Domain Modeling

Yonglei Tao

Classes and Objects in UML

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3

SSN: String

checkin(time:float):void

name: String

checkout(time:float):void

Employee

Representing Type in UML

SaleRegister Records-current 11

association name multiplicity

-"reading direction arrow"-indicate direction of reading the association label-often excluded

Associations

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Multiplicity

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Associations

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Store

Contains

Person

Airline

Em ploys

1..*

SaleRegister Captures1..*

1..*

Paym entPaid-by1

FlightAssigned-to P lane*

Assigned-to

*

Supervises

*

1

1

1

1

1 1

1

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Inheritance

Userid: String

login(id, password)name: String

logout()

Staff Student

applyOnline()processApplication()

Rules for Inheritance A subclass is a (kind of) superclass

A superclass is more general than a subclass 100% of the superclass’s definition should

be applicable to the subclass Attributes Associations

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Is-A Relationship

CashPayment

CreditPayment

CheckPayment

Payment

amount : MoneySalePays-for

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9

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Two Tests for Inheritance

Enginemodel#horse powermanufacturer

start()stop()

Car

drive()

IS-A test: every instance of a subclass is also an instance of the superclass.

Conformance test: relationships of a superclass are also relationships of subclasses.

Professornamephoneteach(...)

Visiting Professor

signContract()

Retirement Planenroll

Visiting professors cannot enroll in a retirement plan at the host university.

Car is not an engine.

Creating a Subclass Include additional features of interest

attributes associations

Include different behavior add new operations redefine superclass operations

Support software reuse (with modification)

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Creating a Superclass Factor out common features among

subclasses common attributes, associations, and behavior code sharing

Allow potential subclasses representing variations of a similar concept provide a common interface support polymorphic processing

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Justifying a Class Hierarchy

CreditAuthorization

Service

CheckAuthorization

Service

CheckPayment

AuthorizationService

addressnamephoneNumber

additional associations

superclass justified by common attributes and associations

StoreAuthorizes-payments-of *

Authorizes

CreditPayment

Authorizes

**

*

1 1

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Abstract Class Represents a class that never has any

concrete instances Defines an interface for related subclasses

Every member of the class must also be a member of a subclass

CashPayment

CreditPayment

CheckPayment

Payment

amount : Money

abstract class indicated by italics

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Abstract Classes

Payment

CashPayment CreditPayment CheckPayment

Payment

CashPayment CreditPayment CheckPayment

If a Payment instance mayexist which is not a CashPayment, CreditPayment or CheckPayment, then Payment is not an abstract conceptual class.

Payment is an abstract conceptual class. A Payment instance must conform to one of the subclasses: CashPayment, CreditPayment or CheckPayment.

(a)

(b)

abstract conceptual class

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Aggregation Relationship

Carmodel#horse powermanufacturer

start()stop()

Enginemodel#horse powermanufacturer

start()stop()

part-of relationship

Composite Relationship

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Part-Of Relationships Composite

the whole solely owns the parts the part’s lifetime is bound within the lifetime of

the whole certain properties of the whole propagate to the

parts Aggregation

logical assembly the parts can be referenced by one or more

wholes

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Why Composition? Help determine the lifetime of a object

a create-delete dependency of the part on the whole

Help identify an object creator Provide a way of grouping

hide parts within the whole

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Association Classes

addressnamephoneNumber

AuthorizationService

addressname

Store

merchantID

ServiceContractan association class

its attributes are related to the association

its lifetime is dependent on the association

Authorizes-payments-via

1..**

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Association Class

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An association class defines properties and operations for an association between two classes.

Enrollgrade: char

getGrade()setGrade(grade:char)

Student Courseenroll **

Understand Association Class

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Alex got an “A” and Eric got a “B” for OOSE.

:Enroll

‘A’: char

getGrade()setGrade()

Alex:Student OOSE:Courseenroll

:Enroll

‘B’: char

getGrade()setGrade()

Eric:Student OOSE:Courseenroll

:Enroll

‘A’: char

getGrade()setGrade()

Alex:Student AI:Courseenroll

Alex also got an

“A” for AI.

Understand Association Class

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Enrollgrade: char

getGrade()setGrade(grade:char)

Student Courseenroll

Student alex=new Student( ... );

Course oose=new Course ( ... );

...

Enroll e=new Enroll(alex, oose);

e.setGrade(‘A’);

class Student { ... }

class Course {...}

class Enroll { private char grade; private Student student; private Course course;

public Enroll (Student s, Course c) { student=s; course=c; } public char getGrade() {…} public void setGrade(char grade) {…}}

Implementation

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Understand Association Class

Enrollgrade: char

getGrade()setGrade(grade:char)

Student Courseenroll

Student

Course

sid phone ... ...name

cn desctitle ... ...

Enrollsid gradecn ... ...

001 ... ... ...Alex002 ... ... ...Eric

c1 ...

... ...oosec2 ..

.... ...AI

001

A ... ...c1001

A ... ...c2002

B ... ...c1

Constraints

Stack

size : Integer { size >= 0 }

push( element )pop() : Object

three ways to show UML constraints

{ post condition: new size = old size + 1 }

{ post condition: new size = old size – 1 }

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Steps for Domain Modeling

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1) Collecting application domain information focus on the functional requirements also consider other requirements and documents also consider business descriptions

2) Brainstorming list important application domain concepts list their properties/attributes list their relationships

Steps for Domain Modeling (Cont.)

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3) Classifying the domain concepts into: classes attributes / attribute values relationships

association, inheritance, aggregation

4) Visualizing the result using a UML class diagram

Brainstorming: Rules to Apply

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Team members get together to identify and list domain specific concepts

1. nouns / noun phrases2. "X of Y" expressions (e.g., color of car)3. transitive verbs4. adjectives5. numeric6. possession expressions (has/have, possess,

etc.)7. "constituents / part of" expressions8. containment / containing expressions9. "X is a Y" expressions

Identify Important Concepts

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“An undergraduate student or a graduate student can apply to no more than two exchange programs per semester. An application consists of an application form, two faculty recommendation letters, and a course equivalent form to be approved by an academic advisor.”…“An exchange program has program name, program type, academic department, academic subject, country, region, term of study, and language.”

Classifying Brainstorming Result

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1. nouns/noun phrases2. "X of Y" expressions

3. transitive verbs4. adjectives 5. numeric

6. possession expressions

(has/have, possess, etc.)7. "consist of/part of"

expression8. containment / containing

expressions9. "X is a Y" expressions

class or attributes X is an attribute of Y X is part of Y X is a role in an association association relationships attribute values attribute / multiplicity values aggregation or attribute

aggregation relationships association or aggregation

inheritance

Examples

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• exchange program• semester• undergraduate student

Domain specific nouns/noun phrases

• apply to (programs)

transitive verbs

Rule: transitive verbs association relationships

Rule: noun/noun phrase class or attribute

Because they existindependently in the application domain.

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A car has make, model, horse power, number of seats ...

(c) car(a) make(a) model(a) horse power(a) number of seats

A customer can rent one or more cars ...

(c) customer(c) car rent

1+

Car has independent existence.Make, model, horse power, andnumber of seats do not.

noun/noun phrases numeric

possession expression

Visualizing in a Class Diagram

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Class Exercise

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Do the following for the vending machine (next slide).

Identify the concepts that exist in the application domain.

Classify the concepts in terms of classes attributes of classes relationships between the classes

inheritance aggregation and association

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Class Exercise: The Vending Machine

The Vending Machine has a display, an alphanumeric keypad, a coin insertion slot, and an item dispenser. The display shows the vending items like chocolates, candies, potato chips, Coke, sprite, etc. Each type of item has a price and a label consisting of a letter A, B, C, ... and a digit 1, 2, ... A customer inserts coins through the coin slot. Each time a coin is inserted an LCD displays the total amount. The customer can press a letter and a digit to enter his selection after enough coins have been inserted. If the total amount is greater than or equals to the item selected, the vending machine dispenses the item and returns the change to the customer. A customer can change his mind and request that the coins be returned by pressing the return button.