Presented at Dutch Spring Meetup on 19-11-2015.

1. Reactive Programming
in Spring 5
Arjen Poutsma
Pivotal

2. About Arjen
• Twenty years of experience in Enterprise
Software Development
• Joined SpringSource in 2005
• Development lead of Spring Web Services,
Spring REST support, Spring Scala
• Working on Spring 5

3. Agenda
• Reactive Systems
• Reactive Streams
• RxJava
• Reactor
• Reactive Programming in Spring 5

4. Reactive Systems

5. Reactive Manifesto
Responsive
Message Driven
ResilientElastic

6. Reactive Manifesto
• Responsive
• Rapid
• Consistent
• Resilient
• Replication
• Isolation
• Elastic
• Scaling
• No bottlenecks
• Message Driven
• Async
• Back-pressure

7. Reactive Streams

8. Reactive Streams Spec
• Focus on Interoperability
• No operators
• Wide support
• Akka,Vert.x, RxJava, Ratpack
• JDK 9 Flow in java.util.concurrent

9. Publisher Subscriber

10. Publisher Subscribersubscribe

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34. Hot & Cold
Cold Hot
Passive Active
Publish when
subscribed
Publish regardless
Queue Mouse Movement

35. Operators
• map, flatMap, take, subscribe, …
• No Operators in Reactive Streams
• Left to implementations

36. Reactor

37. Project Reactor
• Stream extends Publisher
• Wrap Publisher

38. Reactor
Streams.just('a' 'b' 'c')
.take(2)
.map(Character::toUpperCase)
.consume(System.out::println);

39. RxJava

40. RxJava
• Based On Reactive Extensions
• Ported to many languages
• Rx.NET, RxJava, RxJS, ...
• Native support for Reactive Streams
coming in 2.x

41. RxJava
Observable.just('a', 'b', 'c')
.take(2)
.map(Character::toUpperCase)
.subscribe(System.out::println)

42. RxNetty
• RxJava on top of Netty
• Client/server for TCP and HTTP
• Backpressure support

43. Spring 5

44. Spring Reactive
• Experimental work for Spring 5
• Non-blocking runtimes:
• Netty, Jetty,Tomcat, (Undertow)
• RxJava, Reactor
https://github.com/spring-projects/spring-reactive

45. public interface ServerHttpRequest {
HttpMethod getMethod();
URI getURI();
InputStream getBody();
}
public interface ServerHttpResponse {
void setStatusCode(HttpStatus status);
OutputStream getBody();
}
HttpMessage

46. public interface ReactiveServerHttpRequest {
HttpMethod getMethod();
URI getURI();
Publisher<ByteBuffer> getBody();
}
public interface ServerHttpResponse {
void setStatusCode(HttpStatus status);
Publisher<void> setBody(Publisher<ByteBuffer> body);
}
Reactive HttpMessage

47. Reactive Wep App
Web Service Data

48. Wanted: Reactiveness
• JDBC
• MySQL
• Postgres
• NoSQL
• MongoDB
• HTTP Client
• OkHttp
• Spring 5
• …

49. Reactor
@RequestMapping("/capitalize")
@ResponseBody
public Stream<Person> capitalize(
@RequestBody Stream<Person> persons) {
return persons.map(person -> {
person.setName(person.getName().toUpperCase());
return person;
});
}

50. RxJava
@RequestMapping("/capitalize")
@ResponseBody
public Observable<Person> capitalize(
@RequestBody Observable<Person> persons) {
return persons.map(person -> {
person.setName(person.getName().toUpperCase());
return person;
});
}

51. More Spring!
Spring Meetup
http://www.meetup.com/Dutch-Spring-
Meetup/
Spring Track GOTO Amsterdam 2016
http://gotoams.com

52. Q & A
https://github.com/spring-projects/spring-reactive