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:

• Strong Consistency
• High availability
• AutoScaling

API Design

POST parking/checkin

GET parking/availableSlots

POST parking/checkout

GET parking/payment

Detailed Component Design

SQL DB - Lock for update to be used

Tables involved are

Vehicle

Slots

Bills

Race conditions can be managed with select for update that applies locking the slot

Cache is used to get the available slots, not to hit the DB for each and every call

Microservices architecture