Spring WebFlux 는 SSE(Server Sent Event) 를 이용해 데이터를 스트리밍 할 수 있음, SSER 는 HTTP 연결을 통해 서버로부터 전송되는 업데이트 데이터를 지속적으로 수신할 수 있는 단방향 서버 푸시 기술
[코드 21.1]
/**
* 페이지네이션 적용
*/
@Slf4j
@Validated
@Service
@RequiredArgsConstructor
public class BookService {
private final @NonNull R2dbcEntityTemplate template;
...
public Flux<Book> streamingBooks() {
return template
.select(Book.class)
.all()
.delayElements(Duration.ofSeconds(2L));
}
...
}[코드 21.2]
@Configuration
public class BookRouter {
@Bean
public RouterFunction<?> routeBook(BookHandler handler) {
return route()
.POST("/v11/books", handler::createBook)
.PATCH("/v11/books/{book-id}", handler::updateBook)
.GET("/v11/books", handler::getBooks)
.GET("/v11/books/{book-id}", handler::getBook)
.build();
}
@Bean
public RouterFunction<?> routeStreamingBook(BookService bookService,
BookMapper mapper) {
return route(RequestPredicates.GET("/v11/streaming-books"),
request -> ServerResponse
.ok()
.contentType(MediaType.TEXT_EVENT_STREAM)
.body(bookService
.streamingBooks()
.map(book -> mapper.bookToResponse(book))
,
BookDto.Response.class));
}
}[코드 21.3]
@Slf4j
@Configuration
public class BookWebClient {
@Bean
public ApplicationRunner streamingBooks() {
return (ApplicationArguments arguments) -> {
WebClient webClient = WebClient.create("http://localhost:8080");
Flux<BookDto.Response> response =
webClient
.get()
.uri("http://localhost:8080/v11/streaming-books")
.retrieve()
.bodyToFlux(BookDto.Response.class);
response.subscribe(book -> {
log.info("bookId: {}", book.getBookId());
log.info("titleKorean: {}", book.getTitleKorean());
log.info("titleEnglish: {}", book.getTitleEnglish());
log.info("description: {}", book.getDescription());
log.info("author: {}", book.getAuthor());
log.info("isbn: {}", book.getIsbn());
log.info("publishDate: {}", book.getPublishDate());
log.info("=======================================");
},
error -> log.error("# error happened: ", error));
};
}
}