Building Reactive applications with Akka
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The document discusses building reactive applications using Akka. Akka allows for building applications that are message-driven, elastic, resilient and able to handle failures. It enables building applications as systems of actors that communicate asynchronously by message passing. This model allows the applications to scale horizontally across clusters of machines and to recover from failures through supervision. The document provides examples of how to model parts of an application, such as a flight search service, as actor systems.
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Building Reactive applications with Akka
- 2. Building Reactive applications using Akka Nilanjan Raychaudhuri @nraychaudhuri
- 3. Reactive Applications 3 @nraychaudhuri
- 4. Essence of Reactive applications
- 7. Akka is enabler of Reactive applications
- 8. • Individual entities that can only communicate by passing messages • Excellent for isolating mutable state and protecting it without locks • Location transparency for remote and clustered topologies • Supervision • Well-suited for creating state machines • Fault tolerance via Supervision Reactive Applications 8
- 9. Reference Architecture Web Tier (Play) Work Tier (Akka) responsive event driven Reactive Applications 9 Play Server Play Server Play Server Play Server Akka Master Router Akka Router Standby Akka Worker Akka Worker Akka Worker Akka Worker Akka Worker scalable resilient
- 10. Message-driven Reactive applications are architected based on loosely coupled design
- 11. Reactive Applications Message-Driven • Loosely coupled architecture, easier to extend, maintain, evolve • Asynchronous and non-blocking • Concurrent by design, immutable state • Lower latency and higher throughput 11 “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
- 13. 13 Actor model 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
- 14. Actor model Actor Actor Thread pool
- 15. Akka actor -‐ Definition 15
- 16. Akka actor -‐ Create 16
- 17. Akka actor -‐ Send 17
- 18. Elastic Reactive applications scale up and down to meet demand
- 19. Elastic • Scalability and elasticity to embrace the Cloud • Leverage all cores via asynchronous programming • Clustered servers support joining and leaving of nodes • More cost-efficient utilization of hardware “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 19
- 20. 20
- 22. FlightSearch Actor - I 22
- 23. FlightSearch Actor - II 23
- 25. SearchWorker - I 25
- 26. SearchWorker - II 26
- 28. ProviderProxy - I 28
- 29. ProviderProxy - II 29
- 30. Flight search flow 30
- 31. Let it crash
- 32. Reactive applications are architected to handle failure at all levels.
- 33. 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 33 “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
- 34. Failure? 34
- 36. Think Vending Machine Coffee Inserts coins Add more coins Programmer Machine Gets coffee
- 37. Think Vending Machine Service Guy Coffee Inserts coins Programmer Machine Gets coffee Out of coffee beans error Adds more beans OutW of corfofeen begans error
- 38. The Right Way Supervisor Request Validation Error Client Service Response Application Error Manages Failure
- 39. Supervision 39
- 40. A Foo Bar B C B E A C system.actorOf(Props[Foo], “Foo”) context.actorOf(Props[A], “A”) Actor Topology
- 41. OneForOne
- 42. AllForOne
- 43. Isolate failure at all levels • Within one node • Across many nodes (JVMs) • Across many physical servers • Across data centers Reactive Applications 43
- 44. Scale out
- 46. Reactive Applications IoT 46
- 47. Reactive Applications Precision Farming 47 Akka Cluster Journal
- 48. Code
- 49. Q & Option[A] @nraychaudhuri
- 50. ©Typesafe 2014 – All Rights Reserved