akka-typed(6) - cluster：group router, cluster-load-balancing

先谈谈akka-typed的router actor。route 分pool router, group router两类。我们先看看pool-router的使用示范：

      val pool = Routers.pool(poolSize = )(
        // make sure the workers are restarted if they fail
        Behaviors.supervise(WorkerRoutee()).onFailure[Exception](SupervisorStrategy.restart))
      val router = ctx.spawn(pool, "worker-pool")

      ( to ).foreach { n =>
        router ! WorkerRoutee.DoLog(s"msg $n")
      }

上面例子里的pool是个pool-router，意思是一个有4个routees的routee池。每个routee都是通过WorkerRoutee()构建的，意味着routee池中只有一个种类的actor。pool-router是通过工厂方法直接在本地（JVM）构建（spawn）所有的routee。也就是说所有routee都是router的子actor。

再看看group-router的使用例子：

val serviceKey = ServiceKey[Worker.Command]("log-worker")

      // this would likely happen elsewhere - if we create it locally we
      // can just as well use a pool
      val workerRoutee = ctx.spawn(WorkerRoutee(), "worker-route")
      ctx.system.receptionist ! Receptionist.Register(serviceKey, workerRoutee)

      val group = Routers.group(serviceKey)
      val router = ctx.spawn(group, "worker-group")

      // the group router will stash messages until it sees the first listing of registered
      // services from the receptionist, so it is safe to send messages right away
      ( to ).foreach { n =>
        router ! WorkerRoutee.DoLog(s"msg $n")
      }

group-router与pool-router有较多分别：

1、routee是在router之外构建的，router是用一个key通过Receptionist获取同key的actor清单作为routee group的

2、Receptionist是集群全局的。任何节点上的actor都可以发送注册消息在Receptionist上登记

3、没有size限制，任何actor一旦在Receptionist上登记即变成routee，接受router管理

应该说如果想把运算任务分配在集群里的各节点上并行运算实现load-balance效果，group-router是最合适的选择。不过对不同的运算任务需要多少routee则需要用户自行决定，不像以前akka-classic里通过cluster-metrics根据节点负载情况自动增减routee实例那么方便。

Receptionist: 既然说到，那么就再深入一点介绍Receptionist的应用：上面提到，Receptionist是集群全局的。就是说任何节点上的actor都可以在Receptonist上注册形成一个生存在集群中不同节点的actor清单。如果Receptionist把这个清单提供给一个用户，那么这个用户就可以把运算任务配置到各节点上，实现某种意义上的分布式运算模式。Receptionist的使用方式是：通过向本节点的Receptionist发送消息去登记ActorRef，然后通过Receptionist发布的登记变化消息即可获取最新的ActorRef清单：

  val WorkerServiceKey = ServiceKey[Worker.TransformText]("Worker")

  ctx.system.receptionist ! Receptionist.Register(WorkerServiceKey, ctx.self)

  ctx.system.receptionist ! Receptionist.Subscribe(Worker.WorkerServiceKey, subscriptionAdapter)

Receptionist的登记和清单获取是以ServiceKey作为关联的。那么获取的清单内应该全部是一种类型的actor，只不过它们的地址可能是跨节点的，但它们只能进行同一种运算。从另一个角度说，一项任务是分布在不同节点的actor并行进行运算的。

在上篇讨论里提过：如果发布-订阅机制是在两个actor之间进行的，那么这两个actor也需要在规定的信息交流协议框架下作业：我们必须注意消息类型，提供必要的消息类型转换机制。下面是一个Receptionist登记示范：

object Worker {

  val WorkerServiceKey = ServiceKey[Worker.TransformText]("Worker")

  sealed trait Command
  final case class TransformText(text: String, replyTo: ActorRef[TextTransformed]) extends Command with CborSerializable
  final case class TextTransformed(text: String) extends CborSerializable

  def apply(): Behavior[Command] =
    Behaviors.setup { ctx =>
      // each worker registers themselves with the receptionist
      ctx.log.info("Registering myself with receptionist")
      ctx.system.receptionist ! Receptionist.Register(WorkerServiceKey, ctx.self)

      Behaviors.receiveMessage {
        case TransformText(text, replyTo) =>
          replyTo ! TextTransformed(text.toUpperCase)
          Behaviors.same
      }
    }
}

Receptionist登记比较直接：登记者不需要Receptionist返回消息，所以随便用ctx.self作为消息的sender。注意TransformText的replyTo: ActorRef[TextTransformed]，代表sender是个可以处理TextTransformed消息类型的actor。实际上，在sender方是通过ctx.ask提供了TextTransformed的类型转换。

Receptionist.Subscribe需要Receptionist返回一个actor清单，所以是个request/response模式。那么发送给Receptionist消息中的replyTo必须是发送者能处理的类型，如下：

  def apply(): Behavior[Event] = Behaviors.setup { ctx =>
    Behaviors.withTimers { timers =>
      // subscribe to available workers
      val subscriptionAdapter = ctx.messageAdapter[Receptionist.Listing] {
        case Worker.WorkerServiceKey.Listing(workers) =>
          WorkersUpdated(workers)
      }
      ctx.system.receptionist ! Receptionist.Subscribe(Worker.WorkerServiceKey, subscriptionAdapter)

...
    }
  

ctx.messageAdapter进行了一个从Receptionist.Listing返回类型到WorkersUpdated类型的转换机制登记：从Receptionist回复的List类型会被转换成WorkersUpdated类型，如下：

...
   Behaviors.receiveMessage {
      case WorkersUpdated(newWorkers) =>
        ctx.log.info("List of services registered with the receptionist changed: {}", newWorkers)

...

另外，上面提过的TextTransformed转换如下：

          ctx.ask[Worker.TransformText,Worker.TextTransformed](selectedWorker, Worker.TransformText(text, _)) {
            case Success(transformedText) => TransformCompleted(transformedText.text, text)
            case Failure(ex) => JobFailed("Processing timed out", text)
          }

ctx.ask将TextTransformed转换成TransformCompleted。完整的Behavior定义如下：

object Frontend {

  sealed trait Event
  private case object Tick extends Event
  private final case class WorkersUpdated(newWorkers: Set[ActorRef[Worker.TransformText]]) extends Event
  private final case class TransformCompleted(originalText: String, transformedText: String) extends Event
  private final case class JobFailed(why: String, text: String) extends Event

  def apply(): Behavior[Event] = Behaviors.setup { ctx =>
    Behaviors.withTimers { timers =>
      // subscribe to available workers
      val subscriptionAdapter = ctx.messageAdapter[Receptionist.Listing] {
        case Worker.WorkerServiceKey.Listing(workers) =>
          WorkersUpdated(workers)
      }
      ctx.system.receptionist ! Receptionist.Subscribe(Worker.WorkerServiceKey, subscriptionAdapter)

      timers.startTimerWithFixedDelay(Tick, Tick, .seconds)

      running(ctx, IndexedSeq.empty, jobCounter = )
    }
  }

  private def running(ctx: ActorContext[Event], workers: IndexedSeq[ActorRef[Worker.TransformText]], jobCounter: Int): Behavior[Event] =
    Behaviors.receiveMessage {
      case WorkersUpdated(newWorkers) =>
        ctx.log.info("List of services registered with the receptionist changed: {}", newWorkers)
        running(ctx, newWorkers.toIndexedSeq, jobCounter)
      case Tick =>
        if (workers.isEmpty) {
          ctx.log.warn("Got tick request but no workers available, not sending any work")
          Behaviors.same
        } else {
          // how much time can pass before we consider a request failed
          implicit val timeout: Timeout = .seconds
          val selectedWorker = workers(jobCounter % workers.size)
          ctx.log.info("Sending work for processing to {}", selectedWorker)
          val text = s"hello-$jobCounter"
          ctx.ask[Worker.TransformText,Worker.TextTransformed](selectedWorker, Worker.TransformText(text, _)) {
            case Success(transformedText) => TransformCompleted(transformedText.text, text)
            case Failure(ex) => JobFailed("Processing timed out", text)
          }
          running(ctx, workers, jobCounter + )
        }
      case TransformCompleted(originalText, transformedText) =>
        ctx.log.info("Got completed transform of {}: {}", originalText, transformedText)
        Behaviors.same

      case JobFailed(why, text) =>
        ctx.log.warn("Transformation of text {} failed. Because: {}", text, why)
        Behaviors.same

    }

现在我们可以示范用group-router来实现某种跨节点的分布式运算。因为group-router是通过Receptionist来实现对routees管理的，而Receptionist是集群全局的，意味着如果我们在各节点上构建routee，然后向Receptionist登记，就会形成一个跨节点的routee ActorRef清单。如果把任务分配到这个清单上的routee上去运算，应该能实现集群节点负载均衡的效果。下面我们就示范这个loadbalancer。流程很简单：在一个接入点 （serviceActor）中构建workersRouter，然后3个workerRoutee并向Receptionist登记，把接到的任务分解成子任务逐个发送给workersRouter。每个workerRoutee完成任务后将结果发送给一个聚合器Aggregator，Aggregator在核对完成接收所有workerRoutee返回的结果后再把汇总结果返回serverActor。先看看这个serverActor：

object Service {
  val routerServiceKey = ServiceKey[WorkerRoutee.Command]("workers-router")

  sealed trait Command extends CborSerializable

  case class ProcessText(text: String) extends Command {
    require(text.nonEmpty)
  }

  case class WrappedResult(res: Aggregator.Response) extends Command

  def serviceBehavior(workersRouter: ActorRef[WorkerRoutee.Command]): Behavior[Command] = Behaviors.setup[Command] { ctx =>
    val aggregator = ctx.spawn(Aggregator(), "aggregator")
    val aggregatorRef: ActorRef[Aggregator.Response] = ctx.messageAdapter(WrappedResult)
    Behaviors.receiveMessage {
      case ProcessText(text) =>
        ctx.log.info("******************** received ProcessText command: {} ****************",text)
        val words = text.split(' ').toIndexedSeq
        aggregator ! Aggregator.CountText(words.size, aggregatorRef)
        words.foreach { word =>
          workersRouter ! WorkerRoutee.Count(word, aggregator)
        }
        Behaviors.same
      case WrappedResult(msg) =>
        msg match {
          case Aggregator.Result(res) =>
            ctx.log.info("************** mean length of words = {} **********", res)
        }
        Behaviors.same
    }
  }

  def singletonService(ctx: ActorContext[Command], workersRouter: ActorRef[WorkerRoutee.Command]) = {
    val singletonSettings = ClusterSingletonSettings(ctx.system)
      .withRole("front")
    SingletonActor(
      Behaviors.supervise(
        serviceBehavior(workersRouter)
      ).onFailure(
        SupervisorStrategy
          .restartWithBackoff(minBackoff = .seconds, maxBackoff = .seconds, randomFactor = 0.1)
          .withMaxRestarts()
          .withResetBackoffAfter(.seconds)
      )
      , "singletonActor"
    ).withSettings(singletonSettings)
  }

  def apply(): Behavior[Command] = Behaviors.setup[Command] { ctx =>
    val cluster = Cluster(ctx.system)
    val workersRouter = ctx.spawn(
      Routers.group(routerServiceKey)
        .withRoundRobinRouting(),
      "workersRouter"
    )
    ( until ).foreach { n =>
      val routee = ctx.spawn(WorkerRoutee(cluster.selfMember.address.toString), s"work-routee-$n")
      ctx.system.receptionist ! Receptionist.register(routerServiceKey, routee)
    }
    val singletonActor = ClusterSingleton(ctx.system).init(singletonService(ctx, workersRouter))
    Behaviors.receiveMessage {
      case job@ProcessText(text) =>
        singletonActor ! job
        Behaviors.same
    }
  }

}

整体goup-router和routee的构建是在apply()里，并把接到的任务转发给singletonActor。singletonActor是以serviceBehavior为核心的一个actor。在servceBehavior里把收到的任务分解并分别发送给workersRouter。值得注意的是：serviceBehavior期望接收从Aggregator的回应，它们之间存在request/response模式信息交流，所以需要Aggregator.Response到WrappedResult的类型转换机制。还有：子任务是通过workersRoute发送给个workerRoutee的，我们需要各workerRoutee把运算结果返给给Aggregator,所以发送给workersRouter的消息包含了Aggregator的ActorRef，如：workersRouter ! WorkerRoutee.Count(cnt,aggregatorRef)。

Aggregator是个persistentActor, 如下：

object Aggregator {
  sealed trait Command
  sealed trait Event extends  CborSerializable
  sealed trait Response

  case class CountText(cnt: Int, replyTo: ActorRef[Response]) extends Command
  case class MarkLength(word: String, len: Int) extends Command
  case class TextCounted(cnt: Int) extends Event
  case class LengthMarked(word: String, len: Int) extends Event
  case class Result(meanWordLength: Double) extends Response

  case class State(expectedNum: Int = , lens: List[Int] = Nil)

  var replyTo: ActorRef[Response] = _

  def commandHandler: (State,Command) => Effect[Event,State] = (st,cmd) => {
    cmd match {
      case CountText(cnt,ref) =>
        replyTo = ref
        Effect.persist(TextCounted(cnt))
      case MarkLength(word,len) =>
        Effect.persist(LengthMarked(word,len))
    }
  }
  def eventHandler: (State, Event) => State = (st,ev) => {
    ev match {
      case TextCounted(cnt) =>
        st.copy(expectedNum = cnt, lens = Nil)
      case LengthMarked(word,len) =>
        val state = st.copy(lens = len :: st.lens)
        if (state.lens.size >= state.expectedNum) {
          val meanWordLength = state.lens.sum.toDouble / state.lens.size
          replyTo ! Result(meanWordLength)
          State()
        } else state
    }
  }
  val takeSnapShot: (State,Event,Long) => Boolean = (st,ev,seq) => {
      if (st.lens.isEmpty) {
          if (ev.isInstanceOf[LengthMarked])
            true
          else
            false
      } else
         false
  }
  def apply(): Behavior[Command] = Behaviors.supervise(
    Behaviors.setup[Command] { ctx =>
      EventSourcedBehavior(
        persistenceId = PersistenceId("",""),
        emptyState = State(),
        commandHandler = commandHandler,
        eventHandler = eventHandler
      ).onPersistFailure(
        SupervisorStrategy
          .restartWithBackoff(minBackoff = .seconds, maxBackoff = .seconds, randomFactor = 0.1)
          .withMaxRestarts()
          .withResetBackoffAfter(.seconds)
      ).receiveSignal {
        case (state, RecoveryCompleted) =>
          ctx.log.info("**************Recovery Completed with state: {}***************",state)
        case (state, SnapshotCompleted(meta))  =>
          ctx.log.info("**************Snapshot Completed with state: {},id({},{})***************",state,meta.persistenceId, meta.sequenceNr)
        case (state,RecoveryFailed(err)) =>
          ctx.log.error("*************recovery failed with: {}***************",err.getMessage)
        case (state,SnapshotFailed(meta,err)) =>
          ctx.log.error("***************snapshoting failed with: {}*************",err.getMessage)
      }.snapshotWhen(takeSnapShot)
    }
  ).onFailure(
    SupervisorStrategy
      .restartWithBackoff(minBackoff = .seconds, maxBackoff = .seconds, randomFactor = 0.1)
      .withMaxRestarts()
      .withResetBackoffAfter(.seconds)
  )
}

注意这个takeSnapShot函数：这个函数是在EventSourcedBehavior.snapshotWhen(takeSnapShot)调用的。传入参数是（State,Event,seqenceNr)，我们需要对State,Event的当前值进行分析后返回true代表做一次snapshot。

看看一部分显示就知道任务已经分配到几个节点上的routee：

::59.072 [ClusterSystem-akka.actor.default-dispatcher-] INFO com.learn.akka.WorkerRoutee$ - ************** processing [this] on akka://ClusterSystem@127.0.0.1:51182 ***********
::59.072 [ClusterSystem-akka.actor.default-dispatcher-] INFO com.learn.akka.WorkerRoutee$ - ************** processing [text] on akka://ClusterSystem@127.0.0.1:51182 ***********
::59.072 [ClusterSystem-akka.actor.default-dispatcher-] INFO com.learn.akka.WorkerRoutee$ - ************** processing [be] on akka://ClusterSystem@127.0.0.1:51182 ***********
::59.236 [ClusterSystem-akka.actor.default-dispatcher-] INFO com.learn.akka.WorkerRoutee$ - ************** processing [will] on akka://ClusterSystem@127.0.0.1:51173 ***********
::59.236 [ClusterSystem-akka.actor.default-dispatcher-] INFO com.learn.akka.WorkerRoutee$ - ************** processing [is] on akka://ClusterSystem@127.0.0.1:25251 ***********
::59.236 [ClusterSystem-akka.actor.default-dispatcher-] INFO com.learn.akka.WorkerRoutee$ - ************** processing [the] on akka://ClusterSystem@127.0.0.1:51173 ***********
::59.236 [ClusterSystem-akka.actor.default-dispatcher-] INFO com.learn.akka.WorkerRoutee$ - ************** processing [that] on akka://ClusterSystem@127.0.0.1:25251 ***********
::59.236 [ClusterSystem-akka.actor.default-dispatcher-] INFO com.learn.akka.WorkerRoutee$ - ************** processing [analyzed] on akka://ClusterSystem@127.0.0.1:25251 ***********

这个例子的源代码如下：

package com.learn.akka

import akka.actor.typed._
import akka.persistence.typed._
import akka.persistence.typed.scaladsl._
import scala.concurrent.duration._
import akka.actor.typed.receptionist._
import akka.actor.typed.scaladsl.Behaviors
import akka.actor.typed.scaladsl._
import akka.cluster.typed.Cluster
import akka.cluster.typed.ClusterSingleton
import akka.cluster.typed.ClusterSingletonSettings
import akka.cluster.typed.SingletonActor
import com.typesafe.config.ConfigFactory

object WorkerRoutee {
  sealed trait Command extends CborSerializable
  case class Count(word: String, replyTo: ActorRef[Aggregator.Command]) extends Command

  def apply(nodeAddress: String): Behavior[Command] = Behaviors.setup {ctx =>
    Behaviors.receiveMessage[Command] {
      case Count(word,replyTo) =>
        ctx.log.info("************** processing [{}] on {} ***********",word,nodeAddress)
        replyTo ! Aggregator.MarkLength(word,word.length)
        Behaviors.same
    }
  }
}
object Aggregator {
  sealed trait Command
  sealed trait Event extends  CborSerializable
  sealed trait Response

  case class CountText(cnt: Int, replyTo: ActorRef[Response]) extends Command
  case class MarkLength(word: String, len: Int) extends Command
  case class TextCounted(cnt: Int) extends Event
  case class LengthMarked(word: String, len: Int) extends Event
  case class Result(meanWordLength: Double) extends Response

  case class State(expectedNum: Int = , lens: List[Int] = Nil)

  var replyTo: ActorRef[Response] = _

  def commandHandler: (State,Command) => Effect[Event,State] = (st,cmd) => {
    cmd match {
      case CountText(cnt,ref) =>
        replyTo = ref
        Effect.persist(TextCounted(cnt))
      case MarkLength(word,len) =>
        Effect.persist(LengthMarked(word,len))
    }
  }
  def eventHandler: (State, Event) => State = (st,ev) => {
    ev match {
      case TextCounted(cnt) =>
        st.copy(expectedNum = cnt, lens = Nil)
      case LengthMarked(word,len) =>
        val state = st.copy(lens = len :: st.lens)
        if (state.lens.size >= state.expectedNum) {
          val meanWordLength = state.lens.sum.toDouble / state.lens.size
          replyTo ! Result(meanWordLength)
          State()
        } else state
    }
  }
  val takeSnapShot: (State,Event,Long) => Boolean = (st,ev,seq) => {
      if (st.lens.isEmpty) {
          if (ev.isInstanceOf[LengthMarked])
            true
          else
            false
      } else
         false
  }
  def apply(): Behavior[Command] = Behaviors.supervise(
    Behaviors.setup[Command] { ctx =>
      EventSourcedBehavior(
        persistenceId = PersistenceId("",""),
        emptyState = State(),
        commandHandler = commandHandler,
        eventHandler = eventHandler
      ).onPersistFailure(
        SupervisorStrategy
          .restartWithBackoff(minBackoff = .seconds, maxBackoff = .seconds, randomFactor = 0.1)
          .withMaxRestarts()
          .withResetBackoffAfter(.seconds)
      ).receiveSignal {
        case (state, RecoveryCompleted) =>
          ctx.log.info("**************Recovery Completed with state: {}***************",state)
        case (state, SnapshotCompleted(meta))  =>
          ctx.log.info("**************Snapshot Completed with state: {},id({},{})***************",state,meta.persistenceId, meta.sequenceNr)
        case (state,RecoveryFailed(err)) =>
          ctx.log.error("*************recovery failed with: {}***************",err.getMessage)
        case (state,SnapshotFailed(meta,err)) =>
          ctx.log.error("***************snapshoting failed with: {}*************",err.getMessage)
      }.snapshotWhen(takeSnapShot)
    }
  ).onFailure(
    SupervisorStrategy
      .restartWithBackoff(minBackoff = .seconds, maxBackoff = .seconds, randomFactor = 0.1)
      .withMaxRestarts()
      .withResetBackoffAfter(.seconds)
  )
}
object Service {
  val routerServiceKey = ServiceKey[WorkerRoutee.Command]("workers-router")

  sealed trait Command extends CborSerializable

  case class ProcessText(text: String) extends Command {
    require(text.nonEmpty)
  }

  case class WrappedResult(res: Aggregator.Response) extends Command

  def serviceBehavior(workersRouter: ActorRef[WorkerRoutee.Command]): Behavior[Command] = Behaviors.setup[Command] { ctx =>
    val aggregator = ctx.spawn(Aggregator(), "aggregator")
    val aggregatorRef: ActorRef[Aggregator.Response] = ctx.messageAdapter(WrappedResult)
    Behaviors.receiveMessage {
      case ProcessText(text) =>
        ctx.log.info("******************** received ProcessText command: {} ****************",text)
        val words = text.split(' ').toIndexedSeq
        aggregator ! Aggregator.CountText(words.size, aggregatorRef)
        words.foreach { word =>
          workersRouter ! WorkerRoutee.Count(word, aggregator)
        }
        Behaviors.same
      case WrappedResult(msg) =>
        msg match {
          case Aggregator.Result(res) =>
            ctx.log.info("************** mean length of words = {} **********", res)
        }
        Behaviors.same
    }
  }

  def singletonService(ctx: ActorContext[Command], workersRouter: ActorRef[WorkerRoutee.Command]) = {
    val singletonSettings = ClusterSingletonSettings(ctx.system)
      .withRole("front")
    SingletonActor(
      Behaviors.supervise(
        serviceBehavior(workersRouter)
      ).onFailure(
        SupervisorStrategy
          .restartWithBackoff(minBackoff = .seconds, maxBackoff = .seconds, randomFactor = 0.1)
          .withMaxRestarts()
          .withResetBackoffAfter(.seconds)
      )
      , "singletonActor"
    ).withSettings(singletonSettings)
  }

  def apply(): Behavior[Command] = Behaviors.setup[Command] { ctx =>
    val cluster = Cluster(ctx.system)
    val workersRouter = ctx.spawn(
      Routers.group(routerServiceKey)
        .withRoundRobinRouting(),
      "workersRouter"
    )
    ( until ).foreach { n =>
      val routee = ctx.spawn(WorkerRoutee(cluster.selfMember.address.toString), s"work-routee-$n")
      ctx.system.receptionist ! Receptionist.register(routerServiceKey, routee)
    }
    val singletonActor = ClusterSingleton(ctx.system).init(singletonService(ctx, workersRouter))
    Behaviors.receiveMessage {
      case job@ProcessText(text) =>
        singletonActor ! job
        Behaviors.same
    }
  }

}

object LoadBalance {
  def main(args: Array[String]): Unit = {
    if (args.isEmpty) {
      startup("compute", )
      startup("compute", )
      startup("compute", )
      startup("front", )
    } else {
      require(args.size == , "Usage: role port")
      startup(args(), args().toInt)
    }
  }

  def startup(role: String, port: Int): Unit = {
    // Override the configuration of the port when specified as program argument
    val config = ConfigFactory
      .parseString(s"""
      akka.remote.artery.canonical.port=$port
      akka.cluster.roles = [$role]
      """)
      .withFallback(ConfigFactory.load("cluster-persistence"))

    val frontEnd = ActorSystem[Service.Command](Service(), "ClusterSystem", config)
    if (role == "front") {
      println("*************** sending ProcessText command  ************")
      frontEnd ! Service.ProcessText("this is the text that will be analyzed")
    }

  }

}

cluster-persistence.conf

akka.actor.allow-java-serialization = on
akka {
  loglevel = INFO
  actor {
    provider = cluster
    serialization-bindings {
      "com.learn.akka.CborSerializable" = jackson-cbor
    }
  }
 remote {
    artery {
      canonical.hostname = "127.0.0.1"
      canonical.port =
    }
  }
  cluster {
    seed-nodes = [
      "akka://ClusterSystem@127.0.0.1:25251",
      "akka://ClusterSystem@127.0.0.1:25252"]
  }
  # use Cassandra to store both snapshots and the events of the persistent actors
  persistence {
    journal.plugin = "akka.persistence.cassandra.journal"
    snapshot-store.plugin = "akka.persistence.cassandra.snapshot"
  }
}
akka.persistence.cassandra {
  # don't use autocreate in production
  journal.keyspace = "poc"
  journal.keyspace-autocreate = on
  journal.tables-autocreate = on
  snapshot.keyspace = "poc_snapshot"
  snapshot.keyspace-autocreate = on
  snapshot.tables-autocreate = on
}

datastax-java-driver {
  basic.contact-points = ["192.168.11.189:9042"]
  basic.load-balancing-policy.local-datacenter = "datacenter1"
}

build.sbt

name := "learn-akka-typed"

version := "0.1"

scalaVersion := "2.13.1"
scalacOptions in Compile ++= Seq("-deprecation", "-feature", "-unchecked", "-Xlog-reflective-calls", "-Xlint")
javacOptions in Compile ++= Seq("-Xlint:unchecked", "-Xlint:deprecation")

val AkkaVersion = "2.6.5"
val AkkaPersistenceCassandraVersion = "1.0.0"

libraryDependencies ++= Seq(
  "com.typesafe.akka" %% "akka-cluster-sharding-typed" % AkkaVersion,
  "com.typesafe.akka" %% "akka-persistence-typed" % AkkaVersion,
  "com.typesafe.akka" %% "akka-persistence-query" % AkkaVersion,
  "com.typesafe.akka" %% "akka-serialization-jackson" % AkkaVersion,
  "com.typesafe.akka" %% "akka-persistence-cassandra" % AkkaPersistenceCassandraVersion,
  "com.typesafe.akka" %% "akka-slf4j" % AkkaVersion,
  "ch.qos.logback"     % "logback-classic"             % "1.2.3"
)