RxJava - Getting Started

Les applications sont de plus en plus interconnectées. Une architecture type WOA (Web Oriented Archiecture) et l’utilisation des micros-services nécessitent de faire de plus en plus appel à différents services web. Comment composer un résultat à partir de ces différents services, sans avoir à ce soucier de l’ordre dans lequel les serveurs vont répondre ?

RxJava offre une manière élégante de faire de l’asynchrone et de la composition au sein de son application. David vous exposera les concepts de Rx (Reactive eXtension) avant de vous montrer une mise en application avec des exemples de code venant d’une application Android.

David Wursteisen / Soat / 16 Octobre 2014

Transcript

2. Getting Started RxJava David Wursteisen 16 Octobre 2014
3. David Wursteisen @dwursteisen Direction Expertise Innovation
4. David Wursteisen
5. Architecture distribuée Sync/Async/Concurrence
6. Architecture distribuée
7. Architecture distribuée
8. Architecture distribuée The Internet
9. Architecture distribuée The Internet
10. Synchrone
11. Synchrone Appel bloquant
12. Asynchrone
13. Asynchrone Appel non bloquant
14. Complexité
15. Complexité future.get();
16. Complexité future1.get(); future2.get(); future3.get(); future4.get(); future5.get(); future6.get(); future7.get();
17. Complexité future1.get(); future2.get(); future3.get(); future4.get(); future5.get(); future6.get(); future7.get(); Ordonnancement optimal ?
18. Complexité 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) { } }); } });
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) { } }); } });
21. 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
22. Concurrence
23. Concurrence
24. Concurrence Concurrence
25. Concurrence
26. Concurrence RxJava permet de manipuler des évènements d’une manière synchrone et/ou asynchrone.
27. Historique Il était une fois...
28. Historique
29. Historique
30. Historique
31. Historique
32. Historique ReactiveX.io
33. Observables Travailler avec des flux
34. Flux d’évènements fini Évènements Fin du flux
35. Flux d’évènements en erreur Évènements Erreur
36. Flux d’évènements infini Évènements
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(...)
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
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 2 3
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(...) 1 4400
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(...) 0 t t + 5 secondes
43. 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
44. Flux d’évènements λ ϕ φ json json json Observable<json> Observable<Integer> Observable<Click>
45. Observer Push des données
46. Observer OnNext* (OnCompleted|OnError)?
47. Observer OnNext* (OnCompleted|OnError)?
48. Observer OnNext* (OnCompleted|OnError)?
49. Observer OnNext* (OnCompleted|OnError)?
50. Observer Observable.range(1, 4400)
51. Observer Observable.range(1, 4400).subscribe()
52. Observer Observable.range(1, 4400).subscribe(onNext)
53. Observer Observable.range(1, 4400).subscribe(System.out::println)
54. Observer Observable.range(1, 4400).subscribe(System.out::println, onError)
55. Observer Observable.range(1, 4400).subscribe(System.out::println, System.err::println)
56. Observer Observable.range(1, 4400).subscribe(System.out::println, System.err::println, onCompleted)
57. Observer Observable.range(1, 4400).subscribe(System.out::println, System.err::println, () -> System.out.println(“finished”))
58. Manipulation d’évènements Quand l’écoute ne suffit plus
59. Manipulation d’évènements 0 1
60. Manipulation d’évènements 0 1 map
61. Manipulation d’évènements 0 1 A B map
62. Manipulation d’évènements 1 4
63. Manipulation d’évènements 1 4 filter ( x <= 2 )
64. Manipulation d’évènements 1 4 1 filter ( x <= 2 )
65. Manipulation d’évènements 1 2
66. Manipulation d’évènements 1 2 delay ( 5, SECONDS )
67. Manipulation d’évènements 1 2 1 delay ( 5, SECONDS ) 2
68. Manipulation d’évènements Observable.from(0, 1, 2, 3, 4) Observable<Integer>
69. Manipulation d’évènements Observable.from(0, 1, 2, 3, 4) .filter((i) -> i < 3) Observable<Integer> Observable<Integer>
70. Manipulation d’évènements Observable.from(0, 1, 2, 3, 4) .filter((i) -> i < 3) .delay(5, TimeUnit.SECONDS) Observable<Integer> Observable<Integer> Observable<Integer>
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'))) 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); Observable<Integer> Observable<Integer> Observable<Integer> Observable<String>
73. 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>
74. Manipulation d’évènements
75. Manipulation d’évènements
76. Manipulation d’évènements
77. Composition Création d’un flux à partir d’un ensemble de flux
78. Composition
79. Composition
80. Composition
81. Mise en pratique de composition Learn from the trenches
82. Composition
83. Composition
84. Composition
85. Composition
86. Composition
87. Composition merge
88. Composition merge
89. Composition
90. Composition
91. Composition zip
92. Composition zip
93. Subscription Et gestion de l’unsubscribe
94. Subscription Observable.create(new OnSubscribe<T>() { … });
95. Subscription Observable.create(new OnSubscribe<T>() { @Override public void call(Subscriber<? super T> s) { s.onNext(123); s.onCompleted(); } });
96. Subscription Observable.create(new OnSubscribe<T>() { @Override public void call(Subscriber<? super T> s) { s.onNext(123); s.onCompleted(); } }); Émission synchronne
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); } }); } });
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); } }); } }); Émission asynchronne
101. 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
102. Subscription La souscription permet d’uniformiser des API différentes par leurs natures (Callback, etc...)
103. Unsubscribe Subscription subscription = Observable.interval(1, TimeUnit.SECONDS).subscribe();
104. Unsubscribe Subscription subscription = Observable.interval(1, TimeUnit.SECONDS).subscribe(); Souscription
105. Unsubscribe Subscription subscription = Observable.interval(1, TimeUnit.SECONDS).subscribe(); Handler sur la souscription
106. Unsubscribe Subscription subscription = Observable.interval(1, TimeUnit.SECONDS).subscribe(); /* ... */ subscription.unsubscribe();
107. Unsubscribe Subscription subscription = Observable.interval(1, TimeUnit.SECONDS).subscribe(); /* ... */ subscription.unsubscribe(); Arrêt de la souscription
108. Schedulers
109. Schedulers observableReadingSynchronously(“strings.txt”) .take(10) .delay(1, SECONDS) .map(parse()) .map(n -> “=> ” + n)) .subscribe(to_the_view())
110. Schedulers main
111. Schedulers observableReadingSynchronously(“strings.txt”) .take(10) .delay(1, SECONDS) .map(parse()) .map(n -> “=> ” + n)) .subscribe(to_the_view())
112. Schedulers Computation IO UI main
113. Schedulers Computation IO UI main
114. Schedulers Computation IO UI main
115. Schedulers Computation IO UI main
116. Schedulers Computation IO UI main
117. Schedulers Computation IO UI main
118. Schedulers observableReadingSynchronously(“strings.txt”) .subscribeOn(scheduler) .take(10) .delay(1, SECONDS, scheduler) .map(parse()) .observeOn(scheduler) .map(n -> “=> ” + n)) .subscribe(to_the_view())
119. 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())
120. Schedulers UI Computation
121. Schedulers UI Computation
122. Schedulers UI Computation
123. Schedulers UI Computation
124. Schedulers UI Computation
125. Hot & Cold Observable
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); 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); Subscribe
130. Cold Observable Observable<Integer> obs = Observable.from(1, 2, 3, 4); obs.subscribe(System.out::println); obs.subscribe(System.out::println); Souscription différente
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); 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(); Subscribe
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(); Partage la même souscription
138. Hot Observable ConnectableObservable<Integer> obs = Observable.from(1, 2, 3, 4).publish(); obs.subscribe(System.out::println); obs.subscribe(System.out::println); obs.connect();
139. Hot Observable ConnectableObservable<Integer> obs = Observable.from(1, 2, 3, 4).publish(); obs.connect(); obs.subscribe(System.out::println); obs.subscribe(System.out::println); Souscription
140. Cold & Hot Observable Cold Observable = flux passif Hot Observable = flux actif
141. Back Pressure Contrôler la production
142. Back Pressure Production
143. Back Pressure Production buffer
144. Back Pressure Production Pression arrière
145. Back Pressure Production Pression arrière Demande de production de n élements
146. Retour d’expérience
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) .reduce(new LinkedList<Integer>(), (seed, value) -> { seed.add(value); return seed; }) .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);
151. Opérateurs Observable.from(1, 2, 3, 4) .toList() .first() .subscribe(System.out::println); Différence entre first() / single() / take(1) ?
152. Gestion des erreurs Observable.from(1, 2, 3, 4) .toList() .single() .subscribe(System.out::println);
153. Gestion des erreurs Observable.from(1, 2, 3, 4) .toList() .single() .subscribe(System.out::println); Notification des erreurs absentes
154. Gestion des erreurs static { RxJavaPlugins.getInstance().registerErrorHandler(new RxJavaErrorHandler() { @Override public void handleError(Throwable e) { e.printStackTrace(); } }); }
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); } });
156. 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
157. Lambda & Java 8 Observable.from(1, 2, 3, 4) .filter(i -> i > 3) .subscribe(System.out::println);
158. 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
159. Concurrence obs1.mergeWith(obs2) .take(5) .subscribe(System.out::println);
160. Concurrence obs1.mergeWith(obs2) .take(5) .subscribe(System.out::println);
161. Concurrence obs1.mergeWith(obs2) .take(5) .subscribe(System.out::println); Doit gérer la concurrence
162. Concurrence obs1.mergeWith(obs2) .take(5) .subscribe(System.out::println);
163. Concurrence obs1.mergeWith(obs2) .take(5) .subscribe(System.out::println); non concurrence
164. Sync & Async Observable<Integer> generator();
165. Sync & Async Observable<Integer> generator(); Sync ?
166. Sync & Async Observable<Integer> generator(); Sync ? Async ?
167. Sync & Async Observable<Integer> generator(); Sync ? Async ? Computation ?
168. Sync & Async Observable<Integer> generator(); Sync ? Async ? Computation ? Acteur ?
169. “Leak” des Observables everything is an event
170. “Leak” des Observables ViewPager
171. “Leak” des Observables ViewPager Preferences Observable
172. “Leak” des Observables ViewPager Preferences UserService Observable Observable
173. Future<RxJava>
174. Future<RxJava> Support RxJava
175. Reactive Streams
176. 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/
177. Reactive Streams RxJava | Akka Streams | Reactor Composable | Ratpack
178. Reactive Streams RxJava | Akka Streams | Reactor Composable | Ratpack > 700 Ko | Java | Android
179. Reactive Streams RxJava | Akka Streams | Reactor Composable | Ratpack > 2.5 Mo | Scala | Akka
180. Reactive Streams RxJava | Akka Streams | Reactor Composable | Ratpack ~1Mo | Java | RingBufferDispatcher
181. Reactive Streams RxJava | Akka Streams | Reactor Composable | Ratpack Java 8 | Http
182. Si il ne fallait retenir qu’une chose
183. Si il ne fallait retenir qu’une chose RxJava est un modèle de programmation pour écrire des applications asynchrones Frontend | Backend | Crossplatform
184. Questions ? david.wursteisen@soat.fr @dwursteisen