UML (Unified Modeling Language) is a standardized modeling language used to create visual representations of object-oriented software systems. It includes various diagram types to depict different views of a system, such as use case diagrams (user functionality), class diagrams (system structure), statechart diagrams (object states), sequence diagrams (object interactions), and activity diagrams (system workflows). UML provides a common language for discussing and designing software systems and standard visual symbols for expressing models.

1. Unified Modeling Language
(UML)

2. Why do we need models?
To create a simplified representation
of a real software system

3. What is UML?
A popular, standardized modeling
language for object-oriented software
The Object Management Group (OMG) is
the group that dictates the UML standard
Created by Grady Booch, James
Rumbaugh, and Ivar Jacobson

4. UML Models
Functional Models
Use case diagrams
Structural Models
Class diagrams
Dynamic/Behavioral Models
Statechart diagrams
Sequence diagrams
Activity diagrams

5. UML Conventions
Rectangles are classes or instances
Ovals are functions or use cases
Instances are underlined
Types are not underlined

6. Poseidon for UML
Available from
http://www.gentleware.com/
Get the free Community Edition
Caveat: Slow on older computers, a little
sluggish on newer ones

7. Poseidon for UML demo

8. Use case diagrams

9. Use case diagrams
Describes the functional behavior of the system
from the user’s point of view
Used during the requirements elicitation stage to
represent external behavior
Actor: User, external system, or a physical
environment
Use case: a class of functionality provided by
the system as an event flow
Has entry and exit conditions, flow of events, and
participating actors

10. Use case diagram symbols
Actor
Relationships
Use case
System

11. Use case example
Find arrival times
Report location
Report error
GPS System
Passenger

12. Use case example explanation
Actors don’t have to be people
Shows how actors interact with the
system
Three use cases

13. Class diagrams

14. UML Class Diagram
Depict the classes within the model
Illustrates the class attributes (member
variables), operations (member functions),
and relationships with other classes

15. UML Class Diagram Symbols
CLASS Class Name
Composition relationship
Class 1 is composed of a Class 2
Class 1 Class 2
Inheritance relationship
Class 2 and Class 3 derive from Class 1
#
Number of links each class object
may contain
Class 1
Class 2 Class 3
Class 1 Class 2 Aggregation
A collection of other classes

16. UML Class Diagram Example
SimpleWatch
PushButton Display Battery Time
1
1111
1 22
SimpleWatch class contains
2 PushButtons
1 Display
2 Batteries
1 Time

17. UML Class Diagram Example
http://pigseye.kennesaw.edu/~dbraun/csis4650/A&D/UML_tutorial/class.htm

18. UML Class Diagram Example
The class Order is associated with the class Customer
The multiplicity denotes the number of objects
For example, Order object can be associated only one customer
but a customer can be associated to many orders

19. Statechart diagrams

20. UML Statechart Diagram
A statechart diagram shows the behavior
of classes in response to external stimuli
This diagram models the dynamic flow of
control from state to state within a system.

21. Basic Statechart Diagram Symbols and
Notations
 States represent situations
during the life of an object
 A solid arrow represents the
path between different
states of an object
 A filled circle followed by an
arrow represents the
object's initial state.
 An arrow pointing to a filled
circle nested inside another
circle represents the object's
final state.

23. Description of state chart diagram
 State:
 Display alarm time
 Display clock time
 No sound
 Sound on
 Buzzing
 Playing radio
 Transition:
 On
 Off
 Hold alarm
 Alarm switch off
 Change Hrs/Min
 Radio
 Activity:
 Do/wait for clock time to alarm time

24. Sequence diagrams

25. Sequence Diagrams
Describe the dynamic behavior between
actors and the system and between
objects of the system
Used during requirements analysis
To refine use case descriptions
To find additional objects
Used during system design
To refine subsystem interfaces

26. Sequence diagram notation
Classes are represented by columns
Messages are represented by arrows
Activations represented by narrow
rectangles
Lifelines are represented by dashed lines

27. Example:- sequence diagram for SimpleWatch
O
- | - :SimpleWatch :Display :Time
/ | | |
:WatchUser | | |
pressButton1() blinkHours() |
――――――― ―――――――――――― |
pressButton1() | blinkMinutes() | |
――――――― ―――――――――――― |
|
pressButton2() | | |
――――――― | incrementMinutes() |
――――――――――――――――――――――――――――――
| | refresh()
pressButton1And2() | ―――――――――――――
――――――― |
| commitNewTime() |
―――――――――――――――――――――――――――――――
|
stopBlinking()
―――――――――――――

28. Example cont.
-The left-most column represents the timeline of the WatchUser who initiates the use
case.
-The other columns represent the timeline of the objects that participate in this use case.
References: Page 33 Object-Oriented Software Engineering Bernd Bruegge, Allen H. Dutoit

29. Activity diagrams

30. Activity Diagrams
Used to represent the behavior of a system in terms of
activities and their precedence constraints
Compared to flowchart diagrams because …
 They can be used to represent control flow (order in which
operations occur)
 They can be used to represent data flow (objects exchanged
among operations)
The completion of an activity triggers an outgoing transition
which may initiate another activity

31. Symbols
- Synchronization of the control flow
- Activities in the system
- Transitions between activities

32. Activity Diagram Example
Open
Incident
Document
Incident
Allocate
Resources
Coordinate
Resources
Archive
Incident

33. Example Explained
The 1st
activity initiated is Open Activity. After all the
operations in this activity have been executed, the
activities Allocate Resources, Coordinate Resources &
Document Incident are initiated. (Note: There is a
complex transition between Open Activity and the next
three activities).
These three activities may occur in sequence or
concurrently.
Even if the three activities don’t occur concurrently,
Archive Incident is not initiated until all three have been
completed.

34. References
B. Bruegge, A. Dutoit. Object-Oriented
Software Engineering: Using UML,
Patterns and Java, Second Edition. 2003.