System Design: Airline Booking Platform
You are tasked with designing a global airline booking platform. This system must support core functionalities including searching for flights, creating bookings, selecting seats, and modifying or cancelling itineraries. The platform will serve a global consumer base, implying significant geographical distribution. Key performance characteristics include a read-heavy workload for flight search and a write-critical workload for booking operations. A paramount constraint is that seat inventory must never be oversold.
Functional Scope
- Flight Search: Support for one-way, round-trip, and multi-leg connections (up to a maximum of 2 stops). Includes filtering by cabin class and passenger types.
- Booking: Core processes for creating reservations, temporarily holding seats, processing payments, and issuing tickets.
- Seat Selection: Ability to retrieve a visual seat map and assign specific seats per flight segment.
- Modify/Cancel: Functionality to reprice and change existing flights, perform partial or whole cancellations, and process refunds.
API Requirements
Define core APIs using both REST and gRPC protocols for the following operations:
- Search flights
- Retrieve prices and offers
- Book and confirm reservations
- Modify existing bookings
- Cancel bookings
- Select seats
- Retrieve fare calendar (for flexible date searches)
All write operations (booking, modify, cancel) must explicitly handle idempotency.
Data Model Specification
Specify the necessary data models, including but not limited to:
- Flights, legs/segments
- Fare classes and rules
- Seat inventory (categorized by fare bucket and cabin)
- Offers
- Reservations (including PNR - Passenger Name Record)
- Tickets
- Payments
- Users
- Refunds
Guarantees and Controls
- Seat Availability: Ensure atomicity and accurate seat availability across all connecting segments within a multi-leg itinerary.
- Idempotency: Guarantee idempotency for all booking, modification, and cancellation operations.
- Consistency & Concurrency: Define consistency guarantees (strong vs. eventual) and implement robust concurrency control mechanisms to strictly prevent overbooking.
- Multi-Region Strategy: Outline a strategy for data consistency (strong vs. eventual) across different geographical regions.
Integrations
Design for integrations with external services, including:
- Payment gateways (authorize, capture, void, refund)
- Ticketing issuance systems
- Notification services (e.g., email, SMS)
Search and Performance
Address performance considerations for search, including:
- Indexing and caching strategies for queries based on origin, destination, dates, and cabin class.
- Support for pagination and sorting of search results.
- Optimization for flexible-date search (fare calendar).
Scale and Resilience
Detail strategies for:
- Scaling: Horizontal scaling, sharding, and optimizing read/write patterns.
- Resilience: Failover mechanisms, retry logic, distributed transaction patterns (e.g., Sagas with compensations).
- Observability: Monitoring, logging, tracing, and defining Service Level Agreements (SLAs).
Multi-Tenancy and Partners
Discuss the architectural trade-offs between supporting a single airline versus a multi-tenant Online Travel Agency (OTA) scenario. Include considerations for partner API integration and rate limiting for external access.
Deliverable
Provide a coherent system design that addresses all the above requirements, clearly stating any minimal assumptions made to make the system concrete.
AI interview prep
Core dilemma
Balancing the need for strong consistency and atomicity for critical write operations (like seat inventory and booking) to prevent overselling, with the demands of high availability, low latency, and global distribution for both read-heavy search and write-critical booking workloads.
3 tradeoffs and 3 stress tests locked
Interview prep
Unlock the interviewer X-Ray rubric, tradeoff matrix, stress tests, clarifying questions, and key concepts.
System Design: Airline Booking Platform
You are tasked with designing a global airline booking platform. This system must support core functionalities including searching for flights, creating bookings, selecting seats, and modifying or cancelling itineraries. The platform will serve a global consumer base, implying significant geographical distribution. Key performance characteristics include a read-heavy workload for flight search and a write-critical workload for booking operations. A paramount constraint is that seat inventory must never be oversold.
Functional Scope
- Flight Search: Support for one-way, round-trip, and multi-leg connections (up to a maximum of 2 stops). Includes filtering by cabin class and passenger types.
- Booking: Core processes for creating reservations, temporarily holding seats, processing payments, and issuing tickets.
- Seat Selection: Ability to retrieve a visual seat map and assign specific seats per flight segment.
- Modify/Cancel: Functionality to reprice and change existing flights, perform partial or whole cancellations, and process refunds.
API Requirements
Define core APIs using both REST and gRPC protocols for the following operations:
- Search flights
- Retrieve prices and offers
- Book and confirm reservations
- Modify existing bookings
- Cancel bookings
- Select seats
- Retrieve fare calendar (for flexible date searches)
All write operations (booking, modify, cancel) must explicitly handle idempotency.
Data Model Specification
Specify the necessary data models, including but not limited to:
- Flights, legs/segments
- Fare classes and rules
- Seat inventory (categorized by fare bucket and cabin)
- Offers
- Reservations (including PNR - Passenger Name Record)
- Tickets
- Payments
- Users
- Refunds
Guarantees and Controls
- Seat Availability: Ensure atomicity and accurate seat availability across all connecting segments within a multi-leg itinerary.
- Idempotency: Guarantee idempotency for all booking, modification, and cancellation operations.
- Consistency & Concurrency: Define consistency guarantees (strong vs. eventual) and implement robust concurrency control mechanisms to strictly prevent overbooking.
- Multi-Region Strategy: Outline a strategy for data consistency (strong vs. eventual) across different geographical regions.
Integrations
Design for integrations with external services, including:
- Payment gateways (authorize, capture, void, refund)
- Ticketing issuance systems
- Notification services (e.g., email, SMS)
Search and Performance
Address performance considerations for search, including:
- Indexing and caching strategies for queries based on origin, destination, dates, and cabin class.
- Support for pagination and sorting of search results.
- Optimization for flexible-date search (fare calendar).
Scale and Resilience
Detail strategies for:
- Scaling: Horizontal scaling, sharding, and optimizing read/write patterns.
- Resilience: Failover mechanisms, retry logic, distributed transaction patterns (e.g., Sagas with compensations).
- Observability: Monitoring, logging, tracing, and defining Service Level Agreements (SLAs).
Multi-Tenancy and Partners
Discuss the architectural trade-offs between supporting a single airline versus a multi-tenant Online Travel Agency (OTA) scenario. Include considerations for partner API integration and rate limiting for external access.
Deliverable
Provide a coherent system design that addresses all the above requirements, clearly stating any minimal assumptions made to make the system concrete.