Use Case diagram-UML diagram-2

Descriptive slides for the Use case Diagrams in UML

1. Duration: 3 Hrs
1
RamakantSoni
Assistant Professor
Dept. of Computer Science
B K Birla Institute of Engineering & Technology, Pilani, India
Ramakant Soni @ BKBIET Pilani

2. Each use case represents a unit of useful functionality that subjectsprovide to
actors.
An associationbetween an actor and a use case indicates that the actor and the
use case somehow interact or communicate with each other.
Only binary associations are allowed between actors and use cases.
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Only binary associations are allowed between actors and use cases.
An actor could be associated to one or several use cases.
Customer actor is associated with two use cases -Browse Items and Place Order.

3. A use case may have one or several associated actors.
Manage Account use case is associated with Customer and Bank actors.
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If there are several actors associated to the same use case, it may not be obvious
from use case diagram which actor initiatesthe use case, i.e. is a "primary
actor". (In non-standard UML, primary actorsare those using system services,
and supporting actorsare actors providing services to the system.)

4. UML allows the use of multiplicityat one or both ends of an association between the
actor and the use case.
Multiplicity of a Use Case
When an actor has an association to a use casewith a multiplicitythat is greater than
one at the use case end, it means that a given actor can be involved in multiple use
casesof that type.
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Bank actor is involved in multiple Transfer Funds use cases.
use case multiplicitycould mean that an actor interacts with multiple use cases:
•in parallel (concurrently), or
•at different points in time (overlapping), or
•mutually exclusive (sequentially, random, etc).

5. Multiplicity of an Actor
Requiredactormaybeexplicitlydenotedusingmultiplicity1orgreater.
Multiplicity0..1ofactormeansthattheactormayormaynotparticipatein
anyoftheirassociatedusecases.
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CheckoutusecaserequiresCustomeractor,hencethe1multiplicityof
Customer.TheusecasemaynotneedCreditPaymentService(for
example,ifpaymentisincash),thusthe0..1multiplicity.

6. Two or more Player actors are involved in the Play Game use case.
Each Player participates in one Play Game.
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Each Player participates in one Play Game.
For instance, multiplicity of actorcould mean that interaction of a particular
use case with several separate actor instances might be:
•simultaneous (concurrent) interaction, or
•overlapping interaction, at different points in time, or
•mutually exclusive (sequential, random, etc.) interaction.

7. Use cases could be organized using following relationships:
•Generalization
•Association
•Extend
•Include
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•Include

8. Generalization between Use Cases
Generalizationbetween use cases is similar to generalization between classes –
child use case inherits properties and behavior of the parent use case and may
override the behavior of the parent.
Generalization is shown as a solid directed line with a large hollow triangle
arrowhead, the same as for generalizationbetween classifiers, directed from the
more specific use case to the general use case.
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Web User Authentication use case is abstract use case specialized by Login,
Remember Me and Single Sign-On use cases.

9. Use cases can only be involved in binary associations.
Binary Association
Binary associationrelates twotyped instances. It is normally rendered as a
solid line connecting two classifiers, or a solid line connecting a single
classifier to itself (the two ends are distinct). The line may consist of one or
more connected segments.
Job and Year classifiers are associated
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Job and Year classifiers are associated
Two use cases specifying the same subject cannot be associated since
each of them individually describes a complete usage of the system.

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11. Example 1:
Airport check-in and security screening business model
Purpose: An example of a business use case diagram for airport check-in
and security screening.
Credits to: http://www.uml-diagrams.org
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and security screening.
Summary: Business use cases are:
Individual Check-In
Group Check-In (for groups of tourists)
Security Screening, etc.
representing business functions or processes taking place in an airport and
serving needs of passengers.

12. Actors are :
•Passenger,
•Tour Guide,
•Minor (Child),
•Passenger with Special Needs (e.g. with disabilities), all playing external
roles in relation to airport business.
Use cases are :
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•Individual Check-In
•Group Check-In (for groups of tourists),
•Security Screening , etc. -representing business functions or processes
taking place in airport and serving the needs of passengers.
•Baggage Check-in and Baggage Handling <<extend>> Check-In use
cases, because passenger might have no luggage, so baggage
check-in and handling are optional.

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14. Example 2: Bank ATM
Purpose:Describeusecasesthatanautomatedtellermachine(ATM)
providestothebankcustomers.
Summary:
Customer(actor)usesbankATMtocheckbalancesofhis/herbank
accounts,depositfunds,withdrawcashand/ortransferfunds(usecases).
ATMTechnicianprovidesmaintenanceandrepairs.
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AlltheseusecasesalsoinvolveBankactorwhetheritisrelatedto
customertransactionsortotheATMservicing.
ATMisabankingsubsystemthatprovidesbankcustomerswithaccessto
financialtransactionsinapublicspacewithouttheneedforacashier,
clerkorbankteller.

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16. OnmostbankATMs,thecustomerisauthenticatedbyinsertingaplastic
ATMcardandenteringapersonalidentificationnumber(PIN).Customer
AuthenticationusecaseisrequiredforeveryATMtransactionsoweshowit
asincluderelationship.
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Ifneeded,customermayaskATMforhelp.ATMTransactionusecaseis
<<extended>>viaMenuextensionpointbytheATMHelpusecase
wheneverATMTransactionisatthelocationspecifiedbytheMenuand
thebankcustomerrequestshelp,e.g.byselectingHelpmenuitem.

17. ATMTechnicianmaintainsorrepairsBankATM.Maintenanceusecase
includesReplenishingATMwithcash,inkorprinterpaper,Upgradesof
hardware,firmwareorsoftware,andremoteoron-siteDiagnostics.
Diagnosticsisalsoincludedin(sharedwith)Repairusecase.
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18. Example 3:
e-Library online public access catalog (OPAC)
Purpose: List top level use cases for e-Library online public access catalog.
AnOnlinePublicAccessCatalog(OPAC)isane-Librarywebsitewhichis
partofIntegratedLibrarySystem(ILS),alsoknownasaLibrary
ManagementSystem(LMS),andmanagedbyalibraryorgroupoflibraries.
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Summary:Patronsofalibrarycansearchlibrarycatalogonlinetolocate
variousresources-books,periodicals,audioandvisualmaterials,orother
itemsundercontrolofthelibrary.Patronsmayreserveorrenewitem,
providefeedback,andmanagetheiraccount.

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20. Example 3:
Online shopping use case diagrams
Purpose: Provide top level use cases for a web customer making purchases
online.
Summary: Web customer actoruses some web site to make purchases
online.
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online.
Top level use casesare:
•View Items,
•Make Purchaseand
•Client Register.

21. Description:
WebCustomerusessomewebsitetomakepurchasesonline.Toplevel
usecasesareViewItems,MakePurchaseandClientRegister.
ViewItems(usecase)couldbeusedbycustomerastoplevelusecaseif
customeronlywantstofindandseesomeproducts.Thisusecasecould
alsobeusedasapartofMakePurchaseusecase.
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ClientRegister(usecase)allowscustomertoregisteronthewebsite.
Note,thatCheckoutusecaseis<<included>>usecasenotavailableby
itself.
checkoutis part of make purchase.
ExceptfortheWebCustomeractorthereareseveralotheractorswhich
willbedescribedbelowwithdetailedusecases.

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23. ViewItemsusecaseisextendedbyseveraloptionalusecases-customer
maysearchforitems,browsecatalog,viewitemsrecommended for
him/her,additemstoshoppingcartorwishlist.Alltheseusecasesare
extendingusecasesbecausetheyprovidesomeoptionalfunctions
allowingcustomertofinditem.
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CustomerAuthenticationusecaseisincludedinViewRecommended Items
andAddtoWishListbecausebothrequirecustomertobeauthenticated.
Atthesametime,itemcouldbeaddedtotheshoppingcartwithoutuser
authentication.

24. Checkoutuse case includes several required uses cases. Web customer
should be authenticated. It could be done through user login page, user
authentication cookie ("Remember me") or Single Sign-On (SSO).
Web site authentication service is used in all these use cases, while SSO also
requires participation of external identity provider.
Checkoutuse case also includes Paymentuse case which could be done
either by using credit card and external credit payment service or with
PayPal.
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PayPal.

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26. Example 4:
Credit card processing system
Purpose: Define major use cases for a credit card processing system(credit
card payment gateway).
Summary:Themerchantsubmitsacreditcardtransactionrequesttothe
creditcardpaymentgatewayonbehalfofacustomer.Bankwhichissued
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creditcardpaymentgatewayonbehalfofacustomer.Bankwhichissued
customer'screditcardisactorwhichcouldapproveorrejectthe
transaction.Iftransactionisapproved,fundswillbetransferredto
merchant'sbankaccount.

27. Creditcardprocessingsystemdescription
CreditCardProcessingSystemisasystemunderdesignorconsideration.
PrimaryactorforthesystemisaMerchant’sCreditCardProcessingSystem.
Themerchantsubmitssomecreditcardtransactionrequesttothecredit
cardpaymentgatewayonbehalfofacustomer.Bankwhichissued
customer'screditcardisactorwhichcouldapproveorrejectthe
transaction.Iftransactionisapproved,fundswillbetransferredto
merchant'sbankaccount.
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AuthorizeandCaptureusecaseisthemostcommontypeofcreditcard
transaction.Therequestedamountofmoneyshouldbefirstauthorizedby
Customer'sCreditCardBank,andifapproved,isfurthersubmittedfor
settlement.Duringthesettlementfundsapprovedforthecreditcard
transactionaredepositedintotheMerchant'sBankaccount.

28. Credit card processing system description
Insomecases,onlyauthorizationisrequestedandthetransactionwillnot
besentforsettlement.Inthiscase,usuallyifnofurtheractionistakenwithin
somenumberofdays,theauthorizationexpires.Merchantscansubmitthis
requestiftheywanttoverifytheavailabilityoffundsonthecustomer’s
creditcard,ifitemisnotcurrentlyinstock,orifmerchantwantstoreview
ordersbeforeshipping.
Capture(requesttocapturefundsthatwerepreviouslyauthorized)use
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Capture(requesttocapturefundsthatwerepreviouslyauthorized)use
casedescribesseveralscenarioswhenmerchantneedstocompletesome
previouslyauthorizedtransaction-eithersubmittedthroughthepayment
gatewayorrequestedwithoutusingthesystem,e.g.usingvoice
authorization.

29. Credit card processing system description
Credituse case describes situations when customer should receive a refund
for a transaction that was either successfully processed and settled through
the system or for some transaction that was not originally submitted through
the payment gateway.
Voiduse case describes cases when it is needed to cancel one or several
related transactions that were not yet settled. If possible, the transactions
will not be sent for settlement. If the Void transaction fails, the original
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will not be sent for settlement. If the Void transaction fails, the original
transaction is likely already settled.
Verifyuse case describes zero or small amount verification transactions
which could also include verification of some client's data such as address.

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31. References:
[1] http://www.uml-diagrams.org/
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