the system life cycle

8/17/2019 The System Life Cycle

1/22

Dhruv goel

THE SYSTEM LIFE CYCLE


2/22

ANALYSIS STAGE• • methods of research!g a! e"st!g s#stem

• $ de!tf# a!d descr%e methods of research!g a! e"st!g s#stem &e'g' o%ser!terve)s(

• *uesto!!ares a!d e"am!ato! of e"st!g docume!ts+

• $ dscuss the dsadva!tages a!d adva!tages of the d,ere!t methods

• • record!g a!d a!al#s!g !formato! a%out the curre!t s#stem

• $ descr%e the !eed to de!tf# !-uts( out-uts a!d -rocess!g of the curre!t s

• $ descr%e the !eed to de!tf# -ro%lems )th the curre!t s#stem

• $ descr%e the !eed to de!tf# the user a!d !formato! re*ureme!ts for the

• • s#stem s-ec.cato!

• $ de!tf# a!d /ustf# suta%le hard)are for the !e) s#stem

• $ de!tf# a!d /ustf# suta%le soft)are for the !e) s#stem


3/22

SYSTEM


4/22

1EC01DING AND ANALYSING THE C31SYSTEM

• Develo-!g a!d actvat!g a !e) com-uter s#stlo!g -rocess' It s m-orta!t to %rea4 the -roces!to smaller stages( each o!e re*ur!g a d,ereof -rofesso!al s4lls'

• A! m-orta!t -art of ths -rocess s the .rst sta

5 analysis' Dur!g ths stage the s#stems a!al#!vestgate ho) the curre!t s#stem )or4s a!d )!eeds to %e m-roved' Ths !volves .!d!g out)hether a !e) com-uter s#stem s !eeded at ae"actl# )hat t )ll %e used for'


5/22

1EC01DING AND ANALYSING THE C31SYSTEM

1 fact .!d!g7collect!g data from the curre!t s#stem2 descr-to! of the curre!t s#stem 8 esta%lsh!g the !-uts( ou

-rocess!g %e!g do!e

3 de!t.cato! of the -ro%lems )th the curre!t s#stem

4 agree!g the o%/ectves )th the customer

5 de!tf#!g a!d agree!g the customer9s re*ureme!ts

6 !ter-ret!g the customer9s re*ureme!ts

7 -roduc!g a cost5%e!e.t a!al#ss

8 -roduc!g a data :o) dagram'


6/22

1ESEA1CHING AND ANALYSING A SYST

•

Hav!g !vestgated the -rese!t s#stem( the s#stems a!al#st )-roduce a feasibility study' Ths )ll loo4 at )hether the !e) s;

• Technically feasible 5 s the !e) s#stem tech!call# -oss%le tm-leme!t ! the tme avala%le<

• Economically viable 5 )ll the cost of the !e) s#stem %e o,se

sav!gs o!ce t s m-leme!ted( e )ll t save the orga!sato! tmo!e# or !crease ts -erforma!ce<

• The -ro/ect )ll o!l# co!t!ue to the !e"t stage f the a!s)er tothese *uesto!s s #es' At ths -o!t the decso! ma4ers ! theorga!sato!( eg the %oard of drectors( decde )hether or !ot tahead'


7/22

THE DESIGN STAGE

• descr%e ho) t s !ecessar# to desg! docume!ts( .les( formre-orts7out-uts a!d valdato!

• -roduce desg!s to solve a gve! -ro%lem

• desg! data ca-ture forms a!d scree! la#outs

• desg! re-ort la#outs a!d scree! ds-la#s

• desg! valdato! rout!es &!clud!g le!gth chec4( t#-e chec

chec4( -rese!ce(chec4 dgt+

• desg! the re*ured data7.le structures &e'g' .eld le!gth( .eld

t#-e+


8/22

DESIGNING THE NE2 SYSTEM• desg!!g data ca-ture forms7!-ut forms

• desg!!g scree! la#outs

• desg!!g out-ut forms a!d re-orts

• -roduc!g s#stems :o)charts a!d7or pseudo code

• select!g a!d desg!!g valdato! rules that !eed to %e used

• select!g the most a--ro-rate data ver.cato! methods

• desg!!g a!d agree!g the .le structures a!d ta%les

• select!g a!d desg!!g the hard)are re*ureme!ts

• select!g a!d desg!!g the soft)are re*ureme!ts

• -roduc!g algorthms or -rogram :o)charts

• desg!!g a test!g strateg#7-la!'


9/22

DATA CA=T31E TECHNI>3ES

• A paper form &a tmesheet+ 5 sm-le a!d chea-the !eeds to %e ma!uall# !-ut &slo)+ a!d the fca! %e lost

• Barcode reader 5 em-lo#ees could have ID cas)-e them at the start a!d e!d of )or4 &ca! ch

easl#+• in!erprint reader 5 em-lo#ees could -ut a .

the reader at the start a!d e!d of )or4 &hard to


10/22

DESIGNING 0N SC1EEN F01MS F01 DIN=3T

Much of the data that e!ters com-uter s#stems !eeds to %e typed

A "ell#desi!ned on#screen form ca! ma4e thstas4 easier a!d $uic%er'

Have all of the !ecessar# &elds

Have obvious -laces for user !-ut &%o"es( use of colour( etc'+ 3se a--ro-rate controls &see %elo)+ for each .eld

Have te"t %o" co!trols that are the ri!ht si'e for the data

Have eas#5to5u!dersta!d instructions &f !eeded+

Ma4e good use of the scree! area avala%le


11/22

DATA ?E1IFICATI0N TECHNI>3ES

•

?er.cato! s a )a# of -reve!t!g errors )he! daco-ed from o!e medum to a!other

1( )ouble entry; ! ths method( data s e!teredus!g t)o d,ere!t -eo-le' The com-uter com-the t)o e!tres( ether after data e!tr# or dur!g

data e!tr# -rocess( a!d de!t.es a!# d,ere!c•. *isual chec% ; ths s the chec4!g for errors %#

com-ar!g e!tered data o! the scree! )th the dthe org!al docume!t &ths s not the same as -rread!g+'


12/22

?ALIDATI0N TECHNI>3ES


13/22

DESIGNING DATA AND FILE ST13CT31

•

A data structure s a! orga!sed collecto! of data' Mostcommo!l#( ths )ll %e some sort of data%ase ! )hch d%e stored as t s %e!g -rocessed' 2he! desg!!g a datthe s#stem desg!er !eeds to co!sder;

@' The t#-e of data %e!g stored &!um%ers( te"t( dates( et

' The sBe of the data &ho) lo!g s a t#-cal !ame( etc'+

' The .eld !ames to use

' Ho) ma!# records )ll !eed to %e stored'

• The desg!er also !eeds to co!sder )hch %ac4!g stordevce a!d meda )ll %e suta%le to store the data


14/22


15/22

DESIGNING 0N SC1EEN 1E=01TS

•

Desg!!g a! o!5scree! re-ort s smlar to desg!o!5scree! form' There are a !um%er of th!gs thatdesg!er should co!sder'

• 0!5scree! re-orts should'''

Sho) all of the !ecessar# .elds

Have .elds that are the rght sBe for the data

Have eas#5to5u!dersta!d !structo!s &f !eeded+

Ma4e good use of the scree! area avala%le

Ma4e good use of colours a!d fo!ts to ma4e the data clear


16/22

TESTING The .rst -hase of test!g s do!e %# the desg!ers a!d e!g!eers )ho created the

usuall# %efore the s#stem s delvered to the customer' The seco!d -hase of test!

after the s#stem has %ee! delvered a!d ! stalled )th the customer' The data us

seco!d -hase s usuall# data that s actuall# -art of the customers %us!ess a!d

real users( )th real data( A test -la! s usuall# )rtte! )hlst the s#stem s %e!g

For e"am-le;

Does the s#stem o-e! a!d close -ro-erl#< Ca! data %e e!tered<

Ca! data %e saved<

Ca! re-orts %e -r!ted<

2he! #ou do someth!g )ro!g( does a! error message a--ear<

Is !vald data re/ected< E'g' f #ou are !ot allo)ed to e!ter a! amou!t a%ove @( o!

the s#stem the! a value of @(@ should !ot %e acce-ted &'e' does the valdato! )or4


17/22

TESTING ST1ATEGIES

• Normal; ths s data )hch s acce-ta%le7vald a!d has a! e"-ecteoutcome( e'g' the mo!th ca! %e a!# )hole !um%er ! the ra!ge @

• E"treme; ths s data at the lmts of acce-ta%lt#7valdt#( e'g' thca! %e ether of the t)o e!d values 'e' @ or @'

• A%!ormal; ths s data outsde the lmts of acce-ta%lt#7valdt# a%e re/ected or cause a! error message' For e"am-le( all the follo)are !ot allo)ed as !-uts for the mo!th;

a+ !egatve !um%ers &e'g' 8@( 8@+

%+ a!# value greater tha! @ &e'g' ( +

c+ letters or other !o!5!umerc data &e'g' ul#+

d+ !o!5!teger values &e'g' '( @'J+'


18/22

D0C3MENTATI0N

3ser Docume!tato!; The user docume!tato! s !te!ded to hel- thethe s#stem' The users are usuall# !o!tech!cal -eo-le( )ho do!t !eho) the s#stem )or4s' The# /ust !eed to 4!o) ho) to use t'

3ser docume!tato! usuall# !cludes;

A' Lst of m!mum hard)are a!d soft)are re*ured to use the s#stem

K' Ho) to !stall the s#stem

C' Ho) to start 7 sto- the s#stem

D' Ho) to use the features of the s#stem

E' Scree!shots sho)!g the s#stem ! t#-cal use

F' E"am-le !-uts a!d out-uts

G' E"-la!ato!s of a!# error messages that mght %e sho)!

H' A trou%leshoot!g gude


19/22

D0C3MENTATI0N

The tech!cal docume!tato! s !te!ded to hel- the ma!ta!ers of s#stem &the -eo-le )ho !eed to 4ee- the s#stem ru!!!g smoothl#-ro%lems( etc'+' The ma!ta!ers are usuall# tech!cal -eo-le( )ho !4!o) e"actl# ho) the s#stem )or4s'

Tech!cal docume!tato! usuall# !cludes;

• Detals of the hard)are a!d soft)are re*ured for the s#stem

• Detals of data structures &data t#-es( .eld !ames( etc'+

• Detals of e"-ected !-uts

• Detals of valdato! chec4s

• Detals of ho) data s -rocessed

• Dagrams sho)!g ho) data moves through the s#stem

• Flo)charts descr%!g ho) the s#stem )or4s


20/22

IM=LEMENTATI0N


21/22

E?AL3ATI0N

The -ur-ose of a! evaluato! s to assess the s#stem to see f t dot )as su--osed to do( that t s )or4!g )ell( a!d that ever#o!e s)th t'

2he! the s#stems a!al#st evaluates the !e) s#stem( the follo)!

*uesto!s )ll %e as4ed;

• Is the s#stem sav!g tme( a!d resources<

• Are all of the s#stems users a%le to use the s#stem e,ectvel#<

• Ca! !e) sta, u!dersta!d a!d use the s#stem )th m!mal tra!!g<


22/22

E?AL3ATI0N The s#stems a!al#st )ll use a !um%er of tech!*ues to evaluate the s#

Chec4 aga!st the re*ureme!ts S-ec.cato!

The s#stems a!al#st )ll use ths docume!t to chec4 the !e) s#stem' Gthrough the re*ureme!ts o!e5%#5o!e the a!al#st )ll chec4 f the# have

Chec4 the users 1es-o!ses

• Do the# l4e t<

• Does t ma4e ther )or4 easer<

• 2hat( f a!#th!g( could %e m-roved<

The s#stems a!al#st ca! get ths feed%ac4 ! the same )a# the# colle!formato! a%out the org!al s#stem'''

• >uesto!!ares

• I!terve)s

• 0%servato!s

the system life cycle

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