RxJava in Microservices World

Transcript

1. 26-27/05/2016
   RxJava in Microservices
   World
   Piotr Kafel (@PiotrKafel)
   

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2. 26-27/05/2016
   Microservices
   

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3. 26-27/05/2016
   Trade-offs
   

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4. 26-27/05/2016
   Microservices
   time
   

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5. 26-27/05/2016
   Microservices
   time
   

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6. 26-27/05/2016
   CompletableFuture
   CompletableFuture result = getUuid().thenApply(this::getString);
   public CompletableFuture getUuid() {
   // incredibly smart code goes here
   }
   public String getString(UUID uuid) {
   // incredibly smart code goes here
   }
   

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7. 26-27/05/2016
   CompletableFuture
   CompletableFuture>> ohMyGod = getUuids()
   .thenApply(uuids -> uuids.stream()
   .map(this::getString)
   .collect(Collectors.toList()));
   public CompletableFuture> getUuids() {
   // incredibly smart code goes here
   }
   public CompletableFuture getString(UUID uuid) {
   // incredibly smart code goes here
   }
   

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8. 26-27/05/2016
   Observable
   Observable result = getUuids().flatMap(this::getString);
   public Observable getUuids() {
   // incredibly smart code goes here
   }
   public Observable getString(UUID uuid) {
   // incredibly smart code goes here
   }
   

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9. 26-27/05/2016
   RxJava
   

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10. 26-27/05/2016
    Observable
    Observable.create(subscriber -> {
    subscriber.onNext("Hello World !");
    subscriber.onCompleted();
    }).forEach(System.out::println);
    

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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);
    

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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()
    );
    

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13. 26-27/05/2016
    Documentation
    

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14. 26-27/05/2016
    Example
    public Observable retrieveDivisions (List 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)));
    }
    

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15. 26-27/05/2016
    Pattern
    doHttpCallForUUids()
    .buffer(50)
    .flatMap(listOfUuids -> doHttpCallForEntities(listOfUuids));
    

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16. 26-27/05/2016
    Pattern
    doHttpCall().retry(
    (i, throwable) -> i < 5 && throwable instanceof Status503Exception
    );
    

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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);
    }
    }));
    

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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)
    

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19. 26-27/05/2016
    Adaptation
    Observable.defer(() -> Observable.just(completelySynchronousHttpCall()))
    .subscribeOn(Schedulers.io());
    

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20. 26-27/05/2016
    Testing
    TestSubscriber 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);
    

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21. 26-27/05/2016
    Retrofit
    

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22. 26-27/05/2016
    Retrofit
    public interface InventoryUnitClient {
    @GET("/inventory/v2/{entity}/search/redemption")
    Observable getInventoryUnitRedemption(
    @Path("uuid") UUID uuid);
    @POST("/inventory/v2/{entity}/search/redemption")
    Observable redeemUnit(
    @Path("uuid") UUID uuid,
    @Body JsonHolder redemption);
    }
    

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23. 26-27/05/2016
    Hystrix
    

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24. 26-27/05/2016
    Hystrix
    public class CommandHelloWorld extends HystrixCommand {
    private final String name;
    public CommandHelloWorld(String name) {
    super(HystrixCommandGroupKey.Factory.asKey("ExampleGroup"));
    this.name = name;
    }
    @Override
    protected String run() {
    return "Hello " + name + "!";
    }
    }
    

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25. 26-27/05/2016
    Spring
    

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26. 26-27/05/2016
    Spring
    @RequestMapping(value = PATH_ACCOUNT_MANAGERS, method = RequestMethod.GET)
    public DeferredResult getAccountManagers() {
    DeferredResult result = new DeferredResult<>();
    getAccountManagersObservable().subscribe(
    item -> result.setResult(item),
    exception -> result.setErrorResult(exception)
    );
    return result;
    }
    

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27. 26-27/05/2016
    Wow, is it really that cool !?
    

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28. 26-27/05/2016
    That’s all folks !
    

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