Even More on The Architecture of Kafka

Consumer groups #

An event like neworder42 should probably be processed only once by one instance of the invoicing microservice. Only one instance of a microservice should receive it, ensuring that only one invoice is written for this order. However, another instance of a microservice might work on neworder21 in parallel.

Consumers are organized in consumer groups where each partition sends records to exactly one consumer in the consumer group. One consumer can be responsible for several partitions.