RxJava, RxJava 2, Reactor: State of the art of Reactive Streams on the JVM

RxJava is used on Android or in backend side thanks to Hystrix. RxJava 2 is now available and will be able to use the path build by the previous version. Pivotal promote Reactor that will be available in Spring Boot 2.

What is the differences between each of these implementations of the Reactive Streams? Why chose RxJava 2 over Reactor or over RxJava?

This conference talk will focus on the history of each implementation then will compare APIs, performances and use cases of these Reactive Streams.

- DevDays Vilinus - may 2018

1. Got a question during this session? 
 Post it on sli.do ( #K100 )
2. RxJava, RxJava 2, Reactor State of the art of Reactive Streams on the JVM
3. David Wursteisen
5. Writing asynchronous code: 
 it sucks
6. Future ExecutorService ex = Executors.newCachedThreadPool();
 Future<String> future = ex.submit(() -> longProcessing());
 String result = future.get(); Blocking call
7. Future Future<?> future1 = /* ... */
 Future<?> future2 = /* ... */
 Future<?> future3 = /* ... */
 Future<?> future4 = /* ... */
 Future<?> future5 = /* ... */ Optimal Orchestration ?
8. Callback RemoteService service = buildRemoteService();
 service.getUser(id -> {
 service.getData(id, data -> {
 service.getSomething(data, whut -> { service.neverEndingCallBack(whut, () -> { }); });
 });
 }); Callback Hell
9. Relationship Status:
 it’s complicated
10. The problem of synchronous code
11. Synchronous Waiting for the response Caller Called
12. Impact on response time Slow server
13. It never works! It piss me off!
14. Asynchronous Caller Called Continuous work
15. Asynchronous allow to take advantage of the waiting time
16. Minimal impact on the response time
17. Write asynchronous code easily?
18. Emergence 
 of different approaches
19. 2 Reactive Streams
20. Reactive Streams Reactive Streams API RxJava 2 Reactor Interface Implementation
21. Reactive Streams API is 
 a bridge 
 between implementations
22. Reactive Streams contract onSubscribe onNext onError onComplete
23. RxJava is not compatible 
 with Reactive Streams (You’ll have to use an adapter: RxJavaReactiveStreams) https://github.com/ReactiveX/RxJavaReactiveStreams
24. onNext * ( onError | onComplete ) 
 onNext * ( onError | onCompleted ) RxJava Reactive Streams
25. onNext * ( onError | onComplete ) 
 onNext * ( onError | onCompleted ) RxJava Reactive Streams Different name
26. Common approach
27. A P I t o h a n d l e e v e n t s synchronously or asynchronously through a flow of events
29. Map ( ⃝ →
    ⬛)
31. remoteApi.people(1).flatMap(luke -> { 
 Observable<String> vehicles = Observable.from(luke.getVehiclesIds())
 .flatMap(remoteApi::vehicle)
 .map(vehicle -> luke.getName() + " can drive " + vehicle.getName());
 
 Observable<String> starships = Observable.from(luke.getStarshipsIds())
 .flatMap(remoteApi::starship)
 .map(starship -> luke.getName() + " can fly with " + starship.getName());
 
 return Observable.merge(vehicles, starships); 
 }).subscribe(System.out::println);
32. remoteApi.people(1).flatMap(luke -> { 
 Observable<String> vehicles = Observable.from(luke.getVehiclesIds())
 .flatMap(remoteApi::vehicle)
 .map(vehicle -> luke.getName() + " can drive " + vehicle.getName());
 
 Observable<String> starships = Observable.from(luke.getStarshipsIds())
 .flatMap(remoteApi::starship)
 .map(starship -> luke.getName() + " can fly with " + starship.getName());
 
 return Observable.merge(vehicles, starships); 
 }).subscribe(System.out::println); Push of the result
33. remoteApi.people(1).flatMap(luke -> { 
 Observable<String> vehicles = Observable.from(luke.getVehiclesIds())
 .flatMap(remoteApi::vehicle)
 .map(vehicle -> luke.getName() + " can drive " + vehicle.getName());
 
 Observable<String> starships = Observable.from(luke.getStarshipsIds())
 .flatMap(remoteApi::starship)
 .map(starship -> luke.getName() + " can fly with " + starship.getName());
 
 return Observable.merge(vehicles, starships); 
 }).subscribe(System.out::println); Get Luke’s vehicles Get Luke’s starships
34. remoteApi.people(1).flatMap(luke -> { 
 Observable<String> vehicles = Observable.from(luke.getVehiclesIds())
 .flatMap(remoteApi::vehicle)
 .map(vehicle -> luke.getName() + " can drive " + vehicle.getName());
 
 Observable<String> starships = Observable.from(luke.getStarshipsIds())
 .flatMap(remoteApi::starship)
 .map(starship -> luke.getName() + " can fly with " + starship.getName());
 
 return Observable.merge(vehicles, starships); 
 }).subscribe(System.out::println); Merge of two flows
35. remoteApi.people(1).flatMap(luke -> { 
 Observable<String> vehicles = Observable.from(luke.getVehiclesIds())
 .flatMap(remoteApi::vehicle)
 .map(vehicle -> luke.getName() + " can drive " + vehicle.getName());
 
 Observable<String> starships = Observable.from(luke.getStarshipsIds())
 .flatMap(remoteApi::starship)
 .map(starship -> luke.getName() + " can fly with " + starship.getName());
 
 return Observable.merge(vehicles, starships); 
 }).subscribe(System.out::println); Really execute the code
36. remoteApi.people(1).flatMap(luke -> { 
 Observable<String> vehicles = Observable.from(luke.getVehiclesIds())
 .flatMap(remoteApi::vehicle)
 .map(vehicle -> luke.getName() + " can drive " + vehicle.getName());
 
 Observable<String> starships = Observable.from(luke.getStarshipsIds())
 .flatMap(remoteApi::starship)
 .map(starship -> luke.getName() + " can fly with " + starship.getName());
 
 return Observable.merge(vehicles, starships); 
 }).subscribe(System.out::println); Flow of events
37. remoteApi.people(1).flatMap(luke -> { 
 Observable<String> vehicles = Observable.from(luke.getVehiclesIds())
 .flatMap(remoteApi::vehicle)
 .map(vehicle -> luke.getName() + " can drive " + vehicle.getName());
 
 Observable<String> starships = Observable.from(luke.getStarshipsIds())
 .flatMap(remoteApi::starship)
 .map(starship -> luke.getName() + " can fly with " + starship.getName());
 
 return Observable.merge(vehicles, starships); 
 }).subscribe(System.out::println); Flow of events Flow of events
39. Button btn = new Button();
 btn.setText("Click Me");
 
 JavaFx.fromClick(btn) 
 .observeOn(Schedulers.io()) 
 .switchMap(evt -> remoteApi.getData())
 .observeOn(javaFx()) 
 .doOnNext(value -> btn.setText("Data: " + value))
 .subscribe();
40. Button btn = new Button();
 btn.setText("Click Me");
 
 JavaFx.fromClick(btn) // Observable<Event>
 .observeOn(Schedulers.io())
 .switchMap(evt -> remoteApi.getData())
 .observeOn(javaFx()) 
 .doOnNext(value -> btn.setText("Data: " + value))
 .subscribe(); Listen for clicks
41. Button btn = new Button();
 btn.setText("Click Me");
 
 JavaFx.fromClick(btn) // Observable<Event>
 .observeOn(Schedulers.io())
 .switchMap(evt -> remoteApi.getData())
 .observeOn(javaFx()) 
 .doOnNext(value -> btn.setText("Data: " + value))
 .subscribe(); Execution context switch
42. Button btn = new Button();
 btn.setText("Click Me");
 
 JavaFx.fromClick(btn) // Observable<Event>
 .observeOn(Schedulers.io())
 .switchMap(evt -> remoteApi.getData()) // Observable<Data>
 .observeOn(javaFx()) 
 .doOnNext(value -> btn.setText("Data: " + value))
 .subscribe(); Asynchronous call to a web service
43. Button btn = new Button();
 btn.setText("Click Me");
 
 JavaFx.fromClick(btn) // Observable<Event>
 .observeOn(Schedulers.io())
 .switchMap(evt -> remoteApi.getData()) // Observable<Data>
 .observeOn(javaFx()) 
 .doOnNext(value -> btn.setText("Data: " + value))
 .subscribe(); Execution context switch
44. Button btn = new Button();
 btn.setText("Click Me");
 
 JavaFx.fromClick(btn) // Observable<Event>
 .observeOn(Schedulers.io())
 .switchMap(evt -> remoteApi.getData()) // Observable<Data>
 .observeOn(javaFx()) 
 .doOnNext(value -> btn.setText("Data: " + value))
 .subscribe(); Update on the UI
45. Button btn = new Button();
 btn.setText("Click Me");
 
 JavaFx.fromClick(btn) // Observable<Event>
 .observeOn(Schedulers.io())
 .switchMap(evt -> remoteApi.getData()) // Observable<Data>
 .observeOn(javaFx()) 
 .doOnNext(value -> btn.setText("Data: " + value))
 .subscribe(); Flow of events
46. Thanks to RxJava and Reactor …
47. Writing asynchronous code: 
 it sucks
48. Once upon a time…
49. Creation of 
 Reactive Extensions Creation of RxJava Active Participation Resumption of 
 RxJava & RxJava 2 Creation of Reactor Work on Reactor
50. RxJava 
 is a 
 proved
 technologie
51. Reactor
 benefits from the experience of
 RxJava (and vice versa)
52. Object types
53. Observable
59. Single
61. Completable
63. RxJava Contrat Backpressure Observable [N] Yes Single [1] No Completable [0] No Added afterward Web service call Background process
64. Listen a websocket, for each received command, compose a response by calling 3 different webservices, then execute 2 jobs sequentially ?
65. Listen a websocket, for each received command, compose a response by calling 3 different webservices, then execute 2 jobs sequentially ?
66. Listen a websocket, for each received command, compose a response by calling 3 different webservices, then execute 2 jobs sequentially ?
67. Listen a websocket, for each received command, compose a response by calling 3 different webservices, then execute 2 jobs sequentially ?
68. websocket("/topics/cmd")
 .observeOn(Schedulers.io())
 .switchMap(cmd ->
 Single.zip(
 api.getActions(),
 api.getScore(),
 api.getUserData(),
 this::composeResult).toObservable())
 .observeOn(Schedulers.computation())
 .concatMap(result -> updateDb(result).andThen(getLastResults()))
 .subscribe(last -> System.out.println("last results -> " + last));
69. websocket("/topics/cmd")
 .observeOn(Schedulers.io())
 .switchMap(cmd ->
 Single.zip(
 api.getActions(),
 api.getScore(),
 api.getUserData(),
 this::composeResult).toObservable())
 .observeOn(Schedulers.computation())
 .concatMap(result -> updateDb(result).andThen(getLastResults()))
 .subscribe(last -> System.out.println("last results -> " + last)); Listen a websocket Observable
70. websocket("/topics/cmd")
 .observeOn(Schedulers.io())
 .switchMap(cmd ->
 Single.zip(
 api.getActions(),
 api.getScore(),
 api.getUserData(),
 this::composeResult).toObservable())
 .observeOn(Schedulers.computation())
 .concatMap(result -> updateDb(result).andThen(getLastResults()))
 .subscribe(last -> System.out.println("last results -> " + last)); Webservices composition Single
71. websocket("/topics/cmd")
 .observeOn(Schedulers.io())
 .switchMap(cmd ->
 Single.zip(
 api.getActions(),
 api.getScore(),
 api.getUserData(),
 this::composeResult).toObservable())
 .observeOn(Schedulers.computation())
 .concatMap(result -> updateDb(result).andThen(getLastResults()))
 .subscribe(last -> System.out.println("last results -> " + last)); Completable 2 jobs executions
72. websocket("/topics/cmd")
 .observeOn(Schedulers.io())
 .switchMap(cmd ->
 Single.zip(
 api.getActions(),
 api.getScore(),
 api.getUserData(),
 this::composeResult).toObservable())
 .observeOn(Schedulers.computation())
 .concatMap(result -> updateDb(result).andThen(getLastResults()))
 .subscribe(last -> System.out.println("last results -> " + last)); Listen a websocket Observable Webservices composition Single Completable 2 jobs executions
73. RxJava 2 Contrat Backpressure Observable [N] No Single [1] No Completable [0] No Maybe [0|1] No New! Close to Java 8 Optional
74. Maybe
76. Backpressure using RxJava 2
77. Consumer
78. Consumer To many things !
79. backpressure
80. MissingBackpressureException ?
81. acceptedIntent
 .filter(intent -> !intent.getBooleanExtra("UpdatePhoneMode", false))
 .concatMap(intent -> approximatedEngine.detectCurrentPlace())
 .doOnNext(score -> Log.info(TAG, "Scan completed with result " + score))
 .concatMap(this::detectSleepMode)
 .concatMap((score) -> isNewPlace(score.getScore().getPlace()).map(p -> score))
 .doOnNext((p) -> Log.info(TAG, "Current place found is : " + p))
 .subscribe()
82. acceptedIntent
 .filter(intent -> !intent.getBooleanExtra("UpdatePhoneMode", false)) .onBackpressureDrop()
 .concatMap(intent -> approximatedEngine.detectCurrentPlace())
 .doOnNext(score -> Log.info(TAG, "Scan completed with result " + score))
 .onBackpressureDrop() .concatMap(this::detectSleepMode)
 .onBackpressureDrop()
 .concatMap((score) -> isNewPlace(score.getScore().getPlace()).map(p -> score))
 .doOnNext((p) -> Log.info(TAG, "Current place found is : " + p))
 .subscribe() Added while I panicked
83. RxJava 2 Contrat Backpressure Observable [N] No Single [1] No Completable [0] No Maybe [0|1] No New! Close to Java 8 Optional
84. RxJava 2 Contrat Backpressure Observable [N] No Single [1] No Completable [0] No Maybe [0|1] No Flowable [N] Yes New! Observable with 
 back pressure Close to Java 8 Optional
85. Observable → less than 1000 events → User interface management → To be used instead of Java 8 Streams Flowable → more than 10 000 events → Control the data flow → Network stream with flow management
86. What does Reactor offer ?
87. Flux Mono Maximum of 1 element
88. Reactor Contrat Backpressure Flux [N] Yes Mono [0|1] Yes Identical to Flowable Flux with only 
 1 element
89. Object types and
 Reactive Streams
90. Publisher Flux Flowable Reactive Streams
91. Flux.range(1, 10)
 .flatMap(i -> Flux.just(1))
 .subscribe();
92. Flux.range(1, 10)
 .flatMap(i -> Flux.just(1))
 .subscribe(); Publisher
93. Flux.range(1, 10)
 .flatMap(i -> Flowable.just(1))
 .subscribe(); Publisher RxJava 2
94. Flowable.defer(() -> Flux.range(1, 10))
 .subscribe(System.out::println); RxJava 2 Reactor
95. Flux.defer(() -> Flowable.range(1, 10))
 .subscribe(System.out::println); RxJava 2 Reactor
96. You can use a library which use RxJava 2 in your Reactor project (and vice versa)
97. Operators
98. Consequent and homogenous Catalogue
99. all amb ambArray ambWith any as awaitOnSubscribe blockFirst blockFirstMillis blockLast blockLastMillis blockingFirst blockingForEach blockingIterable blockingLast blockingLatest blockingMostRecent blockingNext blockingSingle blockingSubscribe buffer bufferMillis bufferSize bufferTimeout bufferTimeoutMillis bufferUntil bufferWhile cache cacheWithInitialCapacity cancelOn cast checkpoint collect collectInto collectList collectMap collectMultimap collectSortedList combineLatest combineLatestDelayError compose concat concatArray concatArrayDelayError concatArrayEager concatDelayError concatEager concatMap concatMapDelayError concatMapEager concatMapEagerDelayError concatMapIterable concatWith contains count create debounce defaultIfEmpty defer delay delayElements delayElementsMillis delayMillis delaySubscription delaySubscriptionMillis dematerialize distinct distinctUntilChanged doAfterNext doAfterTerminate doFinally doOnCancel doOnComplete doOnEach doOnError doOnLifecycle doOnNext doOnRequest doOnSubscribe doOnTerminate elapsed elementAt elementAtOrError empty equals error filter first firstElement firstEmitting firstEmittingWith firstOrError flatMap flatMapCompletable flatMapIterable flatMapMaybe flatMapSequential flatMapSingle forEach forEachWhile from fromArray fromCallable fromFuture fromIterable fromPublisher fromStream generate getClass getPrefetch groupBy groupJoin handle hasElement hasElements hashCode hide ignoreElements interval intervalMillis intervalRange isEmpty join just last lastElement lastOrError lift limitRate log map mapError materialize merge mergeArray mergeArrayDelayError mergeDelayError mergeSequential mergeWith never next notify notifyAll observeOn ofType onBackpressureBuffer onBackpressureDrop onBackpressureError onBackpressureLatest onErrorResumeNext onErrorResumeWith onErrorReturn onErrorReturnItem onExceptionResumeNext onTerminateDetach parallel publish publishNext publishOn range rangeLong rebatchRequests reduce reduceWith repeat repeatUntil repeatWhen replay replayMillis retry retryUntil retryWhen safeSubscribe sample sampleFirst sampleFirstMillis sampleMillis sampleTimeout scan scanWith sequenceEqual serialize share single singleElement singleOrEmpty singleOrError skip skipLast skipMillis skipUntil skipUntilOther skipWhile sort sorted startWith startWithArray strict subscribe subscribeOn subscribeWith switchIfEmpty switchMap switchMapDelayError switchOnError switchOnNext switchOnNextDelayError take takeLast takeMillis takeUntil takeUntilOther takeWhile test then thenEmpty thenMany throttleFirst throttleLast throttleWithTimeout timeInterval timeout timeoutMillis timer timestamp to toFuture toIterable toList toMap toMultimap toObservable toSortedList toStream toString transform unsafeCreate unsubscribeOn using wait window windowMillis windowTimeout windowTimeoutMillis windowUntil windowWhile withLatestFrom zip zipArray zipIterable zipWith zipWithIterable
100. RxJava RxJava 2 Reactor flatMap flatMap flatMap Emit Noe, one or more events amb amb firstEmitting Emit events from the first emitting stream … … … … debounce debounce N/A Ignore events during a time laps
101. RxJava RxJava 2 Reactor flatMap flatMap flatMap Emit Noe, one or more events amb amb firstEmitting Emit events from the first emitting stream … … … … debounce debounce N/A Ignore events during a time laps Renamed
102. Operators cover a lot of scenarios
103. Nota bene
104. https://github.com/ReactiveX/RxJava/wiki/Implementing-custom-operators-(draft) writing operators is hard when one writes an operator, the Observable protocol, unsubscription, backpressure and concurrency have to be taken into account and adhered to the letter
105. Writing a new operator with RxJava 2 is more complex than with RxJava
106. Make a application Reactive
107. Reactive Reactive Synchronous API Callback Reactive Reactive
108. Factory
109. RxJava
 RxJava 2 Reactor Flowable.just Flux.just Emitting existing value Flowable.defer Flux.defer Lazy emitting Flowable.fromCallable Mono.fromCallable Lazy emitting, computed from a method call Flowable.create Flux.create Manual emitting Flowable.using Flux.using Resource management Flowable.fromPublisher Flux.from Using a Publisher (Reactive Streams) Flowable.generate Flux.generate Using a value generator
110. RxJava
 RxJava 2 Reactor Flowable.just Flux.just Emitting existing value Flowable.defer Flux.defer Lazy emitting Flowable.fromCallable Mono.fromCallable Lazy emitting, computed from a method call Flowable.create Flux.create Manual emitting Flowable.using Flux.using Resource management Flowable.fromPublisher Flux.from Using a Publisher (Reactive Streams) Flowable.generate Flux.generate Using a value generator
111. RxJava
 RxJava 2 Reactor Flowable.just Flux.just Emitting existing value Flowable.defer Flux.defer Lazy emitting Flowable.fromCallable Mono.fromCallable Lazy emitting, computed from a method call Flowable.create Flux.create Manual emitting Flowable.using Flux.using Resource management Flowable.fromPublisher Flux.from Using a Publisher (Reactive Streams) Flowable.generate Flux.generate Using a value generator
112. RxJava
 RxJava 2 Reactor Flowable.just Flux.just Emitting existing value Flowable.defer Flux.defer Lazy emitting Flowable.fromCallable Mono.fromCallable Lazy emitting, computed from a method call Flowable.create Flux.create Manual emitting Flowable.using Flux.using Resource management Flowable.fromPublisher Flux.from Using a Publisher (Reactive Streams) Flowable.generate Flux.generate Using a value generator
113. example of wrapping
114. @RestController
 public class HelloController {
 
 private static final byte[] TOPIC_NAME = "topic".getBytes();
 
 @RequestMapping(value = "/redis")
 private String redis() throws InterruptedException {
 CountDownLatch latch = new CountDownLatch(1);
 AtomicReference<String> result = new AtomicReference<>();
 this.connection.subscribe((message, pattern) -> {
 result.set(message.toString());
 latch.countDown();
 }, TOPIC_NAME);
 latch.await();
 return result.get();
 } }
115. @RestController
 public class HelloController {
 
 private static final byte[] TOPIC_NAME = "topic".getBytes();
 
 @RequestMapping(value = "/redis")
 private String redis() throws InterruptedException {
 CountDownLatch latch = new CountDownLatch(1);
 AtomicReference<String> result = new AtomicReference<>();
 this.connection.subscribe((message, pattern) -> {
 result.set(message.toString());
 latch.countDown();
 }, TOPIC_NAME);
 latch.await();
 return result.get();
 } }
116. @RestController
 public class HelloController {
 
 private static final byte[] TOPIC_NAME = "topic".getBytes();
 
 @RequestMapping(value = "/redis")
 private String redis() throws InterruptedException {
 CountDownLatch latch = new CountDownLatch(1);
 AtomicReference<String> result = new AtomicReference<>();
 this.connection.subscribe((message, pattern) -> {
 result.set(message.toString());
 latch.countDown();
 }, TOPIC_NAME);
 latch.await();
 return result.get();
 } }
117. @RestController
 public class HelloController {
 
 private static final byte[] TOPIC_NAME = "topic".getBytes();
 
 @RequestMapping(value = "/redis")
 private String redis() throws InterruptedException {
 CountDownLatch latch = new CountDownLatch(1);
 AtomicReference<String> result = new AtomicReference<>();
 this.connection.subscribe((message, pattern) -> {
 result.set(message.toString());
 latch.countDown();
 }, TOPIC_NAME);
 latch.await();
 return result.get();
 } } Code for synchronisation Code for synchronisation
118. Step 1 
 Wrapping
119. @RestController
 public class HelloController {
 
 private static final byte[] TOPIC_NAME = "topic".getBytes();
 
 @RequestMapping(value = "/redis")
 private String redis() throws InterruptedException {
 
 String result = Flowable.create(sub -> {
 this.connection.subscribe((message, pattern) -> {
 sub.onNext(message.toString());
 sub.onComplete();
 }, TOPIC_NAME);
 }, BackpressureStrategy.BUFFER)
 .blockingFirst();
 return result;
 } }
120. @RestController
 public class HelloController {
 
 private static final byte[] TOPIC_NAME = "topic".getBytes();
 
 @RequestMapping(value = "/redis")
 private String redis() throws InterruptedException {
 
 String result = Flowable.create(sub -> {
 this.connection.subscribe((message, pattern) -> {
 sub.onNext(message.toString());
 sub.onComplete();
 }, TOPIC_NAME);
 }, BackpressureStrategy.BUFFER)
 .blockingFirst();
 return result;
 } } Wrapping Synchronisation Reactive Contract
121. Step 2 Asynchronous
122. @RestController
 public class HelloController {
 
 private static final byte[] TOPIC_NAME = "topic".getBytes();
 
 @RequestMapping(value = "/redis")
 private DeferredResult<String> redis() throws InterruptedException {
 
 DeferredResult<String> result = new DeferredResult<>(10_000l);
 
 Flowable.create(sub -> {
 this.connection.subscribe((message, pattern) -> {
 sub.onNext(message.toString());
 sub.onComplete();
 }, TOPIC_NAME);
 }, BackpressureStrategy.BUFFER)
 .subscribe(result::setResult);
 
 return result;
 }
123. @RestController
 public class HelloController {
 
 private static final byte[] TOPIC_NAME = "topic".getBytes();
 
 @RequestMapping(value = "/redis")
 private DeferredResult<String> redis() throws InterruptedException {
 
 DeferredResult<String> result = new DeferredResult<>(10_000l);
 
 Flowable.create(sub -> {
 this.connection.subscribe((message, pattern) -> {
 sub.onNext(message.toString());
 sub.onComplete();
 }, TOPIC_NAME);
 }, BackpressureStrategy.BUFFER)
 .subscribe(result::setResult);
 
 return result;
 } Lazy result Use of DeferredResult
124. Step 3 
 Reactive Streams
125. @RestController
 public class HelloController {
 
 private static final byte[] TOPIC_NAME = "topic".getBytes();
 
 @RequestMapping(value = "/redis", produces = MediaType.TEXT_EVENT_STREAM_VALUE)
 private Flux<String> redis() throws InterruptedException {
 
 Flowable<String> rxjava = Flowable.create(sub -> {
 this.connection.subscribe((message, pattern) -> sub.onNext(message.toString()), TOPIC_NAME);
 }, BackpressureStrategy.BUFFER);
 
 return Flux.defer(() -> rxjava);
 } }
126. @RestController
 public class HelloController {
 
 private static final byte[] TOPIC_NAME = "topic".getBytes();
 
 @RequestMapping(value = "/redis", produces = MediaType.TEXT_EVENT_STREAM_VALUE)
 private Flux<String> redis() throws InterruptedException {
 
 Flowable<String> rxjava = Flowable.create(sub -> {
 this.connection.subscribe((message, pattern) -> sub.onNext(message.toString()), TOPIC_NAME);
 }, BackpressureStrategy.BUFFER);
 
 return Flux.defer(() -> rxjava);
 } } RxJava 2 → Flux Flux → SSE Return a Flux
127. @RestController
 public class HelloController {
 
 private static final byte[] TOPIC_NAME = "topic".getBytes();
 
 @RequestMapping(value = "/redis", produces = MediaType.TEXT_EVENT_STREAM_VALUE)
 private Publisher<String> redis() throws InterruptedException {
 return Flowable.create(sub -> {
 this.connection.subscribe((message, pattern) -> sub.onNext(message.toString()), TOPIC_NAME);
 }, BackpressureStrategy.BUFFER);
 
 }
128. @RestController
 public class HelloController {
 
 private static final byte[] TOPIC_NAME = "topic".getBytes();
 
 @RequestMapping(value = "/redis", produces = MediaType.TEXT_EVENT_STREAM_VALUE)
 private Publisher<String> redis() throws InterruptedException {
 return Flowable.create(sub -> {
 this.connection.subscribe((message, pattern) -> sub.onNext(message.toString()), TOPIC_NAME);
 }, BackpressureStrategy.BUFFER);
 
 } Publisher
130. Reactor use Java 8 while RxJava 2 use Java 6
131. Reactor use Java 8 while RxJava 2 use Java 6
132. Asynchronous Execution context management
133. Schedulers Rethink cette partie là
134. Scheduler 
 (Thread Pool) Task 1 Task 2 Task 3 Task 4
135. Task 1 Task 2 Task 3 Task 4 Scheduler 
 (Thread Pool)
136. Task 1 Task 2 Task 3 Task 4 Scheduler 
 (Thread Pool)
137. Task 1 Task 2 Task 3 Task 4 Scheduler 
 (Thread Pool)
138. Task 1 Task 2 Task 3 Task 4 Scheduler 
 (Thread Pool)
139. Task 1 Task 2 Task 3 Task 4 Scheduler 
 (Thread Pool)
140. Task 1 Task 2 Task 3 Task 4 Scheduler 
 (Thread Pool)
141. Task 1 Task 2 Task 3 Task 4 Scheduler 
 (Thread Pool)
142. Task 1 Task 2 Task 3 Task 4 Scheduler 
 (Thread Pool)
143. java.lang.IllegalStateException: 
 Not on the main thread NetworkOnMainThreadException
144. JavaFx.fromClick(btn) 
 .observeOn(Schedulers.io())
 .switchMap(evt -> remoteApi.getData())
 .observeOn(Schedulers.computation())
 .flatMap(data -> intensiveComputation(data))
 .observeOn(javaFx())
 .doOnNext(value -> btn.setText("Data: " + value)) 
 .subscribe();
145. JavaFx.fromClick(btn) 
 .observeOn(Schedulers.io())
 .switchMap(evt -> remoteApi.getData())
 .observeOn(Schedulers.computation())
 .flatMap(data -> intensiveComputation(data))
 .observeOn(javaFx())
 .doOnNext(value -> btn.setText("Data: " + value)) 
 .subscribe(); i/o computation UI Thread
146. RxJava RxJava 2 Reactor Description io() io() elastic() Thread pool which grow up if needed computation() computation() parallel() Limited thread pool single() single() single() Pool of 1 thread immediate() immediate() Execute the task immediately trampoline() trampoline() Queue the current task
147. RxJava RxJava 2 Reactor Description io() io() elastic() Thread pool which grow up if needed computation() computation() parallel() Limited thread pool single() single() single() Pool of 1 thread immediate() immediate() Execute the task immediately trampoline() trampoline() Queue the current task
148. RxJava RxJava 2 Reactor Description io() io() elastic() Thread pool which grow up if needed computation() computation() parallel() Limited thread pool single() single() single() Pool of 1 thread immediate() immediate() Execute the task immediately trampoline() trampoline() Queue the current task
149. Reactor Technical naming
150. RxJava Functional naming
151. Performance
152. Generation 3 4 5+ Fusion RxJava 2 Reactor
153. Warning Conceptuel slides
154. Without fusion
155. Transform (
     ⬛ → ⃝ ) Transform ( ⃝ →
     ⬛)
156. Transform (
     ⬛ → ⃝ ) Transform ( ⃝ →
     ⬛)
157. Transform (
     ⬛ → ⃝ ) Transform ( ⃝ →
     ⬛)
158. Transform (
     ⬛ → ⃝ ) Transform ( ⃝ →
     ⬛)
159. Transform (
     ⬛ → ⃝ ) Transform ( ⃝ →
     ⬛)
160. Transform (
     ⬛ → ⃝ ) Transform ( ⃝ →
     ⬛)
161. With fusion
162. Transform (
     ⬛ → ⃝ ) Transform ( ⃝ →
     ⬛)
163. Transform (
     ⬛ → ⃝ ) Transform ( ⃝ →
     ⬛)
164. Transform (
     ⬛ → ⃝ ) Transform ( ⃝ →
     ⬛)
165. Transform (
     ⬛ → ⃝ ) Transform ( ⃝ →
     ⬛)
166. Transform (
     ⬛ → ⃝ ) Transform ( ⃝ →
     ⬛)
167. Fusion decreases memory consumption and increases performances
168. for (int x = 0; x < 10_000; x++) {
 
 Observable.interval(10, TimeUnit.MILLISECONDS)
 .takeWhile(i -> take.get())
 .flatMap(i -> Observable.range(1, 100))
 .subscribe();
 }
169. RxJava 2 RxJava Reactor
170. http://akarnokd.blogspot.fr/2016/12/the-reactive-scrabble-benchmarks.html Java 8 Stream RxJava 2 / Reactor RxJava December 2016
171. Java 8 Stream RxJava 2 / Reactor RxJava https://twitter.com/akarnokd/status/844555409012740096 March 2017
172. Ecosystem
173. RxJava RxJava 2 Reactor Retrofit Yes Yes No RxAndroid Yes Yes No Realm Yes No No Hystrix Yes No No Couchbase Yes No No MongoDB Yes No No Spring Data 2.0 Yes No Yes Reactor IPC No No Yes WebFlux No Yes Yes Android Spring
174. RxJava RxJava 2 Reactor Retrofit Yes Yes No RxAndroid Yes Yes No Realm Yes No No Hystrix Yes No No Couchbase Yes No No MongoDB Yes No No Spring Data 2.0 Yes No Yes Reactor IPC No No Yes WebFlux No Yes Yes Android Spring
175. We are aggressively 
 migrating our internal code to RxJava 2 https://github.com/uber/AutoDispose
176. RxJava RxJava 2 Reactor Retrofit Yes Yes No RxAndroid Yes Yes No Realm Yes No No Hystrix Yes No No Couchbase Yes No No MongoDB Yes No No Spring Data 2.0 Yes No Yes Reactor IPC No No Yes WebFlux No Yes Yes Android Spring
177. Inertia to migrate
178. RxJava RxJava 2 Reactor Retrofit Yes Yes No RxAndroid Yes Yes No Realm Yes No No Hystrix Yes No No Couchbase Yes No No MongoDB Yes No No Spring Data 2.0 Yes No Yes Reactor IPC No No Yes WebFlux No Yes Yes Android Spring
179. Spring 5 will accelerate the adoption of Reactor
180. Android RxJava 2
181. Backend RxJava 2
182. Spring Reactor
183. Thanks for your attention We stay in touch? david.wursteisen@soat.fr @dwursteisen http://blog.soat.fr Post your question on sli.do ( #K100 )