How to Model an Airline Reservation System

Modeling an airline reservation system is a common exercise in object-oriented design, particularly in technical interviews. This system involves various entities and relationships that need to be carefully considered to create a robust and scalable design. In this article, we will explore the key components and how to model them effectively.

Key Entities

1. Flight
   Represents a specific flight with attributes such as flight number, departure and arrival times, origin and destination airports, and available seats.

2. Airport
   Represents an airport with attributes like airport code, name, and location. Airports are linked to flights to indicate where they depart from and arrive at.

3. Passenger
   Represents a person who books a flight. Attributes include name, contact information, and a unique passenger ID.

4. Reservation
   Represents a booking made by a passenger for a specific flight. It includes attributes such as reservation ID, passenger details, flight details, and seat assignments.

5. Ticket
   Represents the actual ticket issued for a reservation. It includes ticket ID, reservation ID, and payment status.

6. Payment
   Represents the payment details for a reservation, including payment ID, amount, and payment method.

Relationships

• Flight to Airport: A flight is associated with two airports (departure and arrival).
• Reservation to Flight: A reservation is linked to a specific flight.
• Reservation to Passenger: A reservation is made by a passenger.
• Reservation to Ticket: Each reservation can have one or more tickets associated with it.
• Ticket to Payment: A ticket is linked to a payment record.

Class Diagram

To visualize the relationships and attributes, we can create a class diagram:

+----------------+       +----------------+       +----------------+
|     Flight     |       |     Airport     |       |   Passenger    |
+----------------+       +----------------+       +----------------+
| - flightNumber |       | - airportCode  |       | - passengerID  |
| - departureTime|       | - name         |       | - name         |
| - arrivalTime  |       | - location     |       | - contactInfo  |
| - origin       |       +----------------+       +----------------+
| - destination  |                                   |
| - availableSeats|                                   |
+----------------+                                   |
        |                                            |
        |                                            |
        |                                            |
+----------------+                                   |
|   Reservation   |                                   |
+----------------+                                   |
| - reservationID |                                   |
| - flight        |                                   |
| - passenger     |                                   |
| - seatAssignment |                                   |
+----------------+                                   |
        |                                            |
        |                                            |
+----------------+                                   |
|     Ticket      |                                   |
+----------------+                                   |
| - ticketID      |                                   |
| - reservation    |                                   |
| - paymentStatus  |                                   |
+----------------+                                   |
        |                                            |
        |                                            |
+----------------+                                   |
|     Payment      |                                   |
+----------------+                                   |
| - paymentID      |                                   |
| - amount         |                                   |
| - method         |                                   |
+----------------+                                   |

Design Considerations

1. Scalability: The system should be able to handle a large number of flights, passengers, and reservations. Consider using a database to manage data efficiently.

2. Extensibility: Future features such as loyalty programs or additional payment methods should be easy to integrate into the existing design.

3. Error Handling: Implement robust error handling for scenarios such as overbooking, payment failures, and flight cancellations.

4. Security: Ensure that sensitive passenger information and payment details are securely stored and transmitted.

Conclusion

Modeling an airline reservation system requires a clear understanding of the entities involved and their relationships. By applying object-oriented design principles, you can create a system that is not only functional but also scalable and maintainable. This exercise is a valuable addition to your preparation for technical interviews, showcasing your ability to design complex systems.