System requirements


Functional:

  • Get a feed of tweets aggregated from a list of followers and popular posts
  • be able to follow and unfollow a user
  • post pictures or videos potentially?



Non-Functional:

  • high availability
  • quick reads
  • eventual consistency on posts




Capacity estimation

  • assume 100 million daily active users
  • assume 1 out of 10 users post tweets per minute
  • 1 tweet will have max 160 b we should have around around 160 gb worth of tweets a day
  • each tweet will have another 160b or so of meta data for uid, likes, retweets, and etc, doubling the amount of storage a day approximately
  • band with we would want at least 1 mpbs per user to load multiple tweets and tweets meta data
  • if we have photos or videos then we would have to consider a blob storage based on limits we set on media posts



API design

  • postTweet(uid, content)
  • post request
  • getTweetFeed(uid)
  • get request
  • postTweetMedia(uid, content, fileType)
  • post request




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...






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?