System requirements

Functional:

1. Provide search vacant hotel rooms given the location and date range
2. User can reserve a room with a range of date. And can cancel the rooms before the arrival
3. After payment for the booking, the room booked are guaranteed to be reserved by the user. No data inconsistency / racing problem here.
4. User can see their historical booking records.

Non-Functional:

1. Data strong consistency. No over-sale issue.
2. The system can scale to 1M hotels globally.

Capacity estimation

1. 1M hotels, each hotel has 100 rooms on average.
2. We only do room booking for the future 1 year -> 365 days.
3. So total of 365 * 100M = 36B (room, date) pairs for the storage requirements.

API design

1.Get all available room from a hotel: GET /v1/{hotelID}?date_range={date_range}&other_filters

2.Book a room with a date range: POST/v1/book/;

payload: {

hotelID: str,

roomID: str,

userID: str,

dateRange: (datetime, datetime)

}

response: {bookingID: str, status: str}

3.Cancel a booking: POST/v1/cancel;

payload: {

bookingID: str,

userID: str

}

Database design

Table Hotel:

HotelID (PK)

Rating

Location

// Other features

Table Room:

RoomID (PK)

HotelID

RoomSize etc

Table RoomDate:

RoomDateID (PK)

RoomID

Date

Status

Table Reservation:

UserID (co-PK)

RoomDateID (co-PK)

High-level design

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?