The employee.class.php file contains an abstract, base class named Employee. One of the

attributes of the class is an object of Person. This demonstrates one of the three

relationship types among classes: composition. This class also contains a static attribute and

method that keep track of number of Employee objects created in the system.

4. The person.class.php file contains the Person class.

 

Person -first name: String -last name: String + __construct +getFirstName: String +getLastName: String +toString: void (abstract) Employee -person: Person -ssn: String -employee_count: integer + __construct +getPerson: Person +getSSN: String +getEmployeeCount: integer +toString: void