1. Course Instructor: Aisha Azeem
Introduction to UML
Course Instructor: Aisha Azeem

2. Introduction UML stands for Unified Modeling Language.
It is a standard language for specifying, visualizing, constructing, and documenting the artifacts of software systems.
Specifying
Visualizing
Constructing
Documenting
Business Modeling
Communications

3. UML Building Blocks Class:
Class represents set of objects having similar responsibilities.
Use case:
Use case represents a set of actions performed by a system for a specific goal.
Interaction:
Interaction is defined as a behavior that consists of a group of messages exchanged among elements to accomplish a specific task.

4. Cont . . .
State machine:
State machine is useful when the state of an object in its life cycle is important.
It defines the sequence of states an object goes through in response to events. Events are external factors responsible for state change.
Note:
A note is used to render comments, constraints etc of an UML element.

5. Cont . . . Generalization: Aggregation: Composition:
Generalization can be defined as a relationship which connects a specialized element with a generalized element. It basically describes inheritance relationship in the world of objects.
Aggregation:
Whole part relationship i.e. large part “whole” contains one or more parts. E.g. building “whole” contains rooms ”parts”
Composition:
Is a relationship in which if the “whole” part dies, the child has to die as well. E.g. if building collapse , rooms no more exist

6. UML Models, Views, Diagrams
UML is a multi-diagrammatic language
Each diagram is a view into a model
Diagram presented from the aspect of a particular stakeholder
Provides a partial representation of the system
Is semantically consistent with other views
Example views

7. Models, Views, Diagrams

8.   UML Diagrams
UML diagrams are the ultimate output of the entire discussion.
All the elements, relationships are used to make a complete UML diagram and the diagram represents a system.
UML includes the following nine diagrams
Class diagram
Object diagram
Use case diagram
Sequence diagram
Collaboration diagram
Activity diagram
State chart diagram
Deployment diagram
Component diagram

9. UML Modeling Types
Different diagrams are used for different type of UML modeling.
There are three important type of UML modeling :
Structural modeling:
Structural modeling captures the static features of a system.
They consist of the followings: Class diagrams , Objects diagrams , Deployment diagrams , Component diagram etc
Structural model represents the framework for the system and this framework is the place where all other components exist.
They all represent the elements and the mechanism to assemble them.
E.g. class written once remain same through out the execution.

10. Cont . . . Behavioral Modeling:
Behavioral model describes the interaction in the system.
It represents the interaction among the structural diagrams.
Behavioral modeling shows the dynamic nature of the system
Activity diagrams , Interaction diagrams, Use case diagrams
Depends upon the behavior of an object/entity object can have more then one state, and depending upon its state its behavior would be different.
E.g. bank account may be working(deposit/ withdraw)
Not working(closed/ dead)

11. Cont . . . Dynamic Modeling:
The dynamic model is used to express and model the behavior of the system over time.
It includes support for activity diagrams, state diagrams, sequence diagrams
e.g. user login(id, password), valid tries to login , its set of sequences will be different as compared to an invalid user. 

12. Use-Case Diagram
Use Case Diagram is used to describe the functionalities provided by a system and the users associated with that system.
The Use case diagram is used to identify the primary elements and processes that form the system.
The primary elements are termed as "actors" and the processes are called "use cases."
The Use case diagram shows which actors interact with each use case.

13. Use-Case Diagram The main purpose of the use-case diagram is:
to help development teams visualize the functional requirements of a system
To help identify relationship of "actors" (human beings who will interact with the system) with essential processes
and understand the relationships among different use cases

14. Elements of a use-case diagram
Use-case diagrams contain the following elements:
Actors, which represent users of a system, including human users and other systems.
Use Cases, which represent functionality or services provided by a system to users.

15. UML notation used to represent an actor
Definition:
The outside entity which communicates with the system:
A Person (user)
An external system
Physical Environment
An Actor has a unique name and an optional description
Symbol:
UML notation used to represent an actor

16. Actor (Example)
Consider the following scenario related to a “University Management System” :
In a university management system, a Student can submit the assignments, the instructor marks those assignments and then uploads the result. The Student is allowed to view the Results.
Now, by recalling the definition of actor, can you identify the actors in this System?
Student
Instructor

17. Actor (Example/2) Student Instructor
Student is an external entity which interacts with the system. Student is a user of this system, as some services are used by it.
Instructor is another external entity which interacts with the university management system.
Student
Instructor

18. Use-case
Represent functionality or services provided by a system to users.
It is a description of set of sequence of actions that a system perform that produces an observable result.
A use case represents a class of functionality provided by the system as an event flow.
Use cases describe the interaction between a primary actor and the system itself

19. UML notation used to represent a use-case
The use case technique is used in software and systems engineering to capture the functional requirements of a system.
Each use case describes how the actor will interact with the system to achieve a specific goal.
One or more scenarios may be generated from each use case, corresponding to the detail of each possible way of achieving that goal.
Symbol :
UML notation used to represent a use-case

20. Use-case (Example) Consider the same example again:
In a university management system, a Student can submit the assignments, the instructor marks those assignments and then uploads the result. The Student is allowed to view the Results.
Now, by recalling the definition of use-case, can you identify the use-cases in this System?
Submit Assignments
Mark Assignments
Upload Results
View Results

21. Use-case (Example/2)
The use-cases are linked with the functional requirements of this system. In this example :
Student submit the assignments.
Instructor marks the assignments.
Instructor upload the marks.
Student can view the marks.
It is now clear that how actors are interacting with different use-cases of this system.
Now, lets combine actors and use-cases in one diagram?

22. Symbols in Use-Case Diagrams
ACTOR
USE-CASE
INTERACTION:
denotes set of messages exchanged among objects
NOTES/COMMENTS

23. Use-Case Diagram (University Management System)
SYSTEM BOUNDARY
Submit Assignments
Mark Assignments
Student
Upload Results
View Results
Instructor
Package: University Management System

24. Cont . . . Other types of associations and relationships;
Generalization between use cases
Generalization between actors
Include relationship between use cases
Extend relationship between use cases

25. Generalization between Use cases
Represented by a line and a hollow arrow
From child to parent
A use case generalization shows that one use case is simply a special kind of another.
A child can be substituted for its parent whenever necessary.
Generalization appears as a line with a triangular arrow head toward the parent use case
Child use case
Parent use case

26. Example Example : ATM Register car sharer
CarMatch Administrator
Web Server
Register car sharer
Transfer car sharer from web server
Manually add car sharer
Example : ATM

27. Generalization between Actors (examples)
student
Foreign student
Local student

28. Include relationship between use cases
Some times one use case includes the functionality of another use case.
Include relationship is drawn as an open arrow with dashed lines that points towards the use case that is being included
The word include is written in << >> Or
If x is a task and y is a sub task but acting as a part of it then use <<include >> stereotype
Arrowhead towards the subtask

29. Example

30. Extend relationship between use cases
There are occasions where one use case may optionally be extended by the functionality in another use case.
The relationship is drawn as an open arrow with dashed line the points towards the use case that is being extended.
The word extend is written in <<……..>> Or
If x is a task and y is a sub task of x but little bit different
Arrow head towards the main task

31. Example Driver Passenger Purchase Ticket TimeOut NoChange OutOfOrder
Turn left
Turn right
Take turn
<<extends>>
Driver
Passenger
Purchase Ticket
TimeOut
<<extends>>
NoChange
OutOfOrder
Cancel

32. Practice Read the following case : Identify the actors
Identify (extract ) the use cases
Construct a proper use-case diagram (with proper symbols & notations)

33. Case-Study
Consider the Library Management System of UOW. A Student is allowed to issue books for a period of two weeks. Student can read newspapers/magazines in the library and can even access the databases for e-books. The Library Staff is responsible for maintaining the records of students and along with the issued books. The Staff marks an entry in the register whenever a student issue or return a book. A fine is charged on a student if he/she fail to return the book on time. The Librarian is there to manage the staff, check the records and prepare reports for DG/DEAN.

34. Class diagrams Gives a graphical representation of domain model.
It represents relationship of classes objects with object specification in detail.
It gives static view of the system
Each class is represented by a rectangle subdivided into three compartments
Name
Attributes
Operations

35. Class Diagram: Visibilities
Modifiers are used to indicate visibility of attributes and operations.
‘+’ is used to denote Public visibility (everyone)
‘#’ is used to denote Protected visibility (derived)
‘-’ is used to denote Private visibility (no one)
By default, attributes are hidden and operations are visible.
The last two compartments may be omitted to simplify the class diagrams

36. An example of Class Account_Name - Custom_Name - Balance Name
+AddFunds( )
+WithDraw( )
+Transfer( )
Name
Attributes
Operations

37. Other representations of class
Boeing 737
Boeing 737
length: meter
fuelCapacity: Gal
doors: int
lift ( )
roll ( )
thrust ( )
Boeing 737
length: meter
fuelCapacity: Gal
doors: int
Boeing 737
lift()
roll()

38. Class Attributes (Cont’d)
Person
Attributes are usually listed in the form:
attributeName : Type
A derived attribute is one that can be
computed from other attributes, but
doesn’t actually exist. For example,
a Person’s age can be computed from
his birth date. A derived attribute is
designated by a preceding ‘/’ as in:
/ age : Date
name : String
address : Address
birthdate : Date
/ age : Date
ssn : Id

39. Class Attributes (Cont’d)
Person
+ name : String
# address : Address
# birthdate : Date
/ age : Date
- ssn : Id
Attributes can be:
+ public
# protected
- private
/ derived

40. Class Diagram: Association
Associations represent relationships between instances
of classes .
An association is a link connecting two classes.
Bi-directional association Associations are assumed to be bi-directional
Uni-directional association e.g. Bank Account and person
BankAccount
Person
BankAccount
Person

41. Association: Multiplicity and Roles
Instructor
Student
1..*
learns from
teaches
Multiplicity
Symbol Meaning
1 One and only one
0..1 Zero or one
M..N From M to N (natural language)
* From zero to any positive integer
0..* From zero to any positive integer
1..* From one to any positive integer
Note: if no multiplicity is given it is assumed to be 1
Association name: represents nature
of participants classes in a relationship.
Association Role: role played by the
participant class

42. Notation of Class Diagram: Generalization
Student
TeachingAssistant
Employee
Subtype2
Supertype
Subtype1
Person
Student
Generalization expresses a relationship among related classes. It is a class that includes its subclasses.

43. Cont . . . Separate target style Shared target style Vehicle Bus Truck
Car
Boeing 737
BoeingAirplane
Boeing 757
Boeing 767
Shared target style
Separate target style

44. Notation of Class Diagram: Composition
Class W
Class P1
Class P2
COMPOSITION
Whole Class
Part Classes
Automobile
Engine
windows
Example
Composition: expresses a relationship among instances of related classes.
It is a specific kind of Whole-Part relationship.
It expresses a relationship where an instance of the Whole-class has the responsibility to create and initialize instances of each Part-class. Composition should also be used to express relationship where instances of the Whole-class have exclusive access to and control of instances of the Part-classes.

45. Cont . . .
Car 4
Wheel
Light
Door
Engine
4, 10
2, 5 1

46. Notation of Class Diagram: Aggregation
Aggregation: expresses a relationship among instances of related classes. It is a specific kind of Container-Containee relationship.
It expresses a relationship where an instance of the Container-class has the responsibility to hold and maintain instances of each Containee-class
Aggregation is appropriate when Container and Containees have no special access privileges to each other.
Class C
Class E1
Class E2
AGGREGATION
Container Class
Containee Classes
Bag
Apples
Milk
Example

47. Cont. . .
Player
class
Team 1 *
Consists Of

48. Aggregation vs. Composition
Composition is really a strong form of aggregation
components have only one owner
components cannot exist independent of their owner;
both have coincident lifetimes
components live or die with their owner
e.g. (1)Each car has an engine that can not be share with other car
(2) If the polygon is destroyed, so are the points.
Aggregations may form "part of" the aggregate, but may not be essential to it.
They may also exist independent of the aggregate. Less rigorous than a composition
e.g. (1)Apples may exist independent of the bag.
(2)An order is made up of several products, but the products are still there even if an order is cancelled.

49. Class Diagram example class * Multiplicity: mandatory Association
Order
-dateReceived
-isPrepaid
-number :String
-price : Money
+dispatch()
+close()
Customer
-name
-address
+creditRating() : String()
Corporate Customer
-contactName
-creditRating
-creditLimit
+remind()
+billForMonth(Integer)
Personal Customer
-creditCard#
OrderLine
-quantity: Integer
-price: Money
-isSatisfied: Boolean
Product * 1
Employee
0..1
Operations
Attributes
Name
Association
Multiplicity: mandatory
Multiplicity:
Many value
Multiplicity: optional
Generalization
class

50. Interaction Diagrams
In object oriented systems, tasks are performed by objects interacting with other by passing messages.
In UML this interaction is provided by sequence diagrams.
Class diagrams model static nature of system
Interactions diagrams model the dynamic nature of system and emphasis the order of the message over time

51. Cont . . .
squares with object type, optionally preceded by object name and colon

52. Purpose of interaction diagrams
These are used to model :
high level interaction between active objects in system
Interaction between objects involved in a use case
Interaction between objects involved in an operation
Generic interactions (showing all possible paths through interaction)

53. Sequence Diagram
Shows how objects communicate with each other over time.
That is, sequence diagrams are used to model object interactions arranged in time sequence and to distribute use case behavior to classes.
They can also be used to illustrate all the paths a particular use case can ultimately produce.
The sequence diagram consists of Active Objects, Messages represented as solid-line arrows, and Time represented as a vertical progression.

54. Sequence Diagram - Objects
A life line illustrates what is happening to an object in a chronological fashion.
:Name
Life line
Activation(focus of control)
Object

55. Sequence Diagram – Time & Messages
Messages are used to illustrate communication between different active objects of a sequence diagram.
:Name1
:Name2
Message Two
Actor
Message One

56. Types of Messages
Synchronous (flow interrupt until the message has completed.
1st object waits until the 2nd object completes its operations
Asynchronous (don’t wait for response)
1st object does not wait for the 2nd object to
completes its operations
Flat – no distinction between sysn/async
Return – control flow has returned to the caller.

57. Steps in drawing a sequence diagram
1.Decide the context of the interaction
System, subsystem, use case or operation
2. Identify the structural elements(objects) necessary to carry our functionality of use case
3. Consider alternative scenario that may be required
4. Draw the sequence diagram
Layout the objects from left to right
Starting with the message that starts the interaction
Add focus of control
Add timing constructs

58. Sequence Diagram – Compilation
:Compiler
Linker
Actor
Compile
FileSystem
Load Files
Save OBJ Files
Compile files
Link
Load OBJ files
Link OBJ files
Write EXE file

59. Example :making phone call
Caller
Phone
Recipient
Picks up
Dial tone
Dial
Ring notification
Ring
Hello

60. Task 1 Draw a sequence diagram for:
In Beauty and the Beast kitchen items came to life. Draw a sequence diagram for making a peanut butter and jelly sandwich if the following objects are alive: knife, peanut butter jar (and peanut butter), jelly jar (and jelly), bread, plate. I may or may not want the crusts cut off. Don’t forget to open and close things like the jars, and put yourself away, cleanup, etc…

61. Task 2
Draw a sequence diagram showing a customer’s interaction to withdraw money from ATM .
Show all sequence of steps involved e.g. insert card, enter pin number , amount etc.

62. Activity diagrams Purpose of Activity diagrams is listed as under :
Are a means of describing workflows
Can be used as an analysis tool to describe business flows in different level of detail
Describe complex flows within or between use case
At design level, it can be use to describe flow within an operation.

63. Cont . . .
Activity diagram consists of:
Activities
States
transitions

64. Notations An activity is a unit of work that needs to be carried out
symbol used to represent an activity
Each activity can be followed by another activity (sequencing).
Activity name

65. Triggering an activity
There are four ways in which an activity can be triggered
On Entry: these actions are triggered as soon as the activity starts
Do: these actions take place during the life time of the activity
On Event: these actions take place in response to an event
On Exit: these actions takes place just before the activity completes

66. Cont . . . Actions -> is triggering of an event Activity name
Entry/ action
Do/action
Event name/action
Exit/action

67. States & Activities
A state in an activity diagram is a point where some event needs to take place before activity continues
Activities & states are roughly equivalent and states can carry out actions just as an activity can.
However activities need to complete all their actions before exiting normally.
States are used to imply waiting, not doing
Wait for
payment

68. Cont . . . There are two special states:
Start State: is the entry point to a flow
Only one start state is allowed in an diagram
Shows as a block dot and is labeled
End State: are drawn as black dots with a surrounding circle

69. Transition Transition : Is the movement from one activity to another
The change from one state to another
The movement between states and an activity in either direction.
A transition normally occurs when all the actions of an activity have been completed.
Or when an event triggers the exit from a particular state or activity.
Are shown as arrowed lined between two activity
Wait for
payment
Request payment

70. Cont . . . There are two types of transitions:
Trigger-less transitions: are permissible when exiting activities, and meaning is that the activity has completed all its actions and next phase of workflow can begin
Triggered Transitions: when exiting a state, some event needs to trigger it.
E.g. when waiting for payment, exit from the state could be triggered by a PaymentArrives event
Wait for
payment
Request payment
PaymentArrives

71. Cont . . .
There can be more than one transition out of a single activity or a state.
This is used when different events results in a state or activity termination
Wait for
payment
Chase payment
Process payment
PaymentPeriodExpires
PaymentArrives (amount)

72. Decision Points
A decision points in a workflow where the exit transition from a state or an activity may branch in alternative direction
Depending on a condition
Represented by a diamond.

73. Synchronisation bar Synchronisation bar.
All triggers from this attach to activities that can occur in parallel, with no specific sequence, or concurrently.
Symbol or

74. Example Process payment Update cash balance Process Cheque Clear Debt
Cheque payment
Cash payment
Clear Debt

75. Activity Diagrams - Notation
Start at the top black circle
If condition 1 is TRUE, go right; if condition 2 is TRUE, go down
At first bar (a synchronization bar), break apart to follow 2 parallel paths
At second bar, come together to proceed only when both parallel activities are done

76. Example

77. Example 2

78. Creating an activity diagram
Modelling a workflow in an activity diagram
Identify a workflow objective.
Decide the pre and post-conditions of the workflow.
Define all activities and states.
Define any objects that are created or modified.
Decide on responsibility for performing the activities.
Connect all elements on the diagram with transitions.
Place decisions on the diagram.
Evaluate your diagram for concurrent workflows.
Set all actions, triggers and guard conditions in the specifications of each model element.

79. Task
Draw an activity diagram to issue book from library

80. Possible solution