Devoxx Belgium 2019 報告会 Vol.1

%FWPYY#FMHJVN ใࠂձ7PM ೥݄೔ ։ాཅհ

ࣗݾ঺հ • ։ా ཅհ (@hirakida_) • LINE Fukuokaגࣜձࣾ ։ൃ1ࣨ •
αʔόʔαΠυΤϯδχΞ

Vol.1Ͱ͸ɺSpring FrameworkͷηογϣϯΛ঺ հ͠·͢ Vol.2Ͱ͸ɺVictor Rentea͞ΜͷClean Codeʹͭ ͍ͯ࿩͢༧ఆͰ͢

5BMLT • Reactive Revolution • Deepdive into Reactive Spring with
Coroutines and Kotlin Flow • Bootiful Kotlin • Bootiful Testing

R2DBCͱRSocket͸ෳ਺ͷηογϣϯͰऔΓ্ ͛ΒΕ͍ͯͨͷͰɺઌʹ঺հ͠·͢

3%#$ https://r2dbc.io/ • Reactive Relational Database Connectivity • R2DBC is
an endeavor to bring a reactive programming API to SQL databases. • ΧϯϑΝϨϯεظؒதʢ11/4ʙ11/8ʣ͸·ͩGAͰ͸ͳ ͔ͬͨͷͰ͕͢ɺ12্݄०ʹGAʹͳΓ·ͨ͠ • https://r2dbc.io/2019/12/02/r2dbc-0-8-0-goes-ga

3%#$%SJWFST • First-party • PostgreSQL • Microsoft SQL Server •
H2 Database ※ ﬁrst-party https://github.com/r2dbc • Community • MySQL • https://github.com/mirromutth/r2dbc-mysql • https://github.com/jasync-sql/jasync-sql • SAP HANA • Google Cloud Spanner

3%#$$MJFOUT ˞,PUZTB ,PUMJOUZQFTBGF IUUQTHJUIVCDPNQVMMWFSULPUZTB pSTUQBSUZͷSECDDMJFOU΋͋Γ·͢ IUUQTHJUIVCDPNSECDSECDDMJFOU

4QSJOH%BUB3%#$ https://github.com/spring-projects/spring-data-r2dbc • Spring Data R2DBC͸12݄ʹGA • Spring Boot R2DBC
Starter͸·ͩexperimentalʢૣͯ͘΋ Spring Boot 2.3ʹͳΔΑ͏Ͱ͢ʣ • https://twitter.com/mp911de/status/ 1202987229024522245?s=20 • https://github.com/spring-projects-experimental/spring- boot-r2dbc

4QSJOH%BUB3%#$ !5SBOTBDUJPOBM 4QSJOH%BUB3FQPTJUPSZ public class User { @Id private Integer
id; … } public interface UserRepository extends ReactiveCrudRepository<User, Integer> { } @Service @Transactional public class UserService { private final UserRepository userRepository; public UserService(UserRepository userRepository) { this.userRepository = userRepository; } public Flux<User> findAll() { return userRepository.findAll(); } public Mono<User> findById(int id) { return userRepository.findById(id); } } )ͷ৔߹ TQSJOHSECDVSMSECDINFNEBUBCBTF PQUJPOT%#@$-04&@%&-":%#@$-04&@0/@&9*5'"-4&

4QSJOH%BUB3%#$ 'VODUJPOBM5SBOTBDUJPOT @Service public class UserService { private final UserRepository
userRepository; private final TransactionalOperator transactionalOperator; public UserService(UserRepository userRepository, TransactionalOperator transactionOperator) { this.userRepository = userRepository; this.transactionalOperator = transactionOperator; } public Flux<User> saveAll(String... names) { return transactionalOperator.transactional( Flux.fromArray(names) .map(name -> new User(null, name)) .flatMap(reservationRepository::save)); } }

4QSJOH%BUB3%#$ 3FBDUJWF"1*T @Component public class UserRepository { private final DatabaseClient
client; public UserRepository(DatabaseClient client) { this.client = client; } public Flux<User> findAll() { return client.select().from(User.class).fetch().all(); } public Mono<User> findById(Integer id) { return client.select().from(User.class).matching(where("id").is(id)).fetch().one(); } public Mono<Void> insert(User user) { return client.insert().into(User.class).using(user).then(); } public Mono<Void> update(User user) { return client.update().table(User.class).using(user).then(); } public Mono<Void> deleteById(Integer id) { return client.delete().from(User.class).matching(where("id").is(id)).then(); } }

34PDLFU http://rsocket.io/ • Application protocol providing Reactive Streams semantics •
RSocket is a binary protocol for use on byte stream transports such as TCP, WebSockets, and Aeron(UDP). • marking͞Μͷࢿྉ͕೔ຊޠͰॻ͔Ε͍ͯͯ෼͔Γ΍͍͢ Ͱ͢ • https://docs.google.com/presentation/d/1ygSM85- RQ3NZjCg6RaZ52mGzxbWiItVwzlCpr1vaWBw/ edit#slide=id.g75f375afa0_0_0

34PDLFU • Duplex • Server͕requesterʹͳΕΔʢServer͕σʔλΛૹ৴ͨ͠ΓϨεϙϯεΛड৴Ͱ͖Δʣ • Reactive Streams • JVM಺͚ͩͰ͸ͳ͘ɺωοτϫʔΫ্ͰReactive
StreamΛ࣮૷Ͱ͖Δ • Back Pressure • Session/Stream resumption (Session/Streamͷ࠶։) • ࠶઀ଓޙʹSession͕࠶։͢Δ • Back pressure͸stream͝ͱ • Leasing • ϦΫΤετͷεϩοτϦϯά • Fragmentation And Reassembly

JOUFSBDUJPONPEFMT • Request Response (stream of 1) • Request Stream
(ﬁnite stream of many) • Request Channel (bi-directional streams) • Request Fire-and-Forget (no response)

3FRVFTU3FTQPOTF send one / receive one 3&26&45 3&410/4& 1":-0"%

3FRVFTU4USFBN send one / receive many 3&26&45 453&". 1":-0"% 1":-0"%
1":-0"%

3FRVFTU$IBOOFM send many / receive many 3&26&45 $)"//&- 1":-0"% 1":-0"%
1":-0"% 1":-0"% 1":-0"%

3FRVFTU'JSFBOE'PSHFU send one 3&26&45 '/'

H31$ gRPCʹ΋ࣅͨΑ͏ͳ4छྨͷαʔϏεϝιου͕͋Δ • Unary RPC (send one / receive one)
• Server streaming RPC (send one / receive many) • Client streaming RPC (send many / receive one) • Bidirectional streaming RPC (send many / receive many) https://grpc.io/docs/guides/concepts/

H31$ͱ34PDLFUͷҧ͍ https://medium.com/netiﬁ/differences-between-grpc-and- rsocket-e736c954e60 H31$ 34PDLFU 04*-BZFS 04*MBZFS 31$MBZFSCVJMUPOUPQPG)551 04*MBZFS 1SPUPDPM
OPUBQSPUPDPM *UJTDPNQSJTFEPG)551IFBEFST HFOFSBUFEDPEF BOEDPOWFOUJPOTJO QSPUPCVG CJOBSZQSPUPDPM 'MPX $POUSPM )551qPXDPOUSPM BQQMJDBUJPOMFWFMqPXDPOUSPM

34PDLFU 4QSJOH#PPU • Spring BootͰ͸Transport ProtocolʹTCPͱWebSocketΛ αϙʔτ͍ͯ͠Δ https://docs.spring.io/spring/docs/current/spring-framework- reference/pdf/rsocket.pdf

3FRVFTU3FTQPOTF 5SBOTQPSUʹ5$1Λ࢖ͬͨ৔߹ 5$1ͷ࣍ͷϨΠϠ͕)551Ͱ͸ͳ͘34PDLFU 3&26&45@3&410/4& 1":-0"%

3FRVFTU3FTQPOTF public class HelloRequest { private String name; } public
class HelloResponse { private String message; private LocalDateTime dateTime; } @Bean public RSocketRequester rSocketRequester(RSocketRequester.Builder builder) { return builder.connectTcp("localhost", 7000).block(); } public Mono<HelloResponse> requestResponse(String name) { return rSocketRequester.route("requestResponse") .data(new HelloRequest(name)) .retrieveMono(HelloResponse.class); } @MessageMapping("requestResponse") public Mono<HelloResponse> requestResponse(HelloRequest request) { return Mono.just(new HelloResponse(String.format("Hello %s!", request.getName()), LocalDateTime.now())); } 3FRVFTUFS 3FTQPOEFS 4FOEPOF3FDFJWFPOF

3FRVFTU4USFBN 3FRVFTU@/ͳͷͰɺ3FTQPOEFS͸1BZMPBEΛૹ৴ ͦͷޙɺ3FTQPOEFS͸৽͍͠3FRVFTU@/͕དྷΔ·Ͱ଴ͭ

3FRVFTU4USFBN public Flux<HelloResponse> requestStream(String name) { return rSocketRequester.route("requestStream") .data(new HelloRequest(name))
.retrieveFlux(HelloResponse.class); } @MessageMapping("requestStream") public Flux<HelloResponse> requestStream(HelloRequest request) { Stream<HelloResponse> responses = Stream.generate(() -> new HelloResponse("Hello " + request.getName() + "!"), LocalDateTime.now())); return Flux.fromStream(responses); } 3FRVFTUFS 3FTQPOEFS 4FOEPOF3FDFJWFNBOZ

3FRVFTU$IBOOFM

3FRVFTU$IBOOFM public Flux<HelloResponse> requestChannel(String name) { Flux<HelloRequest> requests = Flux.fromStream(Stream.generate(()
-> new HelloRequest(name))); return rSocketRequester.route("requestChannel") .data(requests) .retrieveFlux(HelloResponse.class); } @MessageMapping("requestChannel") public Flux<HelloResponse> requestChannel(Flux<HelloRequest> requests) { return Flux.from(requests) .map(request -> new HelloResponse("Hello " + request.getName() + "!"), LocalDateTime.now())); } 3FRVFTUFS 3FTQPOEFS 4FOENBOZ3FDFJWFNBOZ

3FRVFTU'JSFBOE'PSHFU

3FRVFTU'JSFBOE'PSHFU public Mono<Void> fireAndForget(String name) { return rSocketRequester.route("fireAndForget") .data(new HelloRequest(name))
.send(); } @MessageMapping("fireAndForget") public Mono<Void> fireAndForget(HelloRequest request) { return Mono.empty(); } 3FRVFTUFS 3FTQPOEFS 4FOEPOF

34PDLFU 8FC4PDLFU REQUEST RESPONSE 5SBOTQPSUʹ8FC4PDLFUΛ࢖ͬͨ৔߹ 8FC4PDLFUͷ1BZMPBE͕34PDLFUϑϨʔϜ

3FBDUJWF3FWPMVUJPO https://devoxx.be/talk/?id=25802 • 3࣌ؒͷDeep Dive • SpringͷReactiveϓϩάϥϛϯάʹ͍ͭͯͷϥΠϒίʔσΟϯά • YouTube •
https://www.youtube.com/watch?v=4-vEW8Ck_6g • Sample Code • https://github.com/joshlong/reactive-revolution • https://github.com/joshlong/reactive-spring-livelessons-2e

3FBDUJWF3FWPMVUJPO ηογϣϯͷ಺༰ • Java + Spring Boot 2.2 + Spring
Data Reactive MongoDB • Java + Spring Boot 2.2 + Spring Data R2DBC • Java + Spring Boot 2.2 + WebFlux + WebSocket • Kotlin + Spring Boot 2.2 + Spring Cloud Gateway • Kotlin + Spring Boot 2.2 + Spring Cloud Gateway + Spring Security + Spring Data Reactive Redis(Redis Rate Limiter) • Kotlin + Spring Boot 2.2 + WebFlux.fn + WebClient • Kotlin + Spring Boot 2.2 + RSocket

4QSJOH%BUB3FBDUJWF .POHP%# • Spring InitializrͰҎԼΛબ୒ • Dependencies • Spring Data
Reactive MongoDB • Lombok

4QSJOH%BUB3FBDUJWF .POHP%# @Document @Data @AllArgsConstructor public class Reservation { @Id
private String id; private String name; } public interface ReservationRepository extends ReactiveCrudRepository<Reservation, String> { } @Component @RequiredArgsConstructor @Slf4j public class DataInitializer { private final ReservationRepository reservationRepository; @EventListener(ApplicationReadyEvent.class) public void ready() { Flux<Reservation> saved = Flux.just("AAA", "BBB", "CCC") .map(name -> new Reservation(null, name)) .flatMap(reservationRepository::save); reservationRepository.deleteAll() .thenMany(saved) .thenMany(reservationRepository.findAll()) .subscribe(reservation -> log.info("{}", reservation)); } }

4QSJOH%BUB3%#$ • Spring InitializrͰҎԼΛબ୒ • Spring Data R2DBC [Experimental] •
H2 Database ※ ͜ͷηογϣϯͰ͸PostgreSQLΛ࢖͍ͬͯ·͕ͨ͠ɺH2Ͱઆ໌͠·͢

4QSJOH%BUB3%#$ @Data @NoArgsConstructor @AllArgsConstructor public class Reservation { @Id private
Integer id; private String name; } public interface ReservationRepository extends ReactiveCrudRepository<Reservation, Integer> { } @Service @RequiredArgsConstructor @Slf4j public class ReservationService { private final ReservationRepository reservationRepository; private final TransactionalOperator transactionalOperator; public Flux<Reservation> saveAll(String... names) { return transactionalOperator.transactional( Flux.fromArray(names) .map(name -> new Reservation(null, name)) .flatMap(reservationRepository::save) .doOnNext(r -> log.info("{}", r))); } } TQSJOHSECDVSMSECDINFNEBUBCBTF PQUJPOT%#@$-04&@%&-":%#@$-04&@0/@&9*5'"-4& TQSJOHSECDVTFSOBNFVTFSOBNF TQSJOHSECDQBTTXPSEQBTTXPSE

8FC'MVY 8FC4PDLFU • Spring InitializrͰҎԼΛબ୒ • Dependencies • Spring Reactive
Web • Lombok

8FC'MVY 8FC4PDLFU KBWB @Data @AllArgsConstructor public class GreetingRequest { private
String name; } @Data @AllArgsConstructor public class GreetingResponse { private String message; } @Service public class GreetingService { public Flux<GreetingResponse> greet(GreetingRequest request) { return Flux .fromStream(Stream.generate(() -> new GreetingResponse( String.format("%s @ %s", request.getName(), Instant.now())))) .delayElements(Duration.ofSeconds(1)); } }

8FC'MVY 8FC4PDLFU KBWB @Configuration public class WebSocketConfig { @Bean public
WebSocketHandler webSocketHandler(GreetingService greetingService) { return session -> { Flux<WebSocketMessage> messages = session.receive() .map(WebSocketMessage::getPayloadAsText) .map(GreetingRequest::new) .flatMap(greetingService::greet) .map(GreetingResponse::getMessage) .map(session::textMessage); return session.send(messages); }; } @Bean public SimpleUrlHandlerMapping simpleUrlHandlerMapping(WebSocketHandler webSocketHandler) { return new SimpleUrlHandlerMapping(Map.of("/ws/greetings", webSocketHandler), 1); } @Bean public WebSocketHandlerAdapter webSocketHandlerAdapter() { return new WebSocketHandlerAdapter(); } }

8FC'MVY 8FC4PDLFU KT <!DOCTYPE html> <html lang="en"> <head> </head> <body>
<script> window.addEventListener('load', () => { const ws = new WebSocket('ws://localhost:8080/ws/greetings'); ws.addEventListener('open', () => { ws.send('Devoxx Belgium') }); ws.addEventListener('message', (msg) => { console.log(msg.data) }) }); </script> </body> </html>

,PUMJO 4QSJOH$MPVE (BUFXBZ • Spring InitializrͰҎԼΛબ୒ • Language • Kotlin
• Dependencies • Gateway

,PUMJO 4QSJOH$MPVE (BUFXBZ @SpringBootApplication class Application { @Bean fun gateway(rlb:
RouteLocatorBuilder) = rlb.routes { route { path("/proxy") and host("*.spring.io") filters { setPath("/reservations") addResponseHeader(HttpHeaders.ACCESS_CONTROL_ALLOW_ORIGIN, "*") } uri("http://localhost:8080") } } } fun main(args: Array<String>) { runApplication<Application>(*args) } ҎԼΛ࣮ߦ͢ΔͱɺIUUQMPDBMIPTUSFTFSWBUJPOTʹసૹ͞ΕΔ DVSMW)IPTUEFWPYYTQSJOHJPIUUQMPDBMIPTUQSPYZ TFSWFSQPSU

,PUMJO 4QSJOH$MPVE(BUFXBZ 4QSJOH4FDVSJUZ 3FEJT3BUF-JNJUFS • Spring InitializrͰҎԼΛબ୒ • Language
• Kotlin • Dependencies • Gateway • Spring Security • Spring Data Reactive Redis

,PUMJO 4QSJOH$MPVE(BUFXBZ 4QSJOH4FDVSJUZ 3FEJT3BUF-JNJUFS @Bean fun authorization(http: ServerHttpSecurity) =
http.httpBasic(Customizer.withDefaults()) .csrf { it.disable() } .authorizeExchange { it.pathMatchers("/proxy").authenticated() .anyExchange().permitAll() } .build() @Bean fun authentication(passwordEncoder: PasswordEncoder) = MapReactiveUserDetailsService( User.withUsername("user1") .password(passwordEncoder.encode("pass1")) .roles("USER", "ADMIN") .build()) @Bean fun passwordEncoder() = BCryptPasswordEncoder() σϞ༻ͷϢʔβʔΛ௥Ճ

,PUMJO 4QSJOH$MPVE(BUFXBZ 4QSJOH4FDVSJUZ 3FEJT3BUF-JNJUFS @Bean fun redisRateLimiter() = RedisRateLimiter(5,
7) @Bean fun gateway(rlb: RouteLocatorBuilder, redisRateLimiter: RedisRateLimiter) = rlb.routes { route { path("/proxy") and host("*.spring.io") filters { setPath("/reservations") addResponseHeader(HttpHeaders.ACCESS_CONTROL_ALLOW_ORIGIN, "*") requestRateLimiter { it.rateLimiter = redisRateLimiter } } uri("http://localhost:8080") } } !QBSBNEFGBVMU3FQMFOJTI3BUFIPXNBOZUPLFOTQFSTFDPOEJOUPLFOCVDLFUBMHPSJUIN !QBSBNEFGBVMU#VSTU$BQBDJUZIPXNBOZUPLFOTUIFCVDLFUDBOIPMEJOUPLFOCVDLFU ҎԼΛ࣮ߦ͢ΔͱSBUFMJNJUUFS͕༗ޮʹͳΓɺϨεϙϯεʹʮ93BUF-JNJU3FNBJOJOHʯ ͳͲͷϔομʔ͕ૠೖ͞ΕΔ DVSMWVVTFSQBTT)IPTUEFWPYYTQSJOHJPIUUQMPDBMIPTUQSPYZ

,PUMJO 4QSJOH$MPVE(BUFXBZ 4QSJOH4FDVSJUZ 3FEJT3BUF-JNJUFS fun main(args: Array<String>) { runApplication<Application>(*args)
{ val context = beans { bean { RedisRateLimiter(5, 7) } } addInitializers(context) } } ,PUMJOͷ৔߹ɺCFBO͸,PUMJO%4-Λ࢖ͬͯ͜ͷΑ͏ʹॻ͘͜ ͱ΋Ͱ͖·͢

,PUMJO 8FC'MVYGO 8FC$MJFOU • Spring InitializrͰҎԼΛબ୒ • Language •
Kotlin • Dependencies • Spring Reactive Web

,PUMJO 8FC'MVYGO 8FC$MJFOU data class Reservation(val id: Int, val
name: String) @Bean fun webClient(builder: WebClient.Builder) = builder.build() @Bean fun route(webClient: WebClient) = router { GET("/reservations/names") { val reservations = webClient.get() .uri("http://localhost:8080/reservations") .retrieve() .bodyToFlux<Reservation>() .map { it.name } .retryBackoff(10, Duration.ofSeconds(1)) ServerResponse.ok().body(reservations) } }

,PUMJO 34PDLFU • Spring InitializrͰҎԼΛબ୒ • Language • Kotlin •
Dependencies • RSocket • Spring Reactive Web

,PUMJO 34PDLFU DMJFOU data class GreetingRequest(val name: String) data class
GreetingResponse(val message: String) @SpringBootApplication class Application { @Bean fun rSocketClient(rSocketRequester: RSocketRequester.Builder) = rSocketRequester.connectTcp("localhost", 7777).block() @Bean fun route(rSocketClient: RSocketRequester) = router { GET("/greetings/{name}") { val request = GreetingRequest(it.pathVariable("name")) val greetings: Flux<GreetingResponse> = rSocketClient.route("greetings") .data(request) .retrieveFlux() ServerResponse.ok() .contentType(MediaType.TEXT_EVENT_STREAM) .body(greetings) } } } 3FRVFTU4USFBN

,PUMJO 34PDLFU TFSWFS data class GreetingRequest(val name: String) data class
GreetingResponse(val message: String) @Controller class RSocketController { @MessageMapping("greetings") fun greet(request: GreetingRequest): Flux<GreetingResponse> { return Flux.fromStream(Stream.generate { GreetingResponse("${request.name} @ $ {Instant.now()}") }) .delayElements(Duration.ofSeconds(1)) } } TQSJOHSTPDLFUTFSWFSQPSU

%FFQEJWFJOUP3FBDUJWF4QSJOH XJUI$PSPVUJOFTBOE,PUMJO'MPX https://devoxx.be/talk/?id=40958 • 3࣌ؒͷDeep Diveʢ࣮ࡍ͸2࣌ؒ͘Β͍Ͱͨ͠ʣ • Kotlin + Reactive
Springͷηογϣϯ • YouTube • https://www.youtube.com/watch?v=BoidEr_ZCGc • Sample Code • https://github.com/sdeleuze/spring-messenger

,PUMJO !$POpHVSBUJPO1SPQFSUJFT 4QSJOH#PPU·Ͱ @ConfigurationProperties("example.kotlin") class KotlinExampleProperties { lateinit var name:
String lateinit var description: String val myService = MyService() class MyService { lateinit var apiToken: String lateinit var uri: URI } } example: kotlin: name: xxxxx description: xxxxx my-service: api-token: xxxxx uri: xxxxx

,PUMJO !$POpHVSBUJPO1SPQFSUJFT 4QSJOH#PPU @ConfigurationPropertiesScan // or @EnableConfigurationProperties(KotlinExampleProperties::class) class Application @ConstructorBinding
@ConfigurationProperties("example.kotlin") data class KotlinExampleProperties(val name: String, val description: String, val myService: MyService) { data class MyService(val apiToken: String, val uri: URI) }

,PUMJO 8FC.WDGO @SpringBootApplication class Application { @Bean fun routes() =
router { GET("/hello", ::hello) } fun hello(request: ServerRequest) = ServerResponse.ok().body("Hello world!") }

,PUMJO 8FC.WDGO data class User(val id: Int, val name: String)
@SpringBootApplication class Application { @Bean fun routes(handler: UserHandler) = router { accept(MediaType.APPLICATION_JSON).nest { GET("/users", handler::findAll) GET("/users/{id}", handler::findById) } } } @Component class UserHandler(private val userRepository: UserRepository) { fun findAll(request: ServerRequest): ServerResponse = ok().body(userRepository.findAll()) fun findById(request: ServerRequest): ServerResponse { val id = request.pathVariable("id").toInt() return ok().body(userRepository.findById(id)) } }

$PSPVUJOFT • Coroutinesͱ͸ϓϩάϥϛϯάͷߏ଄ͷҰछ • Subroutines͕ΤϯτϦʔ͔ΒϦλʔϯ·ͰΛҰͭͷॲཧ୯Ґͱ ͢Δͷʹର͠ɺCoroutines͸͍ͬͨΜॲཧΛதஅʢsuspendʣ͠ ͨޙɺଓ͖͔ΒॲཧΛ࠶։ʢresumeʣͰ͖Δ • Coroutineͱ͍͏໊শ͸ɺMelvin Conwayͷ1963೥ͷ࿦จ͕ىݯ
https://en.wikipedia.org/wiki/Coroutine https://ja.wikipedia.org/wiki/ίϧʔνϯ

$PSPVUJOFT • Kotlinͷ৔߹͸ɺJetBrainsʹΑͬͯﬁrst-party libraryͱͯ͠ kotlinx.coroutinesʹ࣮૷͞Ε͍ͯΔ • KotlinͰ͸ɺlight-weight threadsͱఆٛ͞Ε͍ͯΔ https://kotlinlang.org/docs/reference/coroutines- overview.html

$PSPVUJOFT • Coroutineʹ͍ͭͯ͸ɺผͷηογϣϯʮCoroutines for Java Developersʯ͕෼͔Γ΍͍͢Ͱ͢ • YouTube • https://www.youtube.com/watch?v=wBpKAv4i8Ug
• Slide • https://docs.google.com/presentation/d/ 192JLr64isB5WCmeqo4Fvf3snsDLWxrfkZ7A2nsNxb84/ edit#slide=id.p

5ISFBET$PSPVUJOFT • Threads • Context Switch • OS decision •
Coroutines • Suspend & Resume • Coroutine Decision

$POUFYU4XJUDI4VTQFOE • Context Switch • Save CPU state: stack, registers,
EIP • Done by OS, no control • Suspend of a coroutine • Saves the function state, stack • Done by the code, 100% control

NBJOCVJMEJOHCMPDLT • Suspending Functions • Structured concurrency • Flow<T>

4VTQFOEJOHGVODUJPOT fun main() = runBlocking { launch { doWorld() }
println("Hello,") } suspend fun doWorld() { delay(1000L) println("World!") } • ؔ਺ʹsuspendम০ࢠΛ෇͚Δ • Suspending function͸ɺcoroutine಺Ͱ௨ৗͷؔ਺ͷΑ͏ʹ࢖༻͞ΕΔ • Suspending function͸ɺdelayͷΑ͏ͳଞͷsuspending functionΛॱ൪ʹ࢖༻Ͱ͖Δ https://kotlinlang.org/docs/reference/coroutines/basics.html#extract-function-refactoring

(MPCBM4DPQF • ͜ͷྫͰ͸ɺGlobalScopeʹ৽͍͠coroutineΛىಈ͍ͯ͠Δ • ͜ͷcoroutineͷlifetime͸ɺΞϓϦέʔγϣϯશମͷlifetimeʹΑͬͯͷΈ੍ݶ͞ΕΔ • https://kotlinlang.org/docs/reference/coroutines/basics.html#your-ﬁrst-coroutine fun main() {
GlobalScope.launch { delay(1000L) println("World!") } println("Hello,") Thread.sleep(2000L) }

4USVDUVSFEDPODVSSFODZ fun main() = runBlocking { // this: CoroutineScope launch
{ // launch a new coroutine in the scope of runBlocking delay(1000L) println("World!") } println("Hello,") } • ࣮ߦ͢ΔΦϖϨʔγϣϯͷಛఆͷείʔϓ಺ͰcoroutinesΛىಈͰ͖ΔʢGlobalScope಺Ͱىಈ͠ͳ͍ʣ • ্هͷྫͰ͸ɺmainؔ਺͸runBlocking coroutine builderΛ࢖༻ͯ͠coroutineʹม׵͞ΕΔ • શͯͷcoroutine builderʢrunBlocking, launchͳͲʣ͸ɺͦͷbuilderͷίʔυϒϩοΫͷείʔϓʹ CoroutineScopeͷΠϯελϯεΛ௥Ճ͢Δ • ֎ଆͷcoroutineʢ͜ͷྫͰ͸runBlockingʣ͸ɺείʔϓ಺Ͱىಈ͞Εͨશͯͷcoroutines͕׬ྃ͢Δ·Ͱ׬ྃ ͠ͳ͍ https://kotlinlang.org/docs/reference/coroutines/basics.html#structured-concurrency ग़ྗ݁Ռ͸ )FMMP 8PSME

'MPX5 • Suspending functions͸୯Ұͷ஋Λඇಉظʹฦ͕͢ɺFlow͸ෳ਺ͷ஋Λඇಉظʹฦ͢ • flow builderϒϩοΫ಺ͰαεϖϯυͰ͖Δ • FlowΛฦؔ͢਺ʹ͸suspendम০ࢠΛ෇͚ͳ͍ •
Flow͸cold streamsͰɺFlow͕collect͞ΕΔ·Ͱflow builder಺ͷίʔυ͸࣮ߦ͞Εͳ͍ • Flow͸Reactive Streamsͱ૬ޓӡ༻࡞༻ͯ͠ɺbackpressueΛαϙʔτ͢Δ https://kotlinlang.org/docs/reference/coroutines/flow.html fun foo(): Flow<Int> = flow { // flow builder for (i in 1..3) { delay(100) // pretend we are doing something useful here emit(i) // emit next value } } fun main() = runBlocking { // Collect the flow foo().collect { value -> println(value) } }

4QSJOH $PSPVUJOFT • Coroutines allows to consume Spring Reactive stack
with a nice balance between imperative and declarative style • Context interoperability between Coroutines and Reactor • Allows to support Reactive transactions and security

4QSJOHQSPWJEFTP⒏DJBM $PSPVUJOFTTVQQPSU • Spring WebFlux • Spring Data Redis •
Spring Data MongoDB • Spring Data Cassandra • Spring Data R2DBC • Spring Vault • RSocket

4UBUVTPG$PSPVUJOFT TVQQPSU

)PX3FBDUPS"1*T USBOTMBUFUP$PSPVUJOFT fun handler(): Mono<Void> → suspend fun handler() fun
handler(): Mono<T> → suspend fun handler(): T fun handler(): Flux<T> → suspend fun handler(): Flow<T>

$PSPVUJOFT 8FC'MVY data class User(val id: Int, val message: String)
@RestController class UserController { @GetMapping("/users") suspend fun findAll(): Flow<User> { delay(1000) return flowOf(User(1, "name1"), User(2, "name2"), User(3, "name3")) } @GetMapping("/users/{id}") suspend fun findOne(@PathVariable id: Int): User { delay(1000) return User(id, "name$id") } }

$PSPVUJOFT 8FC'MVYGO data class User(val id: Int, val message: String)
@SpringBootApplication class Application { @Bean fun routes() = coRouter { "/users".nest { GET("/", ::findAll) GET("/{id}", ::findOne) } } suspend fun findAll(request: ServerRequest): ServerResponse { delay(1000) val users: Flow<User> = (1..5).map { User(it, "name$it") }.asFlow() return ok().bodyAndAwait(users) } suspend fun findOne(request: ServerRequest): ServerResponse { delay(1000) val id = request.pathVariable("id").toInt() return ok().bodyValueAndAwait(User(id, "name$id")) } }

$PSPVUJOFT 8FC$MJFOU @RestController class UserController(private val webClient: WebClient) { @GetMapping("/users")
suspend fun findAll(): Flow<User> = webClient.get() .uri("/users") .accept(MediaType.APPLICATION_JSON) .retrieve() .bodyToFlow() @GetMapping("/users/{id}") suspend fun findOne(@PathVariable id: Int): User = webClient.get() .uri("/users/{id}", id) .accept(MediaType.APPLICATION_JSON) .retrieve() .awaitBody() }

$PSPVUJOFT 34PDLFU @Bean fun route(requester: RSocketRequester) = coRouter { GET("/greetings/{name}")
{ val request = GreetingRequest(it.pathVariable("name")) val greetings: Flow<String> = requester.route("greetings") .data(request) .retrieveFlow<GreetingResponse>() .map { response -> response.message } ok().sse().bodyAndAwait(greetings) } } @Controller class RSocketController { @MessageMapping("greetings") fun greet(request: GreetingRequest) = flow { while (true) { emit(GreetingResponse("${request.name} @ ${Instant.now()}")) delay(1000) } } } 4QSJOH#PPUͰ͸όά͕͋ΔͷͰSFUSJFWF'MPX͸࢖͑ͳ͍Ͱ͢ IUUQTHJUIVCDPNTQSJOHQSPKFDUTTQSJOHGSBNFXPSLJTTVFT

$PSPVUJOFT 4QSJOH%BUB3%#$ 'VODUJPOBM5SBOTBDUJPOT @SpringBootApplication class Application(private val operator: TransactionalOperator, private
val repository: UserRepository) { @EventListener(ApplicationReadyEvent::class) fun readyEvent() = runBlocking { operator.executeAndAwait { repository.insert(User(1, "name1")) repository.insert(User(2, "name2")) repository.insert(User(3, "name3")) } } } !5SBOTBDUJPOBM͸ݱ࣌఺Ͱ͸ະαϙʔτ

$PSPVUJOFT 4QSJOH%BUB3%#$ 3FBDUJWF"1*T data class User(@field:Id val id: Int, val
name: String) @Component class UserRepository(private val client: DatabaseClient) { fun findAll(): Flow<User> = client.select().from<User>().orderBy(asc("id")).fetch().flow() suspend fun findOne(id: Int) = client.select().from<User>().matching(where("id").`is`(id)).fetch().awaitOneOrNull() suspend fun insert(user: User) = client.insert().into<User>().using(user).await() suspend fun insertUntyped(name: String) = client.insert().into("user").value("name", name).await() suspend fun update(user: User) = client.update().table<User>().using(user).then().awaitFirstOrNull() suspend fun delete(id: Int) = client.delete().from<User>().matching(where("id").`is`(id)).then().awaitFirstOrNull() } 4QSJOH%BUB3FQPTJUPSJFT͸ݱ࣌఺Ͱ͸ະαϙʔτ IUUQTKJSBTQSJOHJPCSPXTF%"5"$./4

$PSPVUJOFT 4QSJOH%BUB.POHP%# 3FBDUJWF"1*T @Component class UserRepository(private val operations: ReactiveFluentMongoOperations) {
fun findAll(): Flow<User> = operations.query<User>().flow() suspend fun findOne(id: String): User = operations.query<User>() .matching(query(where(User::id).isEqualTo(id))) .awaitOne() suspend fun insert(user: User): User = operations.insert<User>().oneAndAwait(user) suspend fun update(user: User): User = operations.update<User>() .replaceWith(user) .asType<User>() .findReplaceAndAwait() }

4QSJOH'V https://github.com/spring-projects-experimental/spring-fu • Spring BootͷઃఆΛSpring Kotlin DSLͰߦ͑Δ • ىಈ͕ૣͯ͘ϝϞϦফඅྔ͕গͳ͍ •
Experimental

4QSJOH'V val app = application(WebApplicationType.REACTIVE) { logging { level =
LogLevel.INFO } beans { bean<UserHandler>() bean<UserRepository>() } webFlux { port = if (profiles.contains("test")) 8181 else 8080 router { val userHandler = ref<UserHandler>() GET("/users", userHandler::findAll) } codecs { string() jackson() } } } fun main() { app.run() } data class User(val id: Int, val name: String) @Suppress("UNUSED_PARAMETER") class UserHandler(private val repository: UserRepository) { fun findAll(request: ServerRequest): Mono<ServerResponse> = ok().body(fromValue(repository.findAll())) }

4QSJOH'V $PSPVUJOFT val app = application(WebApplicationType.REACTIVE) { logging { level
= LogLevel.INFO } beans { bean<UserHandler>() bean<UserRepository>() } webFlux { port = if (profiles.contains("test")) 8181 else 8080 coRouter { val userHandler = ref<UserHandler>() GET("/users", userHandler::findAll) } codecs { string() jackson() } } } fun main() { app.run() } data class User(val id: Int, val name: String) @Suppress("UNUSED_PARAMETER") class UserHandler(private val repository: UserRepository) { suspend fun findAll(request: ServerRequest): ServerResponse = ok().bodyAndAwait(repository.findAll()) }

#PPUJGVM,PUMJO https://devoxx.be/talk/?id=128352 • 50෼ͷηογϣϯ • Kotlin + Spring BootͷϥΠϒίʔσΟϯά •
YouTube • https://www.youtube.com/watch?v=etwrkcqIMnk • Sample Code • https://github.com/joshlong/kotlin-and-spring-livelessons

#PPUJGVM,PUMJO 1. Kotlin + Spring Boot 2.2 + Spring JDBC
2. Kotlin + Spring Boot 2.2 + Exposed 3. Kotlin + Spring Boot 2.2 + Spring Data Reactive MongoDB + Spring Gateway + Coroutines ※ 3͸લड़ͷηογϣϯͱࣅ͍ͯΔͨΊׂѪ͠·͢

,PUMJO 4QSJOH+%#$ • Spring InitializrͰҎԼΛબ୒ • Language • Kotlin •
Dependencies • JDBC API

,PUMJO 4QSJOH+%#$ @SpringBootApplication class Application fun main(args: Array<String>) { runApplication<Application>(*args)
} data class Customer(val id: Int, val name: String) @Service class CustomerService(private val jdbcTemplate: JdbcTemplate) { fun findAll(): List<Customer> = jdbcTemplate.query("SELECT * FROM customer") { rs, _ -> Customer(rs.getInt("id"), rs.getString("name")) } }

4QSJOH#PPU &YQPTFE https://github.com/JetBrains/Exposed • KotlinͰॻ͔ΕͨJetBrains੡ͷܰྔͳSQLϥΠϒϥϦ • ݱࡏ͸Maven Centralʹ͸ͳ͘ɺBintray (JCenter)ͷΈ •
exposed-spring-boot-starter͕͋ΓɺҎԼͷػೳ͕ఏڙ͞Ε͍ͯΔ • SpringTransactionManagerͷࣗಈઃఆ • schemaͷࣗಈੜ੒ ※ ͜ͷηογϣϯͰ͸exposed-spring-boot-starter͸࢖͍ͬͯ·ͤΜͰ͕ͨ͠ɺ starterΛ࢖ͬͨํ๏Λ঺հ͠·͢

&YQPTFE CVJMEHSBEMFLUT repositories { mavenCentral() jcenter() } dependencies { …
implementation(“org.jetbrains.exposed:exposed-spring-boot-starter:0.20.2") … }

&YQPTFE LU import org.jetbrains.exposed.sql.Table object Customers : Table() { val
id = integer("id").autoIncrement() val name = varchar("name", 255) override val primaryKey = PrimaryKey(id) } data class Customer(val id: Int, val name: String) TQSJOHFYQPTFEHFOFSBUFEEEMUSVFʹ͢Ε͹ɺҎԼͷ%%-͕࣮ߦ͞ΕΔ $3&"5&5"#-&*'/05&9*454 $6450.&34 *%*/5"650@*/$3&.&/513*."3:,&: /".&7"3$)"3 /05/6--

&YQPTFE LU @Service @Transactional class CustomerService { fun selectAll(): List<Customer>
= Customers.selectAll().map { Customer(it[Customers.id], it[Customers.name]) } fun insert(customer: Customer) = Customers.insert { it[name] = customer.name } fun update(customer: Customer) = Customers.update({ Customers.id eq customer.id }) { it[name] = customer.name } fun delete(id: Int) = Customers.deleteWhere { Customers.id eq id } } 4QSJOHͷ!5SBOTBDUJPOBM͕࢖༻Ͱ͖Δ

#PPUJGVM5FTUJOH https://devoxx.be/talk/?id=25801 • 50෼ͷηογϣϯ • Spring Bootͷςετʹ͍ͭͯͷϥΠϒίʔσΟϯά • YouTube •
https://www.youtube.com/watch?v=wAYt4Z4SF7g • Sample Code • https://github.com/joshlong/bootiful-testing

#PPUJGVM5FTUJOH 1. Spring Boot 2.2 + WebFlux + Spring Data
Reactive MongoDB 2. Spring Boot 2.2 + WebClient + WireMock (Contract Stub Runner) 3. Spring Boot 2.2 + WebFlux,WebClient + Spring Cloud Contract (Contract Veriﬁer, Contract Stub Runner) ※ ͜ͷηογϣϯͰ͸JUnit 4Λ࢖͍ͬͯ·͕ͨ͠ɺJUnit 5Ͱઆ໌͠·͢

8FC'MVY5FTU @WebFluxTest public class ControllerTest { @Autowired private WebTestClient webTestClient;
@Test public void test() { webTestClient.get() .uri("http://localhost:8080/reservations") .exchange() .expectHeader().contentType(MediaType.APPLICATION_JSON) .expectStatus().isOk() .expectBody().json("[{\"id\":1,\"name\":\"name1\"},...]"); } } ςετର৅ͷ FOEQPJOU

3FBDUJWF.POHP%#5FTU @DataMongoTest public class ReservationRepositoryTest { @Autowired private ReservationRepository reservationRepository;
@Test public void test() { Reservation reservation = new Reservation(null, "name1"); StepVerifier.create(reservationRepository(reservation)) .expectNextMatches(result -> result.getId() != null && "name1".equals(result.getName())) .verifyComplete(); } } ςετର৅ͷ SFQPTJUPSZ

8FC$MJFOU5FTU 8JSF.PDL http://wiremock.org/ • WebClientͷςετʹ͸ɺOkHttp MockWebServer΍ WireMockͳͲͷMock Web Server͕࢖༻Ͱ͖Δ •
RestTemplateͷςετͰ࢖༻Ͱ͖ΔMockRestServiceServer ͸ɺWebClientΛαϙʔτ͍ͯ͠ͳ͍ • https://docs.spring.io/spring-framework/docs/current/springframework-reference/web-reactive.html#webﬂux-client-testing • https://github.com/spring-projects/spring-framework/issues/ 19852

8FC$MJFOU5FTU 8JSF.PDL •Spring InitializrͰҎԼΛબ୒ • Spring Reactive Web • Contract
Stub Runner

8FC$MJFOU TPVSDFDPEF @Component public class GitHubApiClient { private final WebClient
webClient; public GitHubApiClient(WebClient.Builder builder, @Value("${github.baseUrl:https://api.github.com}") String baseUrl) { webClient = builder.baseUrl(baseUrl).build(); } public Mono<User> getUser(String username) { return webClient.get() .uri("/users/{username}", username) .retrieve() .bodyToMono(User.class); } }

8JSF.PDL UFTUDPEF @SpringBootTest(properties = "github.baseUrl=http://localhost:8080") @AutoConfigureWireMock(port = 8080) public class
GitHubApiClientTest { @Autowired private GitHubApiClient client; @Test public void getUserTest() { String body = "{\"login\":\"hirakida\"}"; stubFor(get(urlEqualTo("/users/hirakida")) .willReturn(aResponse() .withBody(body) .withHeader(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE) .withStatus(HttpStatus.OK.value()))); Mono<User> user = client.getUser("hirakida"); StepVerifier.create(user) .expectNextMatches(result -> result != null && "hirakida".equals(result.getLogin())) .verifyComplete(); } }

4QSJOH$MPVE$POUSBDU https://spring.io/projects/spring-cloud-contract • Consumer Driven Contract(CDC) Testing͕Ͱ͖Δ • Producer͸Contract VeriﬁerΛ࢖͏
• Consumer͸Contract Stub RunnerΛ࢖͏

1SPEVDFS •Spring InitializrͰҎԼΛબ୒ •Contract Veriﬁer

1SPEVDFS TPVSDFDPEF @RestController @RequiredArgsConstructor public class UserController { private final
UserService userService; @GetMapping("/users/{id}") public Mono<User> getUser(@PathVariable long id) { return userService.getUser(id); } } @Data @NoArgsConstructor @AllArgsConstructor public class User { private long id; private String name; }

1SPEVDFS CVJMEHSBEMF import org.springframework.cloud.contract.verifier.config.TestFramework plugins { id 'org.springframework.boot' version '2.2.2.RELEASE'
id 'org.springframework.cloud.contract' version '2.2.0.RELEASE' } dependencies { … testImplementation('org.springframework.boot:spring-boot-starter-test') { exclude group: 'org.junit.vintage', module: 'junit-vintage-engine' } testImplementation 'org.springframework.cloud:spring-cloud-starter-contract-verifier' } contracts { testFramework = TestFramework.JUNIT5 testMode = 'EXPLICIT' baseClassForTests = 'com.example.BaseClass' } ޙड़͢Δ#BTF$MBTTͷQBUIΛࢦఆ ͢Δ 4QSJOH$MPVE$POUSBDU (SBEMF1MVHJO

1SPEVDFS #BTF$MBTT'PS5FTUT @SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT, properties = "server.port=0") public class
BaseClass { @LocalServerPort private int port; @MockBean private UserService userService; @BeforeEach public void setup() { RestAssured.baseURI = "http://localhost"; RestAssured.port = port; when(userService.getUser(1)).thenReturn(Mono.just(new User(1, "name1"))); } }

1SPEVDFS HSPPWZ import org.springframework.cloud.contract.spec.Contract Contract.make { description('User API test') request
{ method "GET" url "/users/1" } response { status 200 headers { contentType(applicationJson()) } body """ { "id": 1, "name": "name1" } """ } } ͜ͷHSPPWZϑΝΠϧΛʮTSDUFTUSFTPVSDFTDPOUSBDUTʯʹஔ͘ CVJME͢Δͱ<BSUJGBDU*E><WFSTJPO>TUVCTKBS͕Ͱ͖ΔͷͰɺ͜ΕΛ DPOTVNFSଆ͕࢖༻͢Δ $POTVNFSଆ͕ظ଴͢Δ݁Ռ

$POTVNFS •Spring InitializrͰҎԼΛબ୒ •Contract Stub Runner

$POTVNFS TPVSDFDPEF @Component public class UserApiClient { private final WebClient
webClient; public UserApiClient(WebClient.Builder builder, @Value("${producer.host:localhost}") String host, @Value("${producer.port:8080}") int port) { webClient = builder.baseUrl("http://" + host + ':' + port).build(); } public Mono<User> getUser(long id) { return webClient.get() .uri("/users/{id}", id) .retrieve() .bodyToMono(User.class); } } @Data @NoArgsConstructor @AllArgsConstructor public class User { private long id; private String name; } 1SPEVDFSͷ"1*Λݺͼग़͢ίʔυ

$POTVNFS UFTUDPEF @SpringBootTest(webEnvironment = WebEnvironment.NONE, properties = "producer.port=${stubrunner.runningstubs.contract-producer.port}") @AutoConfigureStubRunner(ids =
"com.example:contract-producer:+", stubsMode = StubsMode.LOCAL) public class UserApiClientTest { @Autowired private UserApiClient client; @Test public void getUserTest() { Mono<User> response = client.getUser(1); StepVerifier.create(response) .expectNextMatches(result -> result != null && result.getId() == 1 && "name1".equals(result.getName())) .verifyComplete(); } } ىಈ͍ͯ͠ΔTUVCͷQPSU͕औಘͰ͖Δ DPOUSBDUQSPEVDFS͸BSUJGBDU*E JETʹTUVCΛࢦఆ͢Δ <HSPVQ*E>BSUJGBDU*E<WFSTJPO><DMBTTJpFS><QPSU>

Devoxx Belgium 2019 報告会 Vol.1

Devoxx Belgium 2019 報告会 Vol.1

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