Booking & Reservation Systems
Selling something that only exists once — a specific slot, seat, or room, at a specific time.
2.17.1Definition & Purpose
Booking and reservation systems sell access to a finite, time-bound resource — a hotel room, an appointment slot, a seat — where the central technical problem is avoiding double-booking the same resource to two different people at once, especially under concurrent demand.
2.17.2Architecture Priorities
Concurrency control is the defining architectural challenge — two nearly simultaneous booking requests for the same slot must resolve so only one succeeds, which requires deliberate database-level locking or transaction design, not simple application-level checks that leave a race-condition window. Calendar and availability logic needs to correctly account for time zones, buffers, and recurring schedules.
2.17.3UX Priorities
- Real-time availability display so users aren't shown slots that are no longer actually bookable.
- Clear cancellation and modification policies, visible before commitment, not discovered after the fact.
- Time zone clarity for any product serving users across regions — a frequent, high-friction source of missed bookings.
2.17.4Common Mistakes
- Checking availability and creating the booking as two separate, non-atomic steps, opening a race-condition window for double-booking.
- Poor time zone handling, causing bookings to silently land at the wrong actual time for one party.
2.17.5Best Practices
- Use database-level constraints or transactions to make availability checks and booking creation atomic, closing the race-condition window structurally rather than hoping application logic catches it.
- Always store and reason about times in a fixed reference (typically UTC), converting only for display.