Spring Webflux send event when any new data

I'm trying to learn Spring webflux & R2DBC. The one I try is simple use case:

1. have a book table
2. create an API (/books) that provides text stream and returning Flux<Book>
3. I'm hoping when I hit /books once, keep my browser open, and any new data inserted to book table, it will send the new data to browser.

Scenario 2, still from book table:

1. have a book table
2. create an API (/books/count) that returning count of data in book as Mono<Long>
3. I'm hoping when I hit /books/count once, keep my browser open, and any new data inserted /deleted to book table, it will send the new count to browser.

But it does not works. After I isnsert new data, no data sent to any of my endpoint.
I need to hit /books or /books/count to get the updated data.
I think to do this, I need to use Server Sent Events? But how to do this in and also querying data? Most sample I got is simple SSE that sends string every certain interval.

Any sample to do this?

Here is my BookApi.java

@RestController
@RequestMapping(value = "/books")
public class BookApi {

    private final BookRepository bookRepository;

    public BookApi(BookRepository bookRepository) {
        this.bookRepository = bookRepository;
    }

    @GetMapping(produces = MediaType.TEXT_EVENT_STREAM_VALUE)
    public Flux<Book> getAllBooks() {
        return bookRepository.findAll();
    }

    @GetMapping(value = "/count", produces = MediaType.TEXT_EVENT_STREAM_VALUE)
    public Mono<Long> count() {
        return bookRepository.count();
    }
}

BookRepository.java (R2DBC)

import org.springframework.data.r2dbc.repository.R2dbcRepository;

public interface BookRepository extends R2dbcRepository<Book, Long> {
}

Book.java

@Table("book")
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Book {

    @Id
    private Long id;

    @Column(value = "name")
    private String name;

    @Column(value = "author")
    private String author;

}