[boredandroid]

To clarify: the transaction feature is a transaction over updates to Kafka and provides transparent, correct processing in Kafka for Kafka Streams or anything else only maintaining state/output in Kafka. The trick you described where you either transactionally or idempotently store your offsets and state updates in an external store when consuming in a general app still works, but obviously for that to work it requires there are no duplicates in the log itself, which the idempotence feature in the producer described here enables.