Yeah totally agree. I focused on real-time data because offline data processing is often able to be less principled about the usage of time and doesn't need an explicit log (e.g. many ETL pipelines work this way).
Coming across article now was quite serendipitous as I'm in the process of designing a Databus like system myself. In regards to Kafka and Databus, one thing I've been wondering about is why the Databus relay isn't implemented with Kafka? Kafka seems to provide the same semantics (at-least-once in order delivery, clients can pull from arbitrary positions in the stream, etc.). I know Databus provides transaction semantics in the stream and a few other differences, but those differences don't seem too large. Is it because Databus is to be embedded in Espresso? Or maybe even something as simple as two different teams converging on the same solutions?
Anyway, thanks again for the article.