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Questions tagged [akka-stream]

Akka implementation for handling streaming data on the JVM

Akka implementation of reactive-streams standard for handling streaming data on the .

This library uses Akka Actor based transformations of data streams which proceed as a series of steps which can be executed in parallel, in a pipelined fashion.

More info:

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OutOfMemmory error when reading many files with many json records in each of them - with Akka & java

I have an input folder with 1000's of files, each of them with 1000's of JSON records. I created an Akka actor system to read these files and process them. I'm reading the JSON from each file using: JSONParser parser = new JSONParser(); …
riorio
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Akka: How to extract a value in one graph stage and use it in the next

I am using Alpakka and Akka to process a CSV file. Since I have a bunch of CSV files that have to be added to the same stream, I would like to add a field that contains information from the file name or request. Currently I have something like this:…
Falk Schuetzenmeister
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Retrieve the local IP and port from an outbound Akka TCP stream

I am dealing with a server for a rather picky protocol (SIP) that needs my local IP and port as part of the header structure. I am using an Akka TCP stream for its awesomeness but I am missing the equivalent of BSD socket's getsockname function. In…
David Weber
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Alpakka MongoDB - override MongoSource implementation

I have similar problem as in Alpakka MongoDB - specify type in MongoSource So I implemented my own MongoSource as was in the solution and used it: object MyMongoSource { def apply[T](query: Observable[T]): Source[T, NotUsed] = …
Funny
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How to sessionize / group the events in Akka Streams?

The requirement is that I want to write an Akka streaming application that listens to continuous events from Kafka, then sessionizes the event data in a time frame, based on some id value embedded inside each event. For example, let's say that my…
dks551
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Alpakka MongoDB - specify type in MongoSource

I'm currently playing around with Akka Streams and the Alpakka MongoDB connector. Is it possible to specify the type for MongoSource? val codecRegistry = fromRegistries(fromProviders(classOf[TodoMongo]), DEFAULT_CODEC_REGISTRY) private val…
user5853948
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Attaching multiple actors as sources to Akka streams

I know a similar question has already been asked: How to attach multiple actors as sources to an Akka stream? But I would like to do the same thing, however I don't know the number of sources in advance. So how can I dynamically add multiple sources…
Will I Am
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How could you handle failures dowstream in an akka stream?

I'm running an akka stream reading from Kafka and I want to commit messages back to Kafka when the file serialization succeeds. But I don't know how to notify upstream stages about a failure downstream. Right now, I've created a GraphStage with…
tonicebrian
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Akka.Net: how to create persistent views through a journal reader

According to the Akka.Net documentation, PersistentView is deprecated, and PersistenceQuery should be used instead. In an ASP.Net Core 2.0 Web-API application I am using Akka.Net with event sourcing. I am using the SQL Server plugin for persistence,…
George
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How to process groupby subflows in groups

I've been playing around with akka-streams and seem to be stuck with one problem that I cannot find a clean way to handle this in a stream. I have events coming from 1..* players with their corresponding positions on the board. I want to check if…
Evaldas Miliauskas
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How to introduce a non blocking delay in akka-http using Flows based on the request parameters

I am starting a server and handling it like this using akka stream connection.handleWith(handleRequest()) where handleRequest():Flow[HttpRequest,HttpRespnse,_] I need to create a delay in sending of response back to client based on the query…
Saksham
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Why does this Akka Streams application exit abnormally?

I am learning about Akka Streams via the Akka Cookbook module from Packt. I run the TransformingStreamsApplication.scala example and get this: To let the actor system exit when the stream processing is completed, I add the following callback: //…
xyz
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Why doesn't the stream continue if the error occurs inside the Source

I have written a scala stream application. My objective is that if during the stream processing an item encounters an error during processing, then the stream ignores it and continues processing the remaining items. Towards this goal, I wrote this…
Knows Not Much
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Akka streams: attach new publishers/subscribers to Flow

I'm building an Akka application and want to expose the FSM state transitions of some actors to external consumers. (The end goal is to be able to push the state transition messages to a websocket so that they can be viewed in realtime.) Based on…
Eric
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Using reactive-kafka to conditionally process messages

I've been trying to use reactive-kafka, and I am having a problem with conditional processing, to which I didn't find a satisfying answer. Basically I'm trying to consume one kafka topic which contains a huge number of messages (around 10 billion…
Thundzz
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