Lecture 1- Intro to SE

7/31/2019 Lecture 1- Intro to SE

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Learning Outcomes

Illustrate the concept of software engineering

Apply the concept of software engineering in thesystem development

Produce formal specification and softwaremodeling in a collaborative team environment


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Assessment

Quiz 5%

Mid Term Exam 20%

Lab work/Assignments 10%

Mini project 25%

Final Exam 40%


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Lecture 1

An Introduction to SoftwareEngineering


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Objectives

To introduce software engineering and toexplain its importance

To set out the answers to key questions aboutsoftware engineering

To introduce ethical and professional issues and

to explain why they are of concern to softwareengineers


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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.


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Figure1.11 The roles of the development team

Maintenance

System Design

Requirements Analysisand Definition

Program Design

Program Implementation

Unit Testing

Integration Testing

System Testing

System DeliverySO

FTWAREDEVELOPMENT

STEPS

DEVELOPERROLES

ANALYST

DESIGNER

PROGRAMMER

TESTER

TRAINER


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FAQs about software engineering

What is software?

What is software engineering?

What is the difference between softwareengineering 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 SoftwareEngineering)

What are the attributes of good software?

What are the key challenges facing softwareengineering?


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What is software? Computer programs and associated

documentation such as requirements, designmodels and user manuals.

Software products may be developed for aparticular customer or may be developed for a

general market. Software products may be

Generic - developed to be sold to a range of different customerse.g. PC software such as Excel or Word.

Bespoke (custom) - developed for a single customer according

to their specification. New software can be created by developing new

programs, configuring generic software systemsor reusing existing software.


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Variety of Software ProductsExamples

Real time : air traffic control

Embedded systems : digital camera, GPS

Data processing : telephone billing, pensions

Information systems : web sites, digital libraries

Sensors : weather data

System software : operating systems, compilers

Communications : routers, mobile telephones

Offices : word processing, video conferences

Scientific : simulations, weather forecasting

Graphical : film making, design


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Categories of Software Product

Generic (e.g., Microsoft Excel)

Packages (e.g., Mathematica)

Customized versions of generic packages (e.g.,UTeM's payroll system)

Bespoke (customized) (e.g., IRS internal system)

Demonstration, prototype, research,


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What is software engineering?

Software engineering is an engineeringdiscipline that is concerned with all aspects of

software production.

Software engineers should adopt a systematicand organised approach to their work and use

appropriate tools and techniques dependingon the problem to be solved, the developmentconstraints and the resources available.


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Computer Science Customer

TheoriesComputer

FunctionsProblem

Software

Engineering

Tools andTechniques

to Solve

Problem


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What is the difference between softwareengineering and computer science?

Computer science is concerned with theory andfundamentals; software engineering is

concerned with the practicalities of developingand delivering useful software.

Computer science theories are still insufficient to

act as a complete underpinning for softwareengineering.


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What is the difference between software

engineering and system engineering?

System engineering is concerned with all aspectsof computer-based systems developmentincluding hardware, software and processengineering. Software engineering is part of this

process concerned with developing the softwareinfrastructure, control, applications anddatabases in the system.

System engineers are involved in system

specification, 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 the

customer 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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Figure1.12 The key factors that have changed software development

Time to market

Shifts in economics

Desktop computing

Networking

Object technology Problems with waterfall

User interfaces

CHANGES IN

SOFTWARE

ENGINEERING


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Human Error Fault Failure

can lead to can lead to


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Software costs

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

Software engineering is concerned with cost-

effective software development.


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Figure 1.5 McCalls quality model.

Correctness

Reliability

Efficiency

Integrity

Usability

MaintainabilityTestability

Flexibility

Portability

Reusability

Interoperability

Traceability

Completeness

Consistency

Accuracy

Error Tolerance

Execution Efficiency

Storage efficiency

Access control

Access audit

Operability

Training

Communicativeness

Simplicity

Conciseness

Instrumentation

Self-descriptiveness

Expandability

GeneralityModularity

Software System Independence

Machine Independence

Communications commonality

Data commonality


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What are the attributes of good software?

The software should deliver the required functionality andperformance to the user and should be maintainable, dependableand acceptable.

Maintainability Software must evolve to meet changing needs;

Dependability

Software must be trustworthy; Efficiency

Software should not make wasteful use of system resources; Acceptability

Software must accepted by the users for which it was

designed. This means it must be understandable, usable andcompatible with other systems.


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What are the key challenges facingsoftware engineering?

Heterogeneity, delivery and trust.

Heterogeneity Developing techniques for building software that can

cope with heterogeneous platforms and executionenvironments;

Delivery

Developing techniques that lead to faster delivery ofsoftware;

Trust Developing techniques that demonstrate that software

can be trusted by its users.


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Key points Software engineering is an engineering

discipline that is concerned with all aspects of

software production. Software products consist of developed

programs and associated documentation.Essential product attributes are maintainability,

dependability, efficiency and usability.


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Continue..

The software process consists of activities thatare involved in developing software products.Basic activities are software specification,development, validation and evolution.

Methods are organised ways of producingsoftware. They include suggestions for theprocess to be followed, the notations to be used,rules governing the system descriptions whichare produced and design guidelines.

Lecture 1- Intro to SE

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