System requirements

Functional:

List functional requirements for the system (Ask the chat bot for hints if stuck.)...

• search for hotels and rooms based on location, dates and number of guests
• view a given room type
• make a reservation
• view a reservation
• cancel a reservation

Non-Functional:

List non-functional requirements for the system...

• highly available
• consistent
• high performance (several users can view and/or book simultaneously)
• responsive and interactive (~50ms page load time on the UI)

Capacity estimation

Estimate the scale of the system you are going to design...

Max number of users browsing or viewing rooms per second = 10K

Max number of users viewing a room per second = 5K

Max number of users trying to book a room per second = 1K

Reads are much more than writes so this is a read-heavy system.

Total number of rooms in the hotel = 500

Given that the data and number of concurrent users is not very high, an SQL Database like MySQL or Postgres will be suitable. SQL DB also provides transaction support and ACID properties which meet our requirements.

API design

Define what APIs are expected from the system...

• Get available room types based on search criteria

GET https:///rooms?start=x&&end=y&&numGuests=n

Returns array of JSON responses

• View a particular room

GET https:///room?type=t

• Make a reservation

POST https:///reserve?roomType=t&&start=s&&end=e

Response type: 201 (success) with reservation id or

40x(error) or 50x(error)

• Cancel a reservation

DELETE https://reservation?id=x

Response type 201 (success) or 40x(error) or 50x(error)

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...

RoomType

=========

Type -- Primary Key

Name

TotalRooms

FeatureA

FeatureB

...

Rate

======

Date --- Primary Key

RoomType --- Primary Key

Rate

Rooms

========

RoomId --- Primary Key

Type

Status (InMarket/OffMarket)

Number

Location

RoomTypeAvailability (used for conflict detection in concurrent booking)

======================================================

RoomType --- Primary Key

Date --- Primary Key

NumAvailable (unreserved) --- Primary Key

Reservation

==========

ReservationId ---- Primary Key

Name

RoomType

NumGuests

Start Date

End Date

Status (complete/pending/canceled)

High-level design

You should identify enough components that are needed to solve the actual problem from end to end. Also remember to draw a block diagram using the diagramming tool to augment your design. If you are unfamiliar with the tool, you can simply describe your design to the chat bot and ask it to generate a starter diagram for you to modify...

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?