An introduction to Reactive applications, Reactive Streams, and options for the JVM (SACon SF 2016)
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This document provides an overview of reactive applications and Reactive Streams. It discusses the need for reactive approaches to address increasing performance demands and microservices. Reactive applications are responsive, resilient, elastic and asynchronous. Reactive Streams provide a common abstraction for data streams and asynchronous data sources using an observer pattern. The document also summarizes several Reactive Streams implementations for the JVM like RxJava and frameworks like Spring WebFlux, Play and Vert.x that support reactive programming.
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An introduction to Reactive applications, Reactive Streams, and options for the JVM (SACon SF 2016)
- 1. An introduction to reactive applications, Reactive Streams, and options for the JVM Steve Pember CTO, ThirdChannel Software Architecture Con, 2016 THIRDCHANNEL @svpember
- 2. THIRDCHANNEL @svpember Agenda • The Problem • To Be Reactive • What are Reactive Streams? • Rx in Depth • An Overview of JVM Options • Demo Time!
- 3. THIRDCHANNEL @svpember The Problem: The Need to go Reactive
- 4. Really, it’s Two problems
- 5. THIRDCHANNEL @svpember 1) Performance Demands Are Always Increasing
- 7. We Use Technology from the Beginning of Web Development
- 11. –Johnny Appleseed “Type a quote here.”
- 12. Let’s Keep Our Users Happy And Engaged
- 13. THIRDCHANNEL @svpember 2) The Rise of Microservices
- 15. It’s Not Only Users That Use Up Resources
- 17. So… what to do?
- 21. THIRDCHANNEL @svpember Reactive Applications • Responsive
- 23. THIRDCHANNEL @svpember Reactive Applications • Responsive • Resilient
- 25. Embrace Failure
- 28. THIRDCHANNEL @svpember Reactive Applications • Responsive • Resilient • Elastic (Scalable)
- 30. THIRDCHANNEL @svpember Reactive Applications • Responsive • Resilient • Elastic (Scalable) • Asynchronous / Message Driven
- 31. Free up resources with Async Operations & Non- Blocking I/O
- 32. Now do all of this at every level of your app…
- 33. All the Way Down
- 36. THIRDCHANNEL @svpember • User Interface: What the user interacts with (JS, iOS, Android) • Inter-Service: Distributed application topology + service communication design (e.g. Kafka for async messaging) • Intra-Service: The code! (well designed with bounded contexts) • Framework: Structures your code + provides external communication, DI, etc • Execution Environment: Broad area, but includes how your code is executed (e.g. in JVM: Tomcat, Jetty, Netty)
- 37. THIRDCHANNEL @svpember Mostly talk about this… We’ll talk a little about this… And a little more about this
- 38. There’s not enough time!
- 39. Writing Reactive Code is the best method of introduction…
- 40. Async is Hard for Humans
- 41. One Excellent Tool is (are?) Reactive Streams
- 42. But Wait…
- 44. THIRDCHANNEL @svpember Agenda • The Problem • What are Reactive Streams?
- 45. “Reactive Streams”, “Reactive Extensions”, or “Rx”
- 48. Single abstraction over data from many sources
- 50. Observer Pattern Push (not Pull) based Iterators
- 53. Streams with Extensions for Reactive Programming
- 54. Rx makes Async behavior easy!
- 57. 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
- 58. Rx Simplifies Complex Work
- 64. THIRDCHANNEL @svpember Story Time 2012 - MS Open Source’s RX!
- 65. THIRDCHANNEL @svpember Story Time 2012 - MS Open Source’s RX!
- 68. THIRDCHANNEL @svpember Agenda • The Problem • What are Reactive Streams? • Rx in depth
- 70. An Observable is like Promise ++
- 72. Observables are most powerful when wrapping external input
- 73. An Observable pushes items to Subscribers
- 74. Subscribers receive and operate on emitted data
- 75. Observables and Subscribers operate on a Scheduler
- 77. Also, try out rxGroovy
- 78. THIRDCHANNEL @svpember Groovy • Dynamic Language for the JVM • Less Verbose (Reduce Java Boilerplate) • Ruby/Python - esque Collections • Run Time Meta Programming • Optionally Typed • AST Transformations • Powerful Annotations • Multi - Inheritance via Traits and @DelegatesTo
- 84. Thankfully, there are shortcuts
- 89. THIRDCHANNEL @svpember You can get much power from 5 functions • filter • map • reduce • groupBy • flatMap
- 94. First Mental Leap: An Observable of Observables
- 95. –Johnny Appleseed “Type a quote here.”
- 97. Let’s get a little crazy
- 99. THIRDCHANNEL @svpember Hot vs Cold
- 100. Cold Observable: finite data, on demand Hot Observable: infinite data, as it’s ready
- 101. Cold Observable: only starts emitting data on .subscribe () Hot Observable: emits data whenever it’s ready
- 108. THIRDCHANNEL @svpember Can only Mitigate Hot Streams • throttle • sample • window • buffer • drop
- 110. Don’t Unsubscribe from Observables Programmatically complete them when another Observable fires
- 112. 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
- 115. keyPress stream creates a sub- stream which is reacting to subsequent data from the parent
- 118. Ok, what about 2.0?
- 119. API hasn’t changed much
- 121. THIRDCHANNEL @svpember RxJava 2.0 • Completely rebuilt for Reactive-Streams.org 1.0 spec • Decreased resource usage • No nulls allowed • New Publisher types
- 122. THIRDCHANNEL @svpember Publishers • Observable - classic. In 2.0: no Backpressure • Flowable - new to 2.0. Use this for Backpressure • Single - only one item will be emitted or signal error • Completable - only signal success or error • Maybe - new to 2.0: one item emitted, signal success, or signal error (think, Promise)
- 123. THIRDCHANNEL @svpember Agenda • The Problem • What are Reactive Streams? • Rx In Depth • An Overview of JVM options
- 125. RxJava, Obviously
- 128. THIRDCHANNEL @svpember ReactiveX JVM Family • rxJava • rxJavaFX • rxGroovy • rxClojure • rxKotlin • rxScala • And many more (beyond JVM): https://github.com/ReactiveX
- 129. THIRDCHANNEL @svpember Akka & Akka Streams • Library • Definition of Reactive System • Created by LightBend • Actor-Based Concurrency • Implemented Streams on Top of Actor Model
- 133. –Johnny Appleseed “Type a quote here.”
- 134. –Johnny Appleseed “Type a quote here.”
- 135. THIRDCHANNEL @svpember • Pivotal Project • Library • Reactive Streams • Built on LMAX Ring Buffer / Disrupter • Multiple libraries to extend Disruptor in multiple ways
- 141. Java 9 will have Flow
- 143. THIRDCHANNEL @svpember • High Performance Web Framework • Non-Opinionated • Non-Blocking Network Stack • Built on Reactive Streams, Netty, Java 8, Guice • Deterministic Asynchronous Execution Take a Look at Ratpack
- 145. Includes rxRatpack module, but we’ll talk about that later
- 147. … specifically, Spring 5
- 148. THIRDCHANNEL @svpember Spring Web Reactive vs Spring Web MVC
- 149. THIRDCHANNEL @svpember Spring 5 • spring-web-reactive instead of spring-mvc • Same @Controller programming model • Different underlying API • Based on Project Reactor • Can run within Tomcat, Jetty, or Netty (e.g. can fallback to use servlets)
- 151. THIRDCHANNEL @svpember Play Framework • Part of the Lightbend family • Built on Akka and Netty • Async I/O • Lightweight and stateless • Encourages RESTful design • Focus on JSON
- 153. THIRDCHANNEL @svpember Vert.X • Event-driven & Non blocking • lightweight, non-opinionated, and modular • integrates with rxJava • support for additional languages (like JS and Ruby) • Can be used as a library embedded in an existing app
- 157. 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 • Advanced RxJava Blog: http://akarnokd.blogspot.com/ • Martin Fowler LMAX breakdown: http://martinfowler.com/articles/lmax.html • Reactive Web Apps with Spring 5: https://www.youtube.com/watch?v=rdgJ8fOxJhc&feature=youtu.be
- 158. Images • Empty Pool: http://www.wtok.com/home/headlines/Water-Problems-205987121.html • Juggling: https://en.wikipedia.org/wiki/Juggling • Directing Traffic: https://www.flickr.com/photos/tracilawson/3474012583L • LMAX Disrupter: http://martinfowler.com/articles/lmax.html • Mailman: thebrandtstandard.com/2013/02/09/u-s-post-office-to-end-saturday-letter-delivery-this-summer/ • Actors Diagram: https://blog.codecentric.de/en/2015/08/introduction-to-akka-actors/ • Cheetah: www.livescience.com/21944-usain-bolt-vs-cheetah-animal-olympics.html • Dominoes: https://www.flickr.com/photos/louish/5611657857/sizes/l/in/photostream/ • Spartans: www.300themovie.com/ • Stampeding Buffalo: news.sd.gov/newsitem.aspx?id=15164 • Turtles (Cosmic): http://synchronicity313.deviantart.com/art/Turtles-All-The-Way-Down-68160813 • XkCD turtles: https://xkcd.com/1416/ • Simpsons “Old Coot”: http://simpsons.wikia.com/wiki/Category:Grandparents • Meditation: http://i.huffpost.com/gen/1405484/images/o-MEDITATION-facebook.jpg • Death Star Architectures: http://www.slideshare.net/adriancockcroft/monitorama-please-no-more