3. Scenarios and Use Cases.pptx

8/16/2019 3. Scenarios and Use Cases.pptx

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Scenarios and Use CasesDr Kristin Stock


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1. Object Oriented Systems Analysis, Modelling

and Design

2. UML

. Use Case Diagrams

!. Ad"anced Use Case Diagram #eat$res

%. Describing Use Cases

&. Additional 'ools

(. Case st$dy) COM*ASS scenarios and $se cases

O$tline


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1. Object Oriented Analysis,Modelling and Design


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SDLC) Met+odologies

∗ Met+odology) a ormali-ed aroac+ toimlementing t+e SDLC

∗ Categories∗ /y area o oc$s

∗ *rocess oriented

∗ Data centered

∗ Object0oriented∗ /y se$encing and em+asis o +ases)

∗ Str$ct$red

∗ aid action de"eloment

∗

Agile de"eloment


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Object0OrientedSystems Analysis 3 Design

∗ Mod$lar 4 5e $se mod$les kno5n as objects

t+at encas$late bot+ data and rocess∗ 6e decomose roblems into objects t+at

combine bot+


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∗ Use0cases are t+e core o t+e met+odology

∗ How the user interacts with the systemto perform some activity.

∗ 7n+erently simle beca$se only one rocessat a time.

OOAD is Use0case Dri"en


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∗ #$nctional 4 +o5 t+e system

be+a"es rom t+e ersecti"e ot+e $ser

∗ Str$ct$ral 0 t+e objects t+e system$ses

∗ /e+a"io$ral 4 8o5 t+e objects

OOAD $ses 9ie5s

oad

oad #ootat+

ail5ay


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OOAD is 7terati"e and

7ncremental

#$nctional

Str$ct$ral

/e+a"io$ral

:rad$al re;nement o models

rom all t+ree "ie5s


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∗ Classes

∗ Objects

∗ Met+ods

∗ Messages

∗


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Classes and Objects

∗ Object =instance>)instantiation o a class

∗ eresentation o a real5orld object

∗ Attrib$tes) inormation t+atdescribes t+e class

∗ /e+a"io$rs) t+ings t+eobject does

∗ State) "al$es at a oint intime

oad

nameseed limit5idt+s$race

5iden

c+ange s$racec+ange seed limitoenclose


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Met+ods 3 Messages

∗ Met+ods) imlement t+e

be+a"io$r o a class

∗ Messages) inormationsent to an object to triggera met+od =roced$re call>

oad


5iden

c+ange s$racec+ange seed limitoenclose


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7n+eritance

∗ 7n+eritance∗

:eneral classes are created=s$erclasses>

∗ S$bclasses can in+erit dataand met+ods rom a

s$erclass∗ Abstract classes are not

instantiated.

oad


5idenc+ange s$racec+ange seed limitoenclose


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*olymor+ism 3 dynamic binding

∗ *olymor+ism) t+e samemessage can +a"e di?erent

meanings∗ Dynamic binding) tye o

object is not determined$ntil r$n0time

∗

Contrast 5it+ staticbinding) tye o objectdetermined at comile time


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2. Uni;ed Modelling Lang$ageUML


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'+e Uni;ed *rocess

∗ A seci;c SDLC met+odology.

∗ A t5o0dimensional rocess consisting o +asesand 5ork@o5s

∗ *+ases are time eriods in de"eloment

∗ 6ork@o5s are t+e tasks t+at occ$r in eac+ +ase

∗ Acti"ities in bot+ +ases 3 5ork@o5s 5ill o"erla


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'+e Uni;ed *rocess


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Uni;ed *rocess *+ases

∗ 7ncetion =similar to *lanning *+ase>∗ #easibility analyses erormed

∗ 6ork@o5s "ary b$t oc$s is on b$siness modeling 3re$irements gat+ering

∗

∗ 'ransition00#oc$s on testing 3 deloyment


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Uni;ed Modeling Lang$age

∗ *ro"ides a common "ocab$lary o object0

oriented terms and diagramming tec+ni$es∗ UML is not t+e only modelling

lang$agenotation =@o5 diagrams, data @o5diagrams, , b$t is no5 t+e

most o$lar.∗ Models are logicalB i.e., indeendent o +o5

t+ey are imlemented =man$al orcom$teri-ed>.


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OOAD 9ie5s

#$nctional

Str$ct$ral

/e+a"io$ral

:rad$al re;nement o models

rom all t+ree "ie5s

8o5 t+eobjectsinteract

'+eobjectst+esystem$ses

8o5 t+esystembe+a"es rom

t+eersecti"eo t+e $ser


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UML Diagrams

eresent t+edata and staticrelations+is inan inormationsystem

Deict t+edynamicrelations+isamong t+einstances orobjects t+atreresent t+eb$sinessinormationsystem


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. Use Case Diagrams


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What are Use Case Diagrams?

∗ '+e ;rst ste in t$rning t+e re$irements into

$nctional models.∗ Model +o5 a $ser interacts 5it+ a system to

erorm an acti"ity.

∗ 9ery +ig+ le"el 4 no details on rocess, str$ct$re,

etc.


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Example Use-Case

Library Book Collection

Management SystemUse Case Diagram


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Elements of Use-Case Diagrams

∗ Actors) $sers or ot+er interacting systems

∗

Associations) lines to connect actors and $se0cases

∗ 7nteractions, incl$sions, etensions orgenerali-ations

∗ Use0case) a major rocess in t+e system

t+at gi"es a bene;t to t+e $sers∗ S$bject bo$ndary) a named bo t+at deicts t+e

scoe o t+e system

∗ An association relations+i) links an actor 5it+ t+e


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!entifying Ma"or Use-Cases

∗ e"ie5 t+e re$irements de;nition

∗ 7dentiy t+e s$bjects bo$ndaries

∗ 7dentiy t+e rimary actors and t+eir goals

∗ 7dentiy t+e b$siness rocesses and major $se0

cases∗ Care$lly re"ie5 t+e c$rrent set o $se0cases

∗ Slit or combine some to create t+e rig+t si-e

∗ 7dentiy additional $se0cases


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∗ A story abo$t an eamle $ser and $se o t+esystem.

∗9ery $se$l or +eling yo$ t+ink abo$t $secases.

Mrs Smit+ likes to +a"e +er car ser"iced once a year ore"ery 1E,EEE kms, 5+ic+e"er is sooner, and is "eryconcerned t+at s+e not lea"e it too long. S+e 5o$ld

like to be reminded o t+e need or t+e ser"ice, b$tdoes not $se any tec+nology ot+er t+an a basic mobile+oneF..

∗ /ridge t+e ga bet5een re$irements and $secases.

Scenarios


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∗ oles t+at interact 5it+ t+e 7' system

∗ 7ncl$ding eternal systems∗ '+ose 5+o only recei"e rom t+e system are

also actors

∗ 'ime can also be an actor

∗ 'riggering timed rocesses∗ '+e role $sing t+e system is t+e actor

∗ e.g. 7 a c$stomer ser"ice re =CS> acts onbe+al o t+e c$stomer t+en GCS is t+e actor,

not GC$stomer

Actors


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∗ A role ma is a $se case diagram t+at s+o5s only

actors∗ Central diagram to deict $sers across t+e 5+ole model

∗ Can $se generali-ation to s+o5 o"erlaing roles

∗ May artially o"erla

∗ One role may comletely encomass anot+er

∗ *artial o"erlas can be eressed $sing abstractions

∗ Can simliy $se case diagrams by red$cing t+en$mber o associations

1%H.22% Systems Analysis and Design 2E1! E

ole Mas and :enerali-ations


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Actor :enerali-ation

Acco$ntingSta?

/ookkeeer

Acco$ntant

C$stomerSer"ice e

Overlapping role(abstraction)

C$stomerSer"ice

Manager

encompasses therole above

Specialized roles

concrete role


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∗ Collections o $se cases and t+e diagrams t+at

describe t+em∗ :ro$ related $se cases into a older

∗ Co$ld gro$ by main actor

∗ Or gro$ by b$siness $se case

∗ Or gro$ $sing anot+er aroac+∗ Iame a ackage 5it+ a no$n +rase related to

its $se case contents

Use Case *ackages


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Use Case Diagram 5it+ *ackages

C$stomerSer"ice e

CSManager

JActor9


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∗ Io r$les

∗ acobsen recommends abo$t 2E or a 1E erson0yearroject

∗ #o5ler reorts abo$t 1EE or a similar si-ed roject

∗ elate $se cases to release lan

∗

oll o$t at least one $se case =or $se casescenario> in eac+ release

∗ elease re$ency may imact on $se case si-eand n$mber

8o5 Many Use Cases in a*rojectN


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∗ Concets rom t+e $se cases become classes in t+estr$ct$ral model

Key /$siness Classes

*eaceCommittee

Case *ayment

*eace CommitteeMember

*eace:at+ering

resolved through

generateshandles


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!. Ad"anced Use CaseDiagram #eat$res


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∗ 7ncrease re$se in t+e $se case model

∗ Certain identical stes may aear in more t+anone case

∗


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∗ A stereotype is an etension o a UML

eat$re∗ o$ can add yo$r o5n

∗ A stereotye name aears in guillemets

∗ J'+ese are g$illemets

∗

One contet in 5+ic+ 5e mig+t $se t+is is tode;ne an actor t+at is not s+o5n as a stick;g$re

∗ Can be $sed to di?erentiate system actorsrom +$man actors

Stereotyes and Actors

JActorMessaging System


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#elations in Use Case Diagrams

∗ An incl$de relations+i) eresents t+e

incl$sion o t+e $nctionality o one $se case5it+in anot+er

∗ An etend relations+i) eresents t+e

etension o t+e $se case to incl$de otionalbe+a"ior.

∗ A generali-ation relations+i) eresents a

seciali-ed $se case to a more generali-ed one.


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Gincl$de Use Cases

Makeeser"atio

n

Change

Reservation

Agent

C+eckA"ailable

Seats

Jincl$de

Jincl$de

base use case

Included / inclusion use case


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∗ 6+ere 5e add re$irements to an eisting $se case withoutchanging the original use case

∗ Original $se case is stand0alone

∗


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Getend Use Case Diagram

Make 1st classreser"ation

Agent

Make

eser"ation

Jetend

extension points

Set seat class

Condition) assenger re$ested 1st classP


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∗ Can be abstract or concrete

∗ An actor co$ld $se a concrete generali-ed $se case∗ *ool common eat$res rom concrete seciali-ed

$se cases

∗ e.g. b$siness rocess s$c+ as credit card "alidation

∗ O"erride or etend asects o t+e $se case∗ Di?erent cards may re$ire di?erent +andling b$t

t+e rocess is m$c+ t+e same

:enerali-ed Use cases


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:enerali-ed Use Case


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+tt).orro.comndk


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%. Describing Use Cases


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∗ System $se cases are tyically described

5it+ tet∗ '+ey may also otionally be described $sing

∗ Acti"ity diagrams

∗ Decision tables

∗ Decision trees∗ Ot+er artiacts

Describing System Use Cases


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∗ 7ncororate best ractice

∗7nstit$tionali-e ractice 5it+in an organi-ation

∗ Can be c$stomi-ed to 5ork 5it+in a gi"en organi-ation

∗ Simle narrati"e to cat$re 5ork@o5s

∗ /asic @o5

∗ Q

∗ Alternati"e s$ccess @o5s

∗ Q

∗ @o5s

Use Case Descrition 'emlates


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∗ Iame, *ersecti"e, 'ye

∗ /rie descrition =one aragra+>

∗ $les o recedence =triggers, re0conditions>

∗ *ost conditions∗

∗ Contet diagram

∗ #lo5 o e"ents

∗ /asic @o5

∗ Alternate @o5s

∗


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∗ Secial re$irements =non0$nctional constraints>

∗

elated materials =links>∗ Acti"ity diagram

∗ User interace

∗ Class diagram

∗ Ass$mtions

∗ 7normation items

∗ *romts and messages

∗ /$siness r$les

∗


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∗ '+e Gideal alication o t+e $se case

∗ 'ell a story 4 $sers narrati"e o interaction

∗ Simle s$bject0"erb0object sentences

∗ Consistent tense =resent or $t$re>

∗


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∗ e"ie5 Case eort =artial>

∗ '+e System dislays a list o resol"ed cases t+at +a"e notbeen re"ie5ed

∗ '+e $ser selects a case

∗ '+e system "alidates t+at a case is ayable

∗ '+e system determines t+e ayment amo$nt

∗ '+e system marks t+e case as ayable

∗

'+e system records t+e ayment amo$nt∗ '+e system c+ecks t+e Cas+ $nd records to ens$re t+at

ade$ate $nds eist

∗ '+e system records t+e act t+at t+e case +as been re"ie5ed

∗ F

/asic #lo5


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∗ Scenarios not co"ered in t+e basic @o5 t+at still

reali-e a $ser goal∗ eco"erable errors otional or alternati"e

acti"ities

∗ Otions =e.g. Gsame day deli"ery>

∗

'ools =e.g. Gsell c+eck>∗ System state =e.g. Gitem o$t o stock>

∗ Data entry errors re"isions =e.g. G$nds too lo5 ort+at 5it+dra5al amo$nt>

Doc$menting Alternate #lo5s


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∗ #or eac+ alternate @o5, yo$ need to identiy)

∗ 'rigger∗ 6+at e"ent or decision ca$ses t+e alternate @o5

∗ Di"ergence oint

∗ 6+ere it occ$rs in t+e basic @o5

∗ Con"ergence oint∗ 6+ere it ret$rns to t+e basic @o5

Alternate #lo5 7ss$es

D i < i


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∗


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&. Additional 'ools


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∗ Describe t+e system resonses to a n$mber

o interrelated actors∗ Iot needed i actors can be e"al$ated

searately

∗ 'able lists all ossible sit$ations and +o5 t+e

system treats t+em∗ Acco$nts or all ossible combinations o

actors

∗ Can be $sed to create test cases

Decision 'ables


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∗ Lie ins$rance actors

Decision 'able


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∗ Alternati"e to a decision table

∗ Using a tree diagram rat+er t+an a table

Decision 'rees


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∗ 7 conditions can be e"al$ated one by one

rat+er t+an in combination, $se aconditionresonse table

Conditionesonse 'able

Condition Response

Under minim$m Io ta ayable

Minim$m 0 1H,EEE 'a bracket A1H,EEE.E1 0 &E,EEE 'a bracket /

&E,EEE.E1 0 %EE,EEE 'a bracket C

O"er %EE,EEE 'a bracket D


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(. CoM*ASS Case St$dy


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∗ Seci;cally a system or ad"anced searc+ and

disco"ery o scienti;c reso$rces)∗ jo$rnal aers

∗ data sets

∗ 5eb ser"ices t+at imlement scienti;c models.

∗ A Gkno5ledge inrastr$ct$re.∗ '+e creation o an ontology 5as central.

∗ Ontology T str$ct$re or describing kno5ledge$sing a ormal =logical> notation t+at allo5s

reasoning.

System :oals


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Scenario 1

1.1 Kno5ledge Disco"ery Scenario ane is a marine scientist and 5ants to b$y e$iment tost$dy a artic$lar +enomenon, abo$t 5+ic+ s+e +as littlekno5ledge. S+e 5ants to ;nd ALL t+e instr$ments t+at arecaable o st$dying t+at +enomenon and kno5ledge abo$t

+o5 to $se t+ose instr$ments and o +o5 t+at +enomenon+as been st$died in t+e ast. S+e is also interested ingat+ering jo$rnal articles and satial datasets o ast researc+on t+is +enomenon 5it+in +er seci;c st$dy area.


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Scenario 2

1.2 Kno5ledge Use Scenario ane +as disco"ered t+at t+ere +as been a lot o researc+ ont+is +enomenon in t+e ast, b$t t+at a ne5 meas$rementinstr$ment +as been de"eloed t+at meas$res t+is+enomenon to a m$c+ greater acc$racy and 5+ic+ +as not

been $sed in +er st$dy area beore. S+e 5ants to comareresearc+ s+e 5ill $ndertake 5it+ t+is ne5 instr$ment to allt+e earlier researc+ $ndertaken by "ario$s researc+ gro$s.S+e needs to collect t+e data o t+is ast researc+, and insome cases reormat t+e data, and do some statistical

analysis t+at comares t+e ast res$lts 5it+ +er data.


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Concet Ma

6orks+o Cometency


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∗For a specic instrument one wants to know:∗ 6+at does it meas$reN

∗ 6+at is t+e acc$racy or recisionN

∗ 6+at en"ironmental arameters are re$ired or s$ccess$l oerationN =e.g. inocean 5ater salinity can be meas$red 5it+ cond$cti"ity, b$t in brackis+ 5ater ac+emical meas$re mig+t be more sensible.>

∗ 6+o s$lies t+e instr$mentN

∗ 6+o +as $sed t+e instr$mentN

∗ 6+at do 7 get or reeN

∗For a specic survey one wants to know:∗ 6+at instr$ments do 7 +a"e to $seN

∗ 6+ic+ resol$tion do 7 needN

∗ 6+at are t+e ad"antages and disad"antages o a"ailable$sed instr$mentsN

∗ 6+at meas$rements +a"e been made =in t+e ast>N

∗ 6+ic+ instr$ments 5ere $sedN

6orks+o CometencyV$estions


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∗ UML is a modelling notation t+at enables OOAD.

∗ A collection o di?erent tyes o diagrams t+atare $sed toget+er.

∗ Use case diagrams gi"e a +ig+ le"el $nctional"ie5 o t+e system re$irements.

∗ Use scenarios to connect $nctional re$irementsto $se cases.

S$mmary

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3. Scenarios and Use Cases.pptx

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