4. software development life cycle

8/9/2019 4. Software Development Life Cycle

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Software Development Life

Cycle


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Analysis

Problem

Statement

Software

Design

Testing anddebugging

Installation

SoftwareConstruction

Maintenance


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Analysis

Acquire a clear idea of existing system

Data used to accomplish the tasks

Outputs produced

Agreement developers & users

System requirementspecifcation must be written


4/17

ro!lem Statement

"t is important !ecause#

$any people involved

%sers need to understand changes

implied

Study costs vs !enefits

System needs to !e tested properly


5/17

act finding#

"nterviews

'uestionnaires

Search existing documentsCheck other solutions for same pro!lem

O!serve people working

Outcome of Analysis Phase:Feasibility Analysis and

Development Plan

ro!lem Statement


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easi!ility Study(eport produced during analysis) design

or !oth#

* +stimates costs

* "dentifies expected !enefits

* +stimates how long the pro,ect will take

* Outlines potential difficulties

If accepted Detailed Design


7/17

Software Design

"nputs -data capture methods.$anual +ntry # key!oard) mouse)

Direct +ntry# O$() OC() $"C() !arcodesAutomatic +ntry# sensors) !uttons) switches

Outputs -formats. /ardcopy# printed reports) graphic plots

Softcopy# temporary output -monitors) displays. hysical# actuators) relays

Data file formats


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$odularity -top down design.

+rror detection

(e0useSplit work

+asier to program small modules

+asier to understand & maintain

Software Design


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rototyping

Def# simple version of a system producedduring the design stage

O!,ective# show the user an interface and togive some idea of how the system is expectedto work

Can !e presented in a different system than theeventually used for the pro,ect -eg 1ava.

Adv# at early stages) the designer can producedifferent alternative solutions for the user togive feed!ack and make a decision


10/17

2esting & De!ugging

Software errorsLogic

(untime

Syntax

unctional 2esting

2esting input data -normal) extreme)

a!normal.


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System Documentation

System documentationrovided for other programmers

"nternal -good programming style.+xternal

%ser documentation3on0technical users


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"nternal Documentation"nclude comments in source code listing to#

+xplain purpose of each su!program

Descri!e type and purpose of parameters or

local varia!les

$eaningful names) small modules &

constant indentation



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+xternal Documentationurpose of program

Data flow in system

/ard and software requirements of the solution

Description of different modules

$odule interface -parameters used.List of identifiers

Description of modules

Description of data structures used

2est plan

Description of testing and de!ugging done+valuation of the system



14/17

%ser Documentation

or non0technical users

"nclude

/ow to install the prg -hardware & softwarespecifications./ow to use the prg -sample inputs & expected

outputs4 Screen shots.

/ow to trou!leshoot difficulties -for quicklyfinding solutions to their pro!lems.

Some include onscreen or online help


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"mplementation2raining

Different methods of changeoverarallel running

hased introduction

5ig 5ang or direct changeover


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$aintenance

+xpensive & time consuming -easier and

cheaper if modular design.eriodic reviews of the systemact finding -interview) questionnaires) etc.

Analysis


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Software Development Life

Cycle

4. software development life cycle

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