System requirements


Functional:

  • users are able to search events given location
  • users are able to view event details
  • users are able to book ticket and pay via 3rd party



Non-Functional:

  • the system should be highly available 99.9% and fast (search/view < 200ms, book should be a few seconds mostly)
  • the system will be able to handle a surge of traffic for high demand events. 10k*10= 100k qps





Capacity estimation

  • 1 million DAU, read 3 events, read qps is 35
  • spiky events have higher qps,





API design

Define what APIs are expected from the system...

  • search events GET /search/lat=?&lng=? return a list of partial event info
  • view event details GET /viewEvent/eventId
  • book POST /book/eventId=?&ticketId=?
  • checkout POST /checkout/




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...


  • event - eventId, date, createAt, artist, tickets, city
  • ticket - ticketId, price, status(available, pending, sold)
  • user



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...

  • message queue in front of the booking service, booking is SSE
  • avoid double booking, set the status of ticket to pending when someone is in the checkout flow




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?