Reactive Streams for Kafka

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Reactive Streams wrapper for Apache Kafka.

Initiated by SoftwareMill

Supports Kafka 0.8.2.1

Available at Maven Central for Scala 2.10 and 2.11:

libraryDependencies += "com.softwaremill" %% "reactive-kafka" % "0.6.0"

Testing

Tests require Apache Kafka and Zookeeper to be available on localhost:9092 and localhost:2181

Example usage

import akka.actor.ActorSystem
import akka.stream.ActorMaterializer
import akka.stream.scaladsl.{Sink, Source}
import com.softwaremill.react.kafka.ReactiveKafka
import kafka.serializer.{StringDecoder, StringEncoder}

implicit val actorSystem = ActorSystem("ReactiveKafka")
implicit val materializer = ActorMaterializer()

val kafka = new ReactiveKafka(host = "localhost:9092", zooKeeperHost = "localhost:2181")
val publisher = kafka.consume("lowercaseStrings", "groupName", new StringDecoder())
val subscriber = kafka.publish("uppercaseStrings", "groupName", new StringEncoder())


Source(publisher).map(_.toUpperCase).to(Sink(subscriber)).run()

Controlling consumer start offset

By default a new consumer will start reading from the beginning of a topic. If you want to start reading from the end, you can use alternative way to create a consumer:

  val publisher = kafka.consumeFromEnd(topic, groupId, new StringDecoder())

Tuning

KafkaActorSubscriber and KafkaActorPublisher have their own thread pools, configured in reference.conf. You can tune them by overriding kafka-publisher-dispatcher.thread-pool-executor and kafka-subscriber-dispatcher.thread-pool-executor in your application.conf file.