akka-stream

I'm totally new in Scala and Akka. I've a simple RunnableFlow: Source -> Flow (do some transformation) -> Sink.runForeach Now I want something like this: Source -> Flow1 (do some transformation) -> Flow2 (do some transformation) -> Sink.runForeach But Flow2 should wait until 100 elements from Flow1 are available and then transform these 100 elements to a new element (which needs all 100 elements from Flow1) and give this new element to the Sink. I did some research and found Explicit user defined buffers but I don´t understand how I can access all 100 elements from flow1 in flow2 and do some

I am not able to figure out how to stop akka stream Runnable Graph immediately ? How to use killswitch to achieve this? It has been just a few days that I started akka streams. In my case I am reading lines from a file and doing some operations in flow and writing to the sink. What I want to do is, stop reading file immediately whenever I want, and I hope this should possibly stop the whole running graph. Any ideas on this would be greatly appreciated. Thanks in advance. Since Akka Streams 2.4.3, there is an elegant way to stop the stream from the outside via KillSwitch . Consider the

Akka-http documentation says: Apart from regarding a socket bound on the server-side as a Source[IncomingConnection] and each connection as a Source[HttpRequest] with a Sink[HttpResponse] Assume we get the merged source containing incoming connections from many Source[IncomingConnection]. Then, assume, we get Source[HttpRequest] from Source[IncomingConnection] (see the code below). Then, no problem, we can provide a flow to convert HttpRequest to HttpResponse. And here is the problem - how can we properly Sink the responses ? How can we join the responses to connections? The whole idea behind

Getting started with akka-streams I want to build a simple example. In chrome using a web socket plugin I simply can connect to a stream like this one https://blockchain.info/api/api_websocket via wss://ws.blockchain.info/inv and sending 2 commands {"op":"ping"} {"op":"unconfirmed_sub"} will stream the results in chromes web socket plugin window. I tried to implement the same functionality in akka streams but am facing some problems: 2 commands are executed, but I actually do not get the streaming output the same command is executed twice (the ping command) When following the tutorial of http:

I'm trying to use new Akka streams and wonder how I can use and return Source queue to caller without materializing it in my code ? Imagine we have library that makes number of async calls and returns results via Source . Function looks like this def findArticlesByTitle(text: String): Source[String, SourceQueue[String]] = { val source = Source.queue[String](100, backpressure) source.mapMaterializedValue { case queue => val url = s"http://.....&term=$text" httpclient.get(url).map(httpResponseToSprayJson[SearchResponse]).map { v => v.idlist.foreach { id => queue.offer(id) } queue.complete() } }

I have a flow with data associated to users. I also have a state for each user, that I can get asynchronously from DB. I want to separate my flow with one subflow per user, and load the state for each user when materializing the subflow, so that the elements of the subflow can be treated with respect to this state. If I don't want to merge the subflows downstream, I can do something with groupBy and Sink.lazyInit : def getState(userId: UserId): Future[UserState] = ... def getUserId(element: Element): UserId = ... def treatUser(state: UserState): Sink[Element, _] = ... val treatByUser: Sink