System requirements

Functional:

• Buy tickets for an event
• View upcoming events
• View booked events
• Sell tickets
• User authentication
• Search for an event

Non-Functional:

• Reliable (2 users can't book same ticket)
• Secure
• Fault tolerant
• Handle large volumes of users during popular events

Capacity estimation

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

API design

GET /tickets

• Params: search parameters (optional)
• Returns: list of events

POST /buy

• Params: ticket id(s), timestamp, user id

POST /buy/confirm

• Params: payment info
• Returns: success/failure

Database design

• SQL database
• Event: id, artist, venue, date, description
• Ticket: id, seat info, event id
• Booking: id, event id, ticket id
• Artist: id, name, description

High-level design

Components

• API Gateway
• Load balancer
• Ticketing service
• Payment service
• DBs
• Caches

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

• Use LRU for caching events
• Cache should be invalidated when the event has passed
• Use cache write-back policy
• Shard the ticket database by events
• Replicate the booking database

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?