On Fri, Aug 21, 2015 at 5:46 PM, Alexey Shuksto <[email protected]> wrote:
> 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.
>
I think that is because elements are prefetched from the source, but that
should be bounded to the buffer size.
>
> 2. Is there a simpler way to produce Flow[O] from Flow[Promise[O]] than
> via `.mapAsync(1)(_.future)`?
>
Isn't that simple enough?
>
> 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?
>
ActorSubscriber doesn't (currently) stop automatically when it receives
OnComplete/OnError. There are some use cases when it is needed to not stop,
but I think we should change the default behaviour to stop.
There is several tickets around this:
https://github.com/akka/akka/issues/17286
>
> 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 <
>> [email protected]>:
>>
>>> 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 ([email protected]) 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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--
Patrik Nordwall
Typesafe <http://typesafe.com/> - Reactive apps on the JVM
Twitter: @patriknw
--
>>>>>>>>>> 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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