Re:Mistakes we made adopting event sourcing and how we recov...
by pondidum on Tuesday July 02, 2019 @01:48AM
(#20332472)
I agree with your post but...You almost certainly shouldn't be doing EventSourcing with Kafka. EventStreaming sure, Kafka is pretty idea for this (as your source of truth).
EventSourced aggregates need to reload their entire history (unless you are snapshotting too) before applying a command, so you shouldn't have all your aggregates in a single Kafka topic, as you would have to read all events since forever, for all aggregates, every time you loaded one.
If you put each aggregate into a separate topic, everything is fine, until you want to add projections - how do your projections know to subscribe to all the new topics being created for each aggregate?
You can probably engineer your way around these limitations, but at that point, why not use a tool which is more suitable for the eventsourcing and keep Kafka for the "Business Process Event"?
EventSourced aggregates need to reload their entire history (unless you are snapshotting too) before applying a command, so you shouldn't have all your aggregates in a single Kafka topic, as you would have to read all events since forever, for all aggregates, every time you loaded one.
If you put each aggregate into a separate topic, everything is fine, until you want to add projections - how do your projections know to subscribe to all the new topics being created for each aggregate?
You can probably engineer your way around these limitations, but at that point, why not use a tool which is more suitable for the eventsourcing and keep Kafka for the "Business Process Event"?