CSC 335: ObjectOriented Programming and Design

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CSC 335 Object-Oriented Programming and Design
Presentation 4 Introduction to Unified Modeling
Language (UML)
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The Unified Modeling Language (UML)

• UML or Unified Modeling Language comes from
  Rumbaugh, Booch, and Jacobson (the three amigos)
  who have combined efforts to standardize on one
  modeling language
• This is primarily a graphical communication
  mechanism for developers and customers
• We will learn some, but not all, of the UML
• it is very complex, few understand all of it

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UML

• The main purpose of UML is to
• support communication about the analysis and
  design of the system being developed
• support the movement from the problem domain in
  the "world" to the solution domain in the machine
• two views of the same system
• one view has pictures such as UML diagrams
• the source code is another view

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UML is a Modeling Language

• UML
• is a graphical notation that describes software
  design
• has rules on how to draw models of
• classes
• associations between objects
• associations between classes and interfaces
• message sends between objects
• has become the industry standard
• is like a blueprint for what is going on during
  analysis, design and implementation

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UML Defined by the Authors

• From The Unified Modeling Language User Guide,
  Booch, Rumbaugh, Jacobson
• The UML is a language for
• visualizing
• specifying
• constructing
• documenting
• the artifacts of a software intensive system

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First up Design Class Diagrams

• A class diagram
• expresses class definitions to be implemented
• lists name, attributes, and methods for each
  class
• shows how instances will connect to one others
• UML allows different levels of detail on both the
  attributes and the methods of one class
• could be just the the class name in a rectangle
• or like the general form shown on the next slide

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Software Specification Class Name
attribute

attribute type
attribute type initial value
classAttribute
derivedAttribute
...
method1()
method2(parameter Type) return type
abstractMethod()
publicMethod()
-privateMethod()
protectedMethod()
classMethod()
...
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AccountCollection

- allAccounts HashMap
AccountCollection ()
getAccountWithID (ID String) Account
add(accountToAdd Account) boolean
iterator() Iterator
Note iterator is needed by the bank manager
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Sterotypes

• Stereotype is a UML element that allows us to
  extends the UML vocabulary
• Often used to distinguish an abstract class name
  from an interface, both of which are written in
  italic

ltltinterfacegtgt Iterator hasNext()
boolean next() Object remove() void
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Different levels of detail

• Tips for modeling
• Express as much or as little detail as needed
• Often, a rectangle with a name is enough
• perhaps a method or an attribute adds to the
  clarity
• Simple is good
• Sketches on paper or white board are effective

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Relationships

• Three Relationships in UML
• 1) Dependency
• 2) Association
• 3) Generalization
• Understanding these relationships is more
  important than the lines that UML uses

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1) Dependency A Uses Relationship

• Dependencies
• occurs when one object depends on another
• if you change one object's interface, you need to
  change the dependent object
• arrow points from dependent to needed objects

CardReader
Jukebox
CDCollection
SongSelector
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2)Association Structural Relationship

• Association
• a relationship between classes indicates some
  meaningful and interesting connection
• Name the association with a hyphen connected verb
  phrase which reads well between concepts

association
getAccountWithID
JukeboxAccountCollection
Jukebox
1
1
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Associations

• Associations imply
• our knowledge that a relationship must be
  preserved for some time (1 ms to forever)
• between what objects do we need to remember a
  relationship?
• Does a Transaction need to remember the Account?
• maybe yours did, maybe you changed it
• Does AccountCollection need to remember Accounts?

Stores
AccountCollection
Account
1

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Notation and Multiplicity Adornments

• UML Association
• a line between two concepts and a name
• they are bi-directional
• can have a multiplicity
• exist in conceptual
• models and
• class diagrams

zero or more

T
"many"

1..
one or more
T
1..40
one to forty
T
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Multiplicity adornments
exactly five
T
3, 5, 8
exactly three,
T
five or eight
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Multiplicity

• Multiplicity defines how many instances of type A
  can be associated with one instance of type B at
  some point can differ

Game
Player
1
2..6
Mother
Child
1
1
Actor is associated with 0 to many films. A film
is associated with 0 to many actors
performs-in
Actor
Film


can optionally name an association
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Depends on Context

• Are all three associations possible?

Car
Wheel
4
1
Car
Wheel
5
1
Car
Wheel
1
3
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Association Names Upcase / hyphenate

• Read this Type-VerbPhrase-Type (POST is a Point
  of Sale Terminal)
• Not yet worrying about messages, instance
  variables, data flow, or classes
• Just shows objects are connected somehow

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Aggregation A Special Association

• Aggregation whole/part relationships
• An association that models HAS-A relationships
• The objects can exist independently or each other
• No one object is more important than the other
• Place an open diamond on the whole
• Could mean School has a HashMap of Students

School
Student
1..

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Composition A Special Association

• Composition Stronger relationship
• One can not exist without the other
• If the school folds, students live on
• but the departments go away also
• If a department closes, the school can go on AIC
  e.g.
• Model aggregation or composition? When in doubt,
  use association (just a simple line)

School
Department
1
1..
1..

Student
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Sequence Diagrams

• A class diagram shows a fixed view of the system
• A sequence diagram represents a dynamic view of a
  system by attempting to capture messages sends
  over time
• Can document a scenario such as
• User Selects Song

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Sequence Diagrams

• Objects are lined up on top in rectangles
• Object names theJukebox
• Dashed lines are the lifetime of the object
• Rectangles are activation lines
• When the object has control
• Activation bar of the receivers of the message is
  smaller than the sender's activation bar
• No branches, no loops, not much detail

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http//www.ifi.uio.no/in219/verktoy/doc/html/doc/u
ser/mg/dgmsuml6.html
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http//www.visual-paradigm.com/ VPGallery/diagrams
/Sequence.html
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Let's try one for Jukebox

• Draw a sequence diagram for the scenario User
  selects a song