Christoph Strobl Pivotal Software Inc. - JUG Saxony Day · Unless otherwise indicated, these slides...

Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under aCreative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/

Going with .

Christoph Strobl Pivotal Software Inc.

@stroblchristoph

http://creativecommons.org/licenses/by-nc/3.0/




In a nutshell, reactive programming is about non-blocking, event-driven applications

that scale with a small number of threadswith back pressure as a key ingredient

that aims to ensure producers to not overwhelm consumers.(Rossen Stoyanchev)




The next 60 Minutes

3 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under aCreative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/

- A bit of recent history.

- Project Reactor / Spring Data Kay / Spring Framework 5.

- Some Code.




A bit of recent history.


Sept 28

5.0 GA

Dec 2017

Oct 2017

Kay GA 2.0 GA

Sept 25

3.1 GA

Sept 29

5.0 M1

Jul 2016

Kay M1

Sept 2016

Nov 2016

3.0 GA

Sept 2015 Sept 21

9




Imperative Applications


{…}




Imperative Applications - Batching


{…}Batching




Imperative Applications - Async


{…}

Dispatcher

Thread: Worker A

Thread: Worker B

Thread: Worker C




Reactive Applications


{…}Subscriber PublisherStream




Reactive Applications


{…}Subscriber PublisherStream

.block()




NoSQL for the win!






Iterator.next() Future.get()

Subscriber.onNext(t)

Remember

vs




Reactor 3.1





Reactive Streams


Provider of a potentially unbounded number of sequenced elements.Publisher<T>

Subscriber<T>

A processing stage - actually both a Subscriber and a Publisher.Processor<T,R>

One-to-one lifecycle of a Subscriber subscribing to a Publisher.Subscription





Publisher<T>

Subscriber<T>

Processor<T,R>

Subscription

.subscribe(Subscriber)

.onSubscribe(Subscription)

.request(long)

.onNext(T)

Reactive Streams




Project Reactor


Publisher<T> (0…n)

Flux<T> (0…n) Mono<T> (0…1)

Reactive Streams




Project Reactor


Publisher<T> (0…n)

Flux<T> (0…n) Mono<T> (0…1)

Reactive Streams

Mono<User> findByEmail(String email);

Flux<User> findByName(String name);

#jürgenized




Flux


[fluhks] - a flowing or flow

Flux.just("red", "white", "blue") .flatMap(v !-> Mono.fromCallable(blockingStuff(v)) .subscribeOn(Schedulers.elastic())) .collect(Result!::new, Result!::add) .doOnNext(Result!::stop) .subscribe(doWithResult);




Mono


[mon-oh] - alone, single, one

Mono.fromCallable(blockingStuff()) .map(v !-> unwarp(v)) .subscribe();




Reactive Applications with Spring


Spring Framework5

Project Reactor3.1

Spring DataKay





Apply familiar conceptsto an new way of expressing functionality.

With minimal fluff and surprise!




Reactive Template (MongoDB)


/** * Query for a {@link Flux} of objects of type T from the specified collection. * * @param entityClass the parametrized type of the returned {@link Flux}. * @param collectionName name of the collection to retrieve the objects from * @return the converted collection */<T> Flux<T> findAll(Class<T> entityClass, String collectionName);

/** * Map the results of an ad-hoc query on the collection for the entity class to a * single instance of an object of the * specified type. * @param query the query class that specifies the criteria * @param entityClass the parametrized type of the returned {@link Mono}. * @return the converted object */<T> Mono<T> findOne(Query query, Class<T> entityClass);




Reactive Repository


<S extends T> Mono<S> save(S entity);

<S extends T> Mono<S> save(Mono<S> entity); <S extends T> Flux<S> saveAll(Iterable<S> entities);

<S extends T> Flux<S> saveAll(Publisher<S> entities); Mono<Boolean> existsById(Mono<ID> id); Flux<T> findAll(); Mono<Long> count(); Mono<Void> deleteById(ID id);




Spring Data Reactive


interface Repo extends ReactiveCrudRepository<Person, String> {

}

Flux<Person> findAllByLastname(String lastname); Flux<Person> findAllByLastname(Mono<String> lastname);

Flux<Person> customQuery(String lastname); @Query("{lastname : ?0}");

Flux<Person> findAllByLastname(String ln, Pageable page);




Spring WebFlux


@RestController static class PersonController { PersonRepository repository; }

@GetMapping("/")Flux<Person> fluxPersons(String name) { return repository.findAllByName(name);}





It’s Demo Time

https://github.com/christophstrobl/going-reactive-with-spring-data




Spring Data - Reactive Repository


interface PersonRepository extends ReactiveCrudRepository<Person, String> {

}

Flux.interval(Duration.ofSeconds(1)) .zipWith(starks) .map(Tuple2!::getT2) .flatMap(repository!::save) .subscribe();

String[] names = { "Eddard", "Catelyn", "Jon", "Rob", "Sansa", "Aria", "Bran", "Rickon" };

Flux<Person> starks = Flux .fromStream(Stream.generate(() !-> names[ramdom.nextInt(names.length)]) .map(Person!::new));




Spring Data - Reactive Repository



}

Flux.interval(Duration.ofSeconds(1)) .zipWith(starks) .map(Tuple2!::getT2) .flatMap(repository!::save) .subscribe();

String[] names = { "Eddard", "Catelyn", "Jon", "Rob", "Sansa", "Aria", "Bran", "Rickon" };

Flux<Person> starks = Flux .fromStream(Stream.generate(() !-> names[ramdom.nextInt(names.length-1)]) .map(Person!::new));

> cstrobl $ ./bin/mongo --port 52291

> use test switched to db test

{ "_id" : ObjectId("591009c5ed68a820fb9956a5"), "name" : "Sansa", "_class" : "com.example.DemoApplication$Person" } { "_id" : ObjectId("591009c6ed68a820fb9956a6"), "name" : "Rob", "_class" : "com.example.DemoApplication$Person" } { "_id" : ObjectId("591009c7ed68a820fb9956a7"), "name" : "Sansa", "_class" : "com.example.DemoApplication$Person" } { "_id" : ObjectId("591009c8ed68a820fb9956a8"), "name" : "Rob", "_class" : "com.example.DemoApplication$Person" } { "_id" : ObjectId("591009c9ed68a820fb9956a9"), "name" : "Jon", "_class" : "com.example.DemoApplication$Person" } { "_id" : ObjectId("591009caed68a820fb9956aa"), "name" : "Aria", "_class" : "com.example.DemoApplication$Person" } { "_id" : ObjectId("591009cbed68a820fb9956ab"), "name" : "Rob", "_class" : "com.example.DemoApplication$Person" } { "_id" : ObjectId("591009cced68a820fb9956ac"), "name" : "Jon", "_class" : "com.example.DemoApplication$Person" } { "_id" : ObjectId("591009cded68a820fb9956ad"), "name" : "Sansa", "_class" : "com.example.DemoApplication$Person" }

> db.person.find();




Spring - WebFlux



Flux<Person> findAllByName(String name); }






Spring - WebFlux



Flux<Person> findAllByName(String name); }



> cstrobl $ curl localhost:8080/?name=Eddard | jq

[ { "name": "Eddard", "id": "591014f2756bac231a23f3a0" }, { "name": "Eddard", "id": "591014f7756bac231a23f3a5" } ]

>




RxJava types



Observable<Person> findByName(String name); }

@RestController static class PersonController { PersonRepository repository; @GetMapping("/rx") Observable<Person> rxPersons(String name) { return repository.findByName(name); }}




RxJava types



Observable<Person> findByName(String name); }

@RestController static class PersonController { PersonRepository repository; @GetMapping("/rx") Observable<Person> rxPersons(String name) { return repository.findByName(name); }}

> cstrobl $ curl localhost:8080/rx?name=Rob | jq [ { "name": "Rob", "id": "590f6e99756bac18a8d62bfe" }, { "name": "Rob", "id": "590f6e9d756bac18a8d62c02" } { "name": "Rob", "id": "590f6e9e756bac18a8d62c03" } ]

>




Tailable Cursors & Event Stream



@Tailable Flux<Person> findBy(); }

@RestController static class PersonController { PersonRepository repository; @GetMapping(value = "/stream", produces = MediaType.TEXT_EVENT_STREAM_VALUE) Flux<Person> streamPersons() { return repository.findBy(); }}




Tailable Cursors & Event Stream



@Tailable Flux<Person> findBy(); }

@RestController static class PersonController { PersonRepository repository; @GetMapping(value = "/stream", produces = MediaType.TEXT_EVENT_STREAM_VALUE) Flux<Person> streamPersons() { return repository.findBy(); }}

> cstrobl $ curl localhost:8080/stream

data:{"name":"Sansa","id":"5910192e756bac26079dd623"}

data:{"name":"Jon","id":"5910192f756bac26079dd624"}

data:{"name":"Catelyn","id":"59101930756bac26079dd625"}

data:{"name":"Eddard","id":"59101931756bac26079dd626"}

data:{"name":"Jon","id":"59101932756bac26079dd627"}

data:{"name":"Eddard","id":"59101933756bac26079dd628"}




WebFlux - Router Functions


@Componentstatic class PersonHandler {

PersonRepository repository;

Mono<ServerResponse> streamPersons(ServerRequest request) { return ServerResponse.ok() .contentType(MediaType.TEXT_EVENT_STREAM) .body(personRepository.findBy(), Person.class); }

@BeanRouterFunction<ServerResponse> routes(PersonHandler requestHandler) { return RouterFunctions .route(RequestPredicates.GET("/stream"), requestHandler!::streamPersons) }




Spring - WebClient


@BeanWebClient client() { return WebClient.create("http:!//localhost:8080/");}@BeanCommandLineRunner run(WebClient client) { return (args) !-> { client.get() .uri("/stream") .retrieve() .bodyToFlux(Person.class) .subscribe(System.out!::println); };}





Reactive is about efficient resource usage. Even if backed with familiar concepts and framework support,

it is no free lunch. The price is complexity.




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Christoph Strobl Pivotal Software Inc. - JUG Saxony Day · Unless otherwise indicated, these slides...

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