akka-stream

问题 Part of application I am writing requires transferring arbitrarily big (for this question I will assume 100-200 GB) files from client to server. Important thing, is that receiver (server) is not storing this file - it just read/examine stream and sends it to next point. Because at no point I need whole file, but expect multiple transfers at same time, I would like to minimize RAM usage and eliminate disk usage. I would like to process files in chunks of 1 MB. Right now, server uses Spring

问题 I have an infinite stream of events: (timestamp, session_uid, traffic) i.e. ... (1448089943, session-1, 10) (1448089944, session-1, 20) (1448089945, session-2, 50) (1448089946, session-1, 30) (1448089947, session-2, 10) (1448089948, session-3, 10) ... These events I want to group by session_uid and calculate sum of traffic for each session. I wrote an akka-streams flow which works fine with finite stream use groupBy (my code base on this example from cookbook). But with infinite stream it

问题 I am writing a pure websocket web application, meaning that prior to the websocket upgrade there is no user/client step, more specifically: Authentication request goes over websockets as does the rest of the communication There is/are: Exactly ONE websocket endpoint on /api/ws Multiple clients connected to that endpoint Multiple projects for multiple clients Now, not each client has access to each project - the access control for that is implemented on the server side (ofc) and has nothing to

问题 I'm creating a simple message delivery service using Akka stream. The service is just like mail delivery, where elements from source include destination and content like: case class Message(destination: String, content: String) and the service should deliver the messages to appropriate sink based on the destination field. I created a DeliverySink class to let it have a name: case class DeliverySink(name: String, sink: Sink[String, Future[Done]]) Now, I instantiated two DeliverySink , let me

问题 I have properly working graph that has flow with loop. Items go through as expected and everything is working. But unfortunately with bounded source graph never ends. Ever. How can I fix it ? Here is schema of my flow. Here is simplified version of the flow with the same topology. val badFlow = Flow.fromGraph(GraphDSL.create() { implicit builder => import GraphDSL.Implicits._ val mergeEntrance = builder.add(MergePreferred[Int](1)) val mergePreExit = builder.add(Merge[Int](2)) val part1 =

问题 Default event name/type in server sent event is "message". I am trying to change the event name but it is not working. I am using Play 2.5 and akka streams. (actorRef,sourcePublisher)= Source .actorRef[T](10, OverflowStrategy.fail) .toMat(Sink.asPublisher(true))(Keep.both) .run() backsource = Source.fromPublisher[T](sourcePublisher).named("test1") Ok.chunked(backsource via EventSource.flow) .as(ContentTypes.EVENT_STREAM) But it is not changing the event name/type. It is still listening to

问题 I have been trying to stream content through HTTP with Play Framework 2.5 in Java with a delay. The problem is that I am not sure if the result is actually streaming, that is why I tried to delay each item from emitting which does not seem to work for some reason. The code public Result test(){ HttpEntity http = new HttpEntity.Streamed(Source.range(0, 99999) .map(i -> ByteString.fromString(i.toString())) .initialDelay(FiniteDuration.create(200, TimeUnit.MILLISECONDS)) , Optional.empty(),

问题 I am calling a method using via like below: myRawStr(id) .take(1) .via(myMethod("someString", someSource) .zip(Source.fromIterator(() => Iterator.from(1))) .collect { ... } myMethod returns type Flow[ByteString, MyValidated[MyClass], NotUsed] but now it will be returning Future[Flow[ByteString, MyValidated[MyClass], NotUsed]] ( Note : Future) but doing this gives me compilation error on via . The error states: [error] found : [as, mat, ec]scala.concurrent.Future[akka.stream.scaladsl.Flow[akka

问题 Whats the easiest way to have the output of a flow be sent to a web socket in Playframework with Scala. I want the WebSocket to act as the sink of the stream. For example the source generate a random number and then go to the sink (Websocket) so it is pushed to client. Thanks 回答1: If you are talking about the new Akka streams integration in Play 2.5.x (still M2), then I think this should do the job as a simple valid flow that represents an echo server (with a touch). def socket = WebSocket

问题 Learning Akka Streams. I have a stream of records, many per time unit, already ordered by time (from Slick), and I want to batch them into time groups for processing by detecting when the time step changes. Example case class Record(time: Int, payload: String) If the incoming stream is Record(1, "a") Record(1, "k") Record(1, "k") Record(1, "a") Record(2, "r") Record(2, "o") Record(2, "c") Record(2, "k") Record(2, "s") Record(3, "!") ... I would like to transform this into Batch(1, Seq("a","k"