Requirements

Functional Requirements:

• Allow reservation of a parking spot.
• Process payment for the reservation.
• Enable parking of a car in the reserved spot.
• Support early departure before reservation time expires.
• Gate check-in/out.
• Handle no show.

Non-Functional Requirements:

-- No two vehicles to be reserved to same spot.

-- low latency, reliability

API Design

Reservation API:

-> VechicleDetails(vehicle entry time, type etc.

-> Reservation Service(db entry with BOOKING_PENDING status)

-> Spot Service, checks spot availability if available, lock the row(pessimistic lock) and return spot details, update the Spot status as OCCUPIED. if not, throw exception "No spot available" and rollback Reservation entry.

-> entry into outbox event

-> Reservation Service consumes the event and updates the status to BOOKED

-> Notification to user about Payment API:

ReservationService(update exit time, status to RELEASED

-> Payment service (payment gateway). if payment fails, rollback Reservation status

-> SpotService - update the spot status as AVAILABLE

-> Notification service - notify to user

High-Level Design

Describe the overall system architecture. Identify the main components needed to solve the problem end-to-end. Use the diagramming tool to create a block diagram.

Detailed Component Design

Deep dive into 2-3 key components. Explain how they work, how they scale, discuss tradeoffs, capacity, and any relevant algorithms or data structures.