System requirements

Functional:

1. Reservation:
   • Users can reserve a parking spot through the system.
   • Users can complete the reservation by making a payment.
2. Parking Management:
   • Allocate parking spots based on user reservations.
   • Handle different vehicle types.
3. Entry and Exit Management:
   • Track vehicle entry and exit from the parking lot.
4. Error Handling:
   • Address scenarios where users make reservations but don’t show up, possibly charging a fee for the first 24 hours.

Non-Functional:

Performance(latency, hight throughput), scalability(vertical/horizontal), availability, security, reliability, consistency etc

Capacity estimation

Number of parking lots = 1000

Parking lot capacity = 200

Reservation requests = 200 * 1000 = 200 000

API design

API used by user:

checkCapacity(lot_id, vechile_type, start_time, end_tine) [is_free, price] - checks if parking lot has a free spot and returns price

reserveSpot(user_id, lot_id, vechile_type, start_time, end_time) -

returns reservation_id and price. Also forwarded on 3d party payment system.

completeReservation(reservation_id, payment_token) - after payment we need to complete payment procedure

API used by parking lot:

vechile_arrived(reservation_id, time)

vechile_left(reservation_id, time)

Database design

Defining the system data model early on will clarify how data will flow among different components of the system. Also you could draw an ER diagram using the diagramming tool to enhance your design...

High-level design

Parking lot - notifies when car arrive or left

Client - user , that wants to get parking spot

Api gateway - mediator fro http requests

Reservation service - checks for empty place and update reservation in database

Payment service - 3d party for payments

Request flows

Explain how the request flows from end to end in your high level design. Also you could draw a sequence diagram using the diagramming tool to enhance your explanation...

Detailed component design

Dig deeper into 2-3 components and explain in detail how they work. For example, how well does each component scale? Any relevant algorithm or data structure you like to use for a component? Also you could draw a diagram using the diagramming tool to enhance your design...

Trade offs/Tech choices

Explain any trade offs you have made and why you made certain tech choices...

Failure scenarios/bottlenecks

Try to discuss as many failure scenarios/bottlenecks as possible.

Future improvements

What are some future improvements you would make? How would you mitigate the failure scenario(s) you described above?