System requirements


Functional:

  • Users shall be able to post tweets of 128 characters or less
  • Users shall be able to view tweets in their feed of users which they follow
  • Users shall be able to follow other users
  • Users shall be able to share tweets via iMessage, Facebook, sms, and email
  • Users shall be able to favorite tweets
  • Users shall be able to like tweets
  • Users shall be able to comment on tweets
  • User shall have the ability to interact on twitter publicly, privately, and folllowers-only



Non-Functional:

  • Tweets should be posted live within 1 second of user submission
  • Tweet metrics should be visible to user, such as number of favorites and comments
  • A users favorited tweets should be collected and available for view privately within a user profile



Capacity estimation

  • Capable of handling over 10 million concurrent users
  • Capable of handling 50,000 requests at any given point





API design

  • Tweet POST
  • Tweet GET
  • Tweet PUT
  • Tweet DELETE
  • Comment POST
  • Comment GET
  • Comment PUT
  • Comment DELETE
  • Follow POST
  • Follow DELETE





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...


NoSQL Graph DB to track followers / users, site metrics

Relational DB to track User information (authentication)




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?