Design Movie Ticket Booking System
Design a Movie Ticket Booking System that allows users to browse movies, select showtimes, choose seats, and book tickets with real-time seat availability and payment processing.
A Movie Ticket Booking System is a software application that enables users to search for movies, view showtimes, select seats, and book tickets at cinemas or multiplexes.
In this chapter, we will explore the low-level design of a movie ticket booking system in detail.
Let's start by clarifying the requirements:
1. Clarifying Requirements
Before starting the design, it's important to ask thoughtful questions to uncover hidden assumptions and better define the scope of the system.
Here is an example of how a conversation between the candidate and the interviewer might unfold:
Candidate: Should the system support only booking tickets, or should it also manage movie scheduling, theaters, and screens?
Interviewer: It should handle the entire flow—movie listing, show scheduling, screen management, and ticket booking.
Candidate: Can a movie play in multiple theaters and have multiple shows at different times and screens?
Interviewer: Yes, a single movie can run in multiple theaters and across multiple screens with different showtimes.
Candidate: Do we need to support movies in multiple languages.
Interviewer: Lets assume all movies are in the same language (ex. english)
Candidate: Should users be able to select specific seats, or should the system assign them automatically?
Interviewer: Users must be able to select specific seats from a seat map during the booking process.
Candidate: Should the system support different seat types such as ‘Standard’, ‘Premium’, and ‘Recliner’, with variable pricing?
Interviewer: Yes, each screen can have multiple seat types with different pricing.
Candidate: Should we support multiple cities and allow users to filter shows based on location?
Interviewer: Yes, the system should support multiple cities and allow users to search and filter by city, movie, and date.
Candidate: Do we need to handle payment processing and refund flows?
Interviewer: You can assume payment is handled externally. Treat it as a successful step. For this version, we can skip refund logic and just support booking cancellations.
Candidate: How should seat locking be handled to prevent race conditions when multiple users try to book the same seat?
Interviewer: Good question. The system should temporarily lock selected seats during the booking process to avoid double booking. If payment isn't completed within a specific timeout, the seats should be released.
After gathering the details, we can summarize the key system requirements.
1.1 Functional Requirements
- Support listing movies by city, theater, language, and date
- Allow theater administrators to manage movie schedules and showtimes per screen
- A movie can be scheduled in multiple theaters, screens, and time slots
- Each screen can have different seat types (e.g., Standard, Premium, Recliner) with variable pricing
- Allow users to search for movies and showtimes by city and date
- Allow users to view a seat map, select specific seats and book one or more seats
- Temporarily lock selected seats during the booking process. Automatically release locked seats after a timeout if the booking is not completed
- Allow users to cancel bookings (refund logic not required)
- Allow users to search for movies, view seat map, select specific seats and book tickets
1.2 Non-Functional Requirements
- Modularity: The system should follow object-oriented design principles with separate modules for movies, theaters, shows, seats, bookings, and users
- Consistency: Booking and seat locking should be handled atomically to avoid race conditions and double bookings
- Extensibility: The design should be easy to extend to support future features like online payments, loyalty programs, discounts, or third-party integrations.
After the requirements are clear, lets identify the core entities/objects we will have in our system.