reactive options for groovy programming
TRANSCRIPT
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Reactive Options for Groovy
Steve PemberCTO, ThirdChannel
@svpemberSpringOne 2GX, 2015
What is ‘Reactive’?
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Possible Reactive Definitions• Reactive Programming
Imperative: A = B+C at that moment in time
Reactive: A = B+C whenever B or C change values
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Possible Reactive Definitions• Reactive Programming
• Reactive Systems
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Possible Reactive Definitions• Reactive Programming
• Reactive Systems
• Reactive Streams / Reactive Extensions (Rx)
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Possible Reactive Definitions• Reactive Programming
• Reactive Systems
• Reactive Streams / Reactive Extensions (Rx)
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Agenda• Reactive Systems
• Reactive Streams / Reactive Extensions
• Reactive Groovy
The Need For Reactive(The Reactive Manifesto)
–Johnny Appleseed
“Type a quote here.”
–Johnny Appleseed
“Type a quote here.”
http://www.internetlivestats.com/internet-users/
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–Johnny Appleseed
“Type a quote here.”
–Johnny Appleseed
“Type a quote here.”
https://medium.com/reactive-programming/what-is-reactive-programming-bc9fa7f4a7fc
Need to Handle As Many Users As Possible
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Reactive Systems• The Need for Reactive
• 4 Reactive Principles
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Reactive Systems• The Need for Reactive
• 4 Reactive Principles
• Responsive
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Reactive Systems• The Need for Reactive
• 4 Reactive Principles
• Responsive
• Resilient
–Johnny Appleseed
“Type a quote here.”
Embrace Failure
Independent Things Fail Independently
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Reactive Systems• The Need for Reactive
• 4 Reactive Principles
• Responsive
• Resilient
• Elastic (Scalable)
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Reactive Systems• The Need for Reactive
• 4 Reactive Principles
• Responsive
• Resilient
• Elastic (Scalable)
• Asynchronous / Message-Driven
Humans Are Terrible At Concurrency
The Manifesto is not Concrete
Recommended: Actors
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Akka
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–Johnny Appleseed
“Type a quote here.”
–Johnny Appleseed
“Type a quote here.”
Anyway.
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Hooray for Microservices
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Agenda• Reactive Systems
• Reactive Streams / Reactive Extensions
–Me (now)
“A standard for asynchronous stream processing of potentially infinite data, across boundaries,
with non-blocking backpressure”
VS
–Jafar Husain https://www.youtube.com/watch?v=XRYN2xt11Ek
“Collection + time”
–Johnny Appleseed
“Type a quote here.”
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Story Time
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Story Time
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Story Time
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Story Time
2012 - MS Open Source’s RX! (wut?)
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Story Time
2012 - MS Open Source’s RX! (wut?)
–Johnny Appleseed
“Type a quote here.”
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Rx: More Than a Stream• Collections + Time
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Rx: More Than a Stream• Collections + Time
• Pull vs Push
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Rx: More Than a Stream• Collections + Time
• Pull vs Push
• Observable / Subscriber
An Observable is a push-based collection
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Rx: More Than a Stream• Collections + Time
• Pull vs Push
• Observable / Subscriber
• Hot / Cold
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Rx: More Than a Stream• Collections + Time
• Pull vs Push
• Observable / Subscriber
• Hot / Cold
• Composable
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Rx: More Than a Stream• Collections + Time
• Pull vs Push
• Observable / Subscriber
• Hot / Cold
• Composable
• Async is Easy!
The Subscriber & Observable can be independently Async
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Rx: More Than a Stream• Collections + Time
• Pull vs Push
• Observable / Subscriber
• Hot / Cold
• Composable
• Async is Easy!
• Backpressure
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Rx: More Than a Stream• Collections + Time
• Pull vs Push
• Observable / Subscriber
• Hot / Cold
• Composable
• Async is Easy!
• Backpressure
• Observable Interaction
Don’t Unsubscribe from Events / Observables.
Programatically complete them when some other event or Observable fires.
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Agenda• Reactive Systems
• Reactive Streams / Reactive Extensions
• Groovy Options
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A Few Groovy Options…• Akka
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A Few Groovy Options…• Akka
• Akka Streams
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Akka & Akka Streams• Library
• Definition of Reactive System
• Typesafe
• Actor-Based Concurrency
• Implemented Streams on Top of Actor Model
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A Few Groovy Options…• Akka
• Akka Streams
• RxJava / RxGroovy
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RxJava• Library
• Comes out of Netflix
• Part of reactivex.io
• Reactive Streams on the JVM
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A Few Groovy Options…• Akka
• Akka Streams
• RxJava / RxGroovy
• Ratpack
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• HTTP application server
• Non-opinionated
• Built on Reactive Streams, Netty, Java 8, Guava
• Fully embodies reactive
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A Few Groovy Options…• Akka
• Akka Streams
• RxJava / RxGroovy
• Ratpack
• Reactor
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• Library
• Reactive Streams
• Reactor Pattern
• Built on LMAX Ring Buffer / Disrupter
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VS
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• Groovy Parallelism and Concurrency
• Built into the language!
• Actors
• DataFlow
• Async Closures
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Getting Started
Demo Time
That’s Great, But How do I get started?
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Advice for exploring RX• Start thinking in terms of streams / pipelines
• Drop in one of the libraries into your project
• Observe a finite data set (Observe.from())
• You only need 4 functions
• Be Aware of Subscribe / Observe On
• Create your own Observables
• Connect your Observables
Final Thought: What About Java 8 Streams?
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Java 8 Streams• Built into the language
• Meant for ‘pull’ on finite Iterables
• Parallelization has rather severe problems (e.g. https://dzone.com/articles/think-twice-using-java-8)
• No Async
• vs Observables -> potentially infinite items, async, with back pressure
Actual Final Thought: Embrace Reactive!
Thank You!@svpember
Questions?
Image Credits• 1000ms Time To glass: https://docs.google.com/presentation/d/1IRHyU7_crIiCjl0Gvue0WY3eY_eYvFQvSfwQouW9368/present?
slide=id.g1e697bbb_0_7• internet users in the world: http://www.internetlivestats.com/internet-users/• internet users vs Facebook: https://medium.com/reactive-programming/what-is-reactive-programming-bc9fa7f4a7fc• reactivex logo: https://www.stickermule.com/marketplace/2223-rx-reactive-extensions-logo-4• cheetah: www.livescience.com/21944-usain-bolt-vs-cheetah-animal-olympics.html• dominoes: https://www.flickr.com/photos/louish/5611657857/sizes/l/in/photostream/• 300 / Spartans: http://www.300themovie.com/• latop punch: http://walls4joy.com/wallpaper/730566-angry-laptops-punch• mailman: http://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/• actor system: http://letitcrash.com/post/30585282971/discovering-message-flows-in-actor-systems-with• slow down: http://forthefamily.org/reminder-slow/• Buffalo: http://news.sd.gov/newsitem.aspx?id=15164• Midvale School for the Gifted: http://www.2ndfirstlook.com/2012/09/gary-larson.html• Blueprints: https://en.wikipedia.org/wiki/File:House_Plans_(Blueprints).pdf
More On Reactive:• 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