Let’s do this before we start git clone https://bitbucket.org/rlippolis/spring-web-reactive-workshop reactive-spring-intro -> mvn clean verify mememon-go-client -> npm install mememon-go-server -> mvn clean verify npm install -g angular-cli 

Making the paradigm-shift to Reactive Programming with Spring 5 Web Reactive Riccardo Lippolis - JDriven Bas W. Knopper - JCore 

Riccardo Lippolis - JDriven Bas W. Knopper - JCore Making the paradigm-shift to Reactive Programming with Spring 5 WebFlux 

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We need to build better software 

Reactive Programming 

Extending the observer pattern 

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Manipulating data 

Java 8 Streams vs. Reactive Streams • A Stream is pull based • It "asks" for items to process • Iterable++ • A Reactive Stream is push based • You are notified when an element is available 

Backpressure what if you can’t handle the data? 

Reactor projectreactor.io 

Reactor • Made by Pivotal! (Spring FTW \0/) • A foundation for asynchronous applications on the JVM • Based on the Reactive Streams Specification (same concepts, different naming) • Latest: 3.0.7.RELEASE 

Flux and Mono 

Flux and Mono 

Examples - Creating Reactive Streams • Arbitrary number of items: Flux flux = Flux. just("Hello", "World!"); • Converting an existing collection: List list = Arrays. asList(1, 3, 5); Flux flux = Flux. fromIterable(list); • Empty stream: Flux.empty(); 

Examples - Manipulating Streams • Filtering Flux.just(1, 2, 3, 4, 5) .filter(n -> n % 2 == 0) .subscribe(System.out::println); // [2, 4] • Transforming Flux.just(1, 2, 3, 4, 5) .map(i -> i * 2) .subscribe(System.out::println); // [2, 4, 6, 8, 10] 

Reactive Spring Web == Spring WebFlux 

Spring WebFlux Uses the familiar Spring Web MVC programming model (@Controller, etc.)... ...but with a new reactive, non-blocking engine 

Current state of implementation • Version: 5.0.0 RC1 (Not production ready!) • Focus on REST (Server & Client) • JSON (Jackson) / XML (JAXB) • SSE streaming • Spring Data Kay M1 • Reactive support for MongoDB, Cassandra and Redis 

Workshop part 1: Master the koans ● Open the reactive-spring-intro project ● Fix all the tests / koans in: src/test/java/com/jdriven/reactive/exercises 

Workshop part 2: Mememon Go ● Demo explaining Use case ● Make all the tests pass by implementing the code ● Make the application work :) 

What’s next? • Support for Reactive types in other Spring projects, e.g.: • Spring Cloud • Spring Security • …? • GA Release • Current release: 5.0.0 RC1 • GA in june/july? 

Great work everybody!