1

OverviewObjectivesFAQs about software engineeringEthical and professional issuesSW engineering vs. Systems

AnalysisCourse Syllabus

2

ObjectivesIntroduce what software engineering is and

why it is importantUnderstand ethical and professional issues

that are important for software engineersUnderstand the relation between this

course and the systems analysis and designView of topics to be discussed this course

3

Class Activity: Technology and us

With your team write down a list of everyday devices we use that contain software?

4

Software development crisesProjects were: LateOver budgetUnreliable Difficult to maintainPerformed poorly

5

Software errors... the cost

Errors in computer software can have devastating effects

6

CNN: Computer glitch delays dozens of UK flights

Saturday 3rd October 2009-London, England (CNN)

Dozens of flights from the UK were delayed Saturday after a glitch in an air traffic control system in Scotland, but the problem was fixed a few hours later.

The agency said it reverted to backup equipment as engineering worked on the system.

The problem did not create a safety issue but could cause delays in flights.

Read more at http://edition.cnn.com/2009/WORLD/europe/10/03/uk.flights.delayed

7

8

Loss of the Mars Climate orbiter in 1999 because an error in a Metric to English conversion formula (pounds and Kilograms)[1]

Ariane 5 ExplosionCaused by an

overflow error. Watch the video

http://www.youtube.com/watch?v=z-r9cYp3tTE

9

10

A well-disciplined approach to software development and

management is necessary. This is called engineering.

Software engineeringThe notion of software engineering was first proposed in 1968.

11

12

What is software?

Software is a product that software engineers design and build

It encompasses programs, documents, and data

Data Documents

Programs

Software

13

What is Software Engineering?

“An engineering discipline that is concerned with all aspects of software production from the early stages of system specification to maintaining the system after it has gone into use” [4]

14

Software Types

There are two types of software products

Generic productsCustomized or bespoke products

15

What is the difference between software engineering and computer science?

Computer science Theory and fundamentals

Software engineering Practicalities of delivering useful

softwareSoftware engineers need computer

science knowledge

16

What is the difference between software engineering and system engineering?

System engineering Hardware + Software + ProcessOlder than software engineering

Software engineering is part of system engineering

17

What is a Software Process?Set of activities and associated results that

produce a software product.There are four fundamental activities

common to all software process models SW specification:

What does the customer need “Requirements”? What are the constraints?

SW development Design & programming

SW validation: Checking whether it meets requirements

SW evolution : Modifications (e.g. customer/market)

18

What is a Software Process Model?A simplified description of a SW process that

presents one view of that process

Examples of process perspectives areWorkflow perspective

Sequence of activities: Human Actions What is input, output, and dependencies

Data-flow perspective - information flow; Activities = transformations of information How the input is transformed into output

Role/action perspective What is the role of people step of the process?

19

What is a Software Process Model?

20

What are the costs of SW engineering?

No simple answer, depends on :The process used, and The type of software being developed

Each generic approach has a different profile of cost distribution.

Roughly 60% of costs are development costs, 40% are testing costs.

For custom software, evolution costs often exceed development costs.

21

Software engineering activity cost distribution

22

Waterfall model

Iterative development

Component-based software engineering

Development and evolution costs for long-lifetime systems

System evolution

10 200 30 4000

System development

Specification Design Development Integration and testing

25 50 75 1000

Specification Development Integration and testing

25 50 75 1000

Specification Iterative development System testing

25 50 75 1000

What are software engineering methods?

Structured approaches to software development which include system models, notations, rules, design advice and process guidance.

Model descriptionsDescriptions of graphical models which should be

produced;Rules

Constraints applied to system models;Recommendations

Advice on good design practice;Process guidance

What activities to follow.

23

What is CASE?CASE (Computer

Aided Software Engineering)

Programs used to support software process activities such as system modeling, debugging, and testing

Some CASE tools include automatic code generation from diagrams.

24

What are the attributes of good software?

Some essential attributes :

25

26

What are the key attributes for..

What are the key challenges facing software engineering?

27

Professional and Ethical responsibility

Please read from the book section 1.2 pages 14-17

28

SW engineering vs. Systems Analysis

29

What you studied in System Analysis course constitutes part of software engineering.

Software Engineering is a broader subject.

To be a software engineer, you must master several skills, one of which is analysis and design.

SW Engineering vs. Systems Analysis and Design

30

Syllabus

31

References1. PRESS&SUN-BULLETIN, The Binghamton Press Co., Binghamton,

NY, October 1,1999.2. “Software Hell: Is there a way out?”, BUSINESS WEEK, December

6, 1999.3. IEEE Standards Collection: Software Engineering, IEEE standard

610.12-1990, IEEE 1993.4. Sommerville, Ian “Software Engineering”, 8th edition, Addison-

Wesley.

32