Since nobody else mentioned it: Often you'll want to have multiple consumers of a given topic for load-balancing/failover - that's on the consumer side. The sup

Since nobody else mentioned it: Often you'll want to have multiple consumers of a given topic for load-balancing/failover - that's on the consumer side. The support for this in the MQTT standard is poorly defined, and popular libraries handle it poorly to the point that I can't recommend trying it. Message queues right-and-proper load-balance consumers by locking the entire topic once per delivery; Kafka does it by assigning "partitions" of a topic to different consumers, and thus you have faster, lock-free delivery (Kafka is essentially a "hot-rodded" message queue, just like hot-rodding a car by removing certain "proper" guard rails).