chap03 Systems Development.pptVIP

? 2007 by Prentice Hall Management Information Systems, 10/e Raymond McLeod and George Schell Chapter 3 Systems Development Learning Objectives Understand that the systems development life cycle SDLC is a methodology – a recommended way to develop systems. Be familiar with the main SDLC approaches – the traditional waterfall cycle, prototyping, rapid application development, phased development, and business process redesign. Learning Objectives Cont’d Know the basics of modeling processes with data flow diagrams and use cases. Understand how systems development projects are managed in a top-down fashion. Be familiar with the basic processes of estimating project cost. Systems Development Life Cycle Methodology is a recommended way of doing something. Systems development life cycle SDLC is an application of the systems approach to the development of an information system. Systems Development Life Cycle Traditional SDLC stages are: Planning Analysis Design Implementation Use. Often called waterfall approach The System Development Life Cycle SDLC Who participates IS personnel User Information specialists can consult Traditional Information specialists working with users. A new strategy: Outsourcing Life Cycle Management Executive responsibility MIS steering committee Functions Set policy Control the purse strings Resolve conflicts Main Advantages of the Steering Committee Total firm support Projects will be characterized by good planning and control Establishes policies, provides fiscal control, and resolves conflicts 生命周期 人的生命周期：出生－成长－死亡 （婴儿期、儿童期、少年期、青年期、中年期、老年期） 生命周期各个阶段的基本任务（I） 软件定义时期（系统分析） 问题定义：这个阶段必须回答的关键问题是：“要解决的问题是什么”。 可行性研究：这个阶段要回答的关键问题是：“上一个阶段所确定的问题是否有行得通的解决办法”。 需求分析：这个阶段的任务仍然不是具体地解决客户的问题，而是准确地回答“目标系统必须做什么”这个问题。它的另外一项重要任务，是用正式文档准确地记录对目标系统的需求，这份文档通常称为规格说明。 生命周期各个阶段的基本任务（II） 软件开发时期（系统设计与实现） 概要设计：这个阶段的基本任务是，概括地回答“怎样实现目标系统?”这个问题。概要设计又称为初步设计、逻辑设计、高层设计或总体设计。首先，应该设计出实现目标系统的几种可能的方案。概要设计的另一项主要任务就是设计程序的体系结构，也就是确定程序由哪些模块组成以及模块间的关系。 详细设计：概要设计阶段以比较抽象概括的方式提