Deep Introduction to Akka

akkaIntroducing

Friday, September 30, 2011

DeepIntroduction to Akka

Patrik NordwallTypesafe

Twitter: @patriknw

Vision

Simpler

Concurrency

Scalability

Fault-tolerance

Actors

What is an Actor?

Event-drivenThread

Behavior

case object Tick

class Counter extends Actor { var counter = 0

def receive = { case Tick => counter += 1 println(counter) }}

Actors

val counter = actorOf[Counter].start()

Create Actors

counter is an ActorRefFriday, September 30, 2011

counter ! Tick

Tell: !

fire-forget

// returns a futureval future = counter ? Current

val count: Option[Int] = future.as[Int]

Ask: ?

returns the Future directly

Replyclass Counter extends Actor { var counter = 0

def receive = { case Tick => counter += 1 case Current => self.reply(counter) }}

Future

future.awaitfuture onResult { ... } onException { ... } onTimeout { ... }

val future = Future { "Hello" + "World"}

object Shared { val myDispatcher = Dispatchers .newExecutorBasedEventDrivenDispatcher("my") .setCorePoolSize(7) .build}

class MyActor extends Actor { self.dispatcher = Shared.dispatcher ...}

Set dispatcher

Translation Service with HTTP API- count words: 100 ms- translate text: 100 ms

We have 8 threads

Must handle 4 concurrent request with average response time of <110 ms

Example

Web Frontend

Translation Service

Text Translator

Word Counter

HTTP Req

Source code: https://github.com/patriknw/akka-playground

Example

Typed Actors

trait Counter { def tick(): Unit def current: Int}

Typed Actors

class CounterImpl extends TypedActor with Counter {

private var counter = 0

def tick() { counter += 1 }

def current = counter}

Typed Actors

val counter = TypedActor.newInstance( classOf[Counter], classOf[CounterImpl]) counter.tick()counter.tick()val cur = counter.current

Typed Actors

Remote Actors

// use host & port in configActor.remote.start()

Actor.remote.start("darkstar", 2552)

Remoting

Scalable implementation based on NIO (Netty) & Protobuf

import Actor._

remote.register(“service:id”, actorOf[MyService])

Server

server partFriday, September 30, 2011

val service = remote.actorFor( “service:id”, “darkstar”, 2552)

service ! message

Client

client part

Problem Deployment (local vs remote) is a dev decision

We get a fixed and hard-coded topology Can’t change it dynamically and adaptively

Needs to be a deployment & runtime decision

Remoting in Akka 1.2

Let it crash fault-tolerance

Fault-tolerant onion-layered Error Kernel

ErrorKernel

link(actor)unlink(actor)

startLink(actor)spawnLink[MyActor]

Linking

AllForOneStrategy( errors, maxNrOfRetries, withinTimeRange)

OneForOneStrategy( errors, maxNrOfRetries, withinTimeRange)

Fault handlers

class MySupervisor extends Actor { faultHandler = AllForOneStrategy( List(classOf[IllegalStateException]) 5, 5000))

def receive = { case Register(actor) => self.link(actor) }}

Supervision

class FaultTolerantService extends Actor { ... override def preRestart(reason: Throwable) = { ... // clean up before restart } override def postRestart(reason: Throwable) = { ... // init after restart }}

Manage failure

Dataflow

Security

...and much much more

Async-HTTP

scalaz

FSMSTM

Spring

MicrokernelTestkit

Get it and learn morehttp://akka.io

EOFFriday, September 30, 2011

Deep Introduction to Akka

Technology

Introduction to concurrent programming with akka actors

Akka: Введение

Akka 2.2.0

AKKA TECHNOLOGIES

Akka/Actor introduction

Susanjani akka

Developing distributed applications with Akka and Akka Cluster

· CONTENTS 1 Introduction 1 1.1 What is Akka?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 1.2 Why Akka

Introducing Akka

Akka 101 - durtchrt.github.io · Akka Actor ActorRef, mailbox, actor, dispatcher 이미지 출처: akka in action. Akka Actor Path Identifies an Actor May also represent a proxy

Introduction to Reactive with Play and Akka - Markus Jura

Akka Fundamentals

Akka frukostseminarium

A gentle introduction into AKKA and the actor model

Javascript Deep Introduction

AKKA BUSINESS UNIT GERMANY - akka-technologies.com · akka group business unit germany grÜndung von akka research grÜndung des ersten unternehmens 1984 1999 2007 2010 2011 2012

Introduction to Actor Model and Akka

Akka Documentation · 2019-03-28 · Akka Documentation, Release 1.1.3 1.2Why Akka? 1.2.1What features can the Akka platform offer, over the competition? Akka is an uniﬁed runtime

An Introduction to Akka http

Practical Akka HTTP - introduction