Class Diagram for the Airline Management System

In the class diagram, we will first design and create the classes, abstract classes, and interfaces for the system. Then, we’ll identify the relationship between classes in accordance with all the requirements of the airline management system.

Components of an airline management system#

In this section, we’ll define the classes for an airline management system. As mentioned earlier, we will design the airline management system using a bottom-up approach. We will create the classes of small components first. Next, we will integrate these components and create the class diagram for the entire airline management system.

Account#

The Account class identifies the username and ID of an airline management system user. . The class definition is represented below:

Person#

Person is an abstract class used to store information related to a person like a name, email, phone number, etc. In this class, the Address object type specifies the person’s address. There can be four types of accounts in the system:

• Admin: This class keeps track of the overall system and flight and aircraft records.

• Crew: This class views assigned flights in the system.

• FrontDeskOfficer: This class manages passenger reservations.

• Customer: This class views flight schedule, and reserves or cancels flight reservations.

The relationship diagram for these classes is shown below:

Airline, airport, and aircraft#

The Airline class has attributes like a name and an airline code to distinguish the airline from other airlines. It is an essential part of the airline management system.

Each airline operates out of different airports. Therefore, we need the Airport class to keep track of all the airports in the system.

Airlines own or hire aircraft to carry out their flights. The Aircraft class has attributes like name, model, manufacturing year, etc.

Here’s a visual representation of these classes:

Seat and flight seat#

The Seat class represents a physical seat in the aircraft. It contains basic information like seat number, seat type, and class. The FlightSeat class is derived from the Seat class and represents the seat assigned to a specific flight instance. It contains the fare for that particular seat and its reference number.

The relationship diagram for these classes is shown below:

Flight and flight instance#

The Flight class contains information about a particular flight, including the flight number, departure and arrival airports, and the duration of the flight. The FlightInstance class represents a single occurrence of a flight, since a flight can fly multiple days in a week.

These classes are represented below:

Flight reservation#

The FlightReservation class manages the reservations made by the customer against a flight instance. It has attributes like unique reservation number, passengers and their assigned seats, and the reservation status.

The UML diagram for this class is given below:

Itinerary and passenger#

Customers create an itinerary for their travel that contains flight reservations. The Itinerary class keeps track of all the reservations made, the list of passengers, and the departure/arrival airport.

The Passenger class keeps a record of all individuals with the reservation. It also includes the basic travel information of the passenger.

Here’s the class diagram for these classes:

Search and catalog#

The Search interface allows the customers to search for any flight using the following criteria:

• Departure and arrival date and time

• Source and destination airports

The SearchCatalog implements the search functionality and contains a list of all flights of the airline. The two classes are shown below:

Payment#

The Payment class will be an abstract class and will have two child classes: CreditCard, and Cash.

The visual representation of these classes is as follows:

Notification#

Notification is an abstract class, since it can send a notification via email or SMS. It is mainly responsible for sending notifications whenever required.

The UML representation of the class is shown below:

Enumerations#

The enumerations required in the airline management system design are listed below:

• AccountStatus: The account status tells us about the status of a customer's account—whether it is active, deactivated, closed, or blocked.

• SeatStatus: The seat status tells us whether the seat is available, booked, or a chance seat.

• SeatType: The seat type tells us whether the seat is of a regular, accessible, emergency exit, or extra legroom type.

• SeatClass: The seat class tells us whether the seat is economy, economy plus, business, or first class.

• FlightStatus: The flight status keeps track of the flight instance—whether it is factive, scheduled, delayed, departed, landed, canceled, diverted, or unknown.

• ReservationStatus: The reservation status tells us about the status of the reservation—whether it is requested, pending, confirmed, checked in, or canceled.

• PaymentStatus: The payment status tells us about the status of the payment—whether it is pending, completed, canceled, failed, declined, or refunded.

Custom data type#

We need to create a custom data type, Address, that will store the physical location of any place.

Relationship between classes#

Now, we’ll discuss the relationships between the classes we have defined above in our airline management system.

Association#

The class diagram has the following association relationships:

One-way association#

• Both FrontDeskOfficer and Customer classes have a one-way association with the Itinerary class.

• The FlightReservation class has a one-way association with the FlightInstance, Payment, and Notification classes.

• The FlightSeat class has a one-way association with the FlightReservation class.

• The Person class has a one-way association with the Search interface.

Two-way association#

• The Airport class has a two-way association with the Flight class.

• Both the Aircraft and Crew classes have a two-way association with the FlightInstance class.

• The Airline class has a two-way association with the Crew class.

Aggregation#

The class diagram has the following aggregation relationship:

• The Itinerary class contains the Passenger class.

Composition#

The class diagram has the following composition relationships:

• The Person class is composed of the Account class.

• The Airline class is composed of the Aircraft class.

• The Aircraft class is composed of the Seat class.

• The Flight class is composed of the FlightInstance class.

• The FlightInstance class is composed of the FlightSeat class.

• The Itinerary class is composed of the FlightReservaion class.

Inheritance#

The following classes show an inheritance relationship:

• The Admin, Crew, FrontDeskOfficer, and Customer classes extend the Person class.

• The FlightSeat class extends the Seat class.

• The CreditCard and Cash classes extend the Payment class.

• The EmailNotification and SmsNotification classes extend the Notification class.

Note: We have already discussed the inheritance relationship between classes in the component section above one by one.

Class diagram of the airline management system#

Here's the complete class diagram for our airline management system:

Design pattern#

The Airline class follows the Singleton design pattern because there will only be a single instance of the Airline class as it is the main organizational class.

The airline management system can also implement the Observer design pattern because all the passengers flying in a particular flight instance must be updated about any changes in their flight schedule. The passengers here will act as subscribers and be notified whenever the flight status changes.

AI-powered trainer#

At this stage, everything should be clear. If you encounter any confusion or ambiguity, feel free to utilize the interactive AI-enabled widget below to seek clarification. This tool is designed to assist you in strengthening your understanding of the concepts.

We have successfully designed the class diagram for the airline management system. Let’s see how we can construct the sequence diagram for the system in our next lesson.