ch01 What is Software Engineering？

软件工程导论

Bilingual language teaching

双语教学(中英，中俄，中韩) 板书、讲授、作业、考试采用两种语言的混杂，比例是外 语不低于20% 是基础英语、科技英语、专业英语的延续，体现英语教学 的不断线。 是英语的应用，不是为了学习英语，经过近20年的英语学 习，现在是大家应用英语的时候了。 双语软件工程是为了学习软件工程的知识，是为了达到国 际水平而开设的。

软件工程导论

Textbook《软件工程——理论与实践》(第四版 影印版) 《SOFTWARE ENGINEERING—Theory and Practice 》Shari Lawrence Pfleeger,高等教育出版社，2009

软件工程导论

软件工程导论

Reference books

软件工程(英文版) (第 9版 ) 机械工业出版社

软件工程导论

Reference books

软件工程导论(第5版)

软件工程导论

Table of ContentsPart 1:motivates the reader, explaining why knowledge of software engineering is important. Chapter 1: What is Software Engineering? Chapter 2: Modeling the Process and Life Cycle Chapter 3: Planning and Managing the Project Chapter 4: Capturing the Requirements Chapter 5: Designing the Architecture Part 2:walks through the major steps of development and maintenance.

Chapter 6: Designing the ModulesChapter 7: Writing the Programs Chapter 8: Testing Chapter 9: Delivering the System Chapter 10: Maintaining the System

软件工程导论

Chapter 1What is Software Engineering?

软件工程导论

Contents1.1 Concept of Software 1.2 Software Crisis 1.3 What is Software Engineering? 1.4 What Is Good Software? 1.5 Who Does Software Engineering? 1.6 A System Approach 1.7 An Engineering Approach 1.8 Members of the Development Team 1.9 How Has Software Engineering Changed? 1.10 Information System Example 1.11 Real Time Example 1.12 What this Chapter Means for You

软件工程导论

Objectives

What we mean by software engineering Software engineering’s track record What we mean by good software Why a system approach is important How software engineering has changed since 1970s

软件工程导论

1.1 Concept of SoftwareDefinition Software

Programs

Data (stru)

Documents

Instructions (computer programs) that when executed provide desired function and performance

Data structures that enable the programs to adequately manipulate information

Documents that describe the operation and use of the programs2015/12/15

软件工程导论

1.1 Concept of Software

Characteristics (main)

Software is developed or engineered, it is not manufactured in the classical sense.

Software doesn’t “wear out”, but it does deteriorate.

Software is a logic entity.

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软件工程导论

1.1 Concept of SoftwareInfant MortalityWear Out

Failure Rate

TimeFailure curve for hardware

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软件工程导论

1.1 Concept of Software

Failure Rate

Continues at same rate until obsolescence

Time Failure curve for software (idealized)

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软件工程导论

1.1 Concept of SoftwareIncreased failure rate due to side effectsActual curve

Failure Rate

Change(修改) Time Failure curve for software )

Most software is custom-built, rather than being assembled from existing component

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软件工程导论

The software cost is expensiveCost %

hardware software

1950

1970

1985

1995

Year

change of hardware and software cost ratio

软件工程导论

1.2 Software Crisis

Projects running over-budget. Projects running over-time. Software was very inefficient. Software was of low quality. Software often did not meet requirements. Projects were unmanageable and code difficult to maintain. Software was never delivered.The major cause of the software crisis is that the machines have become several orders of magnitude more powerful! To put it quite bluntly: as long as there were no machines, programming was no problem at all; when we had a few weak computers, programming became a mild problem, and now we have gigantic computers, programming has become an equally gigantic problem.

– Edsger Dijkstra, The Humble Programmer (EWD340), ACM Turing Lecture 1972.