requirements 4up

7/30/2019 Requirements 4up

1/15

DCS310SystemsAnalysis

Requirements

Slide1

R

equirementsCapture

DCS310

SystemsAnalysis

Basedonmaterial

I.T.Hawryszkiewycz


Requirements

Slide2

Objectives

Followingthislectureyoushould:

Understandtheimportanceanddifficulty

ofcapturingrequirements

Beableto

selectandapplybasictechniquesfor

require

mentscapture

writea

planforgatheringrequirements

D

CS310SystemsAnalysisRequirements

Slide3

Over

view

Whatarerequiremen

ts?

requirementsversusspecification

difficultyofcapturing

requirements

Requirementsgatheringtechniques

Interviewing

Alternativewaytocapturerequirements

D


Slide4

Sou

rces

Object-OrientedSystem

sAnalysisandDesign,

Bennettetal,Chapter6

:6.1-6.4

Seealso:

JacksonsarticleonRe

quirements(handout#1)

Alternativebook

IntroductiontoSystems

AnalysisandDesign,5e,

Hawryszkiewycz

Chapters4,RequirementsAnalysis

Chapter19,Interviewin

g


2/15


Requirements

Slide5

RequirementsandSpecification

whatisthedistinction

whyrequirementsarehard

togetright


Requirements

Slide6

R

equirementsv.Specifica

tion

System

System

Environmen

t

System

Boundar

y

Purpose,i.e.requirement

Behaviour,

i.especification

output

inpu

t

D


Slide7

SystemCorrectness

Asystemiscorrectifitsatisfiesits

specification

BUTasystemiso

nlyusefulifit

satisfiesitsusers

requirementsmustbeunderstood

Manysystemdevelopmentsfail

poorunderstandin

gofrequirementsisa

majorcauseoffailure

D


Slide8

GettingPrecis

eSpecifications

Requirementscaptureisnotanideaapplicable

onlytothedevelopment

ofinformationsystems

Itisusedinotherdisciplinesthatcreatenew

systems

PLAN

HOUSE

BU

ILDING

TO

PLAN


3/15


Requirements

Slide9

SpecifyingInformationSystems

Informa

tionsystemsareverycom

plex

butso

aree.g.aircraft

Nophysicalprincipleoforganisation

c.f.ho

useplan,aircraftdesign

Conversionbetweenusersystemand

computersystem


Requirements

Slide10

Translation

Bankspeak

Computerspeak

Systemspeak

Riskevaluationmust

takeintoa

ccount

customerincome

andas

sets

Setupinterfacesto

captureinputsfrom

managerandcompareto

storedcriteria

Specification

Thesyste

msanalystactsasatranslatorfromthe

languageofthebusinessworldtotha

tofthe

computerworld

D


Slide11

IntermediateLanguage

WhatIntermediateLanguage?

REQUIREMENTS

CAPTURE

Business

process

System

specification

SYSTE

M

ENGIN

EERING

Implementation

Describewhatis

nee

ded

Describewhatwill

beimplemented

D


Slide12

Requiremen

tsSummary

Buildinganewsystem?

understanditspurposerequirements

describebehaviour

writeaspecification

beforeyoubuild

it!

Requirementscaptu

reisdifficult

translatebetweenapplicationandsystem

worlds


4/15


Requirements

Slide13

Example:CrossingtheStraitofGib

raltar

1.Thecapacityofthetransportsystemsacrosst

heStrait

shouldbeincreased,atleastthreefold.

2.Theminim

umheightbelowthecentrespanw

illbe25m.

3.Thebridge

isfortheuseoflightfreight,businesstravellers

andtourists.

4.Shipsupto

100,000tonsshouldbeabletopassthe

crossing.

5.Thecrossingwillbedualcarriageway.

6.ThetimetakentocrosstheStraitshouldbere

ducedbyat

leasthalf.

7.Emergency

escaperouteswillbeprovided.

8.Twoartific

ialislandwillbebuilt,linkedbya

bridge.

SpecificationorRequirements?


Requirements

Slide14

Example:CrossingtheStraitofGib

raltar

1.Thecapacityofthetransportsystemsacrossth

eStrait

shouldbein

creased,atleastthreefold.

2.Thebridgeisfortheuseoflightfreight,businesstravellers

andtourists.

3.Shipsupto100,000tonsshouldbeabletopassthe

crossing.

4.Thetimetak

entocrosstheStraitshouldbered

ucedbyat

leasthalf.

5.Emergencyescaperouteswillbeprovided.

GoodRequirements?

Ambiguous

Implementation

Irrelevant

D


Slide15

ExampleRequirements

Requirementsforbooksonline.com

Detailedrequirements

achievemoreabstractones

A.Cutthecostofsellingaboo

kbyX%

comparedwith

B.Fullyautomatebookorders

frompublishers.

C.Transmitdailybookordertoeachpublisher

usingthestandardBookDataE

xchange

Languagev1.3

More

Detail

D


Slide16

Busines

sGoals

Businessgoalsforboo

ksonline.cominclude

costreduction-requirementA

Businessgoal/objective

closesttouserspurpo

se

canbeusedtoevaluatesuccessofasystem

A.CutthecostofsellingabookbyX%

comparedwith


5/15


Requirements

Slide17

Scope-WhichSystem?

Whereis

thesystem

boundary?

Requirem

ents

gathering

coverslarge

scope

somerequirements

maybe

excluded

Needtospecifythe

systemboundary

how?

system?

ITsystem


Requirements

Slide18

FindingStakeholders

Stakeholders:personseffectedbytheintroduction

ofanITsy

stem---orthosewhohaveastakein

theITproject.

Includesu

sers,management,otherstaff,

customers,membersofpublic

Requirementscapturemustconsiderall

stakeholde

rs---theyarethosewhoarea

ffectedby,

andthosewhoaffect,thesuccessofthe

project.

Whathap

pensiftheydisagree?

D


Slide19

Summary

Severalwaystodistin

guishrequirementsand

specification

purpose(whatitisfor)versusbehaviour(whatit

does)

translationbetweenap

plicationandsystemworlds

abstracttodetailed(businessgoaltouser

requirement)

Keyquestions:

scope:whichsystem?

stakeholders:whosesystem?

D


Slide20

Requireme

ntsCapture


6/15


Requirements

Slide21

Where

doRequirementsComeFrom?

Stakeholders,including

custo

mer

users

Existingsystemsandpractices

Bestpr

acticeandcompetitors

Assumptions

preciserequirementsexist

Cangetrequirementsfromorganisation


Requirements

Slide22

R

equirementsCapture

System

aticprocess

comprehensive:nothingmissed

efficient:avoidduplication

Search

throughanorganisatio

n

nots

tudyinoffice

Multip

letechniques

depe

ndsonapplication

D


Slide23

RequirementsCaptureTechniques

BackgroundReading

Interviewing

Questionnaires

Documentsampling

Observation

D


Slide24

Backgroun

dReading

Companyinformation

reports,organisationchart,

jobdescriptions,

Documentationofexisting

system

mostI.Sreplaceanexisting

system

Bestpractice

!Essentialpreparation,e

speciallyforinterviewing

"Documentationmaybeout

ofdate


7/15


Requirements

Slide25

RequirementKeyPoints

Identifyst

akeholders(inclorganisationaldyn

amics)

Understan

dwhattheywant

Interactwiththemtosharetherequirement(interview/

prototyoping/requirementworkshop...)


Requirements

Slide26

Existingdocumentsanddatacanprovide

information

Formsan

ddocuments

Compute

rprogramsanddatabases

Proceduremanuals

Reports

DocumentSampling/Examining

Data

PROGRESS

ProgramFAST

Procedure

FASTE

R

GoTo

EVEN-FA

STER;

!Quantitativedata,e.g.averageordersize

!Errorratesintheexistingsystem

"Limitedtocurrentsystem

D


Slide27

Questionnaires

HOWOFTENDOYOUUSETHE'EXPERTADVISOR'?

Never

Always

Seldom

Often

Sometimes

HOWMANYQUOTESDIDYOUMAKELASTMONTH?

1-10

11-30

31-50

>50

ONWHATPERCENTAGEOFTHESEDID

YOUUSETHEEXPERTADVISOR?

90%

11-50%

51-90%

DOESTHEADVISORASSISTYOUTO

MAKEBETTERQUOTES?

YES

NO

DOYOUMAKEQUOTESINLESSTIME

WITHTHEADVISOR?

YES

NO

CANYOUSUGGESTANYCHANGESTOTHEADVISOR?

!Goodforgettingfactual

data

manypeople

!Canbedoneelectronically

"Notgoodformorecomplex

data:

E.g.understandingworking

procedures

E.g.identifyingorganisationa

l

problem

D


Slide28

ObservationalMethods

Observepeopleatwork

analystobservesinperson

e.g.usevideo

Participation

analystjoinstheworkpla

ce

Techniques

analysepeoplesrole:practices,problems

informationused

interactionwithotherpeop

le

analyselocation:whathappensinaplace

analyseaprocessorobjecte.g.order:followit!


8/15


Requirements

Slide29

ObservationalMethods

!validityo

fdataaboutthecurrentsystem

!baselineperformancedataforthecurre

ntprocess

!verifyinformationgatheredinotherways

"observer

mustbetrained

"peopledislikebeingobservedandmay

behave

differently

"expensiveandlogisticallydifficult

"ethicalproblemsinsomeapplications


Requirements

Slide30

Interviewing

D


Slide31

InterviewPlan

Selectusers

Beginwithmanagement

Determinebestsequenceofusers

E.g.followtheprocessflow

Planforeachuser

Appointment

Checklist

D


Slide32

WhotoInterview?

Organizationchartsareoften

agoodindicatorofpeopleto

interview

STARTWITH

MANAGEMENT

FOLLOWUPWITHUSERS

goals

commitmenttothe

study

planwhoelsetobe

interview

co-operativeapproach

understandrole

getdetailsabouteach

task


9/15


Requirements

Slide33

TheInterview

#P

RELIMINA

RIES

#B

ODY

#C

ONCL

USION

$

Introduction

$

Definegoal;settimelimit

$

Askquestions

$

Checkunderstandingbysummarising

$

Followupquestions(probes)

$

Summarisefindings


Requirements

Slide34

KindsofQuestions

OPENQUEST

IONS

CLOSEDQUESTIONS

PROBES(followupquestions)

METHOD

Establishrapportandsenseofvalues

Findoutaboutthe

user

e.g.Whatisyoumainrole

Howdoyouregisteranewstudent

Allowusertotell

you

Istheformalw

ayscompletedinfull

Whichfieldsareoftenincorrect

Isiteverdoneinadifferentorder

OpenthenClosed

ClosedthenOpen

D


Slide35

Interview

ingHints

*Getusersconfidence *

Checkoutcomesofpreviousinterviews

*Dontbetoocritical

*Donotaskthesamequestions

Iamheretohelpyouto

improveyoursystem

Last

timeIunderstand

that........Isthistrue?

Ihearthereissomething

terriblywronghere

Iforget,didIaskyou

lasttimewhether..........

"!

!"

D


Slide36

Checking

Findings

Sometimesthereismorethanoneinterviewwiththesame

user

FIRSTINTERVIEW F

OLLOWU

PS

Getanideaofwhattheuserdoes.

Usethisinformation

tobuildaninitialmodel

Analysisresultsinqueries

Checkresultsandyourmodel

Resolvequerieswithfurther

que

stions


10/15


Requirements

Slide37

Plannin

gRequirementsGathering


Requirements

Slide38

RequirementsPlan

Objective

s

whatinformationareyouseeking

Technique

whattechnique(s)canbeusedtoobta

inthe

informa

tioneffectively

Sequence

andduration

startwithoverallorabstractrequirements,

progresstodetails

AgateLt

dcasestudy

D


Slide39

Requireme

ntsAnalysis

D


Slide40

WhatisAnalysis?

Analysisquestions:

arealltherequirementsgathered?

arethedifferentrequirementsconsistent?

whatbehaviourisimp

liedbyalltherequirements

expressedbyusers?

Requirementsareanalysedbybuilding

models

modelsarepartofthe

specification

Thiscourseismainly

aboutmodelling

techniques


11/15


Requirements

Slide41

WhatisaModel?

Abstrac

trepresentation

onlys

omepropertiesrepresented

Usedfo

ranalysisortesting

Commo

ninengineering

scalemodel,thermalmodel,spacemodel

physicalorcomputersimulation

eachmodelexaminesparticularpro

pertiesof

thefinalobject


Requirements

Slide42

ITSystemModels

Whattomodel?

businessprocesses

existingsystem

proposedsystem

Multiplemodels

How

tomodel?

datatransformation

datastructure

scenario

Good

Intermediate

Language?

W

hich

Prop

ertiesare

Represented?

D


Slide43

SHOWINGIN

TERACTIONS

withrich

pictures

Committee

chairperson

Committee

member

Financial

planner

Designer

Resolvingthe

contentsofthereport

andassig

ning

responsibilitiesfor

furtherw

ork

External

advisers

Exchangeof

information

Workgroup

member

Workgroup

member

Draftsections

Draftreport

Workplan

D


Slide44

Scen

arios

Chairpersonwritesabriefandassignsittodifferent

workgroups.

Workgroupleaderscoordinatetheirworkgroupsby

discussingthebriefandthencreatinganinitialdraft

whichispassedbetween

theworkgroupmembers.

Workgroupleadersmeetoccasionallywiththe

chairpersonandexternaladvisersandothernominated

committeememberstoresolveanyconflicts.

IdeabehindUseCases


12/15


Requirements

Slide45

AlternativeApproache

sto

Req

uirementsCapture

and

Analysis


Requirements

Slide46

LimitationsofStandardApproach

Requirementsmaynotbeknown

Differentusersmayhaveconflicting

requirem

ents

Usersmaynotbeabletoexpress

requirem

ents

Hardtovalidaterequirements

Usersdontknowwhattheyw

ant?

D


Slide47

Limitationsofthe

ClassicalApproach

Askuserstohelpw

iththerequirements

gatheringandspecification

Lettheuserstrythesystemout

Twoideastoovercome

thelimitations:

D


Slide48

Requiremen

tWorkshop

AlsocalledJointApplica

tionDevelopment.

Workshops,involving

sponsor,supportingthedevelopment

keyusers

mangersoftheusers

systemanalystsanddesigners

sessionleader

Modelbuildinge.g.richpictures,scenarios

Brainstorming


13/15


Requirements

Slide49

Prototyping

Severalrelatedmeaningsinsoftware

engineering;testout:

ifproblemissusceptibletoacompute

rsolution

whether

requirementsareunderstood

perform

anceofasystemdesign


Requirements

Slide50

Pro

totypingbyStoryboardi

ng

Checkus

errequirements

Checkus

er-interfacedesign

PRODUCER-NAME:

PRODUCT-NAME:

QUANTITY:

QUALITY-RATING:

ASKING-PRICE:

OFFER-NO:

BUY

ER:

PRODUCT-NAME:

OFFER-NO:

QUA

NTITY-REQUIRED:

REQUIRED-DATE:

OFFER-PRICE:

PURCHASE-NUMBER:

PRODUCT

OFFER

Send

Cancel

PURCHASE

OFFER

DELIVERY

ADVICE

PURCHASE-NUMBER:

BUYER:

PRODUCT-NAME:

TRUCKING-COMPANY:

DELIVERY-PRICE:

CONTRACTED-DELIVERY-TIME:

COMMISSION:

SALE-VALUE:

OFFER-NO:

OFFER-DATE:

Purchase

Offer

Buyer

Offer

Buyer

Accept

Visualisation

ofscenarios

Easierfor

usertocheck

Nodata

processing

D


Slide51

Iterative

Methods

Incrementaloriterativ

edevelopment

developinstages;earlyuserfeedback

Eachstagerepeatsreq

uirementcapture,modelling

anddevelopment

partoftheUnifiedSoftwareDevelopmentProcess

Extremeprogramming

highlyiterative

testcasesdefinedbefo

reimplementation

learnaboutthisinthe

SEcourse

D


Slide52

Summary

Requirementscapture

andanalysis

systematicprocesstogatherinformationandbuild

models:translationfromappdomaintomodels

MaintechniquesforR

equirementsCapture

Backgroundreading

Interviewingstakeho

lders

Questionnaires

Examinationofexistingformsanddocuments

(Documentsampling

)

Observationandparticipation


14/15


Requirements

Slide53

Summary

RequirementsAnalysis

builda

modelofthesystemtobe

developed

Conventionalmethodsmayfail

E.g.ne

wsystem,unabletoexpre

ss

require

mentsinsystemlanguage

Prototy

pes

JointA

pplicationDevelopment


Requirements

Slide54

C

aseStudy:Agat

e

(fromObje

ct-OrientedSystemsAnalysisand

Design;Bennett,

McRobbandFarmer)

D


Slide55

AgateHistory&Staff

AdvertisingagencyinBirmingham

Partnershipformedin19

82

Internationalbusiness

Staff

SeniorManagement

3directors

Creative

accountmanagers

graphicdesigners,copywriters

Admin&ITSupport

D


Slide56

AgateOrganisation

A

d

m

in

is

tratio

n

C

re

d

it

C

o

nt

ro

ller

A

c

c

o

u

n

ts

C

le

rks

P

u

rch

a

s

in

g

A

ss

istan

t

A

cco

u

n

ta

n

t

A

c

c

o

u

n

ts

G

rap

h

ics

D

esig

n

ers

C

o

p

y

W

riters

E

d

ito

rs

P

h

o

to

g

rap

h

ers

R

eso

u

rce

L

ib

rarian

A

c

c

o

u

n

t

M

a

n

a

g

e

rs

x

4

C

re

ative

C

o

m

p

u

tin

g

B

o

ard

o

f

D

ire

cto

rs

A

g

a

te

L

td


15/15


Requirements

Slide57

ExistingandProposedSyste

ms

Existingsystem:

clientm

anagement

record

names

assign

clientcontact

campaign

staffma

nagement

names,grades,bonuses

RedevelopexistingsysteminJava,

more

functions


Requirements

Slide58

Plan

forRequirementsGathe

ring

Objective

Technique

Subjects

Togetcompanyand

Backgroundreading

Companyreports,

industrybackground

tradejournals

Businessgoals

Interview

Twodirectors

Likelyscope

Understanddepartmentroles

Interview

Departmentheads

andthemanagem

entstructure

1accountmanager

Agreefurtherinter

views

Understand

Interview

1accountmanager

businessoperation

1graphicsdesigner

1copywriter


Slide59

PlanforRequire

mentsGathering

Objective

Tec

hnique

Subjects

Understandbusiness

Obs

ervation

2creativestaff

Establishrecords

Inte

rview

Resourcelibraria

n

kept

Filingclerk

Establishrecords

Doc

umentsampling

Accountrecords

kept

Establishaccounting

Inte

rview

Accountant

requirements

Purchasingassis

tant

Accountsclerk


Slide60

ClassQ

uestion

Prepareaninterview

checklistfor

interviewingthedire

ctors