![import akka.actor._
!
class GreetingActor extends Actor with ActorLogging {
9
import GreetingActor._
def receive = {
case User(name) =>
log.info(s“Hello there ${name}”)
}
}
!
object GreetingActor {
case class User(name: String)
def props: Props = Props(classOf[GreetingActor])
}](https://image.slidesharecdn.com/activatorplaynyc-140924210414-phpapp02/85/Activator-and-Reactive-at-Play-NYC-meetup-9-320.jpg)
![17
import akka.actor._
!
object Sample extends App {
val system = ActorSystem(“MySystem”)
val greeter = system.actorOf(GreetingActor.props, “greeter”)
greeter ! GreetingActor.User(“PlayNYC”)
Thread.sleep(1000) // wait a little before shutting down
system.shutdown()
}
!
class GreetingActor extends Actor with ActorLogging {
def receive = {
case GreetingActor.User(name) =>
log.info(s“Hello there ${name}”)
}
}
!
object GreetingActor {
case class User(name: String)
def props: Props = Props(classOf[GreetingActor])
}](https://image.slidesharecdn.com/activatorplaynyc-140924210414-phpapp02/85/Activator-and-Reactive-at-Play-NYC-meetup-17-320.jpg)
![18
he-mbp:sample he$ scalac Sample.scala
!
he-mbp:sample he$ scala Sample
!
[INFO] [09/15/2014 16:57:19.879] [MySystem-akka.actor.default-dispatcher-
4] [akka://MySystem/user/greeter] Hello there PlayNYC
!
he-mbp:sample he$](https://image.slidesharecdn.com/activatorplaynyc-140924210414-phpapp02/85/Activator-and-Reactive-at-Play-NYC-meetup-18-320.jpg)
![30
object AppGlobal extends GlobalSettings {
private[this] var _system: Option[ActorSystem] = None
def system = _system.getOrElse(throw new RuntimeException(“…”))
!
override def onStart(app: Application) = {
_system = Some(ActorSystem(“ClusterSystem”))
_system.foreach(createShard(_))
}
!
override def onStop(app: Application) = {
system.foreach(_.shutdown())
}
!
private def createShard(system: ActorSystem) = {
ClusterSharding(system).start(
typeName = User.shardName,
entryProps = Some(User.props),
idExtractor = User.idExtractor,
shardResolver = User.shardResolver
)
}
}](https://image.slidesharecdn.com/activatorplaynyc-140924210414-phpapp02/85/Activator-and-Reactive-at-Play-NYC-meetup-30-320.jpg)
![31
object User {
val shardName = "users"
def props: Props = Props(classOf[User])
!
trait UserMessage { def userId: String }
case class CreateUser(userId: String)
extends UserMessage
case class UpdateUser(userId: String, text: String)
extends UserMessage
val idExtractor: ShardRegion.IdExctrator = {
case um: UserMessage => (um.userId, um)
}
val shardResolver: ShardRegion.ShardResolver = {
case um: UserMessage =>
(Math.abs(um.userId.hashCode) % 20).toString
}
}](https://image.slidesharecdn.com/activatorplaynyc-140924210414-phpapp02/85/Activator-and-Reactive-at-Play-NYC-meetup-31-320.jpg)
![32
class User extends Actor with ActorLogging {
var currentMessage: Option[String] = None
def receive = {
case CreateUser(userId) =>
currentMessage = Some(s"User created: ${userId}”)
case UpdateUser(userId, text) =>
log.info(s“User ${userId} now has msg ${text}”)
currentMessage = Some(text)
}
}](https://image.slidesharecdn.com/activatorplaynyc-140924210414-phpapp02/85/Activator-and-Reactive-at-Play-NYC-meetup-32-320.jpg)
![33
akka {
actor.provider = "akka.cluster.ClusterActorRefProvider"
remote.nettytcp {
port = 0
hostname = "127.0.0.1"
}
!
remote.log-remote-lifecycle-events = on
!
cluster {
seed-nodes = [
"akka.tcp://ClusterSystem@127.0.0.1:2551",
"akka.tcp://ClusterSystem@127.0.0.1:2552"
]
}
!
auto-down-unreachable-after = 30s
}](https://image.slidesharecdn.com/activatorplaynyc-140924210414-phpapp02/85/Activator-and-Reactive-at-Play-NYC-meetup-33-320.jpg)
![36
package controllers
!
import play.api._
import play.api.mvc._
import play.api.libs.json._
import play.api.Play.current
import actors.WebSocketActor
!
object Application extends Controller {
def index = Action {
Ok(views.html.index("Your new application is ready."))
}
!
def socket = WebSocket.acceptWithActor[JsValue, JsValue] {
request => out =>
WebSocketActor.props(out)
}
}](https://image.slidesharecdn.com/activatorplaynyc-140924210414-phpapp02/85/Activator-and-Reactive-at-Play-NYC-meetup-36-320.jpg)
![37
object WebSocketActor {
def props(out: ActorRef) = Props(new WebSocketActor(out))
case object Again
}
!
class WebSocketActor(out: ActorRef) extends Actor {
import WebSocketActor._
var user: Option[String] = None
def receive = {
case json: JsValue =>
val name = (json "name").as[String]
user = Some(name)
reply(name)
context.system.scheduler.scheduleOnce(3 seconds, self, Again)
case Again =>
user.foreach{reply(_)}
}
!
def reply(name: String) = {
out ! Json.obj("message" -> s"Hello there ${name}")
}
}](https://image.slidesharecdn.com/activatorplaynyc-140924210414-phpapp02/85/Activator-and-Reactive-at-Play-NYC-meetup-37-320.jpg)
![# routes file
GET / controllers.Application.index
GET /socket controllers.Application.socket
!
> var ws = new WebSocket("ws://localhost:9000/socket");
> ws.onmessage = function(msg) { console.log(">", msg); };
> ws.send(JSON.stringify({"name": “PlayNYC"}));
!
> MessageEvent {ports: Array[0], data: "{"message":"Hello
there PlayNYC"}", source: null, lastEventId: "", origin:
"ws://localhost:9000"…}
!
> MessageEvent {ports: Array[0], data: "{"message":"Hello
there PlayNYC"}", source: null, lastEventId: "", origin:
"ws://localhost:9000"…}
38](https://image.slidesharecdn.com/activatorplaynyc-140924210414-phpapp02/85/Activator-and-Reactive-at-Play-NYC-meetup-38-320.jpg)
![import play.api.libs.json._
import play.api.mvc.WebSocket.FrameFormatter
!
implicit val inEventFormat = Json.format[InEvent]
implicit val outEventFormat = Json.format[OutEvent]
!
//Play provides default FrameFormatter for String or JsValue
implicit val inEFF = FrameFormatter.jsonFrame[InEvent]
implicit val outEFF = FrameFormatter.jsonFrame[OutEvent]
!
def socket = WebSocket.acceptWithActor[InEvent, OutEvent] {
request => out =>
WebSocketActor.props(out)
}
39](https://image.slidesharecdn.com/activatorplaynyc-140924210414-phpapp02/85/Activator-and-Reactive-at-Play-NYC-meetup-39-320.jpg)
Activator and Reactive at Play NYC meetup
- 1. What Constitutes a Reactive Application Reactive Patterns Applied Henrik Engstrom Software Engineer @h3nk3
- 2. 2
- 3. 3 Activator UI! (JavaScript, Knockout, CSS3, black magic…) websockets Play Application! (Play 2.3.x, Akka 2.3.x, sbt 0.13.x) sbt protocol sbt Server Async Communication! Websockets! Akka Actors Other Clients (Eclipse, Terminal, etc.)
- 4. DEMO 4
- 5. The Four Reactive Traits Reactive Applications 5 http://reactivemanifesto.org/
- 6. Message-Driven ! The Foundation of being Reactive
- 7. Akka Actors in 5 minutes or so… 7
- 8. 8 ACTORS
- 9. import akka.actor._ ! class GreetingActor extends Actor with ActorLogging { 9 import GreetingActor._ def receive = { case User(name) => log.info(s“Hello there ${name}”) } } ! object GreetingActor { case class User(name: String) def props: Props = Props(classOf[GreetingActor]) }
- 10. 10 MAILBOXES
- 11. 11 THREADS
- 12. 12 STATE
- 13. 13 CONTAINERS
- 14. 14 val system = ActorSystem(“MySystem”) val greeter: ActorRef = system.actorOf(GreetingActor.props, “greeter”)
- 15. 15 MESSAGES
- 16. 16 greeter ! GreetingActor.User(“PlayNYC”) // or greeter.tell(GreetingActor.User(“PlayNYC”))
- 17. 17 import akka.actor._ ! object Sample extends App { val system = ActorSystem(“MySystem”) val greeter = system.actorOf(GreetingActor.props, “greeter”) greeter ! GreetingActor.User(“PlayNYC”) Thread.sleep(1000) // wait a little before shutting down system.shutdown() } ! class GreetingActor extends Actor with ActorLogging { def receive = { case GreetingActor.User(name) => log.info(s“Hello there ${name}”) } } ! object GreetingActor { case class User(name: String) def props: Props = Props(classOf[GreetingActor]) }
- 18. 18 he-mbp:sample he$ scalac Sample.scala ! he-mbp:sample he$ scala Sample ! [INFO] [09/15/2014 16:57:19.879] [MySystem-akka.actor.default-dispatcher- 4] [akka://MySystem/user/greeter] Hello there PlayNYC ! he-mbp:sample he$
- 19. Resilient ! Responsive in the Face of Failure
- 20. 20 SUPERVISION
- 21. 21 import akka.actor.OneForOneStrategy import akka.actor.SupervisorStrategy._ import scala.concurrent.duration._ class SupervisorActor extends Actor with ActorLogging { override val supervisorStrategy = OneForOneStrategy(maxNrOfRetries = 10, withinTimeRange = 1 minute) { case _: SomeDbException => Resume case _: SomeOtherDbException => Restart case _: Exception => Escalate } ! val dbActor = context.actorOf(DbActor.props) def receive = { case op: SomeDbOperation => dbActor forward op } }
- 22. 22 BULKHEAD
- 24. Elastic ! Responsive in the Face of Changing Load
- 25. 25 SOME CHALLENGES • Each user has state Proxy (location) • Horizontal scaling => !sticky sessions • How do we route to the right node? • Node Crashes Proxy Play is App SPOF 1 Play App2 Play App n • …
- 26. 26 Play App Akka! Cluster! Node Akka! Cluster! Node Akka! Cluster! Node Akka! Cluster! Node
- 27. 27 Akka! Cluster! Node Akka! Cluster! Node Akka! Cluster! Node Akka! Cluster! Node Shard Coord. Shard Region Shard Region Shard Region Shard Region
- 28. Supported HTTP commands (Play routes file) ! GET / controller.Application.index PUT /create/user/:userId c.Application.createUser(userId: String) POST /update/user/:userId c.Application.updateUser(userId: String) 28
- 29. 29 package controller object Application extends Controller { val userController = AppGlobal.system.actorOf(UserController.props) ! def index = Action { Ok(“Node is up”) } ! def createUser(userId: String) = Action { userController ! UserController.CreateUser(userId) Ok("new user is created") } ! def updateUser(userId: String) = Action { userController ! UserController.UpdateUser(userId, request.getQueryString(“msg")) Ok("user is updated") } }
- 30. 30 object AppGlobal extends GlobalSettings { private[this] var _system: Option[ActorSystem] = None def system = _system.getOrElse(throw new RuntimeException(“…”)) ! override def onStart(app: Application) = { _system = Some(ActorSystem(“ClusterSystem”)) _system.foreach(createShard(_)) } ! override def onStop(app: Application) = { system.foreach(_.shutdown()) } ! private def createShard(system: ActorSystem) = { ClusterSharding(system).start( typeName = User.shardName, entryProps = Some(User.props), idExtractor = User.idExtractor, shardResolver = User.shardResolver ) } }
- 31. 31 object User { val shardName = "users" def props: Props = Props(classOf[User]) ! trait UserMessage { def userId: String } case class CreateUser(userId: String) extends UserMessage case class UpdateUser(userId: String, text: String) extends UserMessage val idExtractor: ShardRegion.IdExctrator = { case um: UserMessage => (um.userId, um) } val shardResolver: ShardRegion.ShardResolver = { case um: UserMessage => (Math.abs(um.userId.hashCode) % 20).toString } }
- 32. 32 class User extends Actor with ActorLogging { var currentMessage: Option[String] = None def receive = { case CreateUser(userId) => currentMessage = Some(s"User created: ${userId}”) case UpdateUser(userId, text) => log.info(s“User ${userId} now has msg ${text}”) currentMessage = Some(text) } }
- 33. 33 akka { actor.provider = "akka.cluster.ClusterActorRefProvider" remote.nettytcp { port = 0 hostname = "127.0.0.1" } ! remote.log-remote-lifecycle-events = on ! cluster { seed-nodes = [ "akka.tcp://ClusterSystem@127.0.0.1:2551", "akka.tcp://ClusterSystem@127.0.0.1:2552" ] } ! auto-down-unreachable-after = 30s }
- 34. 34 Play App Akka! Cluster! Node Akka! Cluster! Node Akka! Cluster! Node Akka! Cluster! Node
- 35. Responsive ! Always Available - Interactive - (near) Real-Time
- 36. 36 package controllers ! import play.api._ import play.api.mvc._ import play.api.libs.json._ import play.api.Play.current import actors.WebSocketActor ! object Application extends Controller { def index = Action { Ok(views.html.index("Your new application is ready.")) } ! def socket = WebSocket.acceptWithActor[JsValue, JsValue] { request => out => WebSocketActor.props(out) } }
- 37. 37 object WebSocketActor { def props(out: ActorRef) = Props(new WebSocketActor(out)) case object Again } ! class WebSocketActor(out: ActorRef) extends Actor { import WebSocketActor._ var user: Option[String] = None def receive = { case json: JsValue => val name = (json "name").as[String] user = Some(name) reply(name) context.system.scheduler.scheduleOnce(3 seconds, self, Again) case Again => user.foreach{reply(_)} } ! def reply(name: String) = { out ! Json.obj("message" -> s"Hello there ${name}") } }
- 38. # routes file GET / controllers.Application.index GET /socket controllers.Application.socket ! > var ws = new WebSocket("ws://localhost:9000/socket"); > ws.onmessage = function(msg) { console.log(">", msg); }; > ws.send(JSON.stringify({"name": “PlayNYC"})); ! > MessageEvent {ports: Array[0], data: "{"message":"Hello there PlayNYC"}", source: null, lastEventId: "", origin: "ws://localhost:9000"…} ! > MessageEvent {ports: Array[0], data: "{"message":"Hello there PlayNYC"}", source: null, lastEventId: "", origin: "ws://localhost:9000"…} 38
- 39. import play.api.libs.json._ import play.api.mvc.WebSocket.FrameFormatter ! implicit val inEventFormat = Json.format[InEvent] implicit val outEventFormat = Json.format[OutEvent] ! //Play provides default FrameFormatter for String or JsValue implicit val inEFF = FrameFormatter.jsonFrame[InEvent] implicit val outEFF = FrameFormatter.jsonFrame[OutEvent] ! def socket = WebSocket.acceptWithActor[InEvent, OutEvent] { request => out => WebSocketActor.props(out) } 39
- 40. 40 Request Response Coord Actor Entry Actor TwActor FBActor WActor Twitter Facebook weather.com
- 41. RESOURCES ! Activator - get it now! http://typesafe.com/platform/getstarted ! Awesome Example Code by Nilanjan Raychaudhuri https://github.com/nraychaudhuri/scaladays2014/tree/master/ play-akka-sharding ! Play Websockets https://www.playframework.com/documentation/2.3.x/ ScalaWebSockets ! Akka Cluster Sharding http://doc.akka.io/docs/akka/2.3.6/contrib/cluster-sharding. 41 html
- 42. The Four Reactive Traits Reactive Applications 42 http://reactivemanifesto.org/
- 43. ©Typesafe 2014 – All Rights Reserved All images in this presentation are from www.morguefile.com