Hi
I have to do a class cast to ge able to get a typed outlet from a flow that
I used in a FlowGraph.
1. I'm wondering if I'm using the API wrong below, can I get the outlet
in a different way?
2. Other suggestions for improvement apart from the single line is
welcome, perhaps my whole approach is off?
Code background: I'm forking off a call to a cache service, which in turn
is an actor that periodically fetches a fresh token from Gcloud and caches
it for the duration of the token validity. If I got a token returned then
enrich the HttpRequest with an Authorization header.
val addAuthenticationToken:Flow[HttpRequest, Option[HttpRequest]] = Flow()
{ implicit b ⇒
import FlowGraph.Implicits._
val bcast = b.add( Broadcast[HttpRequest]( 2 ) )
val zip = b.add( Zip[Option[Token], HttpRequest] )
val fetchToken:FlowShape[HttpRequest, Option[Token]] = b.add(
fetchTokenService )
val addToken:FlowShape[(Option[Token], HttpRequest)] = b.add(
mapTokenRequest )
bcast ~> fetchToken ~> zip.in0
bcast ~> zip.in1
zip.out ~> addToken
// THIS CLASS CAST IS BUGGING ME. AM I USING THE API WRONG HERE?
val output =
addToken.outlets.head.asInstanceOf[Outlet[Option[HttpRequest]]]
( bcast.in, output )
}
This is the reason the class cast is necessary, below shows what the source
code for FlowShape in Akka looks like this:
final case class FlowShape[-I, +O](inlet: Inlet[I], outlet: Outlet[O])
extends Shape {
override val inlets: immutable.Seq[Inlet[_]] = List(inlet) // <=== NO
TYPES HERE
override val outlets: immutable.Seq[Outlet[_]] = List(outlet) // <=== NO
TYPES HERE
...
}
Suggestions appreciated, thanks!
/Magnus
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