中的一个重要环节。

It changes modes of integration between distributed systems, and makes easy to intercommunicate between heterogeneous platforms. Without doubt, it will accelerate integration of different kinds of business and enterprise systems, will reduce cost and improve benefit.

它的出现改变了以往分布式系统间的集成方式，使得运用不同分布式集成架构的系统之间可以容易地相互沟通，这无疑极大地促进各种商务系统、企业系统的集成，降低成本，提高效益。

With the further development of computer network, communication network and the distributed system, communication protocols are more and more complicated, formal description technology plays the indispensable role in the network protocol design. LOTOS - as one of the ISO standards of FDT, is designed for distributed systems, especially for communication service and communication protocol.

随着计算机网络、通信网络以及分布式系统的不断发展，通信协议有日渐复杂化的趋势，形式描述技术在网络协议设计中占有举足轻重的作用，作为国际化标准之一的LOTOS技术是专为分布式系统设计的形式描述技术，特别是通信服务和协议。

By introducing two time operators, the traditional LOTOS is extended and time|based LOTOSs syntax and formal semantics are described.

前 言与传统分布式系统相比，分布式多媒体系统有3个重要特点：连续交互性、提供严格的服务质量机制和实时同步性。

Several experimental applications have been developed finally. In this paper, there areinnovations from the following four aspects:1. Definition and research methods of current distributed system and distributedinteractive simulation system follow those of traditional parallel computing system.While this paper points out it is one-sided to measure the scalability just from thenumber of processors and performance of a system, because the resources of distributed systems are heterogeneous and they can be used in diverse applications. Inthis paper, scalability of distributed interactive simulation platform is defined as theability of scaling (including scale-up and scale-down) in functionality and performanceof systems which is run on the platform when number of processors and otherhardware resources such as network change, i.e. when problem size is scaled up and system resources is increased, the performanceremains fixed and it is easy to expand the functions of simulationapplications.

本文的创新工作主要体现在下述4个方面：1、现有的分布式系统和分布式交互仿真系统可扩性的定义和研究方法都沿用了传统的并行计算系统可扩性的定义和研究方法，本文指出分布式系统的系统资源异构多样、应用种类丰富多样，只从传统方法采用的处理机资源和性能角度衡量一个系统是否可扩是有一定的片面性，提出了分布式交互仿真平台可扩性的定义是在处理机和网络等系统资源变化时，运行在平台上的分布式交互仿真系统在性能和功能方面发生扩缩的能力，即当问题规模扩大时，增加系统资源，系统能获得指定的性能及在功能方面能方便进行扩充。

With computer technology, especially the rapid development of network technology, more and more parallel computation are transferring from traditional, special, and super computer platform to the system that is constituted by cheaper, universal, loose coupling, and with single or multiple processors personal computers or workstations.

充分利用分布式系统解决并行计算，为用户提供透明的使用界面，同时实现分布式系统范围内资源的动态分配，实现负载平衡，提高系统的处理能力及处理效率，是目前研究的重点方向之一。本文设计并实现了一种适用于分布式系统的新的并行编程语言——基于负载平衡的并行C语言。

Its primary goal is to build a universal technology layer that is independent of platforms and languages, based on existing heterogenous platforms.

它的出现改变了以往分布式系统间的集成方式，使得运用不同分布式集成架构的系统之间可以容易地相互沟通。

Heterogeneous distributed systems have different processors and each processor has different capability and robusticity.

研究了基于异构分布式系统的实时容错调度算法，同构分布式系统中的处理机完全相同，而在异构分布式系统中各个处理机均不相同，各个处理机有不同的处理能力和不同的健壮性。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。