How can I convert a listener pattern into a stream with akka streams?

[Mark Hammons]

I am writing a scheduler for mesos, and I'd like to construct it completely from streams instead of the listener functions it currently uses. How would I create a source and emit items when the listening hooks are called?

 

Thanks
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Mark Hammons - +33 06 03 69 56 56

Research Engineer @ BioEmergences

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[Tal Pressman]

Hi,

You could use an ActorPublisher (Source.actorPublisher) and send it messages from the listener. Just remember to handle backpressure - what do you do if the listener is called but the stream isn't ready to accept messages yet?

Tal

[Mark Hammons]

Hmm, Ok. As for backpressure, with these there should be none because only the latest values emitted by the listener are useful. So I guess I would set them to have a buffer of size 1 and to drop the oldest elements in the buffer for that effect right?

[Endre Varga]

I am not sure a simple listener pattern warrants a full Akka Stream to be involved. Streams starts to shine when you need backpressure, but if you don't need any (because events are rare, or there is no way to meaningfully backpressure) then it might be just too heavyweight and lead to frustrations. You can just use plain actors for the simple cases. Of course I don't know what is the context of your problem so streams might be a good idea, I just warn against unconditional use of them.

-Endre

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