【作者】 李洪波；

【导师】 徐志根；

【作者基本信息】 西南交通大学 ， 计算机应用技术， 2004， 硕士

【摘要】 随着Internet／Intranet技术的发展与壮大，企业业务运作模式发生相应的变化，计算机应用系统也由单机模式向网络模式发展。分布式多层结构模式正是在这种环境下产生并发展的。与传统的两层结构模式相比较，多层体系结构实现了业务的集中控制，真正实现了“瘦客户”体系结构，使得系统更具扩展性与伸缩性。 牵引供电运营管理信息系统简称PSMIS系统，通过计算机技术可为铁路供电部门复杂的传统业务提供可靠实现，并能实时监测现场设备运行状态和人员工作情况，为管理决策者提供及时准确的辅助信息和决策依据。在诸如PSMIS系统的大型应用系统中，企业业务庞大而复杂，用户数量多，系统体系结构的选择和设计是其中的关键，它将关系到系统业务如何控制、系统的可扩展性、可维护行、负载均衡能力与数据安全性等诸多问题。因此，PSMIS系统的结构设计与实现作为课题具有一定现实意义的。 多层结构模式是建立在分布式技术基础之上的。当今流行的分布式技术主要有DCOM和CORBA。本文对当今流行的两种分布式技术：DCOM和CORBA的技术特点与工作原理做了介绍。由于DCOM技术具有安装配置简单、速度快等特点，并且结合PSMIS系统的操作系统平台的特点选择其作为系统的分布式环境。在对多层体系结构和传统的两层结构进行分析对比的基础上，结合PSMIS系统资源分布、业务特点以及用户分布的特点，本文突出了前者在系统的可扩展性、可维护性以及数据安全性等方面的特点和优点。本文提出了PSMIS系统的分级的多层结构的解决方案，实现业务层次分布式与层次结构上的分布式，以适应供电段各部门在业务划分、地理分布、资源分布上的特点。 为了保证系统结构层次清晰明确和其它良好特性，在实现当中要严格遵循多层结构的开发规范，逐层实现各个层次。本文给出PSMIS系统中一个简单业务的实现作为例子，通过MIDAS技术实现分布式多层结构。文中的例子对多层结构的开发标准作了强调，列出相关功能的关键性Delphi代码。更多还原

【Abstract】 With the development of the Internet/Intranet, the operation mode of enterprisers in the past have been changed accordingly, and the system of computer application have changed the computing method from mode of single machine to network computing. The mode of multi-tier distributed architecture came into being in this environment. Compared with the conventional tow-tier mode, the multi-tier architecture makes the business centralized control, and brings the real "thin client" into success, all this will cause more expandability and scalability in the system.PSMIS is the shortened form of Power Supply Management Information System. Through the computer technology, PSMIS, which can provide the reliable implementation of the complex business for power supply department, and monitor the real-time state of the devices and the state of the employees in the spot, will provide the veracious information and warrant of decision for managers and decision-makers in time. In the large-scale application system of the enterpriser such as PSMIS, because of heavy and complex business, multitudinous user, the key for success will be the choice for the architecture. The system architecture will affect the control methods of the business rule, expandability and maintainability in the system, the capability of load balance and the security of the data. Therefore the subject study for the design and implementation of the multi-tier distributed architecture in PSMIS has practical meaning in some degree.The multi-tier architecture mode is based on the distributed technology that include tow main technology: DCOM and CORBA. The paper will introduce the technical feature and operating principle of DCOM and CORBA. Because of the merits of DCOM in installation and rate of execution we choose it for the basic technology of the distributed environment. Based on the comparison and analysis between multi-tier distributed architecture and conventional tow-tier mode of C/S, the paper puts the focus on the merits of the former in maintainability, scalability and data security of the system. The paper presents the resolution of hierarchical multi-tier architecture for PSMIS, which willimplement the distributed computing in business an architecture hierarchy.In order to ensure the well-known feature clarity and definitude in the architecture hierarchy, we severely follow the development standard of the multi-tier architecture and complete the code layer by layer in the implementation of the PSMIS. The paper presents a simple example of PSMIS business, and gives the code of the implementation that based on MIDAS. The paper emphasizes the development standard and code rule of the multi-tier architecture.更多还原