Object-Oriented Modeling with UML: Understanding Classes, Objects, and Relationships, Slides of Software Project Management

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Object-Oriented Modeling with

UML

Lecture # 30

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Object-Oriented Modeling

Methods

• Shlaer/Mellor - 1988• Coad/Yourdon – 1991• Booch - 1991• OMT by Rumbaugh et. al. – 1991• Wirfs-Brock – 1991• And many more

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Unified Modeling Language - 1

• Visualizing, specifying, constructing,

and documenting object-orientedsystems is exactly the purpose of theunified modeling language or UML

• The rules of UML focus on the

conceptual and physical representationof a system

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Unified Modeling Language - 2

• Process independent• Notation has well-defined semantics• It has become the de-facto standard for

modeling

• Many vendors provide tools that

support different modeling views

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Static Structure - 1

• Any precise model must first define the

universe of discourse, that is, the keyconcepts from the application, theirinternal properties, and theirrelationships to each other

• This set of constructs is the static view

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Static Structure - 2

• The application concepts are modeled as

classes, each of which describes a set ofdiscrete objects that hold information andcommunicate to implement behavior

• The information they hold is modeled as

attributes; the behavior they perform ismodeled as operations

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Objects and Classes

• An object is an instantiation of a class• It has an identity, state, and behavior

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UML Notation for Objects

aObject

bObject : Class

:Class

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Relationships Between Objects - 2

• Dependencies, generalizations, and

associations are all static thingsdefined at the level of classes

• In the UML, these relationships are

usually visualized in class diagrams

• These relationships convey the most

important semantics in an object-oriented model

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Dependency Relationship

• A dependency is a using relationship that

states that a change in specification of onething may affect another thing that uses it,but not necessarily the reverse

• Graphically, a dependency is rendered as a

dashed line, directed to the thing beingdepended on

• Use dependencies when you want to show

one thing using another thing

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Generalization Relationship

• A generalization is a relationship

between a general thing (called a superclass or parent) and a more specifickind of that thing (called the subclassor child)

• Generalization is sometimes called an

‘is-a-kind-of’ relationship

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Generalization Relationship

Shape originmove()resize()display()

Circle radius: Float

Polygon points: Listdisplay()

Rectangle corner: Point

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Association Relationship - 2

• Use associations when you want to show

structural relationships

• An association can have four adornments
  • Name– Role– Multiplicity– Aggregation
    • Captures the ‘whole-part’ relationship• Composition – a stronger ‘whole-part’ relationship

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Association Relationship: Name

Company

Person

Works for Association Names