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List functional requirements for the system (Ask the chat bot for hints if stuck.)...
List non-functional requirements for the system...
Estimate the scale of the system you are going to design...
Assume 1 billion DAU
30 min per day * 1 billion DAU -> 30 billion minutes per day
30 billion minutes per day * 60 sec/min / 1 billion DAU = 1.8 k second/user/day.
Assume updates are sent 15 secs:
1.8k seconds / 15 secs * 1 billion DAU / 86400 secs/day = 41 million QPS
Define what APIs are expected from the system...
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...
routing tiles: large storage -- object storage like S3
User DB -- relational
location history DB: heavy write and read -- nosql like cassara or dynamo
Geocoding DB: heavy read low write -- relational
Batch/stream service: kafka. Used to send location updates to various helper services like analytics, routing tile service and adaptive ETA service
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...
LB
API Gateway
location service
Search service
Navigation service
Ranking service
ETA service
shortest path service
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...
Location update:
User - > LB -> API Gateway -> location service -> location history db.
Search address:
User - > LB -> API Gateway -> Search service -> redis cache -> geocoding DB -> tile rendering service
navigation:
User - > LB -> API Gateway -> Navigation service -> geocoding DB -> routing service
Three paths after:
routing service -> Ranking service
routing service -> ETA service
routing service -> shortest path service
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...
Explain any trade offs you have made and why you made certain tech choices...
Try to discuss as many failure scenarios/bottlenecks as possible.
What are some future improvements you would make? How would you mitigate the failure scenario(s) you described above?
Adaptive ETA