1.
RxJava
Getting Started
David Wursteisen 16 Octobre 2014

2.
David Wursteisen
Direction Expertise Innovation
@dwursteisen

3.
David Wursteisen

4.
Architecture distribuée
Sync/Async/Concurrence

5.
Architecture distribuée

6.
Architecture distribuée

7.
Architecture distribuée
The Internet

8.
Architecture distribuée
The Internet

9.
Synchrone

10.
Synchrone
Appel bloquant

11.
Asynchrone

12.
Asynchrone
Appel non
bloquant

13.
Complexité

14.
Complexité
future.get();

15.
Complexité
future1.get();
future2.get();
future3.get();
future4.get();
future5.get();
future6.get();
future7.get();

16.
Complexité
future1.get();
future2.get();
future3.get();
future4.get();
future5.get();
future6.get();
future7.get();
Ordonnancement optimal ?

17.
Complexité
client.execute(new Callback() {
@Override
public void completed(HttpResponse response) {
}
});

18.
Complexité
client.execute(new Callback() {
@Override
public void completed(HttpResponse response) {
client.execute(new Callback() {
@Override
public void completed(HttpResponse response) {
}
});
}
});

19.
Complexité
client.execute(new Callback() {
@Override
public void completed(HttpResponse response) {
client.execute(new Callback() {
@Override
public void completed(HttpResponse response) {
client.execute(new Callback() {
@Override
public void completed(HttpResponse response) {
}
});
}
});

20.
Complexité
client.execute(new Callback() {
@Override
public void completed(HttpResponse response) {
client.execute(new Callback() {
@Override
public void completed(HttpResponse response) {
client.execute(new Callback() {
@Override
public void completed(HttpResponse response) {
}
});
}
});
Callback hell

21.
Concurrence

22.
Concurrence

23.
Concurrence
Concurrence

24.
Concurrence

25.
Concurrence
RxJava permet de manipuler des
évènements d’une manière synchrone
et/ou asynchrone.

26.
Historique
Il était une fois...

27.
Historique

28.
Historique

29.
Historique

30.
Historique

31.
Historique
ReactiveX.io

32.
Observables
Travailler avec des flux

33.
Flux d’évènements fini
Évènements Fin du flux

34.
Flux d’évènements en erreur
Évènements Erreur

35.
Flux d’évènements infini
Évènements

36.
Flux d’évènements
Observable.never()
Observable.empty()
Observable.just(1)
Observable.from(1, 2, 3)
Observable.range(1, 4400)
Observable.timer(5, TimeUnit.SECONDS)
Observable.create(...)

37.
Flux d’évènements
Observable.never()
Observable.empty()
Observable.just(1)
Observable.from(1, 2, 3)
Observable.range(1, 4400)
Observable.timer(5, TimeUnit.SECONDS)
Observable.create(...)

38.
Flux d’évènements
Observable.never()
Observable.empty()
Observable.just(1)
Observable.from(1, 2, 3)
Observable.range(1, 4400)
Observable.timer(5, TimeUnit.SECONDS)
Observable.create(...)
1

39.
Flux d’évènements
Observable.never()
Observable.empty()
Observable.just(1)
Observable.from(1, 2, 3)
Observable.range(1, 4400)
Observable.timer(5, TimeUnit.SECONDS)
Observable.create(...)
1 2 3

40.
Flux d’évènements
Observable.never()
Observable.empty()
Observable.just(1)
Observable.from(1, 2, 3)
Observable.range(1, 4400)
Observable.timer(5, TimeUnit.SECONDS)
Observable.create(...)
1 4400

41.
Flux d’évènements
Observable.never()
Observable.empty()
Observable.just(1)
Observable.from(1, 2, 3)
Observable.range(1, 4400)
Observable.timer(5, TimeUnit.SECONDS)
Observable.create(...)
0
t
t + 5 secondes

42.
Flux d’évènements
Observable.never()
Observable.empty()
Observable.just(1)
Observable.from(1, 2, 3)
Observable.range(1, 4400)
Observable.timer(5, TimeUnit.SECONDS)
Observable.create(...)
A C

43.
Flux d’évènements
Observable<json> json json json
λ ϕ φ
Observable<Integer>
Observable<Click>

44.
Observer
Push des données

45.
Observer
OnNext* (OnCompleted|OnError)?

46.
Observer
OnNext* (OnCompleted|OnError)?

47.
Observer
OnNext* (OnCompleted|OnError)?

48.
Observer
OnNext* (OnCompleted|OnError)?

49.
Observer
Observable.range(1, 4400)

50.
Observer
Observable.range(1, 4400).subscribe()

51.
Observer
Observable.range(1, 4400).subscribe(onNext)

52.
Observer
Observable.range(1, 4400).subscribe(System.out::println)

53.
Observer
Observable.range(1, 4400).subscribe(System.out::println,
onError)

54.
Observer
Observable.range(1, 4400).subscribe(System.out::println,
System.err::println)

55.
Observer
Observable.range(1, 4400).subscribe(System.out::println,
System.err::println,
onCompleted)

56.
Observer
Observable.range(1, 4400).subscribe(System.out::println,
System.err::println,
() -> System.out.println(“finished”))

57.
Manipulation d’évènements
Quand l’écoute ne suffit plus

58.
Manipulation d’évènements
0 1

59.
Manipulation d’évènements
0 1
map

60.
Manipulation d’évènements
0 1
map
A B

61.
Manipulation d’évènements
1 4

62.
Manipulation d’évènements
1 4
filter ( x <= 2 )

63.
Manipulation d’évènements
1 4
1
filter ( x <= 2 )

64.
Manipulation d’évènements
1 2

65.
Manipulation d’évènements
1 2
delay ( 5, SECONDS )

66.
Manipulation d’évènements
1 2
delay ( 5, SECONDS )
1
2

67.
Manipulation d’évènements
Observable.from(0, 1, 2, 3, 4)
Observable<Integer>

68.
Manipulation d’évènements
Observable.from(0, 1, 2, 3, 4)
.filter((i) -> i < 3)
Observable<Integer>
Observable<Integer>

69.
Manipulation d’évènements
Observable.from(0, 1, 2, 3, 4)
.filter((i) -> i < 3)
.delay(5, TimeUnit.SECONDS)
Observable<Integer>
Observable<Integer>
Observable<Integer>

70.
Manipulation d’évènements
Observable.from(0, 1, 2, 3, 4)
.filter((i) -> i < 3)
.delay(5, TimeUnit.SECONDS)
.map((i) -> Character.toString((char)(i + 'A')))
Observable<Integer>
Observable<Integer>
Observable<Integer>
Observable<String>

71.
Manipulation d’évènements
Observable.from(0, 1, 2, 3, 4)
.filter((i) -> i < 3)
.delay(5, TimeUnit.SECONDS)
.map((i) -> Character.toString((char)(i + 'A')))
.subscribe(System.out::println);
Observable<Integer>
Observable<Integer>
Observable<Integer>
Observable<String>

72.
Manipulation d’évènements
Observable.from(0, 1, 2, 3, 4)
.filter((i) -> i < 3)
.delay(5, TimeUnit.SECONDS)
.map((i) -> Character.toString((char)(i + 'A')))
.subscribe(System.out::println);
0, 1, 2, 3, 4 => A, B, C
Observable<Integer>
Observable<Integer>
Observable<Integer>
Observable<String>

73.
Manipulation d’évènements

74.
Manipulation d’évènements

75.
Manipulation d’évènements

76.
Composition
Création d’un flux à partir d’un ensemble de flux

77.
Composition

78.
Composition

79.
Composition

80.
Mise en pratique de composition
Learn from the trenches

81.
Composition

82.
Composition

83.
Composition

84.
Composition

85.
Composition

86.
Composition
merge

87.
Composition
merge

88.
Composition

89.
Composition

90.
Composition
zip

91.
Composition
zip

92.
Subscription
Et gestion de l’unsubscribe

93.
Subscription
Observable.create(new OnSubscribe<T>() { … });

94.
Subscription
Observable.create(new OnSubscribe<T>() {
@Override
public void call(Subscriber<? super T> s) {
s.onNext(123);
s.onCompleted();
}
});

95.
Subscription
Observable.create(new OnSubscribe<T>() {
@Override
public void call(Subscriber<? super T> s) {
s.onNext(123);
s.onCompleted();
}
});
Émission synchronne

96.
Subscription
Observable.create(new OnSubscribe<T>() {
@Override
public void call(Subscriber<? super T> subscriber) {
// ...
httpClient.execute(httpRequest, new FutureCallback<HttpResponse>() {
@Override
public void completed(String content) {
subscriber.onNext(content);
subscriber.onCompleted();
}
@Override
public void failed(Exception e) {
subscriber.onError(e);
}
});
}
});

97.
Subscription
Observable.create(new OnSubscribe<T>() {
@Override
public void call(Subscriber<? super T> subscriber) {
// ...
httpClient.execute(httpRequest, new FutureCallback<HttpResponse>() {
@Override
public void completed(String content) {
subscriber.onNext(content);
subscriber.onCompleted();
}
@Override
public void failed(Exception e) {
subscriber.onError(e);
}
});
}
});

98.
Subscription
Observable.create(new OnSubscribe<T>() {
@Override
public void call(Subscriber<? super T> subscriber) {
// ...
httpClient.execute(httpRequest, new FutureCallback<HttpResponse>() {
@Override
public void completed(String content) {
subscriber.onNext(content);
subscriber.onCompleted();
}
@Override
public void failed(Exception e) {
subscriber.onError(e);
}
});
}
});

99.
Subscription
Observable.create(new OnSubscribe<T>() {
@Override
public void call(Subscriber<? super T> subscriber) {
// ...
httpClient.execute(httpRequest, new FutureCallback<HttpResponse>() {
@Override
public void completed(String content) {
subscriber.onNext(content);
subscriber.onCompleted();
}
@Override
public void failed(Exception e) {
subscriber.onError(e);
}
});
}
});
Émission asynchronne

100.
Subscription
Observable.create(new OnSubscribe<T>() {
@Override
public void call(Subscriber<? super T> subscriber) {
// ...
httpClient.execute(httpRequest, new FutureCallback<HttpResponse>() {
@Override
public void completed(String content) {
subscriber.onNext(content);
subscriber.onCompleted();
}
@Override
public void failed(Exception e) {
subscriber.onError(e);
}
});
}
});
Propagation des erreurs

101.
Subscription
La souscription permet d’uniformiser des API
différentes par leurs natures (Callback, etc...)

102.
Unsubscribe
Subscription subscription = Observable.interval(1, TimeUnit.SECONDS).subscribe();

103.
Unsubscribe
Souscription
Subscription subscription = Observable.interval(1, TimeUnit.SECONDS).subscribe();

104.
Unsubscribe
Handler sur la souscription
Subscription subscription = Observable.interval(1, TimeUnit.SECONDS).subscribe();

105.
Unsubscribe
Subscription subscription = Observable.interval(1, TimeUnit.SECONDS).subscribe();
/* ... */
subscription.unsubscribe();

106.
Unsubscribe
Subscription subscription = Observable.interval(1, TimeUnit.SECONDS).subscribe();
/* ... */
subscription.unsubscribe();
Arrêt de la souscription

107.
Schedulers

108.
Schedulers
observableReadingSynchronously(“strings.txt”)
.take(10)
.delay(1, SECONDS)
.map(parse())
.map(n -> “=> ” + n))
.subscribe(to_the_view())

109.
Schedulers
main

110.
Schedulers
observableReadingSynchronously(“strings.txt”)
.take(10)
.delay(1, SECONDS)
.map(parse())
.map(n -> “=> ” + n))
.subscribe(to_the_view())

111.
Schedulers
main
IO
Computation
UI

112.
Schedulers
main
IO
Computation
UI

113.
Schedulers
main
IO
Computation
UI

114.
Schedulers
main
IO
Computation
UI

115.
Schedulers
main
IO
Computation
UI

116.
Schedulers
main
IO
Computation
UI

117.
Schedulers
observableReadingSynchronously(“strings.txt”)
.subscribeOn(scheduler)
.take(10)
.delay(1, SECONDS, scheduler)
.map(parse())
.observeOn(scheduler)
.map(n -> “=> ” + n))
.subscribe(to_the_view())

118.
Schedulers
observableReadingSynchronously(“strings.txt”)
.subscribeOn(Schedulers.io())
.take(10)
.delay(1, SECONDS, Schedulers.computation())
.map(parse())
.observeOn(Schedulers.from(uiExecutor()))
.map(n -> “=> ” + n))
.subscribe(to_the_view())

119.
Schedulers
Computation
UI

120.
Schedulers
Computation
UI

121.
Schedulers
Computation
UI

122.
Schedulers
Computation
UI

123.
Schedulers
Computation
UI

124.
Hot & Cold Observable

125.
Cold Observable
Observable<Integer> obs = Observable.from(1, 2, 3, 4);
obs.subscribe(System.out::println);
obs.subscribe(System.out::println);

126.
Cold Observable
Observable<Integer> obs = Observable.from(1, 2, 3, 4);
obs.subscribe(System.out::println);
obs.subscribe(System.out::println);

127.
Cold Observable
Observable<Integer> obs = Observable.from(1, 2, 3, 4);
obs.subscribe(System.out::println);
Subscribe
obs.subscribe(System.out::println);

128.
Cold Observable
Observable<Integer> obs = Observable.from(1, 2, 3, 4);
obs.subscribe(System.out::println);
obs.subscribe(System.out::println); Subscribe

129.
Cold Observable
Observable<Integer> obs = Observable.from(1, 2, 3, 4);
obs.subscribe(System.out::println);
obs.subscribe(System.out::println);
Souscription différente

130.
Hot Observable
ConnectableObservable<Integer> obs = Observable.from(1, 2, 3, 4).publish();
obs.subscribe(System.out::println);
obs.subscribe(System.out::println);
obs.connect();

131.
Hot Observable
ConnectableObservable<Integer> obs = Observable.from(1, 2, 3, 4).publish();
obs.subscribe(System.out::println);
obs.subscribe(System.out::println);
obs.connect();

132.
Hot Observable
ConnectableObservable<Integer> obs = Observable.from(1, 2, 3, 4).publish();
obs.subscribe(System.out::println);
obs.subscribe(System.out::println);
obs.connect();

133.
Hot Observable
ConnectableObservable<Integer> obs = Observable.from(1, 2, 3, 4).publish();
obs.subscribe(System.out::println);
obs.subscribe(System.out::println);
obs.connect();

134.
Hot Observable
ConnectableObservable<Integer> obs = Observable.from(1, 2, 3, 4).publish();
obs.subscribe(System.out::println);
obs.subscribe(System.out::println);
obs.connect();

135.
Hot Observable
ConnectableObservable<Integer> obs = Observable.from(1, 2, 3, 4).publish();
obs.subscribe(System.out::println);
obs.subscribe(System.out::println);
Subscribe
obs.connect();

136.
Hot Observable
ConnectableObservable<Integer> obs = Observable.from(1, 2, 3, 4).publish();
obs.subscribe(System.out::println);
obs.subscribe(System.out::println);
obs.connect();
Partage la même souscription

137.
Hot Observable
ConnectableObservable<Integer> obs = Observable.from(1, 2, 3, 4).publish();
obs.subscribe(System.out::println);
obs.subscribe(System.out::println);
obs.connect();

138.
Hot Observable
ConnectableObservable<Integer> obs = Observable.from(1, 2, 3, 4).publish();
obs.connect();
Souscription
obs.subscribe(System.out::println);
obs.subscribe(System.out::println);

139.
Cold & Hot Observable
Cold Observable = flux passif
Hot Observable = flux actif

140.
Back Pressure
Contrôler la production

141.
Back Pressure
Production

142.
Back Pressure
Production
buffer

143.
Back Pressure
Production
Pression arrière

144.
Back Pressure
Demande de production de n élements
Production
Pression arrière

145.
Retour d’expérience

146.
Opérateurs
Observable.from(1, 2, 3, 4)
.reduce(new LinkedList<Integer>(), (seed, value) -> {
seed.add(value);
return seed;
})
.first()
.subscribe(System.out::println);

147.
Opérateurs
Observable.from(1, 2, 3, 4)
.reduce(new LinkedList<Integer>(), (seed, value) -> {
seed.add(value);
return seed;
})
.first()
.subscribe(System.out::println);

148.
Opérateurs
Observable.from(1, 2, 3, 4)
.toList()
.first()
.subscribe(System.out::println);

149.
Opérateurs
Observable.from(1, 2, 3, 4)
.toList()
.first()
.subscribe(System.out::println);

150.
Opérateurs
Observable.from(1, 2, 3, 4)
.toList()
.first()
.subscribe(System.out::println);
Différence entre first() / single() / take(1) ?

151.
Gestion des erreurs
Observable.from(1, 2, 3, 4)
.toList()
.single()
.subscribe(System.out::println);

152.
Gestion des erreurs
Observable.from(1, 2, 3, 4)
.toList()
.single()
.subscribe(System.out::println);
Notification des erreurs absentes

153.
Gestion des erreurs
static {
RxJavaPlugins.getInstance().registerErrorHandler(new RxJavaErrorHandler() {
@Override
public void handleError(Throwable e) {
e.printStackTrace();
}
});
}

154.
Lambda & Java 8
Observable.from(1, 2, 3, 4)
.filter(new Func1<Integer, Boolean>() {
@Override
public Boolean call(Integer i) {
return i > 3;
}
})
.subscribe(new Action1<Integer>() {
@Override
public void call(Integer x) {
System.out.println(x);
}
});

155.
Lambda & Java 8
Observable.from(1, 2, 3, 4)
.filter(new Func1<Integer, Boolean>() {
@Override
public Boolean call(Integer i) {
return i > 3;
}
})
.subscribe(new Action1<Integer>() {
@Override
public void call(Integer x) {
System.out.println(x);
}
});
Bruit

156.
Lambda & Java 8
Observable.from(1, 2, 3, 4)
.filter(i -> i > 3)
.subscribe(System.out::println);

157.
Lambda & Java 8
Observable.from(1, 2, 3, 4)
.filter(new Func1<Integer, Boolean>() {
@Override
public Boolean call(Integer i) {
return i > 3;
}
})
.subscribe(new Action1<Integer>() {
@Override
public void call(Integer x) {
System.out.println(x);
}
});
Observable.from(1, 2, 3, 4)
.filter(i -> i > 3)
.subscribe(System.out::println);
Retrolambda

158.
Concurrence
obs1.mergeWith(obs2)
.take(5)
.subscribe(System.out::println);

159.
Concurrence
obs1.mergeWith(obs2)
.take(5)
.subscribe(System.out::println);

160.
Concurrence
obs1.mergeWith(obs2)
Doit gérer la concurrence
.take(5)
.subscribe(System.out::println);

161.
Concurrence
obs1.mergeWith(obs2)
.take(5)
.subscribe(System.out::println);

162.
Concurrence
obs1.mergeWith(obs2)
.take(5)
.subscribe(System.out::println);
non concurrence

163.
Sync & Async
Observable<Integer> generator();

164.
Sync & Async
Observable<Integer> generator();
Sync ?

165.
Sync & Async
Sync ? Async ?
Observable<Integer> generator();

166.
Sync & Async
Sync ? Async ?
Observable<Integer> generator();
Computation ?

167.
Sync & Async
Sync ? Async ?
Observable<Integer> generator();
Computation ? Acteur ?

168.
“Leak” des Observables
everything is an event

169.
“Leak” des Observables
ViewPager

170.
“Leak” des Observables
ViewPager
Observable
Preferences

171.
“Leak” des Observables
ViewPager
Observable
Preferences
Observable
UserService

172.
Future<RxJava>

173.
Future<RxJava>
Support RxJava

174.
Reactive Streams

175.
Reactive Streams
Reactive Streams is an initiative to
provide a standard for asynchronous
stream processing with non-blocking
back pressure on the JVM.
http://www.reactive-streams.org/

176.
Reactive Streams
RxJava | Akka Streams | Reactor Composable | Ratpack

177.
Reactive Streams
RxJava | Akka Streams | Reactor Composable | Ratpack
> 700 Ko | Java | Android

178.
Reactive Streams
RxJava | Akka Streams | Reactor Composable | Ratpack
> 2.5 Mo | Scala | Akka

179.
Reactive Streams
RxJava | Akka Streams | Reactor Composable | Ratpack
~1Mo | Java | RingBufferDispatcher

180.
Reactive Streams
RxJava | Akka Streams | Reactor Composable | Ratpack
Java 8 | Http

181.
Si il ne fallait retenir qu’une chose

182.
Si il ne fallait retenir qu’une chose
RxJava est un modèle de programmation pour
écrire des applications asynchrones
Frontend | Backend | Crossplatform

183.
Questions ?
david.wursteisen@soat.fr
@dwursteisen