What is UML Unified Modeling Language

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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

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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 -gt code generation -gt class diagram
• Programming language
• UML diagram -gt code generation

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UML2 diagrams
Class Diagram
Component Diagram
Composite Diagram
Structure Diagram
Deployment Diagram
Object Diagram
Package Diagram
Diagram
Activity Diagram
Sequence Diagram
Use Case Diagram
Behavior Diagram
Communication Diagram
State Diagram
Interaction Diagram
Interaction Overview Diagram
Timing Diagram
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Class diagram

• The most widely used UML diagram
• Show static relationships between classes

Association
Class Name of A Attributes Operations
Class Name of B Attributes Operations
Role of A
Role of B
Name of Association
1
1..
multiplicity
5
Attribute

• visibility nametype multiplicitydefault
  property-string
• Example -dueDateDate 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

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Operation

• visibility name(param-list) return-type
  property-string
• Example Foo (valueint) void query
• property-string
• query get value without changing the system
  state
• abstract abstract operation, implemented by
  subclass
• ExceptionXXX name the exception returned

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Association

• Dependency
• A depends on B
• Change Bs 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
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Dependency
A
B

• 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

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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
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• Generalization
• Realization
• Provides the implementation

BaseClass
DerivedClass
AbstractClass
DerivedClass
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• Attributes and associations
• Both represents the same thing
• Choose the one that makes your diagram easier to
  understand

0..1
Book dueDateDate0..1
Book
Date
Date is an attribute of Book
Date is associated with Book
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Aggregation and Composition
Car
Wheel

• 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

Rectangle
Point
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Interface and Abstract Classes
ltltinterfacegtgt List
Stereotype
Get
generalization
ltltinterfacegtgt SortedList
Client
dependency
Sort
implementation
AbstractArrayList
Get Sort
Concrete method
Abstract method (italic)
ArrayList
Overriding
Get Sort
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Ball-and-socket Notation (UML2)

• Previous example, alternative representation
• Qualified association
• To model concept like associative array,
  dictionary

SortedList
ArrayList
Client
List
1

StudentInfo
Claslist
1
1
ClassList
StudentInfo
Id
Qualified association
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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

1..

1..
1..
Person
Share
Company
1..
1..
Person
Company
Share quantity
Better, association class add extra constraint
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Association Class

• OK
• Not allowed for association class

personA
CompanyA
personB
CompanyB
personA
CompanyA
personB
CompanyB
17

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

1..
1..
Person
Company
Role
1..
1..
1..
1..
Person
Role
Company
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Constraints

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

ordered
ClassList
Student
Menu
or
Soup
Salad
MainCourse
Dessert
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Template (Parameterized) Class

• class Set ltclass Tgt
• public void Insert(T member) ...
• public void Remove(T member) ...

T
Set Insert(T) Remove(T)
Template parameter
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Package Diagrams

• Each package represents a namespace
• Consists of a group of classes, larger unit
• Example System.IO

System.IO
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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 C
Package D
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Object Diagrams

• To show a snapshot of the objects
• Object instance nameclass name

MapSite
Class diagram
Room
Wall
Door
r1Room roomNumber1
Object diagram
side0Wall
side1Wall
side2Wall
side3Door
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Implementing Packages
GameApplication
AbstractGameEngine
implement
PacMan
LittleFighter
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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
Librarian
UML 2 notation
UML 1 notation
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Component Diagrams
Library
DB
UI
Librarian
Database
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Deployment Diagrams

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

Linux server
TCP/IP
TCP/IP
component connection node
DB
Librarian
A Windows PC
Oracle server
UI
Database
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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

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Composite Structures

• Support hierarchical modeling of a class
  structure

Control UI
Input
port
Control API
Control UI
MediaPlayer
multiplicity
1
MediaPlayer
UI
MediaFilter
Control API
Video stream
Display driver
Output
Video stream
Display driver
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UML Interaction Diagrams (Behavior Model)

• Sequence diagram
• The most common kind of interaction diagram
• Capture the behavior of a scenario

anObjectClassName
Lifeline (dotted line)
Synchronous call
Activation (rectangle)
Asynchronous call (UML gt 1.4)
new
obj
Create object
Asynchronous call (UML lt 1.3)
return (optional)
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Check-out scenario KnowFine()
iteration
guard
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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

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Interaction Frame

• alt alternative, executes only if condition is
  met

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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

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Nested number system (legal UML)
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Not official numbering system, but commonly used
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Activity Diagrams

• Similar to flowcharts, but supports parallel
  behavior

initial state
fork
state
join
decision
guard
final state
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Swimlanes

• Each swimlane shows the activities within a class

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Signals

• Signal send
• To send a message to an activity in another
  process
• Signal receipt
• Accepting an event message from another process

Callback Borrower
signal send
state
ReserveBook
time signal
Overdue
Email To Borrower
Callback Received
signal receipt
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State Machine Diagrams

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

initial state
state
Borrowed
Returned
transition
final state
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History state
H

• The remembered substate before last transition
• E.g. computer screen goes blank after time-out,
  back to original state at keystroke or mouse
  movement

Working
H
substate
Update Display
Process Input
Wait for Input
Keyboard or mouse movement
time-out
Sleeping
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Interaction Overview Diagrams

• Mix sequence diagram with activity diagram

Check fine
Check borrow limit
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Timing Diagrams

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

lecture
Mid-term
lecture
Course
gt6 weeks
gt4 weeks
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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

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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

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Documentation

• Use your good sense
• Dont 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