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Ian Sommerville 2004 Software Engineering, 7th edition. Chapter 1 Slide 1

An Introduction to Software

Engineering

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2/30Ian Sommerville 2004 Software Engineering, 7th edition. Chapter 1 Slide 2

Software Engineering

Syllabus:Introduction: Introduction to software engineering,

Importance of software, The Software evolution,

Software characteristics, Software components,

Software applications, Crisis-Problem andcauses.

Software development life-cycle:Requirement analysis, software design, coding,

testing and maintenance etc.

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contSoftware requirement Specification: Water fall

model, prototyping interactive enhancement, spiralmodel role of management in software development,role of matrices and measurement, Problem analysis,requirement specification, validation, matrices,monitoring and control.

System Design: Problem partitioning, abstraction,top down and bottom up design, structuredapproach, functional versus object oriented approach,

design specification and verification matrices,monitoring and control, Cohesiveness, coupling, 4GL.

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..contCoding: TOP-DOWN and BOTTOM-UP structure

programming, information hiding, programmingstyle, and internal documentation, verification,

metrics, monitoring and control.

Testing: levels of testing, functional testing,

structural testing, test plane, test class

specification, reliability assessment, Software

testing strategies, Verification and validation, Unit,

Integration Testing, Top down and bottom upintegration testing, Alpha and Beta testing, System

testing and debugging.

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..contSoftware project Management: Cost estimation,

project scheduling, staffing, software configuration

management, structured Vs unstructured

maintenance, quality assurance, project monitoring,

risk management.

Function oriented and object oriented Software

design: Overview of SA/SD Methodology, structured

analysis, data flow diagrams, extending DFD to realtime systems, Object oriented design, Graphical

representation of OOD, Generic OO development

paradigm.

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..cont

Software Reliability and Quality

Assurance: Reliability issues, Reliability metrics,

reliability growth modeling, Software quality, ISO 9000certification for software industry, SEI capability

maturity model, comparison between ISO & SEI CMM

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Books & Authors

Software Engineering -Roger S. Pressman

Software Engineering- Ian Sommerville

Reference Books on S/w Engg ByPankaj Jalote,

Rajib Mall,

K.K Agarwal

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Marking

CT1 - 15

CT2 - 15

END SEM40

LAB / LAB EXAM - 20

ATENDANCE+WRITTENASSG/PROJ - 10

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Hardware

Software Mt.

Software Dev.

100

80

60

40

20

1955 1970 1985

Hardware / Software

Cost Trends

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A Software is thought of as either

- a collection of programs

or- Inst ruct ionswhich when executed provide desired

functions and performance

or

- Data struc turesthat enable the program to adequatelymanipulate informations

or

- Document that describes the operation and use of theprograms .

but instead it is Set of all.

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..cont

S/w is not just the programs but also all

associated documentation and configuration data

which is needed to make these programs

operate correctly

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Software is a Collection of- computer programs

- procedures

- rules

- data structures

- associated documentation.and a program

and

programming System Product(Software)

are clearlydifferent .

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Characteristics of Software

- is alogicalor conceptualentity.

- is developedor engineered

not manufactured

- is intangible

no mass, no volume,no color,no odor.

- does not wear out(due to excessive use or environmental hazards)

Instead

it failsor deteriorates.

- is builtrather than assembled- does not have spare parts.

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Software Crisis

- how to develop a software

- how to maintain a software

- how to keep pace with the growing demand of newsoftware.

Real Problem

How to initially estimate and subsequently measure

quality

reliability andCost of end product.

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Programmers Time Spending Schedule

Writing programs 13%

Reading programs and manuals 16%

Job communication 32%

Personal 13%

Training 15%

Mail 6%

Miscellaneous 5%

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A discipline of Software Engg can be achieved

- by combining comprehensive methods for all phasesin software development.

- by procuring better tools for automating the methods.

- by procuring more powerful building blocks forsoftware implementation.

- by an overriding philosophy for coordination,controland management.

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Definition Of Software Engineering

The establishment and use of sound engineeringprinciples in order to obtain economic software thatis reliable and works efficiently on real machines.

- Fritz Baur [1969]

It is the application of science and maths by whichthe capabilities of computer equipments are madeuseful to man via computer programs proceduresand associated documentation.

- Boehm [1981]

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It is the systematic approach to the development

operation,maintenance and retirement of software.

- Jalote

It is a outgrowth of hardware and system engineeringand has three key elements: methods ,tools and

procedures - that enable the manager to control the

process of software development and provide the

practitioner with a foundation for building high-qualitysoftware in a productive manner.

-

Pressman

Definition Of Software Engineering(contd)

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Objectives

To introduce software engineering and to explain

its importance

To set out the answers to key questions about

software engineering

To introduce ethical and professional issues and

to explain why they are of concern to software

engineers

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Software engineering

The economies of ALL developed nations aredependent on software.

More and more systems are software controlled

Software engineering is concerned with theories,

methods and tools for professional softwaredevelopment.

Expenditure on software represents asignificant fraction of GNP in all developed

countries.

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Software costs

Software costs often dominate computer systemcosts. The costs of software on a PC are often

greater than the hardware cost.

Software costs more to maintain than it does to

develop. For systems with a long life,

maintenance costs may be several times

development costs.

Software engineering is concerned with cost-

effective software development.

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FAQs about software engineering

What is software?

What is software engineering?

What is the difference between software

engineering and computer science? What is the difference between software

engineering and system engineering?

What is a software process?

What is a software process model?

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FAQs about software engineering

What are the costs of software engineering?

What are software engineering methods?

What is CASE (Computer-Aided Software

Engineering) What are the attributes of good software?

What are the key challenges facing software

engineering?

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What is software?

Computer programs and associated documentation suchas requirements, design models and user manuals.

Software products may be developed for a particularcustomer or may be developed for a general market.

Software products may be Generic - developed to be sold to a range of different customers

e.g. PC software such as Excel or Word.

Bespoke (custom) - developed for a single customer accordingto their specification.

New software can be created by developing new

programs, configuring generic software systems orreusing existing software.

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What is software engineering?

Software engineering is an engineering disciplinethat is concerned with all aspects of software

production.

Software engineers should adopt a systematic

and organised approach to their work and use

appropriate tools and techniques depending on

the problem to be solved, the development

constraints and the resources available.


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engineering and computer science?

Computer science is concerned with theory andfundamentals; software engineering is concerned

with the practicalities of developing and

delivering useful software.

Computer science theories are still insufficient to

act as a complete underpinning for software

engineering (unlike e.g. physics and electrical

engineering).


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engineering and system engineering?

System engineering is concerned with allaspects of computer-based systemsdevelopment including hardware, software andprocess engineering. Software engineering is

part of this process concerned with developingthe software infrastructure, control, applicationsand databases in the system.

System engineers are involved in systemspecification, architectural design, integrationand deployment.

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What is a software process?

A set of activities whose goal is the developmentor evolution of software.

Generic activities in all software processes are: Specification - what the system should do and its

development constraints Development - production of the software system

Validation - checking that the software is what thecustomer wants

Evolution - changing the software in response to

changing demands.

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What is a software process model?

A simplified representation of a software process,presented from a specific perspective.

Examples of process perspectives are

Workflow perspective - sequence of activities;

Data-flow perspective - information flow;

Role/action perspective - who does what.

Generic process models

Waterfall;

Iterative development;

Component-based software engineering.

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What are the costs of software engineering?

Roughly 60% of costs are development costs,40% are testing costs. For custom software,

evolution costs often exceed development costs.

Costs vary depending on the type of system

being developed and the requirements of system

attributes such as performance and system

reliability.

Distribution of costs depends on the

development model that is used.

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