department of information engineering 351 what is uml (unified modeling language)? uml is a set of...

1Department of Information Engineering

What is UML (Unified Modeling Language)?

• UML is a set of graphical notations used to model software system

• A picture is worth a thousand words

• Equivalent to blueprint used by construction engineers

• Prior to 1995, many different modeling languages

– Confusing, time to establish a common standard

• Current version – UML version 2 (in year 2003)

• You can use Visio to draw the diagrams

• Ref: UML Distilled (3rd Edition) – Martin Fowler


Ways of using the UML

• Sketch

– For communicating a design

– Only highlight the essential components

• Blueprint

– Round-trip engineering

– Class has one-to-one mapping with code

– Class diagram -> code generation -> class diagram

• Programming language

– UML diagram -> code generation


UML2 diagrams

Diagram

StructureDiagram

BehaviorDiagram

Class Diagram

Component Diagram

Composite Diagram

Deployment Diagram

Object Diagram

Package Diagram

Activity Diagram

Use Case Diagram

State Diagram

Interaction Diagram

Sequence Diagram

Communication Diagram

InteractionOverview Diagram

Timing Diagram


Class diagram

• The most widely used UML diagram

• Show static relationships between classes

Class Nameof A

Attributes

Operations

Class Nameof B

Attributes

Operations

Role of A Role of B

Association

1 1..*

multiplicity

Name of Association


Attribute

visibility name:type multiplicity=default {property-string}

• Example: -dueDate:Date [0..1] = null {readOnly}

• Visibility– + (public) - (private)– # (protected) ~ (package)

- $ (static)

• Multiplicity– 1 (exactly one) * (any number)– 0..1 (either zero or one)

• property-string– optional


Operation

visibility name(param-list) : return-type {property-string}

• Example: +Foo (value:int) : void {query}

• property-string– query: get value without changing the system state– abstract: abstract operation, implemented by subclass– Exception=XXX: name the exception returned


Association

• Dependency– A depends on B– Change B’s interface may affect A

• Navigable association– A has a B– implicitly implies dependency

• Bidirectional association– A has a B, and B has an A

• Unidirectional association– A and B has relation– But direction is unspecified

A B

A B

A B

A B


Dependency

• A depends (or use) on B

• But A does not has an instance of B as part of its state

• public class A {

public void foo(B b) {. . .} //OK

public void bar() {

B b = new B(); //OK

}

private B b; //not OK, has an instance of B

}

A B


Association

• A stronger dependency– A depends (or use) on B– A has an instance of B as part of its state

• public class A { private B b; //OK

}

• Navigable association implicitly implies dependency

A B


• Generalization

• Realization

– Provides the implementation

BaseClass

DerivedClass

AbstractClass

DerivedClass


• Attributes and associations

– Both represents the same thing

– Choose the one that makes your diagram easier to understand

BookdueDate:Date[0..1]

Date is an attributeof Book

Book Date

Date is associatedwith Book

0..1


Aggregation and Composition

• Aggregation– Part-of relationship– Shared by other objects, therefore the whole can be deleted,

but not the part– E.g. Car has Wheels

• Composition– Stronger type of aggregation– The part cannot be shared– Delete the whole, then the part must be deleted as well

• Hard to tell the difference between association and aggregation– Fowler suggests always to use association instead of

aggregation

Car Wheel

Rectangle Point


Interface and Abstract Classes <<interface>>List

<<interface>>SortedList

AbstractArrayList

Clientdependency

generalization

implementation

Get

Sort

Stereotype

GetSort

Concrete methodAbstract method (italic)

ArrayList

GetSort

Overriding


Ball-and-socket Notation (UML2)

• Previous example, alternative representation

• Qualified association

– To model concept like associative array, dictionary

List

SortedList

ArrayListClient

Claslist StudentInfo1 *

ClassList StudentInfoId 1 1

Qualified association


Association Class

• To model the association between two classes. The two classes may have many-to-many association, but there can be only one instance of association class between objects of the two classes

• Example

Person Share Company1..* * 1..*1..*

Person Company

Sharequantity

1..* 1..*

Better, association classadd extra constraint


Association Class

• OK

• Not allowed for association class

personA

personB

CompanyA

CompanyB

personA

personB

CompanyA

CompanyB


• A person can take up several roles (director, investor) in a company, cannot be modeled by association class

• More appropriate

Person Company

Role

1..* 1..*

Person Role Company1..* 1..* 1..*1..*


Constraints

• Free format, just put anything you like inside {} to describe constraints in your model

ClassList Student{ordered} *

Menu

Soup Salad MainCourse Dessert

{or}


Template (Parameterized) Class

• class Set <class T> { public void Insert(T member) {...} public void Remove(T member) {...}}

Set

Insert(T)Remove(T)

T

Template parameter


Package Diagrams

• Each package represents a namespace– Consists of a group of classes, larger

unit

• Example: System.IO

System.IO


Package Diagram

• Avoid dependency cycle, at least localized it– Cycle in A, B, and C, but not in A, B and

D

Package A Package B

Package DPackage C


Object Diagrams

• To show a snapshot of the objects– Object = instance name:class name

MapSite

Room Wall Door

Class diagram

Object diagram

r1:RoomroomNumber=1

side[0]:Wall side[1]:Wall side[2]:Wall side[3]:Door


Implementing Packages

GameApplication AbstractGameEngine

PacMan LittleFighter

implement


Component Diagrams

• What is a component?– A piece of software that can be

independently purchased and upgraded, and can integrate seamlessly into customers’ existing software seamlessly

Librarian

UML 1 notation UML 2 notation

Librarian


Component Diagrams

UI Librarian DB

Database

Library


Deployment Diagrams

• To show the physical layout of the system, and the software that run on what pieces of hardware

Librarian

UI

A Windows PC

Linux server

DB

Database

Oracle server

TCP/IP TCP/IPcomponentcomponentconnectionconnectionnodenode


Deployment diagram

• Node – Something that can host the software

• Artifact – The physical manifestation of software,

such as files, assemblies, DLL, or scripts

– Artifact is usually a component


Composite Structures

• Support hierarchical modeling of a class structure

MediaPlayer

Control UI Control API

Video stream Display driver

MediaPlayer

UI

Control UI

MediaFilter

Video stream Display driver

1

multiplicity

Control API

portInput

Output


UML Interaction Diagrams (Behavior Model)• Sequence diagram

– The most common kind of interaction diagram

– Capture the behavior of a scenarioanObject:ClassName

Lifeline (dotted line)

Activation (rectangle)

Synchronous call

Asynchronous call(UML >= 1.4)

Asynchronous call(UML <= 1.3)

objnew Create object

return(optional)


Check-out scenario: KnowFine()

aLibrarian aBorrower aCollection aBook :Date

CheckOut

KnowFine*[for all Book]

Compare

GetFine

IsOverdue

[overdue]

iterationiteration

guardguard


Note

• iteration marker *[for all objects]• [condition]

– the message is sent only if the condition is true

• self-delegation– an message that an object sends to itself

• About loops and conditionals– Sequence diagram is not good at it, better

off with activity diagram or the code itself– UML2 uses a new notation call interaction

frames to support these functions


Interaction Frame

• alt : alternative, executes only if condition is met

aLibrarian aBorrower aCollection aBook :Date

CheckOut

KnowFine

CompareIsOverdueloop [for each book]

[overdue]altGetFine


Communication Diagrams

• Known as Collaboration Diagram in UML 1.x

• Contain the same info as the sequence diagram

• Sequence diagram is more common, communication diagram may good well with CRC cards


Nested number system (legal UML)

aLibrarian

1:Checkout

aBorrower

1.1:

Che

ckou

t

aCollection

1.1.1:KnowFine

aBook

*[for all books]1.1.1.1:IsOverdue

1.1.1.1.1:IsOverdue:Date

1.1.

1.1.

1.1:

Com

pare

[overdue]1.1.1.1.2:GetF

ine


Not official numbering system, but commonly used

aLibrarian

1:Checkout

aBorrower

2:C

heck

out

aCollection

3:KnowFine

aBook

*[for all books] 4:IsOverdue

5:IsOverdue:Date

6:C

ompa

re

[overdue] 7:GetF

ine


Activity Diagrams

• Similar to flowcharts, but supports parallel behavior

initial stateinitial state

forkfork

statestate

joinjoin

decisiondecision

guardguard

final statefinal state

CheckFine CheckBorrowLimit

CheckOut Reject

[CanBorrow] [else]


Swimlanes

• Each swimlane shows the activities within a class BorrowerBook

CheckFine CheckBorrowLimit

CheckOut Reject

[CanBorrow] [else]


Signals

• Signal send– To send a message to an activity in

another process

• Signal receipt– Accepting an event message from another

process

ReserveBook

CallbackBorrower

statestatesignal sendsignal send

time signaltime signal Overdue

CallbackReceived

Email ToBorrower

signal receiptsignal receipt


State Machine Diagrams

• Describe the states and lifetime of an object– State diagram of a Book

initial stateinitial state

BorrowedReturned

final statefinal state

On shelf

On loan

statestate

transitiontransition


History state

• The remembered substate before last transition

• E.g. computer screen goes blank after time-out, back to original state at keystroke or mouse movement

H

Working

UpdateDisplay

ProcessInput

Wait forInput

H

Sleeping

time-outKeyboard ormouse movement

substatesubstate


Interaction Overview Diagrams

• Mix sequence diagram with activity diagram

Check fine

Check borrow limit

:Book :Date :Borrower

IsOverdue

[overdue] GetFine


Timing Diagrams

• Shows the timing of states change of one or more objects, like those use in electronic engineering

Course lecture Mid-term lecture

{>6 weeks} {>4 weeks}


Use of UML

• Requirement and analysis

– Use cases

• Describe how users interact with the system

– Class diagram

• Build up vocabulary, show the conceptual model of the system

– Activity diagram

• Like flowchart, show the work flow of the system

– State diagram

• For objects that have complex life cycle


Use of UML

• Design

– Class diagram

• Fuller and more detailed

– Sequence diagram

• To describe the most important scenarios form use cases

– Package diagram

• To show the large-scale organization of the system

– State diagram

– Deployment diagram

• To show the physical layout of the software


Documentation

• Use your good sense– Don’t overuse UML, too many diagrams with too much

details make the documents difficult to understand

• Use diagrams to show the important architecture, e.g.– Package diagram – show road map of the system– Class diagram – within each package, provide more

detailed information, be selective– Deployment diagram – show physical layout– State diagram – only for complex object

• Detailed documentation can be generated from the code– JavaDoc for Java and Visual Studio for C#

department of information engineering 351 what is uml (unified modeling language)? uml is a set of...

Documents

classes class

roundtrip engineering

association class ok

instance of association

qualified association

b association

attributes operations

propertystring optional