RxJava in Microservices World

1. 26-27/05/2016 RxJava in Microservices World Piotr Kafel (@PiotrKafel)
2. 26-27/05/2016 Microservices
3. 26-27/05/2016 Trade-offs
4. 26-27/05/2016 Microservices time
5. 26-27/05/2016 Microservices time
6. 26-27/05/2016 CompletableFuture CompletableFuture<String> result = getUuid().thenApply(this::getString); public CompletableFuture<UUID> getUuid() { // incredibly smart code goes here } public String getString(UUID uuid) { // incredibly smart code goes here }
7. 26-27/05/2016 CompletableFuture CompletableFuture<List<CompletableFuture<String>>> ohMyGod = getUuids() .thenApply(uuids -> uuids.stream() .map(this::getString) .collect(Collectors.toList())); public CompletableFuture<List<UUID>> getUuids() { // incredibly smart code goes here } public CompletableFuture<String> getString(UUID uuid) { // incredibly smart code goes here }
8. 26-27/05/2016 Observable Observable<String> result = getUuids().flatMap(this::getString); public Observable<UUID> getUuids() { // incredibly smart code goes here } public Observable<String> getString(UUID uuid) { // incredibly smart code goes here }
9. 26-27/05/2016 RxJava
10. 26-27/05/2016 Observable Observable.create(subscriber -> { subscriber.onNext("Hello World !"); subscriber.onCompleted(); }).forEach(System.out::println);
11. 26-27/05/2016 Observable Observable.create(subscriber -> { subscriber.onNext("Hello"); subscriber.onNext("World"); subscriber.onNext("!"); subscriber.onCompleted(); }) .subscribeOn(Schedulers.newThread()) .forEach(System.out::println);
12. 26-27/05/2016 Observable Observable.create(subscriber -> { try { subscriber.onNext(doSomething()); subscriber.onCompleted(); } catch(Exception e) { subscriber.onError(e); } }).forEach( i -> System.out.print(i), e -> e.printStackTrace() );
13. 26-27/05/2016 Documentation
14. 26-27/05/2016 Example public Observable<DealDivision> retrieveDivisions (List <UUID> divisions) { Locale locale = locale(); return Observable.from(divisions) .flatMap(divisionId -> geoPlacesClient.getDivisionsById(divisionId)) .filter(resp -> resp.status == SUCCESS) .flatMapIterable(resp -> resp.data) .filter(div -> div.status == Status.ACTIVE) .map(div -> new DealDivision( div.uuid.toString(), div.getNameOrDefault(locale))); }
15. 26-27/05/2016 Pattern doHttpCallForUUids() .buffer(50) .flatMap(listOfUuids -> doHttpCallForEntities(listOfUuids));
16. 26-27/05/2016 Pattern doHttpCall().retry( (i, throwable) -> i < 5 && throwable instanceof Status503Exception );
17. 26-27/05/2016 Pattern doHttpCall().retryWhen(errorObservable -> errorObservable .zipWith(Observable.range(1, numberOfRetries), Pair::of) .flatMap(pair -> { if(pair.getRight() == numberOfRetries) { return Observable.error(pair.getLeft()); } else { return Observable.timer(wait, TimeUnit.MILLISECONDS); } }));
18. 26-27/05/2016 Pattern Observable.range(1, Integer.MAX_VALUE) .concatMap(page -> doHttpCall(id, page, DEFAULT_PER_PAGE_SIZE)) .map(response -> response.getComments()) .takeWhile(comments -> comments.size() > 0)
19. 26-27/05/2016 Adaptation Observable.defer(() -> Observable.just(completelySynchronousHttpCall())) .subscribeOn(Schedulers.io());
20. 26-27/05/2016 Testing TestSubscriber<String> subscriber = new TestSubscriber<>(); Observable.interval(100, TimeUnit.MILLISECONDS, Schedulers.computation()) .take(5) .map(i -> i + " value") .subscribe(subscriber); subscriber.awaitTerminalEvent(); subscriber.assertNoErrors(); subscriber.assertValueCount(5);
21. 26-27/05/2016 Retrofit
22. 26-27/05/2016 Retrofit public interface InventoryUnitClient { @GET("/inventory/v2/{entity}/search/redemption") Observable<JsonHolder> getInventoryUnitRedemption( @Path("uuid") UUID uuid); @POST("/inventory/v2/{entity}/search/redemption") Observable<JsonHolder> redeemUnit( @Path("uuid") UUID uuid, @Body JsonHolder redemption); }
23. 26-27/05/2016 Hystrix
24. 26-27/05/2016 Hystrix public class CommandHelloWorld extends HystrixCommand<String> { private final String name; public CommandHelloWorld(String name) { super(HystrixCommandGroupKey.Factory.asKey("ExampleGroup")); this.name = name; } @Override protected String run() { return "Hello " + name + "!"; } }
25. 26-27/05/2016 Spring
26. 26-27/05/2016 Spring @RequestMapping(value = PATH_ACCOUNT_MANAGERS, method = RequestMethod.GET) public DeferredResult<AccountManagersResponse> getAccountManagers() { DeferredResult<AccountManagersResponse> result = new DeferredResult<>(); getAccountManagersObservable().subscribe( item -> result.setResult(item), exception -> result.setErrorResult(exception) ); return result; }
27. 26-27/05/2016 Wow, is it really that cool !?
28. 26-27/05/2016 That’s all folks !