1. Class diagram Description
IS351-System Analysis
Class diagram Description

2. Class Diagram Components
Classes
Attribute
Operations
Associations
Aggregation
Composition
Generalization
Multiplicity
A class diagram is a type of static structure diagram that describes the structure of a system by showing the system's classes, their attributes, operations (or methods), and the relationships among objects.

3. The Domain Model Class Diagram
A class diagram that only includes classes from the problem domain.
Design class diagram vs domain model class diagram !!

4. Classes Window Class Name size: Size visibility: boolean Attributes
display() hide()
Class Name
Attributes
Operations
A class is the description of a set of objects having similar attributes, operations, relationships and behavior.

5. Associations Example: “An Employee works for a Company”
To clarify its meaning, an association may be named.
Usually a verb or a verb phrase.
Company
Department
Employee
Associations denote relationships between classes

6. Multiplicity
indicates that (at least) one of the two related classes makes reference to the other
0..1
No instances, or one instance (optional, may) 1
Exactly one instance
0..* or *
Zero or more instances
1..*
One or more instances (at least one)
Student
Course
Doctor
0..*
0..6
1..*
1..2
Registered in
Teaches

7. Aggregation Models a “is a part-part of” relationship. Whole Part Door
Car
Door
House
1..*
2..*
A special form of association that models a whole-part relationship between an aggregate (the whole) and its parts.

8. Composition A strong form of aggregation
Pages
Person
Eye
0..* 2
Book
A strong form of aggregation
The whole is the sole owner of its part.
The part object may belong to only one whole
Multiplicity on the whole side must be zero or one.
The life time of the part is dependent upon the whole.
The composite must manage the creation and destruction of its parts.

9. Generalization (inheritance)
 indicates that one of the two related classes (the subclass) is considered to be a specialized form of the other (the super type) and superclass is considered as 'Generalization' of subclass
“is kind of” relationship.
{abstract} is a tagged value that indicates that the class is abstract. The name of an abstract class should be italicized
Shape {abstract}
Circle
Super Class
Sub Class
An abstract class
Generalization relationship

10. How to model class diagram
Find new classes.
Review name, attribute and methods for each class.
Find associations between classes.
Label the generic associations.
Determine the multiplicity of the associations.
Review associations.

11. Example of identifying Class Relations, Multiplicities,
Attributes

12. The Noun Technique
A technique to identify problem domain objects by finding and classifying the nouns in a dialog or description.
a noun is a person, place, or thing.
The analyst lists all nouns without thinking too much about them and without talking much to users.

13. The Noun Technique
list all the nouns that users mention when talking about the system
add to the list any additional nouns about the problem domain of the system.
Refine the noun list. Ask these questions about each noun:
Is it a unique thing the system needs to know about?
Is it inside the scope of the system I am working on?
Does the system need to remember more than one of these items?

14. Multi-Clinic System Case Study
In a multi-clinic system a patient makes a call for an appointment reservation. Once the call is done, the system has to record all patient information such as patient name, address, and telephone number.
In a multi-clinic system a patient makes a call for an appointment reservation. Once the call is done, the system has to record all patient information such as patient name, address, and telephone number.
During the notification with a patient, he/she should know all possible appointments in order to choose his/her desired appointment.
During the notification with a patient, he/she should know all possible appointments in order to choose his/her desired appointment.
The patient may cancel or change his/her appointment before 24 hours from his actual appointment.
The patient may cancel or change his/her appointment before 24 hours from his actual appointment.
Two daily reports have to be prepared to each doctor, one of them is about patient report and the other is an appointment report.
Two daily reports have to be prepared to each doctor, one of them is about patient report and the other is an appointment report.

15. Multi-Clinic System Case Study
When a patient comes for examination, the doctor writes a prescription which includes all drugs the patient have to take, number of times and dose he has to take for each medicine. In the end, the doctor Prints the prescription to the patient before he leaves.
When a patient comes for examination, the doctor writes a prescription which includes all drugs the patient have to take, number of times and dose he has to take for each medicine. In the end, the doctor Prints the prescription to the patient before he leaves.

16. MCS Class Diagram