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Reactor 3. Reactive Foundation for Java 8 and Spring

Stephane Maldini @smaldini

Reactive ?

Reactive ?

Publisher Subscriber

Reactive Streamsreactive-streams.org

Publisher Subscriber

Reactive Streamsreactive-streams.org

Standard definition

Publisher Subscriber

Reactive Streamsreactive-streams.org

Standard definition0..N Data + 0..1 (Error | Complete)

Publisher Subscriber

Backpressure

Reactive Streamsreactive-streams.org

Standard definition0..N Data + 0..1 (Error | Complete)

Publisher Subscriber

Backpressure

Reactive Streamsreactive-streams.org

Standard definition0..N Data + 0..1 (Error | Complete)

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Reactor Core provides for a minimalist set of Reactive Streams ready

generators and transformers

4

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Reactor Core provides for a minimalist set of Reactive Streams ready

generators and transformers

4

WHY ?

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DIY Reactive Streams

Publisher<User> rickSanchez = userRepository.findUser(“rick”);

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DIY Reactive Streams

Publisher<User> rickSanchez = userRepository.findUser(“rick”);

Produce User when ready

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DIY Reactive Streams

Publisher<User> rickSanchez = userRepository.findUser(“rick”);

Might produce 0, 1 or N Users ! Produce User when ready

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DIY Reactive Streams

Publisher<User> rickSanchez = userRepository.findUser(“rick”);

Might produce 0, 1 or N Users ! Produce User when ready

rickSanchez.subscribe(new Subscriber<User>(){ … });

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DIY Reactive Streams

Publisher<User> rickSanchez = userRepository.findUser(“rick”);

Might produce 0, 1 or N Users ! Produce User when ready

Callback for start, result, error or complete

rickSanchez.subscribe(new Subscriber<User>(){ … });

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DIY Reactive Streams

6

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DIY Reactive Streams

6

Can I have an API ?

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DIY Reactive Streams - top issues

• Should Work with RS TCK • Address reentrance • Address thread safety • Address efficiency • Address state • For Many-To-One flows, implement your own merging operation • For One-To-Many lows, implement your own broadcasting operation • ….

7

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DIY Reactive Streams - top issues

• Should Work with RS TCK • Address reentrance • Address thread safety • Address efficiency • Address state • For Many-To-One flows, implement your own merging operation • For One-To-Many lows, implement your own broadcasting operation • ….

7

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3 years to mature

9

R e a c t i v e S t r e a m s C o m m o n s

I P C

A D D O N S

S p r i n g R x

C O R E

2013: 1.x 2014: 2.x 2016: 3.0

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3 years to mature

9

R e a c t i v e S t r e a m s C o m m o n s

I P C

A D D O N S

S p r i n g R x

C O R E

Existential questions

2013: 1.x 2014: 2.x 2016: 3.0

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3 years to mature

9

R e a c t i v e S t r e a m s C o m m o n s

I P C

A D D O N S

S p r i n g R x

C O R E

Existential questions

2013: 1.x 2014: 2.x 2016: 3.0

Microservices become the norm

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3 years to mature

9

R e a c t i v e S t r e a m s C o m m o n s

I P C

A D D O N S

S p r i n g R x

C O R E

Existential questions

2013: 1.x 2014: 2.x 2016: 3.0

Microservices become the norm

Rocky style revival

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3x Influences and Collaborations

10

R e a c t i v e S t r e a m s C o m m o n s

I P C

A D D O N S

S p r i n g R x

C O R E

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3x Influences and Collaborations

10

R e a c t i v e S t r e a m s C o m m o n s

I P C

A D D O N S

S p r i n g R x

C O R E

Flux

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Flux.just("red", "white", "blue") .flatMap(carRepository::findByColor) .collect(Result::new, Result::add) .doOnNext(Result::stop) .subscribe(doWithResult);

A smarter Publisher ? Flux !

12

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Flux.just("red", "white", "blue") .flatMap(carRepository::findByColor) .collect(Result::new, Result::add) .doOnNext(Result::stop) .subscribe(doWithResult);

A smarter Publisher ? Flux !

12

interface CarRepository { Flux<Car> findByColor(String color);

}

Mono

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Mono, push/pull CompletionStage

14

Mono.delayMillis(3000) .map(d -> "Spring 4") .or(Mono.delayMillis(2000).map(d -> "Spring 5")) .then(t -> Mono.just(t+ " world")) .elapsed() .block();

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Mono, push/pull CompletionStage

14

Mono.delayMillis(3000) .map(d -> "Spring 4") .or(Mono.delayMillis(2000).map(d -> "Spring 5")) .then(t -> Mono.just(t+ " world")) .elapsed() .block();

Non!

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Mono, push/pull CompletionStage

15

Mono.delayMillis(3000) .map(d -> "Spring 4") .or(Mono.delayMillis(2000).map(d -> "Spring 5")) .then(t -> Mono.just(t+ " world")) .elapsed() .subscribe();

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Mono, push/pull CompletionStage

15

Mono.delayMillis(3000) .map(d -> "Spring 4") .or(Mono.delayMillis(2000).map(d -> "Spring 5")) .then(t -> Mono.just(t+ " world")) .elapsed() .subscribe();

Oui!

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Non Blocking and RS types around

16

Type Semantic /Library Java 8 Reactive Streams /Java 9

RxJava1 (java6)

Reactor3 (java8)

RxJava2 (java6)

0 or 1 result CompletableFuture<T> Publisher<T> Observable<T> Mono<T> Maybe<T>

0 or N results Publisher<T> Observable<T> Flux<T> Observable<T>Flowable<T>

1 result CompletableFuture<T> Publisher<T> Single<T> Mono<T> Single<T>

No result CompletableFuture<Void> Publisher<Void> Completable Mono<Void> Completable

*Reactive Streams types are in bold**Akka Streams is also a notable RS implementor

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3x Simpler API

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ONE JAR reactor-core.jar

17

3x Simpler API

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ONE JAR reactor-core.jar

17

3x Simpler API

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ONE JAR reactor-core.jar

17

3x Simpler API Where Flux and Mono live

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ONE JAR reactor-core.jar

17

3x Simpler API Where Flux and Mono live

Make task execution great again and FIFO

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Execution Model Freedom

18

Synchronous

Asynchronous

Scheduler / Scheduler.Worker

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Execution Model Freedom

19

Publisher Subscriber

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Execution Model Freedom

19

Publisher Subscriber

Thread: MAIN

Thread: MAIN

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Execution Model Freedom

20

Publisher Subscriber

+publishOn()Thread: Worker A

Thread: Worker A

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Execution Model Freedom

21

Publisher Subscriber

Thread: Worker B

+subscribeOn() Thread: Worker B

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Execution Model Freedom

22

Publisher Subscriber

+publishOn()Thread: Worker A

+subscribeOn() Thread: Worker B

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3x more focus on Javadoc

23

http://projectreactor.io/core/docs/api

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Learning to Flux & Mono

24

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Learning to Flux & Mono

24

https://spring.io/blog/2016/06/07/notes-on-reactive-programming-part-i-the-reactive-

landscape

https://spring.io/blog/2016/06/13/notes-on-reactive-programming-part-ii-writing-some-code

https://spring.io/blog/2016/07/20/notes-on-reactive-programming-part-iii-a-simple-http-server-

application

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Learning to Flux & Mono

24

https://spring.io/blog/2016/06/07/notes-on-reactive-programming-part-i-the-reactive-

landscape

https://spring.io/blog/2016/06/13/notes-on-reactive-programming-part-ii-writing-some-code

https://spring.io/blog/2016/07/20/notes-on-reactive-programming-part-iii-a-simple-http-server-

application

Just browse spring.io/blog already

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Bridge Existing Asynchronous CodeMono<String> response = Mono.create(sink -> { HttpListener listener = event -> { if (event.getResponseCode() >= 400) { sink.error(new RuntimeExeption("Failed")); } else { String body = event.getBody(); if (body.isEmpty()) { sink.success(); } else { sink.success(body.toLowerCase()); } } }; client.addListener(listener); emitter.setCancellation(() -> client.removeListener(listener)); });

•

25

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Bridge Existing Asynchronous CodeMono<String> response = Mono.create(sink -> { HttpListener listener = event -> { if (event.getResponseCode() >= 400) { sink.error(new RuntimeExeption("Failed")); } else { String body = event.getBody(); if (body.isEmpty()) { sink.success(); } else { sink.success(body.toLowerCase()); } } }; client.addListener(listener); emitter.setCancellation(() -> client.removeListener(listener)); });

•

25

Also exists for Flux of N items

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Debug Mode

26

215 Hooks.onOperator(op -> op.operatorStacktrace()); 216 try { 217 Mono.just(1) 218 .map(d -> { 219 throw new RuntimeException(); 220 }) 221 .filter(d -> true) 222 .timestamp() 223 .elapsed() 224 .map(d -> d) 225 .block(); 226 } 227 catch(Exception e){ 228 e.printStackTrace(); 229 } 230 finally { 231 Hooks.resetOnOperator(); 232 }

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Debug Mode

26

215 Hooks.onOperator(op -> op.operatorStacktrace()); 216 try { 217 Mono.just(1) 218 .map(d -> { 219 throw new RuntimeException(); 220 }) 221 .filter(d -> true) 222 .timestamp() 223 .elapsed() 224 .map(d -> d) 225 .block(); 226 } 227 catch(Exception e){ 228 e.printStackTrace(); 229 } 230 finally { 231 Hooks.resetOnOperator(); 232 }

Capture stack for each operator declared after

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Debug Mode

26

215 Hooks.onOperator(op -> op.operatorStacktrace()); 216 try { 217 Mono.just(1) 218 .map(d -> { 219 throw new RuntimeException(); 220 }) 221 .filter(d -> true) 222 .timestamp() 223 .elapsed() 224 .map(d -> d) 225 .block(); 226 } 227 catch(Exception e){ 228 e.printStackTrace(); 229 } 230 finally { 231 Hooks.resetOnOperator(); 232 }

Capture stack for each operator declared after

Assembly trace from producer [reactor.core.publisher.MonoMapFuseable] :reactor.core.publisher.Mono.map(Mono.java:1795)reactor.HooksTest.testTrace2(HooksTest.java:218)

Composition chain until failing Operator :|_ Mono.map(HooksTest.java:218)|_ Mono.filter(HooksTest.java:221)|_ Mono.timestamp(HooksTest.java:222)|_ Mono.elapsed(HooksTest.java:223)|_ Mono.map(HooksTest.java:224)

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Create Gateways to Flux And Mono

27

EmitterProcessor<Integer> processor = EmitterProcessor.create(); int n = 100_000; processor.publishOn(Schedulers.single()) .subscribe(someService::handleData); BlockingSink<Integer> session = processor.connectSink(); for (int i = 0; i < n; i++) { while (!session.emit(i).isOk()) { if (session.hasFailed()) { throw session.getError(); }

//fake throttling Thread.sleep(1); } } session.finish();

•

EmitterProcessor

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Create Gateways to Flux And Mono

27

EmitterProcessor<Integer> processor = EmitterProcessor.create(); int n = 100_000; processor.publishOn(Schedulers.single()) .subscribe(someService::handleData); BlockingSink<Integer> session = processor.connectSink(); for (int i = 0; i < n; i++) { while (!session.emit(i).isOk()) { if (session.hasFailed()) { throw session.getError(); }

//fake throttling Thread.sleep(1); } } session.finish();

•

EmitterProcessor

Backpressure Companion

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EmitterProcessor<Integer> processor = EmitterProcessor.create(); int n = 100_000; processor.publishOn(Schedulers.single()) .subscribe(someService::handleData); BlockingSink<Integer> session = processor.connectSink(); for (int i = 0; i < n; i++) { while (!session.emit(i).isOk()) { if (session.hasFailed()) { throw session.getError(); } Thread.sleep(1); //fake throttling } } session.finish();

•

Create Gateways to Flux And Mono

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EmitterProcessor

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Operation Fusion

• Reactor has a mission to limit the overhead in stack and message passing

• 2 key categories : • “Macro Fusion” : merge operators in one (assembly time) • “Micro Fusion” : avoid queue creation and short circuit where

possible request lifecycle.

29

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Starve CPU’s with ParallelFlux…

30

Flux.range(1, 100000) .parallel(3) .runOn(Schedulers.parallel()) .collect(ArrayList::new, ArrayList::add) .sequential() .reduce(0, (a, b) -> a + b.size()) .subscribeWith(TestSubscriber.create()) .await(Duration.ofSeconds(5)) .assertValues(100_000) .assertNoError() .assertComplete();

•

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Starve CPU’s with ParallelFlux…

30

Flux.range(1, 100000) .parallel(3) .runOn(Schedulers.parallel()) .collect(ArrayList::new, ArrayList::add) .sequential() .reduce(0, (a, b) -> a + b.size()) .subscribeWith(TestSubscriber.create()) .await(Duration.ofSeconds(5)) .assertValues(100_000) .assertNoError() .assertComplete();

•

x3

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Efficient and micro bench ready

31

https://github.com/akarnokd/akarnokd-misc/tree/master/src/jmh/java/hu/akarnokd/comparison

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Efficient and micro bench ready

31

https://github.com/akarnokd/akarnokd-misc/tree/master/src/jmh/java/hu/akarnokd/comparison

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Efficient and micro bench ready

31

https://github.com/akarnokd/akarnokd-misc/tree/master/src/jmh/java/hu/akarnokd/comparison

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Bridge Fabulous RxJava

32

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Bridge Fabulous RxJava

32

RxJava1Adapter

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Bridge Java 9 Reactive Streams

33

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Bridge Java 9 Reactive Streams

33

JdkFlowAdapter

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Play with Reactor Core .NET

34

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Play with Reactor Core .NET

34

https://www.nuget.org/packages/Reactor.Core/

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Backpressure for JS: Reactor Core TypeScript

35

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Backpressure for JS: Reactor Core TypeScript

35

https://www.npmjs.com/package/reactor-core-js

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EVERYTHING REACTIVE ?

36

µ Service A

Data

Cloud

Messaging

Web

Service B

MessageBroker

Datastore

20 ms

50 ms

150 ms

250 ms

20 ms

15 ms

3 ms

GATEWAY

µ Service A

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Reactor Ecosystem roadmap

39

Reactor Netty

Reactor IPCSpring Framework

Spring 5, Spring Cloud Stream,

Spring Integration,Spring Data, Spring Boot, Spring Cloud,

Spring Security,…

Reactor Kafka

Extra add-ons dashboard, bus,

codecs, more operations & schedulers…

Reactor Redis

Reactor Aeron

Spring Framework 5

Spring Web MVC

@Controller, @RequestMapping

Servlet API

Servlet Container

Spring Web MVC

@Controller, @RequestMapping

Servlet API

Servlet Container

Reactive

Non-blocking

…

Spring Web MVC Spring Web Reactive

@Controller, @RequestMapping

Servlet API

Servlet Container

Spring Web MVC Spring Web Reactive

@Controller, @RequestMapping

Servlet API

Servlet Container

Reactive HTTP

Spring Web MVC Spring Web Reactive

@Controller, @RequestMapping

Servlet API

Servlet Container

Reactive HTTP

Servlet 3.1 Container

Spring Web MVC Spring Web Reactive

@Controller, @RequestMapping

Servlet API

Servlet Container

Reactive HTTP

Servlet 3.1 ContainerServlet 3.1, Netty

Spring Web MVC Spring Web Reactive

@Controller, @RequestMapping

Servlet API

Servlet Container

Reactive HTTP

Servlet 3.1 ContainerServlet 3.1, Netty, Undertow

Non-Blocking HTTP GET

Non-Blocking HTTP POST

WebClient Scatter/Gather

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SpringBootApplication@EnableBinding(Processor.class) public class WordCountApplication { @StreamListener @Output("output") public Flux<WordCount> countWords(@Input("input") Flux<String> words) { return words.window(ofSeconds(5), ofSeconds(1)) .flatMap(window -> window.groupBy(word -> word) .flatMap(group -> group.reduce(0, (counter, word) -> counter + 1) .map(count -> new WordCount(group.key(), count)))); } }

Spring Cloud Stream: Stateful processors

Boot Data Cloud IntegrationSecurity

Reactive Efforts

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@ProjectReactorhttp://github.com/reactorhttp://projectreactor.io

Extra Slideware:www.slideshare.net/SpringCentral/imperative-to-reactive-web-applicationswww.slideshare.net/SpringCentral/designing-implementing-and-using-reactive-apishttp://www.slideshare.net/RobHarrop/going-reactive-63425158