System requirements

Functional:

• users can search for events that fit some criteria, view tickets available for an events, add these tickets to their cart, then purchase them. after purchasing, they will receive an email with their ticket details

Non-Functional:

• low latency: users must be able to see events and view available tickets relatively fast
• consistency: each ticket is sold to at most one user. one ticket cannot be sold twice
• throughput: the system must able to process tens of thousands of ticket sales in a short period of time for the same event at peak traffic times
• high availability: system must be up and running during peak traffic and be able to take sales

Capacity estimation

A very popular concert can sell 100k tickets in 1 hour. If there an artist is going on tour with 10 concerts and all of these tickets go on sale, we can have around 300 write RPS just coming from this one artist.

Outside of peak traffic conditions let's say we have 5M DAU and 1 out of 10 of them will buy a ticket. We have around 500 read RPS and 50 write RPS.

API design

• get_events(start_time, end_time, location) -> list of events
• get_event(event_id) -> list of tickets for this event
• purchase_ticket(event_id, ticket_id, user_id)
• get_tickets(user_id)

Database design

Use relational DB like MySQL to store tables for events, tickets, and users. We are using MySQL because we need high consistency and availability for storing structured data.

Schema could look like:

Events: event_id, time, description, location

Tickets: ticket_id, event_id, seat_info, status, status, user_id

Users: user_id, dob, email, location

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?