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
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
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
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