The document discusses new features in Spring 5.0 that support reactive programming. It introduces reactive programming concepts and the Project Reactor library. It then outlines how Spring Boot 2.0 and other Spring projects like Spring Data now support reactive programming and non-blocking applications through APIs based on the Reactive Streams specification and Project Reactor types like Mono and Flux. Code examples are provided for simple reactive controllers and services using techniques like WebClient and reactive repositories.

1. Spring 5.0
Meets Reactive
Programming

2. Hello!Cláudio E. de Oliveira
Software Engineer and
Architect
At @sensedia
@claudioed
2

3. “ Launched TODAY
3

4. Agenda
⊷ What is Spring Boot
⊷ Reactive Programming
⊷ Project Reactor
⊷ Spring Boot 2
⊷ New Features
⊷ Spring Cloud Projects
4

5. Spring
Boot
Why Spring Boot became a huge
success???
5

6. ⊷ Stand-alone applications
⊷ Starter POMs
⊷ Automatically configurations (a.k.a
JPA, Brokers)
⊷ No code generation and NO XML
anymore
⊷ Production ready features metrics and
monitoring
Spring Boot Main Features
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7. A lot of sub-projects
Spring Data
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Spring AMQP
Spring
Framework
Spring
BatchSpring
Cloud
Spring Cloud Data Flow
Spring SecuritySpring Integration
Spring
Messaging

8. Reactive
Programmin
g
The JVM Scenario
8

9. 9
JVM
Players

10. Project
Reactor
Reactive library implementation for Reactive
Streams Specification
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11. Motivation
11
“Reactor is a fourth-generation
Reactive library for building non-
blocking applications on
the JVM based on the Reactive
Streams Specification”
https://projectreactor.io/

12. Why not RXjava??
12

13. Let’s review some
concepts
Reactive Core
Reactor is a fully non-blocking foundation with efficient
demand management. It directly interacts with Java 8
functional API, Completable Future, Stream and Duration.
Non Blocking IO
Suited for Microservices Architecture, Reactor offers
backpressure-ready network engines for HTTP (including
Websockets), TCP and UDP. Reactive Encoding/Decoding
is fully supported.
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14. 14
Reactor Types
MONO
[0|1]
FLUX
[N]

15. 15
Reactor Types
public Mono<Flight> flight(String id) {
return this.flightRepository.findById(id);
}
public Flux<Flight> flights() {
return this.flightRepository.findAll();
}
Samples

16. Spring Boot 2
What is coming???
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17. 17

18. 18
⊷ Simpler Code, more
readable
⊷ Focus on Business logic
⊷ Stream processing implies
memory efficient
⊷ Flow API Java 9

19. 19

20. 20
Event-Loop

21. 21

22. 22

23. Simple Reactive Controller
// omitted imports
@Bean
public RouterFunction<ServerResponse> routes() {
return route(GET("/api/goodbye"), serverRequest ->
ok().body(fromPublisher(goodbye(),String.class)))
.andRoute(GET("/api/nap"), request -> ok().body(fromPublisher(nap(),String.class)));
}
23

24. Reactive WebClient
// omitted imports
public Mono<Flight> flight(String id) {
return discoveryService.serviceAddressFor(this.flightService).next().flatMap(
address -> this.webClient.mutate()
.baseUrl(address + "/" + this.flightServiceApiPath + "/" + id).build().get().exchange()
.flatMap(clientResponse -> clientResponse.bodyToMono(Flight.class)));
}
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25. 25
Spring Data Reactive

26. 26
Reactive

27. Kotlin Support
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28. Simple REST Controller
// omitted imports
@RestController
@RequestMapping("/api/temperature")
class TemperatureResource(val temperatureService: TemperatureService) {
@GetMapping
fun all() = this.temperatureService.all()
@PostMapping
fun register(request: TemperatureRequest) =
this.temperatureService.register(request)
}28

29. Repository
// omitted imports
interface TemperatureRepository:ReactiveCrudRepository<Temperature,String>{
@Tailable
fun findByDeviceId(deviceId:String):Flux<Temperature>
}
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30. Continuous Queries
Makes queries on DB and get
notification when data
changes.
@Tailable for MongoDB
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31. SSEServer-Sent Events
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32. SSE REST Controller
// omitted imports
@RestController
@RequestMapping("/api/device")
class DeviceResource(val temperatureService: TemperatureService) {
@GetMapping(path = ["/{id}/real-time"],produces =
[MediaType.APPLICATION_STREAM_JSON_VALUE])
fun byDeviceRealTime(@PathVariable("id")deviceId:String) =
this.temperatureService.byDevice(deviceId)
}
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33. 33
Demo SSE

34. Java 9
34

35. Full Support for
Java 9 Module
System
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36. Others changes
Actuator Endpoints
Reactive Thymeleaf
jUnit 5 Support
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37. Spring Boot Actuator
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38. 38
Actuator

39. 39
Spring Cloud
Projects

40. https://github.com/claudioed/kotlin-mongodb-demo
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https://github.com/claudioed/goodbye
https://github.com/PacktPublishing/Spring-5.0-By-Example
GitHub

41. 41