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quiz vs the machine

Gold1480

System Design

Real Time Location Streaming

Pushing a moving object position to interested watchers within a second.

5 min read · core · beat Gold to climb

The push problem

When a rider watches a driver approach, the driver position must flow to the rider with low latency. Polling repeatedly wastes resources and adds delay, so positions are pushed over a persistent connection.

Fan out by interest

  • A driver publishes to a topic keyed by trip or by region.
  • Only the subscribers of that topic receive updates, so a position is not blasted to everyone.
  • A connection layer holds websockets or server sent event streams and routes updates to the right sockets.

Smoothing the experience

  • Send deltas at a steady rate rather than every raw ping to bound bandwidth.
  • The client interpolates between updates so the marker glides instead of jumping.
  • On reconnect the client requests the latest position so it never shows a stale location after a gap.

Key idea

Real time location streaming pushes deltas over persistent connections to interested subscribers, while clients interpolate to render smooth motion.

Check yourself

Answer to earn rating on the learn ladder.

1. Why push positions instead of polling?

2. Why does the client interpolate between updates?