Building Reactive Systems with Akka

Transcript

1. Building Reactive Systems with Akka Jonas Bonér Typesafe CTO &

   co-founder Twitter: @jboner

2. The rules of the game have changed

3. 3 Apps in the 60s-90s were written for Apps today

   are written for

4. 3 Apps in the 60s-90s were written for Apps today

   are written for Single machines

5. 3 Apps in the 60s-90s were written for Apps today

   are written for Single machines Clusters of machines

6. 3 Apps in the 60s-90s were written for Apps today

   are written for Single machines Clusters of machines Single core processors

7. 3 Apps in the 60s-90s were written for Apps today

   are written for Single machines Clusters of machines Single core processors Multicore processors

8. 3 Apps in the 60s-90s were written for Apps today

   are written for Single machines Clusters of machines Single core processors Multicore processors Expensive RAM

9. 3 Apps in the 60s-90s were written for Apps today

   are written for Single machines Clusters of machines Single core processors Multicore processors Expensive RAM Cheap RAM

10. 3 Apps in the 60s-90s were written for Apps today

    are written for Single machines Clusters of machines Single core processors Multicore processors Expensive RAM Cheap RAM Expensive disk

11. 3 Apps in the 60s-90s were written for Apps today

    are written for Single machines Clusters of machines Single core processors Multicore processors Expensive RAM Cheap RAM Expensive disk Cheap disk

12. 3 Apps in the 60s-90s were written for Apps today

    are written for Single machines Clusters of machines Single core processors Multicore processors Expensive RAM Cheap RAM Expensive disk Cheap disk Slow networks

13. 3 Apps in the 60s-90s were written for Apps today

    are written for Single machines Clusters of machines Single core processors Multicore processors Expensive RAM Cheap RAM Expensive disk Cheap disk Slow networks Fast networks

14. 3 Apps in the 60s-90s were written for Apps today

    are written for Single machines Clusters of machines Single core processors Multicore processors Expensive RAM Cheap RAM Expensive disk Cheap disk Slow networks Fast networks Few concurrent users

15. 3 Apps in the 60s-90s were written for Apps today

    are written for Single machines Clusters of machines Single core processors Multicore processors Expensive RAM Cheap RAM Expensive disk Cheap disk Slow networks Fast networks Few concurrent users Lots of concurrent users

16. 3 Apps in the 60s-90s were written for Apps today

    are written for Single machines Clusters of machines Single core processors Multicore processors Expensive RAM Cheap RAM Expensive disk Cheap disk Slow networks Fast networks Few concurrent users Lots of concurrent users Small data sets

17. 3 Apps in the 60s-90s were written for Apps today

    are written for Single machines Clusters of machines Single core processors Multicore processors Expensive RAM Cheap RAM Expensive disk Cheap disk Slow networks Fast networks Few concurrent users Lots of concurrent users Small data sets Large data sets

18. 3 Apps in the 60s-90s were written for Apps today

    are written for Single machines Clusters of machines Single core processors Multicore processors Expensive RAM Cheap RAM Expensive disk Cheap disk Slow networks Fast networks Few concurrent users Lots of concurrent users Small data sets Large data sets Latency in seconds

19. 3 Apps in the 60s-90s were written for Apps today

    are written for Single machines Clusters of machines Single core processors Multicore processors Expensive RAM Cheap RAM Expensive disk Cheap disk Slow networks Fast networks Few concurrent users Lots of concurrent users Small data sets Large data sets Latency in seconds Latency in milliseconds
20. None

21. Cost Gravity is at Work X

22. Cost Gravity is at Work X

23. Reactive  Applications Reactive applications share four traits 5

24. Reactive applications enrich the user experience with low latency response.

25. Responsive • Real-time, engaging, rich and collaborative • Create an

    open and ongoing dialog with users • More efficient workflow; inspires a feeling of connectedness • Fully Reactive enabling push instead of pull 7 “The move to these technologies is already paying off. 
 Response times are down for processor intensive code–such as image 
 and PDF generation–by around 75%.”   Brian Pugh, VP of Engineering, Lucid Software

26. Reactive applications react to 
 changes in the world around

    them.

27. Message-Driven • Loosely coupled architecture, easier to extend, maintain, evolve

    • Asynchronous and non-blocking • Concurrent by design, immutable state • Lower latency and higher throughput 9 “Clearly, the goal is to do these operations concurrently and 
 non-blocking, so that entire blocks of seats or sections are not locked. 
 We’re able to find and allocate seats under load in less than 20ms 
 without trying very hard to achieve it.”   Andrew Headrick, Platform Architect, Ticketfly

28. Introducing the Actor Model

29. 11 The Actor Model

30. 11 A computational model that embodies: The Actor Model

31. 11 A computational model that embodies: ✓ Processing The Actor

    Model

32. 11 A computational model that embodies: ✓ Processing ✓ Storage

    The Actor Model

33. 11 A computational model that embodies: ✓ Processing ✓ Storage

    ✓ Communication The Actor Model

34. 11 A computational model that embodies: ✓ Processing ✓ Storage

    ✓ Communication Supports 3 axioms—when an Actor receives a message it can: The Actor Model

35. 11 A computational model that embodies: ✓ Processing ✓ Storage

    ✓ Communication Supports 3 axioms—when an Actor receives a message it can: 1. Create new Actors The Actor Model

36. 11 A computational model that embodies: ✓ Processing ✓ Storage

    ✓ Communication Supports 3 axioms—when an Actor receives a message it can: 1. Create new Actors 2. Send messages to Actors it knows The Actor Model

37. 11 A computational model that embodies: ✓ Processing ✓ Storage

    ✓ Communication Supports 3 axioms—when an Actor receives a message it can: 1. Create new Actors 2. Send messages to Actors it knows 3. Designate how it should handle the next message it receives The Actor Model

38. The essence of an actor from Akka’s perspective 0. DEFINE

    1. CREATE 2. SEND 3. BECOME 4. SUPERVISE 12

39. public class Greeting implements Serializable { public final String who;

    public Greeting(String who) { this.who = who; } } ! public class Greeter extends AbstractActor {{ receive(ReceiveBuilder. match(Greeting.class, m -> { println(“Hello " + m.who); }). matchAny(unknown -> { println(“Unknown message " + unknown); }).build()); }} 0. DEFINE X

40. public class Greeting implements Serializable { public final String who;

    public Greeting(String who) { this.who = who; } } ! public class Greeter extends AbstractActor {{ receive(ReceiveBuilder. match(Greeting.class, m -> { println(“Hello " + m.who); }). matchAny(unknown -> { println(“Unknown message " + unknown); }).build()); }} 0. DEFINE X Define the message(s) the Actor should be able to respond to

41. public class Greeting implements Serializable { public final String who;

    public Greeting(String who) { this.who = who; } } ! public class Greeter extends AbstractActor {{ receive(ReceiveBuilder. match(Greeting.class, m -> { println(“Hello " + m.who); }). matchAny(unknown -> { println(“Unknown message " + unknown); }).build()); }} 0. DEFINE X Define the message(s) the Actor should be able to respond to Define the Actor class

42. public class Greeting implements Serializable { public final String who;

    public Greeting(String who) { this.who = who; } } ! public class Greeter extends AbstractActor {{ receive(ReceiveBuilder. match(Greeting.class, m -> { println(“Hello " + m.who); }). matchAny(unknown -> { println(“Unknown message " + unknown); }).build()); }} 0. DEFINE X Define the message(s) the Actor should be able to respond to Define the Actor class Define the Actor’s behavior

43. ActorSystem system = ActorSystem.create("MySystem"); ! ActorRef greeter = system.actorOf(Props.create(Greeter.class), “greeter");

    1. CREATE

44. ActorSystem system = ActorSystem.create("MySystem"); ! ActorRef greeter = system.actorOf(Props.create(Greeter.class), “greeter");

    1. CREATE Create an Actor system

45. ActorSystem system = ActorSystem.create("MySystem"); ! ActorRef greeter = system.actorOf(Props.create(Greeter.class), “greeter");

    1. CREATE Create an Actor system Actor configuration

46. ActorSystem system = ActorSystem.create("MySystem"); ! ActorRef greeter = system.actorOf(Props.create(Greeter.class), “greeter");

    Give it a name 1. CREATE Create an Actor system Actor configuration

47. ActorSystem system = ActorSystem.create("MySystem"); ! ActorRef greeter = system.actorOf(Props.create(Greeter.class), “greeter");

    Give it a name 1. CREATE Create the Actor Create an Actor system Actor configuration

48. ActorSystem system = ActorSystem.create("MySystem"); ! ActorRef greeter = system.actorOf(Props.create(Greeter.class), “greeter");

    Give it a name 1. CREATE Create the Actor You get an ActorRef back Create an Actor system Actor configuration

49. 0. DEFINE 13 case class Greeting(who: String) ! class GreetingActor

    extends Actor with ActorLogging { def receive = { case Greeting(who) => log.info(s"Hello ${who}") } }

50. 0. DEFINE 13 Define the message(s) the Actor should be

    able to respond to case class Greeting(who: String) ! class GreetingActor extends Actor with ActorLogging { def receive = { case Greeting(who) => log.info(s"Hello ${who}") } }

51. 0. DEFINE 13 Define the message(s) the Actor should be

    able to respond to case class Greeting(who: String) ! class GreetingActor extends Actor with ActorLogging { def receive = { case Greeting(who) => log.info(s"Hello ${who}") } } Define the Actor class

52. 0. DEFINE 13 Define the message(s) the Actor should be

    able to respond to case class Greeting(who: String) ! class GreetingActor extends Actor with ActorLogging { def receive = { case Greeting(who) => log.info(s"Hello ${who}") } } Define the Actor class Define the Actor’s behavior

53. case class Greeting(who: String) ! class GreetingActor extends Actor with

    ActorLogging { def receive = { case Greeting(who) => log.info("Hello " + who) } } ! val system = ActorSystem("MySystem") val greeter = system.actorOf(Props[GreetingActor], name = "greeter") 1. CREATE

54. case class Greeting(who: String) ! class GreetingActor extends Actor with

    ActorLogging { def receive = { case Greeting(who) => log.info("Hello " + who) } } ! val system = ActorSystem("MySystem") val greeter = system.actorOf(Props[GreetingActor], name = "greeter") 1. CREATE Create an Actor system

55. case class Greeting(who: String) ! class GreetingActor extends Actor with

    ActorLogging { def receive = { case Greeting(who) => log.info("Hello " + who) } } ! val system = ActorSystem("MySystem") val greeter = system.actorOf(Props[GreetingActor], name = "greeter") 1. CREATE Create an Actor system Actor configuration

56. case class Greeting(who: String) ! class GreetingActor extends Actor with

    ActorLogging { def receive = { case Greeting(who) => log.info("Hello " + who) } } ! val system = ActorSystem("MySystem") val greeter = system.actorOf(Props[GreetingActor], name = "greeter") Give it a name 1. CREATE Create an Actor system Actor configuration

57. case class Greeting(who: String) ! class GreetingActor extends Actor with

    ActorLogging { def receive = { case Greeting(who) => log.info("Hello " + who) } } ! val system = ActorSystem("MySystem") val greeter = system.actorOf(Props[GreetingActor], name = "greeter") Give it a name 1. CREATE Create the Actor Create an Actor system Actor configuration

58. case class Greeting(who: String) ! class GreetingActor extends Actor with

    ActorLogging { def receive = { case Greeting(who) => log.info("Hello " + who) } } ! val system = ActorSystem("MySystem") val greeter = system.actorOf(Props[GreetingActor], name = "greeter") Give it a name 1. CREATE Create the Actor You get an ActorRef back Create an Actor system Actor configuration

59. Guardian System Actor Actors can form hierarchies

60. Guardian System Actor system.actorOf(Props.create(Foo.class), “Foo”); Actors can form hierarchies

61. Foo Guardian System Actor system.actorOf(Props.create(Foo.class), “Foo”); Actors can form hierarchies

62. Foo Guardian System Actor context().actorOf(Props.create(A.class), “A”); Actors can form hierarchies

63. A Foo Guardian System Actor context().actorOf(Props.create(A.class), “A”); Actors can form

    hierarchies

64. A B Bar Foo C B E A D C

    Guardian System Actor Actors can form hierarchies

65. Guardian System Actor Actors can form hierarchies

66. Guardian System Actor system.actorOf(Props[Foo], “Foo”) Actors can form hierarchies

67. Foo Guardian System Actor system.actorOf(Props[Foo], “Foo”) Actors can form hierarchies

68. Foo Guardian System Actor context.actorOf(Props[A], “A”) Actors can form hierarchies

69. A Foo Guardian System Actor context.actorOf(Props[A], “A”) Actors can form

    hierarchies

70. A B Bar Foo C B E A D C

    Guardian System Actor Actors can form hierarchies

71. A B Bar Foo C B E A D C

    Guardian System Actor Name resolution—like a file-system

72. A B Bar Foo C B E A D C

    /Foo Guardian System Actor Name resolution—like a file-system

73. A B Bar Foo C B E A D C

    /Foo /Foo/A Guardian System Actor Name resolution—like a file-system

74. A B Bar Foo C B E A D C

    /Foo /Foo/A /Foo/A/B Guardian System Actor Name resolution—like a file-system

75. A B Bar Foo C B E A D C

    /Foo /Foo/A /Foo/A/B /Foo/A/D Guardian System Actor Name resolution—like a file-system

76. 2. SEND X greeter.tell(new Greeting("Charlie Parker”), sender);

77. 2. SEND X Send the message asynchronously greeter.tell(new Greeting("Charlie Parker”),

    sender);

78. 2. SEND X Send the message asynchronously greeter.tell(new Greeting("Charlie Parker”),

    sender); Pass in the sender ActorRef

79. Bring it together X public class Greeting implements Serializable {

    public final String who; public Greeting(String who) { this.who = who; } } public class Greeter extends AbstractActor {{ receive(ReceiveBuilder. match(Greeting.class, m -> { println(“Hello " + m.who); }). matchAny(unknown -> { println(“Unknown message " + unknown); }).build()); } }} ! ActorSystem system = ActorSystem.create("MySystem"); ActorRef greeter = system.actorOf(Props.create(Greeter.class), “greeter"); greeter.tell(new Greeting(“Charlie Parker”));

80. 2. SEND 17 case class Greeting(who: String) ! class GreetingActor

    extends Actor with ActorLogging { def receive = { case Greeting(who) => log.info(s”Hello ${who}") } } ! val system = ActorSystem("MySystem") val greeter = system.actorOf(Props[GreetingActor], name = "greeter") greeter ! Greeting("Charlie Parker")

81. 2. SEND 17 case class Greeting(who: String) ! class GreetingActor

    extends Actor with ActorLogging { def receive = { case Greeting(who) => log.info(s”Hello ${who}") } } ! val system = ActorSystem("MySystem") val greeter = system.actorOf(Props[GreetingActor], name = "greeter") greeter ! Greeting("Charlie Parker") Send the message asynchronously

82. Bring it together 18 case class Greeting(who: String) ! class

    GreetingActor extends Actor with ActorLogging { def receive = { case Greeting(who) => log.info(s”Hello ${who}") } } ! val system = ActorSystem("MySystem") val greeter = system.actorOf(Props[GreetingActor], name = "greeter") greeter ! Greeting("Charlie Parker")

83. DEMO TIME A simple game of ping pong

84. 3. BECOME X public class Greeter extends AbstractActor { public

    Greeter { receive(ReceiveBuilder. match(Greeting.class, m -> { println(“Hello " + m.who); }). matchEquals(“stop" -> { ! ! ! ! }).build(); } }

85. 3. BECOME X public class Greeter extends AbstractActor { public

    Greeter { receive(ReceiveBuilder. match(Greeting.class, m -> { println(“Hello " + m.who); }). matchEquals(“stop" -> { ! ! ! ! }).build(); } } context().become(ReceiveBuilder.

86. 3. BECOME X public class Greeter extends AbstractActor { public

    Greeter { receive(ReceiveBuilder. match(Greeting.class, m -> { println(“Hello " + m.who); }). matchEquals(“stop" -> { ! ! ! ! }).build(); } } Change the behavior context().become(ReceiveBuilder.

87. 3. BECOME X public class Greeter extends AbstractActor { public

    Greeter { receive(ReceiveBuilder. match(Greeting.class, m -> { println(“Hello " + m.who); }). matchEquals(“stop" -> { ! ! ! ! }).build(); } } Change the behavior context().become(ReceiveBuilder. match(Greeting.class, m -> {

88. 3. BECOME X public class Greeter extends AbstractActor { public

    Greeter { receive(ReceiveBuilder. match(Greeting.class, m -> { println(“Hello " + m.who); }). matchEquals(“stop" -> { ! ! ! ! }).build(); } } Change the behavior context().become(ReceiveBuilder. match(Greeting.class, m -> { println(“Go Away!”);

89. 3. BECOME X public class Greeter extends AbstractActor { public

    Greeter { receive(ReceiveBuilder. match(Greeting.class, m -> { println(“Hello " + m.who); }). matchEquals(“stop" -> { ! ! ! ! }).build(); } } Change the behavior context().become(ReceiveBuilder. match(Greeting.class, m -> { println(“Go Away!”); }).build());

90. 3. BECOME X public class Greeter extends AbstractActor { public

    Greeter { receive(ReceiveBuilder. match(Greeting.class, m -> { println(“Hello " + m.who); }). matchEquals(“stop" -> { ! ! ! ! }).build(); } } Change the behavior context().become(ReceiveBuilder. match(Greeting.class, m -> { println(“Go Away!”); }).build());

91. 3. BECOME 19 class GreetingActor extends Actor with ActorLogging {

    def receive = happy ! val happy: Receive = { case Greeting(who) => log.info(s”Hello ${who}") case Angry => context become angry } ! val angry: Receive = { case Greeting(_) => log.info("Go away!") case Happy => context become happy } }

92. 3. BECOME 19 class GreetingActor extends Actor with ActorLogging {

    def receive = happy ! val happy: Receive = { case Greeting(who) => log.info(s”Hello ${who}") case Angry => context become angry } ! val angry: Receive = { case Greeting(_) => log.info("Go away!") case Happy => context become happy } } Redefine the behavior

93. Reactive applications are architected 
 to handle failure at all

    levels.

94. Resilient • Failure is embraced as a natural state in

    the app lifecycle • Resilience is a first-class construct • Failure is detected, isolated, and managed • Applications self heal 21 “The Typesafe Reactive Platform helps us maintain a very 
 aggressive development and deployment cycle, all in a fail-forward manner. 
 It’s now the default choice for developing all new services.”   Peter Hausel, VP Engineering, Gawker Media

95. Think Vending Machine

96. Coffee Machine Programmer Think Vending Machine

97. Coffee Machine Programmer Inserts coins Think Vending Machine

98. Coffee Machine Programmer Inserts coins Add more coins Think Vending

    Machine

99. Coffee Machine Programmer Inserts coins Gets coffee Add more coins

    Think Vending Machine

100. Coffee Machine Programmer Think Vending Machine

101. Coffee Machine Programmer Inserts coins Think Vending Machine

102. Coffee Machine Programmer Inserts coins Think Vending Machine Out of

     coffee beans error

103. Coffee Machine Programmer Inserts coins Think Vending Machine Out of

     coffee beans error Wrong

104. Coffee Machine Programmer Inserts coins Think Vending Machine

105. Coffee Machine Programmer Inserts coins Out of coffee beans error

     Think Vending Machine

106. Coffee Machine Programmer Service Guy Inserts coins Out of coffee

     beans error Think Vending Machine

107. Coffee Machine Programmer Service Guy Inserts coins Out of coffee

     beans error Adds more beans Think Vending Machine

108. Coffee Machine Programmer Service Guy Inserts coins Gets coffee Out

     of coffee beans error Adds more beans Think Vending Machine

109. The Right Way Service Client

110. The Right Way Service Client Request

111. The Right Way Service Client Request Response

112. The Right Way Service Client Request Response Validation Error

113. The Right Way Service Client Request Response Validation Error Application

     Error

114. The Right Way Service Client Supervisor Request Response Validation Error

     Application Error

115. The Right Way Service Client Supervisor Request Response Validation Error

     Application Error Manages Failure
116. None

117. • Isolate the failure • Compartmentalize • Manage failure locally

     • Avoid cascading failures Use Bulkheads

118. • Isolate the failure • Compartmentalize • Manage failure locally

     • Avoid cascading failures Use Bulkheads

119. Enter Supervision

120. Enter Supervision

121. A B Bar Foo C B E A D C

     Automatic and mandatory supervision Supervisor hierarchies

122. 4. SUPERVISE X class Supervisor extends UntypedActor { private SupervisorStrategy

     strategy = new OneForOneStrategy( 10, Duration.create(1, TimeUnit.MINUTES), DeciderBuilder. match(ArithmeticException.class, e -> resume()). match(NullPointerException.class, e -> restart()). matchAny( e -> escalate()). build()); ! @Override public SupervisorStrategy supervisorStrategy() { return strategy; } Every single actor has a default supervisor strategy. Which is usually sufficient. But it can be overridden.

123. 4. SUPERVISE X class Supervisor extends UntypedActor { private SupervisorStrategy

     strategy = new OneForOneStrategy( 10, Duration.create(1, TimeUnit.MINUTES), DeciderBuilder. match(ArithmeticException.class, e -> resume()). match(NullPointerException.class, e -> restart()). matchAny( e -> escalate()). build()); ! @Override public SupervisorStrategy supervisorStrategy() { return strategy; } ActorRef worker = context.actorOf( Props.create(Worker.class), "worker"); public void onReceive(Object i) throws Exception { … } }

124. Monitor through Death Watch X public class WatchActor extends AbstractActor

     { final ActorRef child = context().actorOf(Props.empty(), "child"); ! public WatchActor() { context().watch(child); receive(ReceiveBuilder. match(Terminated.class, t -> t.actor().equals(child), t -> { … // handle termination }).build() ); } }

125. Monitor through Death Watch X public class WatchActor extends AbstractActor

     { final ActorRef child = context().actorOf(Props.empty(), "child"); ! public WatchActor() { context().watch(child); receive(ReceiveBuilder. match(Terminated.class, t -> t.actor().equals(child), t -> { … // handle termination }).build() ); } } Create a child actor

126. Monitor through Death Watch X public class WatchActor extends AbstractActor

     { final ActorRef child = context().actorOf(Props.empty(), "child"); ! public WatchActor() { context().watch(child); receive(ReceiveBuilder. match(Terminated.class, t -> t.actor().equals(child), t -> { … // handle termination }).build() ); } } Create a child actor Watch it

127. Monitor through Death Watch X public class WatchActor extends AbstractActor

     { final ActorRef child = context().actorOf(Props.empty(), "child"); ! public WatchActor() { context().watch(child); receive(ReceiveBuilder. match(Terminated.class, t -> t.actor().equals(child), t -> { … // handle termination }).build() ); } } Create a child actor Watch it Handle termination message

128. 4. SUPERVISE 29 Every single actor has a default supervisor

     strategy. Which is usually sufficient. But it can be overridden.

129. 4. SUPERVISE 29 Every single actor has a default supervisor

     strategy. Which is usually sufficient. But it can be overridden. class Supervisor extends Actor { override val supervisorStrategy = OneForOneStrategy(maxNrOfRetries = 10, withinTimeRange = 1 minute) { case _: ArithmeticException => Resume case _: NullPointerException => Restart case _: Exception => Escalate } ! val worker = context.actorOf(Props[Worker], name = "worker") !

130. 4. SUPERVISE 29 class Supervisor extends Actor { override val

     supervisorStrategy = OneForOneStrategy(maxNrOfRetries = 10, withinTimeRange = 1 minute) { case _: ArithmeticException => Resume case _: NullPointerException => Restart case _: Exception => Escalate } ! val worker = context.actorOf(Props[Worker], name = "worker") ! def receive = { case n: Int => worker forward n } } !

131. Cleanup & (Re)initialization 30 class Worker extends Actor { ...

     override def preRestart( reason: Throwable, message: Option[Any]) { ... // clean up before restart } override def postRestart(reason: Throwable) { ... // init after restart } }

132. Monitor through Death Watch 31 class Watcher extends Actor {

     val child = context.actorOf(Props.empty, "child") context.watch(child) ! def receive = { case Terminated(`child`) => … // handle child termination } }

133. Monitor through Death Watch 31 class Watcher extends Actor {

     val child = context.actorOf(Props.empty, "child") context.watch(child) ! def receive = { case Terminated(`child`) => … // handle child termination } } Create a child actor

134. Monitor through Death Watch 31 class Watcher extends Actor {

     val child = context.actorOf(Props.empty, "child") context.watch(child) ! def receive = { case Terminated(`child`) => … // handle child termination } } Create a child actor Watch it

135. Monitor through Death Watch 31 class Watcher extends Actor {

     val child = context.actorOf(Props.empty, "child") context.watch(child) ! def receive = { case Terminated(`child`) => … // handle child termination } } Create a child actor Watch it Handle termination message

136. Reactive applications scale up 
 and down to meet demand.

137. Elastic • Elasticity and Scalability to embrace the Cloud •

     Adaptive Scale on Demand • Clustered servers support joining and leaving of nodes • More cost-efficient utilization of hardware 33 “Our traffic can increase by as much as 100x for 15 minutes each day. 
 Until a couple of years ago, noon was a stressful time. 
 Nowadays, it’s usually a non-event.”   Eric Bowman, VP Architecture, Gilt Groupe

138. 34 Scale OUT Scale UP

139. 34 Essentially the same thing

140. 35 1. Minimize Contention 2. Maximize Locality of Reference We

     need to

141. 36 Share NOTHING Design

142. Fully event-driven apps are a necessity X Amdahl’s Law will

     hunt you down

143. Define a router X ActorRef router = context().actorOf( new RoundRobinPool(5).props(Props.create(Worker.class)),

     “router”)

144. Define a router 37 val router = context.actorOf( RoundRobinPool(5).props(Props[Worker])), “router”)

145. …or from config 38 akka.actor.deployment { /service/router { router =

     round-robin-pool resizer { lower-bound = 12 upper-bound = 15 } } }

146. Turn on clustering 39 akka { actor { provider =

     "akka.cluster.ClusterActorRefProvider" ... } cluster { seed-nodes = [ “akka.tcp://ClusterSystem@127.0.0.1:2551", “akka.tcp://ClusterSystem@127.0.0.1:2552" ] auto-down = off } }

147. Use clustered routers 40 akka.actor.deployment  {      /service/master  {

              router  =  consistent-­‐hashing-­‐pool          nr-­‐of-­‐instances  =  100   !        cluster  {              enabled  =  on              max-nr-of-instances-per-node = 3              allow-­‐local-­‐routees  =  on              use-­‐role  =  compute          }      }   }

148. Use clustered routers 40 akka.actor.deployment  {      /service/master  {

              router  =  consistent-­‐hashing-­‐pool          nr-­‐of-­‐instances  =  100   !        cluster  {              enabled  =  on              max-nr-of-instances-per-node = 3              allow-­‐local-­‐routees  =  on              use-­‐role  =  compute          }      }   } Or perhaps use an AdaptiveLoadBalancingPool

149. Use clustered pub-sub 41

150. Use clustered pub-sub 41 class Subscriber extends Actor { val

     mediator = DistributedPubSubExtension(context.system).mediator mediator ! Subscribe(“content”, self) def receive = { … } }

151. Use clustered pub-sub 41 class Publisher extends Actor { val

     mediator = DistributedPubSubExtension(context.system).mediator def receive = { case in: String => mediator ! Publish("content", in.toUpperCase) } }

152. • Cluster Membership • Cluster Pub/Sub • Cluster Leader •

     Clustered Singleton • Cluster Roles • Cluster Sharding 42 Other Akka Cluster features

153. • Supports two different models: • Command Sourcing • Event

     Sourcing • Great for implementing • durable actors • replication • CQRS etc. • Messages persisted to Journal and replayed on restart 43 Use Akka Persistence

154. X Command Sourcing Event Sourcing

155. X Command Sourcing Event Sourcing write-ahead-log

156. X Command Sourcing Event Sourcing write-ahead-log derive events from a

     command

157. X Command Sourcing Event Sourcing write-ahead-log derive events from a

     command same behavior during recovery as normal operation

158. X Command Sourcing Event Sourcing write-ahead-log derive events from a

     command same behavior during recovery as normal operation only state-changing behavior during recovery

159. X Command Sourcing Event Sourcing write-ahead-log derive events from a

     command same behavior during recovery as normal operation only state-changing behavior during recovery persisted before validation

160. X Command Sourcing Event Sourcing write-ahead-log derive events from a

     command same behavior during recovery as normal operation only state-changing behavior during recovery persisted before validation events cannot fail

161. X Command Sourcing Event Sourcing write-ahead-log derive events from a

     command same behavior during recovery as normal operation only state-changing behavior during recovery persisted before validation events cannot fail allows retroactive changes to the business logic

162. X Command Sourcing Event Sourcing write-ahead-log derive events from a

     command same behavior during recovery as normal operation only state-changing behavior during recovery persisted before validation events cannot fail allows retroactive changes to the business logic fixing the business logic will not affect persisted events

163. X Command Sourcing Event Sourcing write-ahead-log derive events from a

     command same behavior during recovery as normal operation only state-changing behavior during recovery persisted before validation events cannot fail allows retroactive changes to the business logic fixing the business logic will not affect persisted events naming: represent intent, imperative

164. X Command Sourcing Event Sourcing write-ahead-log derive events from a

     command same behavior during recovery as normal operation only state-changing behavior during recovery persisted before validation events cannot fail allows retroactive changes to the business logic fixing the business logic will not affect persisted events naming: represent intent, imperative naming: things that have completed, verbs in past tense

165. Akka  Persistence  Webinar Domain Events • Things that have completed,

     facts • Immutable • Verbs in past tense • CustomerRelocated • CargoShipped • InvoiceSent “State transitions are an important part of our problem space and should be modeled within our domain.”   Greg Young, 2008

166. Akka  Persistence  Webinar Life beyond Distributed Transactions: an Apostate’s Opinion

     Position Paper by Pat Helland “In general, application developers simply do not implement large scalable applications assuming distributed transactions.”   Pat Helland http://www-­‐db.cs.wisc.edu/cidr/cidr2007/papers/cidr07p15.pdf

167. Akka  Persistence  Webinar Consistency boundary • An Actor is can

     define an Aggregate Root • Each containing one or more Entities • Aggregate Root is the Transactional Boundary • Strong consistency within an Aggregate • Eventual consistency between Aggregates • No limit to scalability

168. DEMO TIME Persist a game of ping pong

169. None

170. http://reactivemanifesto.org

171. Typesafe Activator http://typesafe.com/platform/getstarted

172. 48 Typesafe Reactive Platform • Actors are asynchronous and communicate

     via message passing • Supervision and clustering in support of fault tolerance • Purely asynchronous and non-blocking web frameworks • No container required, no inherent bottlenecks in session management • Asynchronous and immutable programming constructs • Composable abstractions enabling simpler concurrency and parallelism

173. Reactive is being adopted across
 a wide range of industries.

174. 50 Finance Internet/Social Media Mfg/Hardware Government Retail

175. Questions?

176. ©Typesafe 2014 – All Rights Reserved