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USE CASEBayu Adhi Tama, MTI
[email protected]
Faculty of Computer Science, University of Sriwijaya
Slides are adapted from Petrus Mursanto ([email protected])
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To outline the functionality of the system.
To define what will be handled by the system andwhat will be
handled outside the system.
To define who and what will interact with the system.
How to create diagrams of the use-case model.
How to create the use-case specification.
Objectives
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A use case describes a sequence of actions of a systemperforms
that yields a result of value to a particular
actor.
A series of user system interactions that helps theuser to
accomplish something.
What is use case?
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Does ATM provide?
Does a library information system provide?
What kind of services...
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A use case describes a process.
A process describes, from start to finish, a sequence
of events, actions, and transactions required toproduce or
complete something of value to anorganization or actor.
e.g. Withdraw cash from an ATM, Register for courses
at school, etc.
Use case and Domain Process
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Actor-based:
Identify the actors related to a system or organization.
For each actor, identify the process they initiate orparticipate
in.
Event-based:
Identify the external events that a system must respondto.
Relate the events to actors and use cases.
Identifying Use Case
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An actor is an entity external to the system who insome way
participates in the story of the use case.
There is one initiator actor who generates the
starting stimulus, and possibly several other participating
actors.
Kind of actors include: roles that people play,computer systems,
electrical or mechanical devices
Actor
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To find the actors, ask the following questions:
Which user groups require help from the system toperform their
tasks?
Which user groups are needed to execute thesystem's most obvious
main functions?
Which user groups are required to performsecondary functions,
such as system maintenanceand administration?
Will the system interact with any external hardware
or software system?
Find Actors
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A use case diagram illustrates a set of use cases for asystem,
the actors, and the relation between the actors
and use cases.
Use Case Diagram
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Assume that we have been requested to create thesoftware to run
a point-of-sale terminal.
Point of Sale (POS) Terminal (1)
POS Terminal system boundary
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Point of Sale (POS) Terminal (2)
POS Terminal checkout boundary
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UC Specification in ATM System: Withdraw Money
1. The use case begins when a client inserts a card intothe ATM.
The system reads and validates informationon the card.
2. The system prompts for a personal identificationnumber (PIN).
Client enters the PIN. The systemvalidates the PIN.
3. The system asks which operation the client wishes toperform.
Client selects Withdraw Money.
4. The system requests the amount of withdrawal.Client enters
amount.
Use Case Specification
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UC Specification in ATM System: Withdraw Money
5. The system request the account type. Client selectsthe
account type (checking, saving, credit).
6. The system communicates with the ATM network to
validate the account ID, PIN, and availability of theamount
requested.
7. The system asks the Client whether a receipt isdesired. This
step is performed only if there is paperavailable to print the
receipt.
8. The system asks the Client to remove the card. Clientremoves
the card.
9. The system dispenses the requested amount of cash.
10. The system prints a receipt, if required, which ends
the use case.
Use Case Specification
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Example
Use case : Buy Items
Actors : Customer (initiator), Cashier
Description : A Customer arrives at a checkout with
items to purchase. The Cashier records
the purchased items and collectspayment. On completion, the
Customer
leaves with the items.
Use Case Specification
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Use Case Specification
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Use Case Specification
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Name a use case starting with a verb in order toemphasize that
it is a process.
Buy Items
Enter an Order
Maintain Customer Profiles
Naming Use Case
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Include UC Relationship
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Extend UC Relationship
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Library Information System
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Library Information SystemUndergraduates point of view
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Library Information SystemPostgraduates point of view
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Library Information SystemLecturers point of view
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Library Information SystemLibrarians point of view
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Library Information SystemUC
Library Information System
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Library Information SystemUC
Library Information System (REVISE
D)
