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Copyright © 1997 by Rational Software Corporation

Unified Modeling Language (UML)

Based on slides and papers from Rational’s UML website

http://www.rational.com/uml

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The Value of the UML

• Is an open standard

• Supports the entire software development lifecycle

• Supports diverse applications areas

• Is based on experience and needs of the user community

• Supported by many tools

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History of the UML

Booch ´91

Booch ´93

Unified Method 0.8

UML 1.0

OMT - 2

OMT - 1

OOSE

UML 0.9 & 0.91

OOPSLA ´95

June ´96 & Oct ´96

Sep ´97

Other methods

Jan ´97

Industry Feedback

UML 1.1

Nov ‘97UML approved by the OMG

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What is the UML?

• The UML is a language for visualizing, specifying, constructing, and documenting the artifacts of a software-intensive system

• Process and implementation independent– It can be used with a large number of

processes, throughout the development life cycle, and across OO implementation technologies

• The UML combines– Data Modeling concepts (Entity Relationship

Diagrams)

– Business Modeling (work flow)

– Object Modeling

– Component Modeling

• The de facto standard for OO systems

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The UML Usages

• Define the boundaries of a system & its major functions– use cases and actors

• Illustrate use cases– interaction diagrams

• Define the static structure of a system – class diagrams

• Model the behavior of objects– state transition diagrams

• Document the physical implementation architecture– component & deployment diagrams

• Provide for growth– stereotypes

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Modeling Elements

• Structural elements– class, interface, collaboration, use case, active

class, component, node

• Behavioral elements– interaction, state machine

• Grouping elements– package, subsystem

• Other elements– note

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DiagramsThe foundation of UML

• Use Case Diagrams– Requirements

• Activity Diagrams– Generally what, not who - good to detect

parallelism

• Interaction Diagrams– Sequence Diagrams (timeline)

– Collaboration Diagrams (object centered)

• Static Structure Diagrams – Objects/Classes/Packages

• Statechart Diagrams – States of objects with interesting lifecycles

• Implementation Diagrams– Component Diagrams

– Deployment Diagrams

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Actors

• An actor is someone or some thing that interacts with the system

• External Forces– Human interaction

– Automated System

KeyboardOperator

User

Driver

Traffic Control System

<<toll booth>>

<<Backup System>>

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Use Cases

• A use case is a pattern of behavior the system exhibits– Each use case is a sequence of related

transactions performed by an actor and the system in a dialogue

– Details what the system must provide to the actor when the use cases is executed

• A flow of events document is created for each use case– Written from an actor point of view– Actors are examined to determine their how

they interact with the systemBreak down into the most atomic actions

possible

• Typical contents– How the use case starts and ends– Normal flow of events– Alternate flow of events– Exceptional flow of events

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Use Case Diagram

• Captures system functionality as seen by users

• Built in early stages of development

• Purpose– Specify the context of a system

– Capture the requirements of a system

– Validate a system’s architecture

– Drive implementation and generate test cases

• Developed by analysts and domain experts

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Use Case Diagram

• Use case diagrams are created to visualize the relationships between actors and use cases

Passager

Mechanic

Driver

Lost Luggage

Ramp Maintenance

Pay toll

Customer Service Agent

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• Captures system functionality as seen by users

Use Case Diagram

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• As the use cases are documented, other use case relationships may be discovered– A uses relationship shows behavior

that is common to one or more use cases

– An extends relationship shows optional behavior

Ramp Agent

<<uses>>

Loose luggage<<uses>>

Baggage Handler

Uses and Extends Use Case Relationships

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Sequence Diagram

• A sequence diagram displays object interactions arranged in a time sequence

PassengerCounterAgent

Ticket GateAgent

1: Give Info

3: Answer4: Print

6:Present7: Board

9: Return

8: Overbook

2: Questions

Plane

5: Safeguard

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: Registrar

course form :

CourseForm

theManager : CurriculumManageraCourse :

Course

1: set course info2: process

3: add course

4: new course

Collaboration Diagram

• A collaboration diagram displays object interactions organized around objects and their links to one another

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Class Diagrams

• A class diagram shows the existence of classes and their relationships in the logical view of a system

• UML modeling elements in class diagrams– Classes and their structure and behavior

– Association, aggregation, dependency, and inheritance relationships

– Multiplicity and navigation indicators

– Role names

• Attributes– The structure of a class is represented by its

attributes

– Attributes may be found by examining class definitions, the problem requirements, and by applying domain knowledge

• Operations– The behavior of a class is represented by its

operations

– Operations may be found by examining interaction diagrams

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• Captures the vocabulary of a system

Class Diagram

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Relationships

• Relationships provide a pathway for communication between objects

• Sequence and/or collaboration diagrams are examined to determine what links between objects need to exist to accomplish the behavior -- if two objects need to “talk” there must be a link between them

• Three types of relationships are:– Association

– Aggregation

– Dependency

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Relationships

• An association is a bi-directional connection between classes– An association is shown as a line connecting

the related classes

• An aggregation is a stronger form of relationship where the relationship is between a whole and its parts– An aggregation is shown as a line connecting

the related classes with a diamond next to the class representing the whole

• A dependency relationship is a weaker form of relationship showing a relationship between a client and a supplier where the client does not have semantic knowledge of the supplier

• A dependency is shown as a dashed line pointing from the client to the supplier

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• 1 - one and only one

• 4 - four and only 4

• 0..1 - zero or 1

• 5..10 - five to and including 10

• 0..* - zero or more

• 4..* - four or more

Relationship Notation

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Registration

ManagerMath 101:

Course

3: add student(joe)

RegistrationManager

Course

Finding Relationships

• Relationships are discovered by examining interaction diagrams– If two objects must “talk” there must be a

pathway for communication

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RegistrationForm

RegistrationManager

Course

Student

CourseOffering

Professor

addStudent(Course, StudentInfo)

name

numberCredits

open()

addStudent(StudentInfo)name

major

location

open()

addStudent(StudentInfo)

name

tenureStatus

ScheduleAlgorithm

Relationships

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Multiplicity and Navigation

• Multiplicity defines how many objects participate in a relationships– Multiplicity is the number of instances of one

class related to ONE instance of the other class

– For each association and aggregation, there are two multiplicity decisions to make: one for each end of the relationship

• Although associations and aggregations are bi-directional by default, it is often desirable to restrict navigation to one direction

• If navigation is restricted, an arrowhead is added to indicate the direction of the navigation

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RegistrationForm

RegistrationManager

Course

Student

CourseOffering

Professor

addStudent(Course, StudentInfo)

name

numberCredits

open()

addStudent(StudentInfo)major

location

open()

addStudent(StudentInfo)

tenureStatus

ScheduleAlgorithm

10..*

0..*

1

1

1..*4

3..10

0..41

Multiplicity and Navigation

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Inheritance

• Inheritance is a relationships between a superclass and its subclasses

• There are two ways to find inheritance:– Generalization

– Specialization

• Common attributes, operations, and/or relationships are shown at the highest applicable level in the hierarchy

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RegistrationForm

RegistrationManager

Course

Student

CourseOffering

Professor

addStudent(Course, StudentInfo)

name

numberCredits

open()

addStudent(StudentInfo)major

location

open()

addStudent(StudentInfo)

tenureStatus

ScheduleAlgorithm

name

RegistrationUser

Inheritance

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The State of an Object

• A state transition diagram shows – The life history of a given class

– The events that cause a transition from one state to another

– The actions that result from a state change

• State transition diagrams are created for objects with significant dynamic behavior

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InitializationOpen

entry: Register student

exit: Increment count

Closed

Canceled

do: Initialize course

do: Finalize course

do: Notify registered students

Add Student /

Set count = 0

Add student[ count < 10 ]

[ count = 10 ]

Cancel

Cancel

Cancel

State Transition Diagram

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The Physical World

• Component diagrams illustrate the organizations and dependencies among software components

• A component may be – A source code component

– A run time components or

– An executable component

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Component Diagram

• Captures the physical structure of the implementation

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Deploying the System

• The deployment diagram shows the configuration of run-time processing elements and the software processes living on them

• The deployment diagram visualizes the distribution of components across the enterprise.

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• Captures the topology of a system’s hardware

Deployment Diagram

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Extensibility Mechanisms

• Stereotype

• Tagged value

• Constraint

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Extending the UML

• Stereotypes can be used to extend the UML notational elements

• Stereotypes may be used to classify and extend associations, inheritance relationships, classes, and components

• Examples:– Class stereotypes: boundary, control, entity,

utility, exception

– Inheritance stereotypes: uses and extends

– Component stereotypes: subsystem

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Real UML Use Case Diagram

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Real UML

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Real UML

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Real UMLClass Diagram

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Real UMLClass Diagram