1. Domain Modeling
Yonglei Tao

2. Classes and Objects in UML

3. Representing Type in UML
SSN: String
checkin(time:float):void
name: String
checkout(time:float):void
Employee

4. Associations

5. Multiplicity

6. Associations

7. Inheritance User Staff Student id: String name: String
login(id, password)
logout()
Staff
Student
processApplication()
applyOnline()

8. 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

9. Is-A Relationship

10. Two Tests for Inheritance
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.
Engine
model#
horse power
manufacturer
start()
stop()
Car
drive()
Professor
name
phone
teach(...)
Visiting Professor
signContract()
Retirement Plan
enroll
Car is not an engine.
Visiting professors cannot enroll in a retirement plan at the host university.

11. Creating a Subclass Include additional features of interest
attributes
associations
Include different behavior
add new operations
redefine superclass operations
Support software reuse (with modification)

12. 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

13. Justifying a Class Hierarchy

14. 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

15. Abstract Classes

16. Aggregation Relationship
Car
model#
horse power
manufacturer
start()
stop()
Engine
part-of relationship

17. Composite Relationship

18. 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

19. 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

20. Association Classes

21. Association Class
An association class defines properties and operations for an association between two classes.
Student
Course
enroll *
Enroll
grade: char
getGrade()
setGrade(grade:char)

22. Understand Association Class
Alex got an “A” and Eric got a “B” for OOSE.
:Enroll
‘A’: char
getGrade()
setGrade()
Alex:Student
OOSE:Course
enroll
‘B’: char
Eric:Student
:Enroll
‘A’: char
getGrade()
setGrade()
Alex:Student
AI:Course
enroll
Alex also got an
“A” for AI.

23. Understand Association Class
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
Student
enroll
Course
Enroll
grade: char
getGrade()
setGrade(grade:char)
Student alex=new Student( ... );
Course oose=new Course ( ... );
...
Enroll e=new Enroll(alex, oose);
e.setGrade(‘A’);

24. Understand Association Class
Student
Course
sid
phone
...
name cn
desc
title
Enroll
grade
001
Alex
002
Eric c1
oose c2 AI A B
Enroll
grade: char
getGrade()
setGrade(grade:char)
Student
Course
enroll

25. Constraints

26. Steps for Domain Modeling
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

27. Steps for Domain Modeling (Cont.)
3) Classifying the domain concepts into:
classes
attributes / attribute values
relationships
association, inheritance, aggregation
4) Visualizing the result using a UML class diagram

28. Brainstorming: Rules to Apply
Team members get together to identify and list domain specific concepts
nouns / noun phrases
"X of Y" expressions (e.g., color of car)
transitive verbs
adjectives
numeric
possession expressions (has/have, possess, etc.)
"constituents / part of" expressions
containment / containing expressions
"X is a Y" expressions

29. Identify Important Concepts
“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.”

30. Classifying Brainstorming Result
nouns/noun phrases
"X of Y" expressions
transitive verbs
adjectives
numeric
possession expressions (has/have, possess, etc.)
"consist of/part of" expression
containment / containing expressions
"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

31. Examples Domain specific nouns/noun phrases transitive verbs
exchange program
semester
undergraduate student
Domain specific
nouns/noun phrases
apply to (programs)
transitive verbs
Rule: transitive verbs Þ
association relationships
Rule: noun/noun phrase 
class or attribute
Because they exist
independently in the application domain.

32. A car has make, model, horse power, number of seats ...
numeric
noun/noun phrases
A car has make, model, horse power, number of seats ...
possession expression
(c) car
(a) make
(a) model
(a) horse power
(a) number of seats
Car has independent existence.
Make, model, horse power, and
number of seats do not.
A customer can rent one or more cars ...
(c) customer
(c) car
rent 1+

33. Visualizing in a Class Diagram

34. Class Exercise 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

35. 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.