Recently I wanted to learn a bit about Apache Kafka. It is often used as a way to do event sourcing (or similar message-driven architectures). An “add-on” to the simple publish/subscribe pattern in Kafka is Kafka Streams, which provides ways to process unbounded data sets. I wanted to write something slightly more complicated than the examples in the Kafka documentation. Estimating π (Pi) by throwing darts Back in the day we all learned the formula $A=\pi r^2$ for the area of a circle. We place ...