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https://github.com/zio/zio-akka-cluster
ZIO wrapper for Akka Cluster
https://github.com/zio/zio-akka-cluster
akka functional-programming scala zio
Last synced: 9 days ago
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ZIO wrapper for Akka Cluster
- Host: GitHub
- URL: https://github.com/zio/zio-akka-cluster
- Owner: zio
- License: apache-2.0
- Created: 2019-07-06T06:43:51.000Z (over 5 years ago)
- Default Branch: series/2.x
- Last Pushed: 2024-08-20T01:42:31.000Z (5 months ago)
- Last Synced: 2025-01-10T21:06:23.624Z (16 days ago)
- Topics: akka, functional-programming, scala, zio
- Language: Scala
- Homepage: https://zio.dev/zio-akka-cluster
- Size: 165 KB
- Stars: 164
- Watchers: 10
- Forks: 26
- Open Issues: 15
-
Metadata Files:
- Readme: README.md
- License: LICENSE
- Codeowners: .github/CODEOWNERS
Awesome Lists containing this project
- awesome-zio - ZIO Akka Cluster
README
[//]: # (This file was autogenerated using `zio-sbt-website` plugin via `sbt generateReadme` command.)
[//]: # (So please do not edit it manually. Instead, change "docs/index.md" file or sbt setting keys)
[//]: # (e.g. "readmeDocumentation" and "readmeSupport".)
# ZIO Akka Cluster
The [ZIO Akka Cluster](https://github.com/zio/zio-akka-cluster) library is a ZIO wrapper on [Akka Cluster](https://doc.akka.io/docs/akka/current/index-cluster.html). We can use clustering features of the Akka toolkit without the need to use the actor model.
[](https://github.com/zio/zio/wiki/Project-Stages)  [](https://oss.sonatype.org/content/repositories/releases/dev/zio/zio-akka-cluster_2.13/) [](https://oss.sonatype.org/content/repositories/snapshots/dev/zio/zio-akka-cluster_2.13/) [](https://javadoc.io/doc/dev.zio/zio-akka-cluster-docs_2.13) [](https://github.com/zio/zio-akka-cluster)
## Introduction
This library provides us following features:
- **Akka Cluster** — This feature contains two Akka Cluster Membership operations called `join` and `leave` and also it has some methods to retrieve _Cluster State_ and _Cluster Events_.
- **Akka Distributed PubSub** — Akka has a _Distributed Publish Subscribe_ facility in the cluster. It helps us to send a message to all actors in the cluster that have registered and subscribed for a specific topic name without knowing their physical address or without knowing which node they are running on.
- **Akka Cluster Sharding** — Cluster sharding is useful when we need to _distribute actors across several nodes in the cluster_ and want to be able to interact with them using their logical identifier without having to care about their physical location in the cluster, which might also change over time. When we have many stateful entities in our application that together they consume more resources (e.g. memory) than fit on one machine, it is useful to use _Akka Cluster Sharding_ to distribute our entities to multiple nodes.
## Installation
In order to use this library, we need to add the following line in our `build.sbt` file:
```scala
libraryDependencies += "dev.zio" %% "zio-akka-cluster" % "0.3.0"
```
## Example
In the following example, we are using all these three features. We have a distributed counter application that lives in the Akka Cluster using _Akka Cluster Sharding_ feature. So the location of `LiveUsers` and `TotalRequests` entities in the cluster is transparent for us. We send the result of each entity to the _Distributed PubSub_. So every node in the cluster can subscribe and listen to those results. Also, we have created a fiber that is subscribed to the cluster events. All the new events will be logged to the console:
```scala
import akka.actor.ActorSystem
import com.typesafe.config.{ Config, ConfigFactory }
import zio._
import zio.akka.cluster.Cluster
import zio.akka.cluster.sharding.{ Entity, Sharding }
sealed trait Counter extends Product with Serializable
case object Inc extends Counter
case object Dec extends Counter
case class CounterApp(port: String) {
val config: Config =
ConfigFactory.parseString(s"""
|akka {
| actor {
| provider = "cluster"
| }
| remote {
| netty.tcp {
| hostname = "127.0.0.1"
| port = $port
| }
| }
| cluster {
| seed-nodes = ["akka.tcp://[email protected]:2551"]
| }
|}
|""".stripMargin)
val actorSystem: ZLayer[Any, Nothing, ActorSystem] =
ZLayer.scoped(
ZIO.acquireRelease(ZIO.succeed(ActorSystem("CounterApp", config)))(sys =>
ZIO.fromFuture(_ => sys.terminate()).either
)
)
val counterApp: ZIO[Scope, Throwable, Unit] =
(for {
queue <- Cluster.clusterEvents(true)
pubsub <- zio.akka.cluster.pubsub.PubSub.createPubSub[Int]
liveUsersLogger <- pubsub
.listen("LiveUsers")
.flatMap(
_.take.tap(u => Console.printLine(s"Number of live users: $u")).forever
)
.fork
totalRequestLogger <- pubsub
.listen("TotalRequests")
.flatMap(
_.take.tap(r => Console.printLine(s"Total request until now: $r")).forever
)
.fork
clusterEvents <- queue.take
.tap(x => Console.printLine("New event in cluster: " + x.toString))
.forever
.fork
counterEntityLogic = (c: Counter) =>
for {
entity <- ZIO.environment[Entity[Int]]
newState <- c match {
case Inc =>
entity.get.state.updateAndGet(s => Some(s.getOrElse(0) + 1))
case Dec =>
entity.get.state.updateAndGet(s => Some(s.getOrElse(0) - 1))
}
_ <- pubsub.publish(entity.get.id, newState.getOrElse(0)).orDie
} yield ()
cluster <- Sharding.start("CounterEntity", counterEntityLogic)
_ <- cluster.send("LiveUsers", Inc)
_ <- cluster.send("TotalRequests", Inc)
_ <- cluster.send("LiveUsers", Dec)
_ <- cluster.send("LiveUsers", Inc)
_ <- cluster.send("LiveUsers", Inc)
_ <- cluster.send("TotalRequests", Inc)
_ <- cluster.send("TotalRequests", Inc)
_ <- clusterEvents.join zipPar liveUsersLogger.join zipPar totalRequestLogger.join
} yield ()).provide(actorSystem)
}
```
Now, let's create a cluster comprising two nodes:
```scala
object CounterApp1 extends ZIOAppDefault {
override def run = CounterApp("2551").counterApp
}
object CounterApp2 extends ZIOAppDefault {
override def run = CounterApp("2552").counterApp
}
```
## Documentation
Learn more on the [ZIO Akka Cluster homepage](https://zio.dev/zio-akka-cluster)!
## Contributing
For the general guidelines, see ZIO [contributor's guide](https://zio.dev/about/contributing).
## Code of Conduct
See the [Code of Conduct](https://zio.dev/about/code-of-conduct)
## Support
Come chat with us on [![Badge-Discord]][Link-Discord].
[Badge-Discord]: https://img.shields.io/discord/629491597070827530?logo=discord "chat on discord"
[Link-Discord]: https://discord.gg/2ccFBr4 "Discord"
## License
[License](LICENSE)