An Introduction to Reactive Application, Reactive Streams, and options for JVM
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The term “reactive” has lately become a buzzword, with a variety of definitions around the Web. When you hear reactive, what do you think of? Reactive Streams? The Reactive Manifesto? ReactJS? These terms may seem unrelated, but they share a common core concept. Reactive applications and reactive programming result in flexible, concise, performant code and are a superior alternative to the old standard thread-based imperative programming model. The reactive approach has gained popularity recently for one simple reason: we need alternative designs and architectures to meet today’s demands. However, it can be difficult to shift one’s mind to think in reactive terms due to how accustomed we’ve become to the imperative style. Stephen Pember explores the various definitions of reactive and reactive programming with the goal of providing techniques for building efficient, scalable applications. Steve dives into the key concepts of Reactive Streams and examines some sample implementations—including how ThirdChannel is currently using reactive libraries in production code. Steve looks at some of the open source options available in the JVM—including Reactor, RxJava, and Ratpack—giving attendees an idea of where to begin with the reactive ecosystem. If reactive is new to you, this should be an excellent introduction.
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An Introduction to Reactive Application, Reactive Streams, and options for JVM
- 1. An introduction to reactive applications, Reactive Streams, and options for the JVM Steve Pember CTO, ThirdChannel Software Architecture Con, 2016 THIRDCHANNEL @svpember
- 2. “Reactive Streams”, “Reactive Extensions”, or “Rx”
- 3. THIRDCHANNEL @svpember Agenda • The Problem • What are Reactive Streams? • Rx in depth • An Overview of JVM options • 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?
- 20. THIRDCHANNEL @svpember Reactive Applications • Responsive
- 22. THIRDCHANNEL @svpember Reactive Applications • Responsive • Resilient
- 24. Embrace Failure
- 27. THIRDCHANNEL @svpember Reactive Applications • Responsive • Resilient • Elastic (Scalable)
- 29. THIRDCHANNEL @svpember Reactive Applications • Responsive • Resilient • Elastic (Scalable) • Asynchronous / Message Driven
- 30. Free up resources with Async Operations & Non- Blocking I/O
- 31. Async is Hard for Humans
- 32. One Excellent Tool is (are?) Reactive Streams
- 33. THIRDCHANNEL @svpember Agenda • The Problem • What are Reactive Streams?
- 36. Single abstraction over data from many sources
- 38. Observer Pattern Push (not Pull) based Iterators
- 41. Streams with Extensions for Reactive Programming
- 42. Rx makes Async behavior easy!
- 45. 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
- 46. Rx Simplifies Complex Work
- 48. THIRDCHANNEL @svpember Agenda • The Problem • What are Reactive Streams? • Rx in depth
- 50. An Observable is like Promise ++
- 51. An Observable pushes items to Subscribers
- 52. Subscribers receive and operate on emitted data
- 53. Observables and Subscribers operate on a Scheduler
- 55. But, try out rxGroovy
- 56. 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
- 62. Thankfully, there are shortcuts
- 67. THIRDCHANNEL @svpember You can get much power from 5 functions • filter • map • reduce • groupBy • flatMap
- 72. First Mental Leap: An Observable of Observables
- 73. –Johnny Appleseed “Type a quote here.”
- 76. THIRDCHANNEL @svpember Hot vs Cold
- 77. Cold Observable: finite data, on demand Hot Observable: infinite data, as it’s ready
- 78. Cold Observable: only starts emitting data on .subscribe () Hot Observable: emits data whenever it’s ready
- 85. THIRDCHANNEL @svpember Can only Mitigate Hot Streams • throttle • sample • window • buffer • drop
- 87. Don’t Unsubscribe from Observables Programmatically complete them when another Observable fires
- 89. 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
- 92. The keyPress stream is reacting to itself
- 95. THIRDCHANNEL @svpember Agenda • The Problem • What are Reactive Streams? • Rx In Depth • An Overview of JVM options
- 99. THIRDCHANNEL @svpember Story Time 2012 - MS Open Source’s RX!
- 100. THIRDCHANNEL @svpember Story Time 2012 - MS Open Source’s RX!
- 103. THIRDCHANNEL @svpember We should probably start with RxJava
- 105. But Don’t Forget rxGroovy
- 108. THIRDCHANNEL @svpember • High performance web framework • Non-opinionated • Non-Blocking Network Stack • Built on Reactive Streams, Netty, Java 8, Guice • Fully embodies reactive • Light-weight, self-contained deployables Take a Look at Ratpack
- 110. Includes rxRatpack module, but we’ll talk about that later
- 111. THIRDCHANNEL @svpember Akka & Akka Streams • Library • Definition of Reactive System • Created by LightBend • Actor-Based Concurrency • Implemented Streams on Top of Actor Model
- 115. –Johnny Appleseed “Type a quote here.”
- 116. –Johnny Appleseed “Type a quote here.”
- 117. THIRDCHANNEL @svpember • Library • Reactive Streams • Reactor Pattern • Built on LMAX Ring Buffer / Disrupter • Multiple libraries to extend Ring Buffer in multiple ways
- 122. Many Tools Seem to be Moving Towards Reactive Streams
- 126. 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
- 127. 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