共查询到19条相似文献,搜索用时 109 毫秒
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多层分布式应用程序是目前数据库发展的潮流。本文介绍了多层分布式应用服务的结构、特点及开发工具,并举例说明运用Delphi创建多层数据库应用程序的步骤与方法。 相似文献
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指出了多层分布式应用体系与传统的Client/Server体系结构模式的区别,重点阐述了多层分布式应用体系安全性、可维护性等特点。 相似文献
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杜树杰 《信息技术与信息化》2007,38(6):91-93
分布式计算技术在软件开发中得到了广泛的应用,它使复杂的大型网络应用程序在结构上更清晰,更易于开发。组件对象模型COM(Component ObjectModel)和分布式组件对象模型DCOM(Distributed COM)是微软软件体系结构中使用的分布式对象技术。通过分析基于COM/DCOM组件技术的分布式计算的基本原理,总结了开发使用COM/DCOM组件的基本方法和三层分布式应用程序的实现过程。最后给出了一个用DCOM组件构造的三层分布式应用系统实例。 相似文献
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分布式计算技术在软件开发中得到了广泛的应用,它使复杂的大型网络应用程序在结构上更清晰,更易于开发。组件对象模型COM(Component Obiect Model)和分布式组件对象模型DCOM(Distributed COM)是微软软件体系结构中使用的分布式对象技术。通过分析基于COM/DCOM组件技术的分布式计算的基本原理,总结了开发使用COM/DCOM组件的基本方法和三层分布式应用程序的实现过程。最后给出了一个用DCOM组件构造的三层分布式应用系统实例。 相似文献
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高压MZ—JTE终端边界元数值模拟 总被引:2,自引:0,他引:2
本文采用边界元数值方法,编制了统一的多区结终端扩展(Multiple-Zone Junction Ter-mination Extension,MZ-JTE)边界元程序,模拟高压MZ-JTE终端电场,电位分布,以平面结算例验证了边界元数值解精度及可靠性,定量模拟了界面态影响,取得了与国外用差分或有限元得到的结论相一致的结果。边界元方法的提出与算法,程序的成功开发,为MZ-JTE结构及其它终端结构的 相似文献
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本文采用边界元数值方法,编制了统一的多区结终端扩展(Multiple-Zone Junction Ter-mination Extension,MZ-JTE)边界元程序,模拟高压MZ-JTE终端电场,电位分布,以平面结算例验证了边界元数值解精度及可靠性,定量模拟了界面态影响,取得了与国外用差分或有限元得到的结论相一致的结果。边界元方法的提出与算法,程序的成功开发,为MZ-JTE结构及其它终端结构的 相似文献
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英文摘要的写作是本科专业英语教学中重要的一环。本文针对电子信息类专业英语学时短、内容多的现状,针对本科毕业论文中英文摘要写作普遍存在的问题,提出将英文摘要写作培养贯穿整个教学过程的新理念。通过课下积累,课上短时集中学习和练习,让学生逐渐掌握英文摘要的基本结构和常用句型。实践表明,采用该方法后学生的英文摘要写作能力普遍得到提高。 相似文献
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Distributed multimedia information handling and processing 总被引:1,自引:0,他引:1
Requirements for distributed processing of multimedia information are summarized and compared with the latest efforts in standardization. An approach to a communication model that can be viewed as a special form of a model for open distributed applications is outlined. The functions of a system for the handling of multimedia information and a functional model approach, including a supporting environment, are considered. Synchronization aspects of isochronous and anisochronous communication are also outlined. The model is still under development. Detailed work needs to be done in the areas of formal specification of abstract services and modeling of communication protocols 相似文献
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本文对目前代表性的云计算技术进行了回顾,选择其中的HDFS提取主要组成元素分析整理,抽象出若干对象集和关系集,进而提出集群三元空间。从抽象层面回归到具体实现,HDFS对集群三元空间的实现采用了集中式结构,形成了系统性能的瓶颈以及集群扩展的滞点。集群三元空间从抽象层面,剔除具体实现因素之后,给出了系统分析与问题定义的背景。 相似文献
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The stable paths problem and interdomain routing 总被引:1,自引:0,他引:1
Dynamic routing protocols such as RIP and OSPF essentially implement distributed algorithms for solving the shortest paths problem. The border gateway protocol (BGP) is currently the only interdomain routing protocol deployed in the Internet. BGP does not solve a shortest paths problem since any interdomain protocol is required to allow policy-based metrics to override distance-based metrics and enable autonomous systems to independently define their routing policies with little or no global coordination. It is then natural to ask if BGP can be viewed as a distributed algorithm for solving some fundamental problem. We introduce the stable paths problem and show that BGP can be viewed as a distributed algorithm for solving this problem. Unlike a shortest path tree, such a solution does not represent a global optimum, but rather an equilibrium point in which each node is assigned its local optimum. We study the stable paths problem using a derived structure called a dispute wheel, representing conflicting routing policies at various nodes. We show that if no dispute wheel can be constructed, then there exists a unique solution for the stable paths problem. We define the simple path vector protocol (SPVP), a distributed algorithm for solving the stable paths problem. SPVP is intended to capture the dynamic behavior of BGP at an abstract level. If SPVP converges, then the resulting state corresponds to a stable paths solution. If there is no solution, then SPVP always diverges. In fact, SPVP can even diverge when a solution exists. We show that SPVP will converge to the unique solution of an instance of the stable paths problem if no dispute wheel exists 相似文献
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异步机制是构造大规模分布式系统必不可少的机制之一.作为一种典型的分布应用支撑平台,CORBA没有很好的解决异步机制问题,这限制了CORBA在一些领域的应用.如何在CORBA中提供异步通信支持,为上层应用提供异步通信支持成为研究的热点.本文提出一种CORBA异步消息模型Star-Async,该模型通过ReplyHandler对象实现应答处理、通过异常封装对象实现异常处理,通过基于修改抽象语法树的机制实现异步代码生成.在自主研制的分布对象中间件平台StarBus中实现了本文提出的Star-Async异步模型,实现和初步应用表明本文提出的异步消息模型为在CORBA中实现异步机制提供了一种有效的参考. 相似文献
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Summary This paper presents the software architecture and middleware for a distributed smart camera (DSC) system that performs multi-target
tracking. Middleware is used to abstract away important operations from the details of network operation. The paper describes
the tracking algorithms and their middleware needs, the software architecture of the tracker, and the lessons learned for
the next generation of tracker.
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针对实现资源共享和协同工作的网格技术应用研究与发展现状,文章给出网格应用总体结构;根据Petri网系统特点,提出基于Petri网的服务流网SF—net模型,设计了基于UML的网格工作流程序的一般性开发方法。并在此基础上定义了基于Petri网的网格作业描述语言;讨论了当前工业界Web服务业务过程执行语言BPEL4WS及进程代数CSP与文中所提服务流网的结合,引入服务代数概念,表明了服务流网SF-net的灵活性。 相似文献
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Packet switching is a communication technology which has been used extensively in geographically distributed computer networks. It is also applicable to the communication subnetworks of compact multimicrocomputers known as network computers. This paper describes the use of the language Concurrent Pascal to build a packet-switching subsystem for the MICRONET network of DEC LSI-11 microcomputers. Examples of actual Concurrent Pascal source code taken from the system demonstrate the usefulness of high-level languages with abstract data types for complex communication software. 相似文献