Programming Languages As difficult to discuss rationally as religion or politics. Prone to extreme statements devoid of data. Examples: \It is practically impossible to teach good programming to students that have had a prior exposure to BASIC; as potential programmers they are mentally mutilated beyond hope of regeneration.\(Dijkstra)

opyright Nancy Leveson, Sept. 1999 Stage 1: Forming Team members begin to discover what behaviors are acceptable Usually highly unstructured environment Attempt to identify tasks, how to accomplish them Decisions on what information is needed Hesitant participation

1. When you can measure what you are speaking about, and can express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowleage is of a meagre and unsatisfactory kind: It may be the beginning of knowledge, but you have scarcely in your thoughts advanced to the stage of science. Lord Kelvin, a physicist

Reuse (Assume have source code, not a commercial product) Ariane 5. Therac-25. British AtC Expectation Significantly lower development costs and time. Amortize costs among all users or uses Assumptions

Formal design Reviews Associated with each of documentation phases Evaluate with respect to Customer requirements Prescribed standards and practices Contractual requirements

Outline: Software Design Goals History of software design ideas Design principles Design methods Life belt or leg iron?(Budgen)

Abstract Model Specifications Build an abstract model of required software behavior using mathematically defined(perhaps using axioms )types(e. g sets, relations) Define operations by showing effects of that operation on the model Specification includes Model

Evolutionary Model Prototyping- \Do it twice to assess feasibility to verify requirements May only be a front end or executable specification Or develop system with less functionality or quality attributes °3 approaches:

Is there a problem? Why Hard? Syllabus EXamples AAS(FAA Advanced Automation System) FBI CIC IRS Modernization Program

本章首先简单概括了GIS应用项目,提出了GIS应用的三元划分,然后介 绍了几种GIS应用的建立途径以及项目周期在项目开始之前,需要进行策略性 规划和实施规划,如果要进行项目承包,则要签订合同在GIS项目进行过程中, 要进行人员管理,数据管理以及质量控制,本章根据GIS具体技术特点,提出了 相应的建议。在最后,介绍了软件研制和开发的质量控制的两个标准,ISO9000系 列标准和CMM模型,作为项目开发机构的指导。 本章和地理信息系统软件工程技术一章讲述的内容是互相依赖的,后者重点在于技 术,而本章则侧重于组织和管理,往往组织管理对项目成败的影响比所采用的技术 更大