1. Information Systems Engineering
Class Diagram

2. diagrams UML
*Communication diagram(Collaboration diagram)

3. Class Diagram
A Class diagram is used to display some of the classes and packages in your system
It gives you a static picture of the pieces in the system and of the relationships between them
They help the developers see and plan the structure of the system before the code is written, helping to ensure that the system is well designed from the beginning

4. Class Types: Class Utility
A class utility is a collection of operations
Ex: you may have some mathematical functions—squareroot(), cuberoot(), and so on—that are used throughout your system but don't fit well into any particular class
These functions can be gathered together and encapsulated into a class utility for use by the other classes in the system

5. Class Types: Abstract Class
Abstract Class - is a class that will not be instantiated. In other words, if Class A is abstract, there will never be any objects of Type A in memory.
it exists extensively for inheritance and it must be inherited. There are scenarios in which it is useful to define classes that is not intended to instantiate; because such classes normally are used as base-classes in inheritance hierarchies.
(Animal class Example)

6. Class Specifications
Class Name - Unique Name, No spaces, Short, Starting with an upper-case letter
Class Visibility
Public - the class can be seen by all of the other classes in the system
Protected or private - the class can be seen in nested classes
Class Multiplicity - The number of instances that you expect to have of a class
Storage Requirements for a Class - The amount of memory you expect each object of the class to require

7. Class Specifications cont.
Class Persistence
Persistent – the information in objects of the class will be saved to a database or some other form of persistent storage
Transient – the information in objects of the class will not be saved to persistent storage

8. Class Attributes Specifications
Data Type (e.g. string, double, int, etc..)
Initial Value – Not required
Visibility
Public - the attribute is visible to all other classes ( + )
Private - the attribute is not visible to any other class ( - )
Protected - the class and any of its descendants have access to the attribute (#)

9. Class Attributes Specifications cont.
Containment
By Value - the attribute is contained within the class
Reference - the attribute is located outside the class, but the class has a pointer to it
Static Attribute - Shared by all instances of the class
Derived Attribute - Created from other attributes , Ex. Area is created from the height and width attributes

10. Class Operations An operation is a behavior associated with a class
An operation has three parts:
The Operation Name
The Operation Parameters
The Operation Return Type
The parameters are arguments the operation receives as input. The return type is the output of the operation

11. Practice Draw the classes found in the ATM Withdraw Money use case
Attributes
Operations

12. ATM Withdraw Money Class Diagram