Going Reactive with Spring (JugSaxonyDay 2017)

Transcript

1. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
   
   Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
   Going with .
   Christoph Strobl

   Pivotal Software Inc.

   @stroblchristoph
   

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2. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
   
   Creative Commons Attribution-NonCommercial license: 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 threads

   with back pressure as a key ingredient

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

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3. The next 60 Minutes
   3 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
   
   Creative 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.
   

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4. A bit of recent history.
   Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
   
   Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
   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
   

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5. Imperative Applications
   5 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
   
   Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
   {…}
   

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6. Imperative Applications - Batching
   6 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
   
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   {…}
   Batching
   

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7. Imperative Applications - Async
   7 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
   
   Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
   {…}
   Dispatcher
   Thread: Worker A
   Thread: Worker B
   Thread: Worker C
   

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8. Reactive Applications
   8 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
   
   Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
   {…}
   Subscriber Publisher
   Stream
   

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9. Reactive Applications
   9 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
   
   Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
   {…}
   Subscriber Publisher
   Stream
   .block()
   

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10. NoSQL for the win!
    10 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    

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11. 11 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    Iterator.next()
    Future.get()
    Subscriber.onNext(t)
    Remember
    vs
    

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12. Reactor 3.1
    Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    

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13. Reactive Streams
    13 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    Provider of a potentially unbounded number of sequenced elements.
    Publisher
    Subscriber
    A processing stage - actually both a Subscriber and a Publisher.
    Processor
    One-to-one lifecycle of a Subscriber subscribing to a Publisher.
    Subscription
    

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14. 14 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    Publisher
    Subscriber
    Processor
    Subscription
    .subscribe(Subscriber)
    .onSubscribe(Subscription)
    .request(long)
    .onNext(T)
    Reactive Streams
    

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15. View Slide

16. Project Reactor
    16 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    Publisher (0…n)
    Flux (0…n) Mono (0…1)
    Reactive Streams
    

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17. Project Reactor
    17 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    Publisher (0…n)
    Flux (0…n) Mono (0…1)
    Reactive Streams
    Mono findByEmail(String email);
    Flux findByName(String name);
    #jürgenized
    

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18. Flux
    18 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    [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);
    

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19. Mono
    19 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    [mon-oh] - alone, single, one
    Mono.fromCallable(blockingStuff())
    .map(v !-> unwarp(v))
    .subscribe();
    

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20. Reactive Applications with Spring
    Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    Spring Framework

    5
    Project Reactor

    3.1
    Spring Data

    Kay
    

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

    to an new way of expressing functionality.

    With minimal fluff and surprise!
    

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22. Reactive Template (MongoDB)
    22 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    /**

    * 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

    */

    Flux findAll(Class 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

    */

    Mono findOne(Query query, Class entityClass);
    

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23. Reactive Repository
    23 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    Mono save(S entity);
    Mono save(Mono entity);
    Flux saveAll(Iterable entities);
    Flux saveAll(Publisher entities);
    Mono existsById(Mono id);
    Flux findAll();
    Mono count();
    Mono deleteById(ID id);
    

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24. Spring Data Reactive
    24 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    interface Repo extends ReactiveCrudRepository {
    }
    Flux findAllByLastname(String lastname);
    Flux findAllByLastname(Mono lastname);
    Flux customQuery(String lastname);
    @Query("{lastname : ?0}");
    Flux findAllByLastname(String ln, Pageable page);
    

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25. Spring WebFlux
    25 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    @RestController

    static class PersonController {

    

    PersonRepository repository;

    

    

    

    

    

    

    }
    @GetMapping("/")

    Flux fluxPersons(String name) {

    return repository.findAllByName(name);

    }

    

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26. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    It’s Demo Time
    https://github.com/christophstrobl/going-reactive-with-spring-data
    

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27. Spring Data - Reactive Repository
    27 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    interface PersonRepository extends ReactiveCrudRepository {
    }
    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 starks = Flux

    .fromStream(Stream.generate(() !-> 

    names[ramdom.nextInt(names.length)])

    .map(Person!::new));
    

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28. Spring Data - Reactive Repository
    28 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    interface PersonRepository extends ReactiveCrudRepository {
    }
    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 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();
    

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29. Spring - WebFlux
    29 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    interface PersonRepository extends ReactiveCrudRepository {
    Flux findAllByName(String name);
    }
    @RestController

    static class PersonController {

    

    PersonRepository repository;

    

    

    

    

    

    

    }
    @GetMapping("/")

    Flux fluxPersons(String name) {

    return repository.findAllByName(name);

    }

    

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30. Spring - WebFlux
    30 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    interface PersonRepository extends ReactiveCrudRepository {
    Flux findAllByName(String name);
    }
    @RestController

    static class PersonController {

    

    PersonRepository repository;

    

    

    

    

    

    

    }
    @GetMapping("/")

    Flux fluxPersons(String name) {

    return repository.findAllByName(name);

    }

    > cstrobl $ curl localhost:8080/?name=Eddard | jq
    [
    {
    "name": "Eddard",
    "id": "591014f2756bac231a23f3a0"
    },
    {
    "name": "Eddard",
    "id": "591014f7756bac231a23f3a5"
    }
    ]
    >
    

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31. RxJava types
    31 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    interface PersonRepository extends ReactiveCrudRepository {
    Observable findByName(String name);
    }
    @RestController

    static class PersonController {

    

    PersonRepository repository;

    

    @GetMapping("/rx")

    Observable rxPersons(String name) {

    return repository.findByName(name);

    }

    }
    

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32. RxJava types
    32 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    interface PersonRepository extends ReactiveCrudRepository {
    Observable findByName(String name);
    }
    @RestController

    static class PersonController {

    

    PersonRepository repository;

    

    @GetMapping("/rx")

    Observable 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"
    }
    ]
    >
    

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33. Tailable Cursors & Event Stream
    33 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    interface PersonRepository extends ReactiveCrudRepository {
    @Tailable Flux findBy();
    }
    @RestController

    static class PersonController {

    

    PersonRepository repository;

    

    @GetMapping(value = "/stream", produces = MediaType.TEXT_EVENT_STREAM_VALUE)
    Flux streamPersons() {

    return repository.findBy();

    }

    }
    

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34. Tailable Cursors & Event Stream
    34 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    interface PersonRepository extends ReactiveCrudRepository {
    @Tailable Flux findBy();
    }
    @RestController

    static class PersonController {

    

    PersonRepository repository;

    

    @GetMapping(value = "/stream", produces = MediaType.TEXT_EVENT_STREAM_VALUE)
    Flux 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"}
    

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35. WebFlux - Router Functions
    35 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    @Component

    static class PersonHandler {
    PersonRepository repository;
    Mono streamPersons(ServerRequest request) {
    return ServerResponse.ok()

    .contentType(MediaType.TEXT_EVENT_STREAM)

    .body(personRepository.findBy(), Person.class);
    }
    @Bean

    RouterFunction routes(PersonHandler requestHandler) {
    

    return RouterFunctions

    .route(RequestPredicates.GET("/stream"), requestHandler!::streamPersons)
    }
    

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36. Spring - WebClient
    36 Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    @Bean

    WebClient client() {

    return WebClient.create("http:!//localhost:8080/");

    }

    

    @Bean

    CommandLineRunner run(WebClient client) {

    

    return (args) !-> {

    

    client.get()

    .uri("/stream")

    .retrieve()

    .bodyToFlux(Person.class)

    .subscribe(System.out!::println);

    };

    }
    

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