How shall we surface acknowledged Sinks in Akka Streams?

[rkuhn]

This is the much simpler cousin of #13. The primary proposal is to model this as a Flow:

class KafkaSink extends GraphStage[FlowShape[Message, Confirmation]]

This is fundamentally what happens: messages are sent to Kafka, to be turned into confirmations.

[13h3r]

Originally I emit not Confirmation, but Future[Confirmation]. This allows client to keep order of messages and perform some actions in parallel and then join confirmed record with some other job.

Emitting just Confirmation shuffles original order.

Also Future[Confirmation] can be easily turned into Confirmation and allows client to control how many confirmation may be in progress.

[rkuhn]

Ah, my assumption was that the .mapAsync() is already included in the KafkaSink and that the confirmations are emitted in the right order.

[13h3r]

I wanted to provide as minimal abstraction as possible. Then client will decide do he cares about order (and use mapAsync) or dont (and use mapAsyncUnordered)

Same for #13

[rkuhn]

Yes, this is a good point. This case is rather easy, the Source case is vastly different due to needing three ports.

[ktoso]

I agree with #14 (comment) in that we'll want to expose Future[Confirmation], from which can go to Confirmation with or without order 👍