LEC SEPA-0206

8/3/2019 LEC SEPA-0206

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LECTURE-2

8/3/2019 LEC SEPA-0206


Softwa re Is a Product

• Designed by software engineers.• Consists of :

– Programs - that execute within a computer and

provides desired functions . – Documents- describe the operation and use of the

program

– Data - which can be numerical, textual, pictorial,video etc.

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Information

SoftwareVehicle to deliver the

product

Operating System

Network SoftwareCase tools

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In

today’s lecture we will learn about the product that is to be

engineered. And the process (Next class) that provides a frameworkfor the engineering technology

The following questions will addressed in today’s lecture.

•What is computer software ?

•Why do we struggle to build high-quality computer-based systems?

•How can we categorize application domains for computer software ?

•What myths about software still exist?

•Software characteristics.

•Failure curve for hardware

•The crisis of software.

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•Computer software is the product that designed and built bysoftware engineers.•Software is used by virtually everyone in society.•Software engineers have a moral obligation to build reliablesoftware that does no harm to other people.•Software engineers view computer software, as being madeup of the programs, documents, and data required to designand build the system.

•Software users are only concerned with whether or notsoftware products meet their expectations and make theirtasks easier to complete.

Overview

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HOW SHOULD WE DEFINE SOFTWARE ?

A textbook description of software might take the

following form: Software is (1) instructions (computer programs) that when

executed provide desired function and performance,(2) data structures that enable the programs to

adequately manipulate information, and (3)documents that describe the operation and use of the programs.There is no question that other, more complete

definitions could be offered. But we need more thana formal definition.

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Software•Software is both a product and a vehicle

for developing a product.•Software is engineered notmanufactured.

•Software does not wear out, but it doesdeteriorate.•Currently, most software is still custom-

built.

SOFTWARE CHARACTERISTICS

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F A I L U R E R

A T E

TIME

“Infantmortality”

“Wear out”

Figure2.1:- Failure curve for hardware

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F A I L U R E

R A T E

TIME

Figure2.2:- Idealized and actual failurecurves for software

Increased failure ratedue to side effects

Idealized curve

Change

Actualcurve

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Software application

System Software

Real time software

Web-based software

Business software

Engineering and scientific software

Embedded softwarePersonal computer software

Artificial intelligence software.

Compilers, editors, and file management utilities,operating system components , drivers ,

telecommunications processors

Software that monitors/analyzes/controls real-world events as they occur is called real time

Payroll , accounts receivable/payable ,inventory,MIS , Point of sale transaction

processing

Scientific area are moving away from

conventional numerical algorithms . Computer-aided design , system simulation , and otherinteractive applications have begun to take on

real time and even system software

characteristic.

Keypad control for microwave oven , Digitalfunctions in an automobile such as fuel control ,

dashboard displays, and braking systems

Word processing , spreadsheets , computergraphics , multimedia , entertainment , databasemanagement , personal and bussiness financial

applications , external network.

HTML,Perl, or Java and data hypertext and avariety of visual and audio formats

Expert systems , Knowledge based systems ,pattern recognition (image and voice),artificialneural networks, theorem proving , and game

playing.

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Types of Software • System software

– it services other programs – heavy interaction with hardware,

• Real-time software

– data gathering component – analysis component – monitoring component

• Business software – largest single software area – MIS important component

• Engineering and scientific software

– number crunching numerical algorithms

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Types of Software

• Embedded software – resides in read-only memory of any appliances – controls products and system for consumers

• PC software – several hundreds of applications available assoftware packages

• Web-based software – unlimited software resource

• AI software – makes use of non-numerical algorithms

– expert systems, pattern recognition, games

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•Software failures receive a lot more publicitythan software engineering success stories.•The software crisis predicted thirty years agohas never materialized and softwareengineering successes outnumber the failures.•The problems that afflict software developmentare associated more with how to develop andsupport software properly, than with simplybuilding software that functions correctly .

Software Crisis

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Software MythsManagement myths.

Customer myths.

Practitioner’s myths.

Myth?Reality?

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Evolving Role of Software

• Software is both a product, and the meansfor delivering a product or service

• The most important product of our time:information

• Advances in hardware performance resultin ever more complex softwareapplications

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Important Questions

• Why does it take so long to finish asoftware project?• Why does it cost so much to develop

software?• Why do we deliver software with

significant bugs still present?

• Why is it so hard to measure progressduring development?

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KEY POINTS OF TODAY’S LECTURE

1.Software is both a product and a vehicle fordelivering a product.

2. Software is engineered, not manufactured.3.Software doesn’t wear out , but it doesdeteriorate.

4.Most software continues to be custom built .

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LEC SEPA-0206

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Transcript of LEC SEPA-0206