Spring Framework 5.0 Themes and Trends

Spring Framework 5.0 Themes and Trends Sébastien Deleuze @sdeleuze Brian
Clozel @bclozel

Unless otherwise indicated, these slides are © 2013-2015 Pivotal Software,
Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Spring Framework 5 ‣ Reactive foundations ‣ Spring WebFlux ‣ Kotlin builtin support ‣ Functional bean registration ‣ Baseline upgrade & cleanup ‣ Java 9 support ‣ Performance improvements 2

Reactive foundations

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Why going Reactive? 4 More for scalability and  stability than for speed

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ What issue are we trying to solve? 5 1 request = 1 thread

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ From blocking to event-based 6 Neutral to latency

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Reactive Streams 7 Publisher Subscriber Backpressure request(n) data 0..N data then 0..1 (Error | Complete)

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ 8

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Reactive Streams is 4 interfaces (and a TCK) 11 public interface Publisher<T> { void subscribe(Subscriber<? super T> s); } public interface Subscriber<T> { void onSubscribe(Subscription s); void onNext(T t); void onError(Throwable t); void onComplete(); } public interface Subscription { void request(long n); void cancel(); } public interface Processor<T, R> extends Subscriber<T>, Publisher<R> { }

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Spring Framework 5 uses Reactor for its Reactive foundations Reactor, RxJava, Akka Streams, etc. 12 Reactive libraries Your web application can use

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Flux<T> • Implements Reactive Streams Publisher • 0 to n elements • Operators: flux.map(…).zip(…).flatMap(…) 13

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Mono<T> • Implements Reactive Streams Publisher • 0 to 1 element • Operators: mono.then(…).otherwise(…) 14

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ StepVeriﬁer 15 StepVerifier.create(flux)  .expectNext("foo", "bar")  .verifyComplete(); ‣ Designed to test easily Reactive Streams Publishers ‣ Carefully designed after writing thousands of Reactor and Spring WebFlux tests

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Blocking versus Reactive API 16 interface ReactiveUserRepository { Mono<User> findOne(String id); Flux<User> findAll(); Mono<Void> save(Mono<User> user); } interface UserRepository { User findOne(String id); List<User> findAll(); void save(User user); } Blocking API Reactive API ‣ Method returns when all the data has  been received ‣ Exceptions thrown when an error occurs ‣ Method returns immediately ‣ Error event instead of throwing exception ‣ Complete event instead of method return ‣ Mono<Void> = error or success, no data ‣ Data comes as events too the  Mono or Flux return value

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Upcoming high-level features 17

Spring WebFlux

spring-webmvc @Controller, @RequestMapping Servlet API Servlet Container spring-webflux HTTP /
Reactive Streams Servlet 3.1, Netty, Undertow Router Functions

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Spring MVC 20 @RestController public class UserController { private final UserRepository repo; public UserController(UserRepository repo) { this.repo = repo; } @GetMapping("/user/{id}") public User findOne(@PathVariable String id) { return repo.findOne(id); } @GetMapping("/user") public List<User> findAll() { return repo.findAll(); } @PostMapping("/user") public void save(@RequestBody User user) { repo.save(user); } } interface UserRepository { User findOne(String id); List<User> findAll(); void save(User user); }

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ WebFlux annotation-based server 21 @RestController public class ReactiveUserController { private final ReactiveUserRepository repo; public ReactiveUserController(ReactiveUserRepository repo) { this.repo = repo; } @GetMapping("/user/{id}") public Mono<User> findOne(@PathVariable String id) { return repo.findOne(id); } @GetMapping("/user") public Flux<User> findAll() { return repo.findAll(); } @PostMapping("/user") public Mono<Void> save(@RequestBody Mono<User> user) { repo.save(user); } } interface ReactiveUserRepository { Mono<User> findOne(String id); Flux<User> findAll(); Mono<Void> save(Mono<User> user); }

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Flux: array versus stream 22 JSON application/json JSON Streaming application/stream+json Server-Sent Events text/event-stream [ {"a": "foo", "b": "bar"}, {"a": "baz", "b": "boo"} ] ‣ Single Jackson invocation ‣ Doesn’t support infinite streams {"a": "foo", "b": "bar"} {"a": "baz", "b": "boo"} … ‣ Jackson invocation per element ‣ Supports infinite streams data: {"a": "foo", "b": "bar"} data: {"a": "baz", "b": "boo"} … @GetMapping("/user") public Flux<User> findAll()

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ WebFlux functional API 23 ‣ Reactive ‣ Client and server ‣ Lightweight ‣ Flexible ‣ Can be use with or without dependency injection! ‣ Simple functional building blocks

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ WebFlux functional server API 24 ‣ RouterFunction Mono<HandlerFunction<ServerResponse>> route(ServerRequest request) ‣ RequestPredicate boolean test(ServerRequest request) ‣ HandlerFunction Mono<ServerResponse> handle(ServerRequest request) ‣ HandlerFilterFunction Mono<ServerResponse> filter(ServerRequest request, HandlerFunction<ServerResponse> next)

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ WebFlux functional server API 25 @Controller public class UserController { public RouterFunction<ServerResponse> route() { return RouterFunctions .route(GET("/users"), this::listUsers) .andRoute(POST("/users"), this::createUser); } Mono<ServerResponse> listUsers(ServerRequest request) { ... } Mono<ServerResponse> createUser(ServerRequest request) { ... } }

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ RequestPredicates 26 ‣ HTTP method ‣ Path ‣ Path prefix ‣ Path extension ‣ Headers ‣ Content type ‣ Accept ‣ Query param

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ New WebClient API 27 WebClient client = WebClient.create(); Mono<GithubUser> githubUser = client .get() .uri("https://api.github.com/users/{username}", username) .exchange() .then(response -> response.bodyToMono(GithubUser.class)); Mono<TwitterUser> twitterUser = client .get() .uri("https://api.twitter.com/1.1/users/show.json?screen_name={username}", username) .exchange() .then(response -> response.bodyToMono(TwitterUser.class)); return githubUser.and(twitterUser, (github, twitter)-> new AppUser(github, twitter));

WebFlux demo

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ WebFlux Streaming Showcase 29 https://github.com/bclozel/webflux-streaming-showcase quote-stream streaming-service GET /quotes  "application/stream+json" GET /quotes/feed  "text/event-stream" MongoDB

Kotlin Support

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Kotlin ‣ Overcome Java limitations ‣ Elegant and pragmatic language ‣ Concise code ‣ Simple and easy to learn ‣ Very good Java interoperability ‣ Embrace both functional and object oriented programming 31

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ How does it compare with … 32 Same conciseness and expressive code,  but Kotlin default static typing and null-safety  make a big diﬀerence. "Kotlin is a software engineering language in contrast to Scala which is a computing science language."  Eric Kolotyluk, Electronic Arts, Scala developer Swift Swift and Kotlin share similar syntax. Swift is coming from native world while Kotlin is coming from JVM world.

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Domain model classes 33 public class User { private String userName; private String firstName; private String lastName; private Point location; public User(String userName, String firstName, String lastName) { this(userName,firstName, lastName, null); } public User(String userName, String firstName, String lastName, Point location) { Assert.notNull(userName); Assert.notNull(firstName); Assert.notNull(lastName); this.userName = userName; this.firstName = firstName; this.lastName = lastName; this.location = location; } public String getUserName() { return userName; } public void setUserName(String userName) { this.userName = userName; } public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } public Point getLocation() { return location; } public void setLocation(Point location) { this.location = location; } @Override public boolean equals(Object o) { if (this == o) { return true; } if (o == null || getClass() != o.getClass()) { return false; } UserJ j = (UserJ) o; if (!userName.equals(j.userName)) { return false; } if (!firstName.equals(j.firstName)) { return false; } if (!lastName.equals(j.lastName)) { return false; } return location != null ? location.equals(j.location) : j.location == null; } @Override public int hashCode() { int result = userName.hashCode(); result = 31 * result + firstName.hashCode(); result = 31 * result + lastName.hashCode(); result = 31 * result + (location != null ? location.hashCode() : 0); return result; } @Override public String toString() { return "User{" + "userName='" + userName + '\'' + ", firstName='" + firstName + '\'' + ", lastName='" + lastName + '\'' + ", location=" + location + '}'; } } data class User(  val userName: String,  val firstName: String?,  val lastName: String?,  val location: Point = Point(0, 0)  ) Generates equals() and hashcode() val = immutable var = mutable String? = nullable String = non-nullable Optional parameter with default value Constructor + properties declaration

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Kotlin is much more than a  "super Java" or than Lombok 34

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ My favorite Kotlin features ‣ Awesome type inference with static typing ‣ Extensions ‣ Reified type parameters ‣ Null safety ‣ Type aliases ‣ Allows to write nice DSL ‣ Smart casts 35

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Spring Initializr 36 https://start.spring.io/#!language=kotlin

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Introducing Kotlin support in Spring Framework 5 37 https://goo.gl/gMnhxN

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Gradle build ﬁles written in Kotlin 38

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ kotlin-spring Gradle and Maven plugin 39 @SpringBootApplication open class Application { @Bean open fun foo() = ... @Bean open fun bar() = ... } Without kotlin-spring @SpringBootApplication class Application { @Bean fun foo() = ... @Bean fun bar() = ... } With kotlin-spring Also available as a kotlin-allopen generic plugin

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ kotlin-noarg Gradle and Maven plugin 40 configure<NoArgExtension> {  annotation("org.springframework.data.mongodb.core.mapping.Document")  } Also available preconfigured for JPA as kotlin-jpa @Document data class User( @Id val login: String, val firstname: String, val lastname: String, val email: String, val company: String? = null, val description: Map<Language, String> = emptyMap(), val logoUrl: String? = null, val role: Role = Role.ATTENDEE)

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Persistence 41 class EventRepository(val template: ReactiveMongoTemplate) { fun findAll() = template.find<Event>(Query().with(Sort("year"))) fun findOne(id: String) = template.findById<Event>(id) fun deleteAll() = template.remove<Event>(Query()) fun save(event: Event) = template.save(event) }

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Extensions 42 // Spring Boot extensions fun run(type: KClass<*>, vararg args: String) = SpringApplication.run(type.java, *args) // Spring Data extensions inline fun <reified T : Any> ReactiveMongoOperations.findById(id: Any): Mono<T> = findById(id, T::class.java) inline fun <reified T : Any> ReactiveMongoOperations.find(query: Query): Flux<T> = find(query, T::class.java) inline fun <reified T : Any> ReactiveMongoOperations.findAll(): Flux<T> = findAll(T::class.java) inline fun <reified T : Any> ReactiveMongoOperations.findOne(query: Query): Mono<T> = find(query, T::class.java).next() inline fun <reified T : Any> ReactiveMongoOperations.remove(query: Query): Mono<DeleteResult> = remove(query, T::class.java) // Other extensions fun ServerRequest.language() = Language.findByTag(this.headers().header(HttpHeaders.ACCEPT_LANGUAGE).first())

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Spring MVC 43 @RestController class UserController(val repo: UserRepository) { @GetMapping("/user/{id}") fun findOne(@PathVariable id: String) = repo.findOne(id) @GetMapping("/user") fun findAll() = repo.findAll() @PostMapping("/user") fun save(@RequestBody user: User) = repo.save(user) } interface UserRepository { fun findOne(id: String): User fun findAll(): List<User> fun save(user: User) } Classes and functions are public by default Static typing + type inference Constructor injection without @Autowired if single constructor

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Spring WebFlux annotation-based 44 @RestController class ReactiveUserController(val repository: ReactiveUserRepository) { @GetMapping("/user/{id}") fun findOne(@PathVariable id: String) = repository.findOne(id) @GetMapping("/user") fun findAll() = repository.findAll() @PostMapping("/user") fun save(@RequestBody user: Mono<User>) = repository.save(user) } interface ReactiveUserRepository { fun findOne(id: String): Mono<User> fun findAll(): Flux<User> fun save(user: Mono<User>): Mono<Void> }

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Spring WebFlux functional Kotlin DSL 45 router { "/blog" { findAllView(it) } "/blog/{slug}" { findOneView(it) } "/api/blog" { findAll(it) } "/api/blog/{id}" { findOne(it) } } Simple path request predicate

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Spring WebFlux functional Kotlin DSL 46 router { GET("/blog") { findAllView(it) } GET("/blog/{slug}") { findOneView(it) } GET("/api/blog") { findAll(it) } GET("/api/blog/{id}") { findOne(it) } POST("/api/blog") { create(it) } } HTTP method + path predicate

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Spring WebFlux functional Kotlin DSL 47 router { GET("/blog", blogController::findAllView) GET("/blog/{slug}", blogController::findOneView) GET("/api/blog", blogController::findAll) GET("/api/blog/{id}", blogController::findOne) POST("/api/blog", blogController::create) } Method references

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Spring WebFlux functional Kotlin DSL 48 router { "/blog".nest { GET("/", blogController::findAllView) GET("/{slug}", blogController::findOneView) } "/api/blog".nest { GET("/", blogController::findAll) GET("/{id}", blogController::findOne) POST("/", blogController::create) } } Nested routing

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Spring WebFlux functional Kotlin DSL 49 router { ("/blog" and accept(TEXT_HTML)).nest { GET("/", blogController::findAllView) GET("/{slug}", blogController::findOneView) } ("/api/blog" and accept(APPLICATION_JSON)).nest { GET("/", blogController::findAll) GET("/{id}", blogController::findOne) POST("/", blogController::create) } } Rich set of RequestPredicate

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Leveraging Kotlin nullable information 50 // "GET /foo" and "GET /foo?bar=baz" are allowed @GetMapping("/foo") fun foo(@RequestParam bar: String?) = ... // "GET /foo?bar=baz" is allowed and "GET /foo" will return an error @GetMapping("/foo") fun foo(@RequestParam bar: String) = ...

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Spring Kotlin extensions 51 Mono<ServerResponse> findAll(ServerRequest request) { return ServerResponse.ok().body(repository.findAll(), User.class); } fun findAll(req: ServerRequest) = ok().body(repository.findAll()) No need to specify explicitly types thanks to Kotlin reified type parameters inline fun <reified T : Any> ServerResponse.BodyBuilder.body(publisher: Publisher<T>) = body(publisher, T::class.java) ServerResponseExtensions provided in spring-webflux.jar

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Spring Framework extensions 52 ‣ ApplicationContext ‣ Spring WebFlux • Client • Server ‣ Spring MVC ‣ RestTemplate ‣ JDBC ‣ Reactor (via reactor-kotlin)

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Kotlin type-safe templates 53 import io.spring.demo.* """ ${include("header")} <h1>${i18n("title")}</h1> <ul> ${users.joinToLine{ "<li>${i18n("user")} ${it.firstname} ${it.lastname}</li>" }} </ul> ${include("footer")} """ See https://github.com/sdeleuze/kotlin-script-templating for more details ‣ Regular Kotlin code, no new dialect to learn ‣ Extensible, refactoring and auto-complete support ‣ Need to cache compiled scripts for good performances

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Tests with JUnit 54 class UserIntegrationTests : AbstractIntegrationTests() { @Test fun `Find Dan North`() { val speaker = client.get() .uri("/api/speaker/tastapod") .accept(APPLICATION_JSON) .exchange().then { r -> r.bodyToMono<User>() } StepVerifier.create(speaker) .consumeNextWith { assertEquals("North", it.lastname) assertTrue(it.role == Role.SPEAKER) } .verifyComplete() } }

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ JUnit 5 will improve Kotlin support 55

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ MiXiT reference web application 56 https://github.com/mixitconf/mixit

Functional bean registration

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Functional bean registration API ‣ After XML and JavaConfig, a third major way to register your beans ‣ Lambda with Supplier act as a FactoryBean ‣ Very efficient, no reflection, no CGLIB proxies involved ‣ Usable with pure Spring Framework apps, not yet with Spring Boot 58

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ API example 59 GenericApplicationContext context = new GenericApplicationContext(); context.registerBean(A.class); context.registerBean(B.class, () -> new B(context.getBean(A.class))); GenericApplicationContext { registerBean<A>() registerBean { B(it.getBean<A>()) }}

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ Choose the ﬂavour you prefer! 60 Boot + WebFlux WebFlux + functional bean registration ‣ Automatic server configuration ‣ All Spring Boot goodness! ‣ Bean registration • Annotation-based • Optimized Classpath scanning ‣ Reference webapp startup: • 3 seconds • 20 Mbytes heap size after GC ‣ Manual server configuration ‣ Bean registration • Lambda-based • No Cglib proxy • No need for kotlin-spring plugin ‣ Reference webapp startup: • 1.2 seconds • 10 Mbytes heap size after GC

Inc. and licensed under a  Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/ See functional-bean-registration MiXiT branch 61 https://goo.gl/iGwzw3 AnnotationConfigApplicationContext { registerBean { ReactiveMongoTemplate(SimpleReactiveMongoDatabaseFactory( ConnectionString(it.environment.getProperty("mongo.uri")))) } registerBean<MarkdownConverter>() registerBean<UserRepository>() registerBean<EventRepository>() registerBean<TalkRepository>() registerBean<PostRepository>() // ... }

Spring Framework 5.0 Themes and Trends

Spring Framework 5.0 Themes and Trends

More Decks by Sébastien Deleuze

Other Decks in Programming

Featured

Transcript