《计算机英语》第五单元.pptx

Unit 5 Software Engineering5.1 Software Engineering5.2 The Methods of Modern Software Design5.3 Software MaintenanceSoftware Engineering 主要内容正文生词正文Software engineering is the application of tools, methods, and disciplines to produce and maintain an automated solution to a real-world problem. It requires the identification of a problem, a computer to execute a software product, and an environment (composed of people, equipment, computers, documentation, and so forth) in which the software product exists. Clearly, without computer programs there would be no software product and no software engineering. But this is only a necessary condition; it is not sufficient.软件工程是工具、方法和规则的应用，用于产生和维护一个现实世界问题的自动化解决方案。它要求我们识别出一个问题，一台执行某一软件产品的计算机及其软件产品存在的环境（包含人员、设备、计算机、文档等）。显然没有计算机程序就没有软件产品，更没有软件工程。但这只是一个必要而非充分条件。正文The first phase, requirements definition, refers to the period during which the requirements of the system desired, that is, its functional characteristics and operational details, are specified. The input to this phase is the stated (often rather loosely stated) needs for the software. Typically, a requirements document is the output of this phase, a set of precisely stated properties or constraints that the final product must satisfy. This is not a design, but rather precedes the design, specifying what the system should do without specifying how it is to do it. The existence of a requirements document provides something against which a design (the next phase in the life cycle) can be validated. Sometimes a quickly developed prototype can be a useful vehicle for debugging requirements.第一阶段，需求定义，表示在这个阶段内系统希望的需求，也就是精确说明它的功能特性和运行细节。该阶段的输入是陈述（一般是不太确切的陈述）对该软件的要求。通常，一个“需求文档”是该阶段的输出，是经过明确说明的特征或约束条件的集合，这也是最终产品必须满足的。这虽然不是设计，但是必须在设计之前，规定系统应该做什么而不规定它如何去做。一个需求文档的存在，提供一些针对设计的（该生存周期的下一个阶段）并可以使其有效化的东西。有的时候一个快速开发的原型可能是调试需求的一个有用的工具。正文The storage structure and access methods used by the database system are specified by a set of definitions in a special of DDL called a data storage