Modeling Behavior
with Sequence Diagrams
Dumitru Radoiu
Dumitru Radoiu
Spring 2009
PETRU MAIOR UNIVERSITY
Object-Oriented World
time
OO Analysis
Create the
vocabulary
Requirements
OO Design
Give
vocabulary
ocabu a y
behavior
(model the
system)
OO Programming
Program the
model
ode
Deliverables
Activity
UML Diagram
Understand System Usage
Use Case Diagram
Identify Classes
Identify Classes
High Level Class Diagram 9
High Level Class Diagram
Define Workflows
Activity Diagram
9
9
Object-Oriented World
time
OO Design
OO Analysis
Create the
vocabulary
Requirements
Give
vocabulary
ocabu a y
behavior
(model the
system)
OO Programming
Program the
model
ode
A ti it
Activity
UML Di
UML Diagram
Identify interactions among objects
Sequence and Collaboration Diagrams
Analyze state changes
l
h
Sate Diagrams
Refine class diagrams
Class Diagrams
Deliverables
Agenda •
•
•
•
•
Why We Model Sequence Diagrams
Why
We Model Sequence Diagrams
Notation
How to Use Messages for Communications
Learn Other techniques Used in Sequence Diagrams
Model a Sequence Diagram: Case Study
Why we model sequence diagrams?
diagnose car
Mechanic
fix car
drive car
Car owner
Why we model sequence diagrams?
diagnose car
Mechanic
[talk]
Diagnosis
Mechanic
Car
Agenda •
•
•
•
•
Why We Model Sequence Diagrams
Why
We Model Sequence Diagrams
Notation
How to Use Messages for Communications
Learn Other techniques Used in Sequence Diagrams
Model a Sequence Diagram: Case Study
Why we model sequence diagrams?
diagnose car
Mechanic
Messages
[talk]
Diagnosis
Mechanic
A ti Objects
Active
Obj t
Car
Types of Messages
Synchronous
Return
Asynchronous
Flat
The execution waits until the
message is
i received
i d and
d completed
l t d
Message received an completed;
control is returned to calling the
active object
The execution does not wait for the
message to be received and
completed; continues
I have no idea what type of message
is; or I don’t care
Why we model sequence diagrams?
Diagnosis
Car
M h i
Mechanic
Car
Diagnosis
Mechanic
Turn On
Turn On
Set to check
Diagnose
Lifeline
Fix the problem
Turn Off
Turn Off
Lifeline and time
ObjectTwo
ObjectOne
Mechanic
MessageOne
MessageTwo
MessageThree
MessageFour
MessageFive
Time flflow;
Ti
messages
displayed in
chronological
g
order
UML Glyphs for Sequence Diagrams
Active objects
Lifeline
Messages types
Flat
ObjectName
Synchronous
Return
A
Asynchronous
h
UML Glyphs for Sequence Diagrams
WebInterface
Email
Teacher
Login
Lookup Student
Component
p
not
part of our system
Distribute Grades
Send Email with Grades
Logout
Agenda •
•
•
•
•
Why We Model Sequence Diagrams
Why
We Model Sequence Diagrams
Notation
How to Use Messages for Communications
Learn Other techniques Used in Sequence Diagrams
Model a Sequence Diagram: Case Study
How to use Synchronous Messages
Database
Wrapper
W bI t
WebInterace
Teacher
Login Teacher
Validate User
[successful validation]
Lookup Student Info
Retrieve Student Info
How to use Asynchronous Messages
Log
WebInterace
Teacher
Login Teacher
Log Logon Attempt
[
[successful
logon]
g ]
Log Successful Logon
[unsuccessful logon]
Log Unsuccessful Logon
[successful validation]
Lookup Student Info
Log Student Retrieval
[successful validation]
Change Student Info
[successful logon]
Logout
Log
g Changes
g to Student Info
Agenda •
•
•
•
•
Why We Model Sequence Diagrams
Why
We Model Sequence Diagrams
Notation
How to Use Messages for Communications
Learn Other techniques Used in Sequence Diagrams
Model a Sequence Diagram: Case Study
Creating Objects
ObjectOne
<<create>>
ObjectTwo
message
The lifeline is
destroyed
<<destroys>>
X
Creating Objects
WebInterface
Validate User
[logged in]
Retrieve User
[invalid user]
<<create>>
MessageBox
[invalid user]
Display Error Message
[invalid user]
<<destroys>>
X
Database
Wrapper
Using States
ObjectOne
ObjectTwo
States belong to
objects and exist
directly on their lifeline
State
Using States
WebInterface
Request New Account
Database
Wrapper
create
<<create>>
Account
Information
Populate with Account Info
Ready
Change Account Info
Change Data
Modified
Save Data
Ready
Branching
ObjectOne
ObjectTwo
ObjectThree
Starting point the same
[[condition two]]
[condition one]
Ending height the
same
Branching
FileSystem
Editor
Load File
BinaryViewer
TextViewer
[binary file]
[[text file]]
Alternative flows
ObjectTwo
ObjectOne
[condition two]
[[condition one]]
Alternative flows
FileSystem
Editor
Developer
Exit App
[delete file]
[
[save
file]
fil ]
Agenda •
•
•
•
•
Why We Model Sequence Diagrams
Why
We Model Sequence Diagrams
Notation
How to Use Messages for Communications
Learn Other techniques Used in Sequence Diagrams
Model a Sequence Diagram: Case Study
Model a Sequence Diagram: Case Study
The following requirements are for a computerized grading system:
•The
The teacher views the grades for a student successfully
•The teacher attempts to view the grades for a student but the student doesn’t
exist in the system
•The teacher attempts to view the grades for a student but the student does not
have any grades
1.
2.
3.
4.
Decide what workflows you will model
Decide
what workflows you will model
Lay out your objects from left to right
Include messages and conditions to build each workflow
Draw a generic diagram to combine the separate diagrams
2. Lay Out Objects
Teacher
WebInterface
Database
Wrapper
StudentInfo
Student
Grades
3. Include Messages and Conditions
Teacher
WebInterface
Database
Wrapper
StudentInfo
Student
Grades
Request
Student Info
Get Student
Data
Load Student
Return Student Info
Load Grades
Return Grades for Student
Return Student Info
Display Student Info
4. Include conditions
Teacher
WebInterface
Database
Wrapper
StudentInfo
Request
Student Info
Get Student
Data
Load Student
(Student not found)
(Failure)
<<create>>
M
MessageBox
B
Display Error
<<destroys>>
destroys
X
Student
Grades