System requirements

Functional:

• Users login to their fitness account
• Users sync or manually put their metric on app (exercise duration, heart rate, calories burnt)
• Users set their goals on app
• Users get recommended goals from app
• Users share their progress on social metric

Non-Functional:

• Should handle peak times
• Should prepare for scaling
• Security issue - fitness data
• Gamification

Capacity estimation

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

API design

POST /login

POST /api/devices/connect

• for wearable device syncing and authorization

GET /api/devices/data

• syncing data from wearable devices (display on dashboard

POST /api/user/fitness-data

• store fitness data in database

Secure third party API for analytics and trend prediction?

Database design

User table

• primary key
• username
• age (important for the nature of this app)
• height
• weight

OverallGoal table

• primary key
• user id (foreign key)
• description (??)

Exercise table

• primary key
• user id (foreign key)
• type (enum or??)
• date
• duration
• heartRate
• caloriesBurnt
• description

ExerciseGoal table

• primary key
• exercise id (foreign key)
• description (??)

High-level design

• Authentication service
• Notification service
• Goals management service (core feature)
• Tracking service (core feature)
  • user inputs manually
  • third party services syncing data from wearable devices
• Metric generation service (core feature)
• Progress analytics service (core feature)

The goals management service should be the most important feature, since the app is about helping people achieve a goal (healthier lifestyle).

The second most important feature would be the progress analytics, where users can see their data. This is how they get educated and learn how to improve.

The third most important feature would be the tracking service, since it prepares the data that educates the users.

Request flows

• Authentication
  • Offers different third-party authentication services, Google OAuth / Microsoft sign-in / Facebook / Instagram
  • The point is offering quick and easy signup, so users can move forward and start their goals
  • User logins in, and an account is created for them if it is the first time they login via the third party authentication services
• Wearable device syncing
  • Through Bluetooth connection / third party API, sync user exercise data and store in their user record
  • The new data will update the tracking
• User inputs exercise data manually
  • User fills in a form, and stores data associated in their user record
  • The new data will update the tracking
• Progress analytics
  • Users will check a dashboard to see their progress and the analysis done by the app

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?