Fan-in and Fan-out
Two patterns every backend engineer need to understand :
Fan-in and Fan-out are fundamental data flow concepts that show up everywhere from microservices to messaging queues.
Fan-in → Many sources, one destination.
Think: 3 services (restaurant, payment, delivery) all merging into one Order Summary screen.
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Fan-out → One source, many destinations.
Think: One order placed triggers email, inventory, payment, and analytics all at once.
In social media systems like Twitter, fan-out write pushes posts to all follower feeds on write, while fan-out read builds the feed at read time. Big platforms use both depending on the user’s follower count.
Understanding these patterns helps you design faster, more scalable systems.
#SystemDesign #BackendEngineering #SoftwareArchitecture #MicroServices
