Design a Hotel Booking Service - System Design Interview (Question + Answer)

Designing a hotel booking system involves careful consideration of various functional and non-functional requirements.

The system should support multiple hotels and functionalities like viewing, updating, adding, and deleting hotel information.

Additionally, crucial features like room search, reservations, and cancellations should be included.

Non-functional requirements such as concurrency, scalability, security, and performance should also be considered.

Functional Requirements

The system should support multiple hotels and offer features like viewing, updating, adding, and deleting hotel information.

Additionally, the system should have the necessary features for room search, reservations, and cancellations. These features are essential to the system's success, and their implementation should be carefully considered.

One approach to designing a hotel booking system is a microservice-based architecture with dedicated databases for each service. This approach is suitable for most business types.

Non-Functional Requirements

A cache can store available room counts to prevent double booking, with updates made through an event queue mechanism.

Images can be stored in S3, and a geographically located CDN can retrieve them, saving space and bandwidth.

Concurrency issues can be addressed by optimizing ways to control additions to the reservation table.

Back-end Approach

Tthe storage required for reservation data can be substantial. Therefore, it is crucial to have multiple databases and transactional features.

One solution is an inventory service that works with reservation and data storage databases. A front-end experience layer can also be implemented to work with various UI platforms.

To avoid double booking, one approach is to intelligently create IDs and optimize methods for adding entries to the reservation table.

There are multiple options for concurrency control, such as two-phase commit and Saga.

Sharding is also commonly used for optimization, although it can add complexity to the microservice-based architecture.

Estimation and Format

It may be preferable for large companies to use separate databases and storage for each service, despite the added complexity. When creating a schematic draft, it's crucial to outline every detail that meets the user requirements list.

These requirements will help estimate the cost, device, and plan needed to create the perfect system.

Other Considerations

The system should be able to handle multiple currencies and languages, as well as integrate with various payment gateways. It's also important to consider security measures to protect user information and prevent fraud.