The document discusses reactive programming with Spring 5. It introduces reactive programming as an asynchronous, non-blocking approach that handles data flows between producers and consumers. It then covers reactive streams, Project Reactor, and an example usage of reactive repositories with Spring 5. The document aims to explain the benefits of reactive programming and how it can be implemented with Spring 5.

1. Why Reactive?
Reactive Programming With Spring 5
Dane Savot

2. Agenda
1. Why Reactive?
1. The Current Processing Model (Spring MVC)
2. The Reactive runtime (Non-Blocking Runtime)
2. Reactive Programming With Spring 5
1. Imperative vs Reactive Style Programming
2. Reactive Stream
3. Project Reactor
4. Example Usage (Reactive Repository)
5. Demo

3. Current Processing Model in Spring MVC World

13. Non-blocking Runtime

15. Reactive Programming
With Spring 5

16. Imperative vs Reactive Style Programming
List<Order> orders = repository.getOrders(id); -> block
filter(orders); -> block
List<Product> products = orders.stream().foreach(order -> {
order.addProducts(getProducts(order.orderId)); ->block
}); ->block
return orders;
Flux<Order> order = repository.getOrder(id)
.filter(order -> order.getName().match(“A**”))
.subscription( order -> {
order.addProduct(getProduct(order.orderId));
return orders;

17. Reactive Programming
Reactive Programming manages asynchronous data flows between producers of data and consumers
that need to react to that data in a non-blocking manner.
So, Reactive Programming is all about non-blocking applications that are asynchronous and
event-driven and require a small number of threads to scale. (Dzone.com)

18. Reactive Streams

19. public interface Subscriber<T> {
void onSubscribe(Subscription sub);
void onNext(T item);
void onError(Throwable ex);
void onComplete();
}
public interface Subscription
{
void request(long n);
void cancel();
}
public interface Publisher<T> {
void subscribe(Subscriber<? super T> subscriber);
}
Reactive Streams

21. Project Reactor

27. onSubscribe
request(unbounded)
onNext(User: Jason)
onNext(User: Jay)
...
onComplete()

29. onSubscribe
request(2)
onNext(User: Jason)
onNext(User: Jay)
request(2)
onNext(User: Joe)
onNext(User: John)
...

37. References
1. SpringOne Platform 2016 Keynote - Reactive Spring
2. From Imperative To Reactive Web Apps
3. Reactive Programming With Spring 5
4. Doing Reactive Programming with Spring 5