PubSub.source

A source that will subscribe to a TopicTopic and stream messages published to the topic.

Actor interop operators

The source can be materialized multiple times, each materialized stream will stream messages published to the topic after the stream has started.

Note that it is not possible to propagate the backpressure from the running stream to the pub sub topic, if the stream is backpressuring published messages are buffered up to a limit and if the limit is hit the configurable OverflowStrategy decides what happens. It is not possible to use the Backpressure strategy.

Dependency

The Akka dependencies are available from Akka’s library repository. To access them there, you need to configure the URL for this repository.

sbt
resolvers += "Akka library repository".at("https://repo.akka.io/maven")
Maven
<project>
  ...
  <repositories>
    <repository>
      <id>akka-repository</id>
      <name>Akka library repository</name>
      <url>https://repo.akka.io/maven</url>
    </repository>
  </repositories>
</project>
Gradle
repositories {
    mavenCentral()
    maven {
        url "https://repo.akka.io/maven"
    }
}

This operator is included in:

sbt
val AkkaVersion = "2.10.0+21-4d1074a3-SNAPSHOT"
libraryDependencies += "com.typesafe.akka" %% "akka-stream-typed" % AkkaVersion
Maven
<properties>
  <scala.binary.version>2.13</scala.binary.version>
</properties>
<dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>com.typesafe.akka</groupId>
      <artifactId>akka-bom_${scala.binary.version}</artifactId>
      <version>2.10.0+21-4d1074a3-SNAPSHOT</version>
      <type>pom</type>
      <scope>import</scope>
    </dependency>
  </dependencies>
</dependencyManagement>
<dependencies>
  <dependency>
    <groupId>com.typesafe.akka</groupId>
    <artifactId>akka-stream-typed_${scala.binary.version}</artifactId>
  </dependency>
</dependencies>
Gradle
def versions = [
  ScalaBinary: "2.13"
]
dependencies {
  implementation platform("com.typesafe.akka:akka-bom_${versions.ScalaBinary}:2.10.0+21-4d1074a3-SNAPSHOT")

  implementation "com.typesafe.akka:akka-stream-typed_${versions.ScalaBinary}"
}

Signature

PubSub.sourcePubSub.source

Reactive Streams semantics

emits a message published to the topic is emitted as soon as there is demand from downstream

completes when the topic actor terminates

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