Engineering that powers SOS emergency on Uber
The emergency button on the Uber app is life-saving; and the service powering it needs to be available 24 x 7, no matter what!
So, how did Uber design such a service? How did they make it highly available; here's a quick gist about its system design 👇
Information Gathering
When the emergency button is pressed, we first need to gather all the critical information and send it to the server. The critical information could be
Current Location
Vehicle and Trip Details
Rider and Driver Details
Capturing Location
When the emergency button is pressed, we do not just need to fetch the location at that moment, instead we continuously capture the location and keep sending it to the backend.
This would help us notify the nearby police and help them keep an eye on the movement.
Lat-long are not enough
To make tracing effective, we cannot just share the lat and long because they are incomprehensible; hence we try to deduce the address from the lat-long.
This process of deducing address from lat-long is called Reverse Geocoding.
Notifying the police
Uber uses a 3rd party service named RapidSOS to notify nearby local authorities.
RapidSOS provides APIs to register an emergency and send live updates about the emergency. It takes care of notifying the local authorities and providing them with the necessary information.
Notifying others
Uber not only notifies the police through RapidSOS, but it also notifies
emergency contacts
internal support staff for close follow-ups
The notification to all channels happens in parallel to increase the probability of someone getting notified.
Reliability and Availability
Given that the emergency service deals with events that are urgent, important, and critical; it is extremely crucial that the service is reliable and highly available; which means
no events loss
persistence and retries
fallback to every single component
Key Decisions
Location getting ingested in Kafka
Kafka guarantees persistence and reprocessing if required
RapidSOS can be down and hence apply retries on consumers
Emergency service notifies emergency and internal staff async
Here's the video of my explaining this in-depth 👇 do check it out
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