Reactive Streams and the Wide World of Groovy
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The concept of Reactive Streams (aka Reactive Extensions, Reactive Functional Programming, or simply Rx) has become increasingly popular recently, and with good reason. The Reactive Streams specification provides a universal abstraction for asynchronously processing data received across multiple sources (e.g. database, user input, third-party services), and includes mechanisms for controlling the rate at which data is received. This makes it a powerful tool within a Microservice platform. And did we mention that the Groovy lang community is quite involved? In this talk we’ll explore the various features and concepts of Reactive Streams. We’ll talk about some typical use cases for Rx and more importantly, how to implement them. We’ll focus primarily on RxGroovy and Ratpack, then provide example implementations that show you how to get started with this powerful technique.
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Reactive Streams and the Wide World of Groovy
- 1. Reactive Streams and the Wide World of Groovy Steve Pember CTO, ThirdChannel Gr8Conf US, 2016 THIRDCHANNEL @svpember
- 2. “Reactive Streams”, “Reactive Extensions”, or “Rx”
- 3. THIRDCHANNEL @svpember Agenda • The Problem • What are Reactive Streams? • … Did someone say ‘Groovy’? • Rx in depth • Demo Time!
- 4. THIRDCHANNEL @svpember The Problem: The Need to go Reactive
- 5. Really, it’s Two problems
- 6. THIRDCHANNEL @svpember 1) Performance Demands Are Always Increasing
- 8. We Use Technology from the Beginning of Web Development
- 10. Things Slow Down
- 12. –Johnny Appleseed “Type a quote here.”
- 13. Let’s Keep Our Users Happy And Engaged
- 14. THIRDCHANNEL @svpember 2) The Rise of Microservices
- 16. It’s Not Only Users That Use Up Resources
- 17. So what to do?
- 18. Free up resources with Async Operations & Non-Blocking I/O
- 19. Async is Hard for Humans
- 20. THIRDCHANNEL @svpember Agenda • The Problem • What are Reactive Streams?
- 23. Single abstraction over data from many sources
- 25. Observer Pattern Push (not Pull) based Iterators
- 28. Groovy Collections supports stream-like options
- 29. If this makes sense to you, then you’re ready for Rx
- 30. Streams with Extensions for Reactive Programming
- 31. Rx makes Async behavior easy!
- 34. THIRDCHANNEL @svpember What is Rx? • Collections + Time • A Single Abstraction over data from different sources • Observer Pattern with Push-based iterators • Stream Based Functional Programming • … with Extensions for Reactive Programming • Async is easy • Backpressure
- 35. Rx Simplifies Complex Work
- 37. THIRDCHANNEL @svpember Agenda • The Problem • What are Reactive Streams? • … Did someone say ‘Groovy’?
- 39. THIRDCHANNEL @svpember We should probably mention RxJava
- 41. But Quickly Switch to rxGroovy
- 44. THIRDCHANNEL @svpember • High performance web framework • Non-opinionated • Non-Blocking Network Stack • Built on Reactive Streams, Netty, Java 8, Guice • Fully embodies reactive • Deterministic Asynchronous code Take a Look at Ratpack
- 45. Includes rxRatpack module, but we’ll talk about that later
- 47. THIRDCHANNEL @svpember Agenda • The Problem • What are Reactive Streams? • … Did someone say ‘Groovy’? • Rx in depth
- 48. … our as much as we can get through
- 49. The following is rxJava 1.x rxJava 2.x will release by EOY
- 51. An Observable is like Promise ++
- 52. An Observable pushes items to Subscribers
- 53. Subscribers receive and operate on emitted data
- 54. Observables and Subscribers operate on a Scheduler
- 58. Thankfully, there are shortcuts
- 63. THIRDCHANNEL @svpember You can get much power from 5 functions • filter • map • reduce • groupBy • flatMap
- 68. First Mental Leap: An Observable of Observables
- 69. –Johnny Appleseed “Type a quote here.”
- 72. THIRDCHANNEL @svpember Hot vs Cold
- 73. Cold Observable: finite data, on demand Hot Observable: infinite data, as it’s ready
- 80. THIRDCHANNEL @svpember Can only Mitigate Hot Streams • throttle • sample • window • buffer • drop
- 82. Don’t Unsubscribe from Observables Programmatically complete them when another Observable fires
- 84. THIRDCHANNEL @svpember AutoComplete Requirements • Wait 250 ms between keypresses before querying • If no keys are pressed, no query • Successful queries should render movies • Any new queries should kill in-flight queries
- 86. Well done.
- 87. The keyPress stream is reacting to itself
- 92. THIRDCHANNEL @svpember More Information • Reactive Groovy & Ratpack Demo: https://github.com/spember/reactive-movie-demo • Jafar Husain: RxJS: https://www.youtube.com/watch?v=XRYN2xt11Ek • Reactive Streams Spec: http://www.reactive-streams.org/ • Reactive Manifesto: http://www.reactivemanifesto.org/ • Akka: http://akka.io/ • rxJava / ReactiveX libraries: https://github.com/ReactiveX • Ratpack: http://ratpack.io/ • Reactor: https://github.com/reactor/reactor • The Introduction to Reactive Programming you’ve been missing: https://gist.github.com/staltz/868e7e9bc2a7b8c1f754 • Martin Fowler: Stream / Pipeline programming: http://martinfowler.com/articles/refactoring-pipelines.html • Or Just on Groovy (Groovy the Awesome Parts): http://www.slideshare.net/SpringCentral/groovy-the-awesome-parts • Ratpack Web Presentation: http://www.infoq.com/presentations/ratpack-2015