Using UML, Patterns, and Java
Object-Oriented Software Engineering
Chapter 4,Use Case and
Statechart Diagrams
Outline of this Class
• Use case diagrams
• Describe the functional behavior of the system as
seen by the user
• Class diagrams
• Describe the static structure of the system: Objects,
attributes, associations
• Sequence diagrams
• Describe the dynamic behavior between objects of
the system
• Statechart diagrams
• Describe the dynamic behavior of an individual
object
• Activity diagrams
• Describe the dynamic behavior of a system, in particular
the workflow.
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Object-Oriented Software Engineering: Using UML, Patterns, and Java
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Another view on UML Diagrams
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UML Use Case Diagrams
Used during requirements elicitation and
analysis to represent external behavior
(“visible from the outside of the system”)
An actor represents a role, that
is, a type of user of the system.
Passenger
A use case represents a class of
functionality provided by the system.
PurchaseTicket
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Use case model: The set of all use
cases that completely describe the
functionality of the system.
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Use Case Example
Handle Returns
Main Success Scenario: A customer arrives at a
checkout with items to return. The cashier uses the
POS system to record each returned item.
Alternate Scenarios:
-If they paid by credit, and the reimbursement
transaction to their credit account is rejected, inform
the customer and play them with cash.
- If the item identifier is not found in the system,
notify the Cashier and suggest manual entry of the
identifier code.
- If the system detects failure to communicate with
the external accounting system, .....
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Actors
• An actor is a model for an external
entity which interacts
(communicates) with the system:
• User
• External system (Another system)
• Physical environment (e.g. Weather)
Passenger • An actor has a unique name and
an optional description
Optional
• Examples:
Name
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Description
• Passenger: A person in the train
• GPS satellite: An external system that
provides the system with GPS
coordinates.
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Use Case
PurchaseTicket
• A use case represents a class of
functionality provided by the
system.
• Use cases can be described
textually, with a focus on the event
flow between actor and system.
• The textual use case description
consists of 6 parts:
1.
2.
3.
4.
5.
6.
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Unique name
Participating actors
Entry conditions
Exit conditions
Flow of events
Special requirements.
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Textual Use Case
Description Example
Passenger
1. Name: Purchase ticket
2. Participating actor:
Passenger
3. Entry condition:
• Passenger stands in front
of ticket distributor
• Passenger has sufficient
money to purchase ticket
4. Exit condition:
• Passenger has ticket
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PurchaseTicket
5. Flow of events:
1. Passenger selects the
number of zones to be
traveled
2. Ticket Distributor displays
the amount due
3. Passenger inserts
money, at least the
amount due
4. Ticket Distributor returns
change
5. Ticket Distributor issues
ticket
6. Special requirements:
None.
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Uses Cases can be related
• Extends Relationship
• To represent seldom invoked use cases or exceptional
functionality
• Includes Relationship
• To represent functional behavior common to more than
one use case.
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The <<extends>> Relationship
• <<extends>> relationships
model exceptional or seldom
invoked cases
• The exceptional event flows
are factored out of the main
event flow for clarity
• The direction of an
<<extends>> relationship is to
the extended use case
• Use cases representing
exceptional flows can extend
more than one use case.
Passenger
PurchaseTicket
<<extends>>
<<extends>>
<<extends>>
OutOfOrder
<<extends>>
Cancel
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TimeOut
NoChange
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The <<includes>> Relationship
•
•
Passenger
•
PurchaseMultiCard
PurchaseSingleTicket
•
<<includes>>
<<includes>>
<<extends>>
CollectMoney
NoChange
Bernd Bruegge & Allen H. Dutoit
<<extends>>
Cancel
<<includes>> relationship
represents common functionality
needed in more than one use case.
<<includes>> behavior is factored
out for reuse, not because it is an
exception.
The direction of a <<includes>>
relationship is to the using use case
(unlike the direction of the
<<extends>> relationship).
Two use cases are related by an
include relationship, if one of them
includes the second one in its own
flow of events.
<<extends>>
Cancel
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Example of <<includes>> relationship - 1
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Example of <<includes>> relationship - 2
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Example of <<includes>> relationship - 3
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Example of <<extends>> relationship
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Textual Use Case
Description Example
1. Name: DoHomework
2. Participating actor:
Student
3. Entry condition:
• Student received exercise
sheet
• Student is in good health
4. Exit condition:
• Student delivered solution
Student
5. Flow of events:
DoHomework
1. Student fetches the
exercise sheet
2. Student reads through
the assignments
3. Student processes the
assignments and types
the solution in his
Computer.
4. Student prints out the
solution
5. Student delivers the
solution in the following
exercise
6. Special requirements:
None.
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Sınıf Çalışması (10 dakika)
- Müşteri, garsona sipariş verir.
- Restoranda
çalışmak
isteyen
adayların
başvurularını restoran yöneticisi değerlendirir. İşe
alımları da o yapar.
- Restoranda kullanılan malzemeler için düzenli
sipariş verilmesi gerekmektedir. Malzemeler belirli
bir tedarikçiden sağlanır.
- Malzemelerin siparişini restoran yöneticisi verir.
Bunu yaparken, sürekli olarak satışları ve stokları
takip etmesi gerekir.
- Stokları takip etmek için, restoran yöneticisinin
tuttuğu düzenli raporlar bulunur.
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Sınıf Çalışması
Order Food
Customer
Service Person
Hire Employee
Applicant
Reorder
supplies
<<uses>>
Supplier
Manager
<<uses>>
Track sales
and inv. data
Produce
mgt. reports
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Another view on UML Diagrams
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Sequence Diagrams
Focus on
Controlflow
• Used during analysis
Passenger
TicketMachine
selectZone()
• To refine use case descriptions
• to find additional objects
(“participating objects”)
• Used during system design
insertCoins()
pickupChange()
pickUpTicket()
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TicketMachine
• to refine subsystem interfaces
zone2price
Messages ->by
• Instances are represented
selectZone()
rectangles. ActorsOperations
by stickyon
insertCoins()
participating Object
figures
pickupChange()
• Lifelines are represented by
pickUpTicket()
dashed lines
• Messages are represented by
arrows
• Activations are represented
by narrow rectangles.
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Sequence Diagrams can also model the
Flow of Data
Passenger
ZoneButton
selectZone()
TarifSchedule
Display
lookupPrice(selection)
price
Dataflow
displayPrice(price)
…continued on next slide...
• The source of an arrow indicates the activation which sent
the message
• Horizontal dashed arrows indicate data flow, for example
return results from a message
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Messages
• Define a particular communication between
lifelines of an interaction
• Examples of communication
• raising a signal
• invoking an operation
• creating or destroying an instance
• Specify (implicitly) sender and receiver
• are shown as a line from the sender to the
receiver
• Form of line and arrowhead reflect message
properties
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Object-Oriented Software Engineering: Using UML, Patterns, and Java
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Message Types
•
•
•
•
•
•
Asynchronous
Synchronous
Call and Object creation
Reply
Lost
Found
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Lifeline and Execution Specification
• A lifeline represents an individual participant
(or object) in the interaction
• A lifeline is shown using a symbol that consists
of a rectangle forming its “head” followed by a
vertical line (which may be dashed) that
represents the lifetime of the participant
• An execution specification specifies a
behavior or interaction within the lifeline
• An execution specification is represented as a
thin rectangle on the lifeline.
Bernd Bruegge & Allen H. Dutoit
Object-Oriented Software Engineering: Using UML, Patterns, and Java
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Sequence Diagrams: Iteration & Condition
…continued from previous slide...
Passenger
ChangeProcessor
*insertChange(coin)
Iteration
CoinIdentifier
Display
CoinDrop
lookupCoin(coin)
price
displayPrice(owedAmount)
[owedAmount<0] returnChange(-owedAmount)
Condition
…continued on next slide...
• Iteration is denoted by a * preceding the message name
• Condition is denoted by boolean expression in [ ] before
the message name
Bernd Bruegge & Allen H. Dutoit
Object-Oriented Software Engineering: Using UML, Patterns, and Java
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Creation and destruction
…continued from previous slide...
Passenger
ChangeProcessor
Creation of Ticket
createTicket(selection)
Ticket
print()
free()
Destruction of Ticket
• Creation is denoted by a message arrow pointing to the object
• Destruction is denoted by an X mark at the end of the
destruction activation
• In garbage collection environments, destruction can be used to
denote the end of the useful life of an object.
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Sequence diagram: An Example
Lifeline
Execution
Specification
Message
Sequence diagrams represent the behavior of a system
as messages (“interactions”) between different objects.
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Sequence Diagram - Ex
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Sequence Diagram - Ex
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Object-Oriented Software Engineering: Using UML, Patterns, and Java
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Sequence
diagram: An
Example
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Sequence diagram: An Example
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Sequence Diagram Properties
• UML sequence diagram represent behavior in
terms of interactions
• Useful to identify or find missing objects
• Time consuming to build, but worth the
investment
• Complement the class diagrams (which
represent structure).
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Sınıf Çalışması (15 dakika)
Müşterinin ATM’den para çekmek istemesine
ait sıralama (sequence) diyagramını çiziniz.
- Sokulan kart kontrol edilmeli.
- Eğer onaylanırsa, müşterinin istediği miktar kontrol
edilmeli.
- Eğer onaylanırsa, işlem başlatılmalı.
- Para verildikten sonra, müşteriye dekont verilmesi.
- Müşteri hesabında yapılan işlemlerin kaydedilmesi.
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Örnek
Çözüm
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Another view on UML Diagrams
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UML first pass: Statechart diagrams
Initial state
Event
button1&2Pressed
Blink
Hours
Transition
button1&2Pressed
State
button2Pressed
Increment
Hours
button1Pressed
Blink
Minutes
button2Pressed
Increment
Minutes
button1Pressed
Stop
Blinking
Blink
Seconds
button2Pressed
Increment
Seconds
Final state
Represent behavior of a single object with interesting
dynamic behavior.
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How to draw statechart diagrams?
• Identify important objects to be analyzed.
• Identify the states.
• Identify the events.
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Statechart Diagram Example
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Statechart Diagram Example
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UML Summary
• UML provides a wide variety of notations for
representing many aspects of software
development
• Powerful, but complex
• UML is a programming language
• Can be misused to generate unreadable models
• Can be misunderstood when using too many exotic
features
• We concentrated on a few notations:
• Functional model: Use case diagram
• Object model: class diagram
• Dynamic model: sequence diagrams, statechart and
activity diagrams
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