Python Faust Stream Processing — ELI5

Imagine a toy factory with a long conveyor belt. Toys roll down the belt one by one, and workers at different stations do things: paint a toy, add wheels, stick on eyes. Each worker only does their one job, and the belt keeps moving.

Faust is like that factory for data. Instead of toys, you have events — “someone signed up,” “a payment arrived,” “a temperature reading came in.” Instead of workers, you write small Python functions that do one thing to each event.

The conveyor belt is actually Kafka — a system that carries millions of events. Faust reads events from Kafka, lets your Python functions process them, and can send results back to another Kafka belt or store them somewhere.

What makes Faust special is that it feels like normal Python. You write regular functions and decorate them to say “run this on every event.” You do not need to learn a complicated new language or tool. If you know Python, you already know most of what you need.

Faust also remembers things between events. If you need to count how many orders each customer placed today, Faust keeps a running tally in a table that survives restarts.

The one thing to remember: Faust is a Pythonic way to process streams of events in real time — think of it as attaching Python functions to a never-ending conveyor belt of data.