Well, I was able to achieve needed behavior with following flow scheme:
Flow() { implicit builder ⇒
val promises = builder add Source(() ⇒ Iterator continually Promise[O]())
val fan = builder add Broadcast[Promise[O]](2)
val zip = builder add Zip[I, Promise[O]]()
val flow = builder add Flow[Promise[O]].mapAsync(1)(_.future)
val sink = builder add Sink.actorSubscriber[I, Promise[O]](props)
//+Flow: @formatter:off
promises ~> fan ~> zip.in1
flow <~ fan
sink <~ zip.out
//-Flow: @formatter:on
zip.in0 → flow.outlet
}
Where `I` and `O` are input and output types, respectfully, and `props` is
`Props(..)` of enrichment Actor, who receives Tuple(i: I, p: Promise[O]),
enriches i to instance of `O` and fulfills promise.
But there is still some questions I would very much like to know answers to:
1. Is there a way to create lazy repeated Source of (: => Promise[O])?
Logs show that Source(() => Iterator continually Promise[O]()) eagerly
produces several promised values, and if actual inlet completes after very
first instance of `I` they are discarded.
2. Is there a simpler way to produce Flow[O] from Flow[Promise[O]] than via
`.mapAsync(1)(_.future)`?
3. Will Sink.actorSubscriber(..) shutdown underlying actor after stream is
completed or it needs to be done from actor itself after OnComplete event?
And what about errors?
четверг, 20 августа 2015 г., 18:33:43 UTC+3 пользователь Alexey Shuksto
написал:
>
> Well, I want to simply connect them, but I want to connect Sink
> .actorSubscriber(...) ~> Source.actorPublisher(...), not other way
> around, like you said.
>
> I've got Actor, that enriches HTTP Requests that our server receives.
> After some enrichment, I need to be able to send request further down for
> processing:
>
> ```
> val source = Source.single(/*HttpRequest*/)
> val sink = Sink.head[ProcessedRequest]
>
> val enrichment: Flow[HttpRequest, EnrichedRequest] = ???
> val processing: Flow[EnrichedRequest, ProcessedRequest] = ???
>
> source.via(enrichment).via(processing).to(sink)
> ```
>
> I want to be able to use our enrichment Actor in Flow[HttpRequest,
> EnrichedRequest] stage. Actor is able to receive HttpRequest and reply (or
> forward) ProcessedRequest, but I don't know how to create Flow from it.
>
>
>
>
>
> чт, 20 авг. 2015 г. в 18:20, Konrad Malawski <konrad.malaw...@typesafe.com
> >:
>
>> Hello there Alexey,
>> I'm not sure I understand what you want to achieve, is it simply to
>> connect such Sink to the Source?
>> That's simply:
>> Source.actorPublisher(...).to(Sink.actorSubscriber(...)).run()
>>
>> Or do you mean to put another processing stage between them?
>> If so then read about custom processing stages:
>> doc.akka.io/docs/akka-stream-and-http-experimental/1.0/scala/stream-customize.html
>>
>>
>> --
>> Cheers,
>> Konrad Malawski
>> Akka @ Typesafe
>>
>> On 20 August 2015 at 17:12:55, Alexey Shuksto (seig...@gmail.com) wrote:
>>
>> Hello there,
>>
>> I could not find answer to this particular question neither in docs nor
>> in this group:
>>
>> Is it possible to wire Sink.actorSubscriber(...) into
>> Source.actorPublisher(...) in one (Partial-) Flow? And by 'wire' I mean to
>> somehow send message from ActorSubscriber, instantiated from given props,
>> to the 'same flow' instance of ActorPublisher?
>>
>> I was thinking about giving some unique Id to both of them and then
>> publish/subscribe events through `context.system.eventStream`, but then I
>> realized that all materialized flows would have same Id and messages would
>> mess up... :(
>>
>> In fact, I'm interested in even more simple task -- create an Actor, that
>> could act as PartialFlow[In, Out]: when you push a value into flow, actor
>> receives it, processes and sends further down the line.
>>
>> Of course, I always could do something like Flow[In] mapAsync (data =>
>> (actor ? data).mapTo[classOf[Out]]) -- but I would really, really prefer to
>> do this message way.
>>
>> --
>> >>>>>>>>>> Read the docs: http://akka.io/docs/
>> >>>>>>>>>> Check the FAQ:
>> http://doc.akka.io/docs/akka/current/additional/faq.html
>> >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user
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--
>>>>>>>>>> Read the docs: http://akka.io/docs/
>>>>>>>>>> Check the FAQ:
>>>>>>>>>> http://doc.akka.io/docs/akka/current/additional/faq.html
>>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user
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