From Streams to Reactive Streams
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The document discusses reactive programming and the Reactive Streams specification. It introduces reactive programming as a programming paradigm for concurrent and asynchronous processing using a stream-based approach. It then describes the Reactive Streams specification, which defines interfaces and protocols for building asynchronous streams with non-blocking back pressure. The rest of the document discusses an implementation of Reactive Streams called Project Reactor and how it can be used with Spring frameworks to build reactive applications.
From Streams to Reactive Streams
- 1. From Streams to Reactive Streams Oleg Tsal-Tsalko JavaDay Kyiv 2017
- 2. SOLUTION ARCHITECT AT EPAM SYSTEMS. PASSIONATE DEVELOPER, SPEAKER, ACTIVE MEMBER OF KIEV JUG. PARTICIPATE IN DIFFERENT EDUCATIONAL INITIATIVES, ENGINEERING EVENTS AND JCP/ADOPTJSR PROGRAMS. MEMBER OF ARCHITECTURE EXCELLENCE INITIATIVE AND ENGINEERING PRODUCTIVITY GROUPS IN EPAM. OLEG TSAL-TSALKO
- 3. CONFIDENTIAL 3 Agenda Reactive Manifesto Reactive Programming Reactive Streams spec Project Reactor
- 8. CONFIDENTIAL 8 Non-blocking architecture • Can’t write imperative code anymore • Can’t assume single thread of control • Must deal with async results (listeners/callbacks) • Everything becomes stream of events
- 9. CONFIDENTIAL 9 What is Reactive Programming?
- 11. CONFIDENTIAL 11 Reactive Use Cases External Non-blocking Service Calls Highly Concurrent Message Consumers Spreadsheets Abstraction Over (A)synchronous Processing …
- 13. CONFIDENTIAL 13 One spec to rule them all
- 14. CONFIDENTIAL 14 Reactive Streams spec Asynchronous stream processing with non-blocking back pressure The Problem Handling streams of “live” data whose volume is not predetermined so that fast data source does not overwhelm the stream destination Scope Minimal set of interfaces, methods and protocols to build asynchronous streams of data with non-blocking back pressure
- 15. CONFIDENTIAL 15 What is back-pressure?
- 16. CONFIDENTIAL 16
- 18. CONFIDENTIAL 18 Reactive Streams API
- 20. CONFIDENTIAL 20 Difference to CompletableFuture If you have a reference to the Future, it means the task processing an asynchronous result is already executing! Deferred - nothing happens before the call to subscribe() Pull - Subscriber pull the next chunk of data when needed Push - Producer push new data to Consumer according to demand CompletableFuture is push only model ReactiveStreams is deferred pull-push model
- 22. CONFIDENTIAL 22 Spring Reactor evolution
- 23. CONFIDENTIAL 23 Reactor in Spring ecosystem
- 24. CONFIDENTIAL 24 Three things you can do with Flux/Mono: 1. operate on it 2. subscribe to it 3. configure it Simple and clear, isn’t it?
- 26. CONFIDENTIAL 26
- 27. CONFIDENTIAL 27 Programming model is very similar Both heavily use operators chaining and lambdas Java8 Streams Reactive Streams However purpose is different!!! Reactive Streams operate on reactive data and represent data over time Java8 streams operate on collections and have all or nothing semantics
- 28. CONFIDENTIAL 28 Reactive streams lifecycle • Assembly-time: When you compose your stream just().subscribeOn().map() • Subscription-time: When Subscriber subscribes to a stream and it triggers a "storm" of subscriptions under the hood • Runtime: When items are generated followed by zero or one terminal event of error/completion
- 29. CONFIDENTIAL 29 Links Exercises to practice: https://github.com/reactor/lite-rx-api- hands-on Examples shown: https://github.com/olegts/ReactiveStreams/tree/master/src/ test/java/org/reactivestreams/reactor/javaday Reactive Streams: https://github.com/reactive- streams/reactive-streams-jvm Project Reactor: https://projectreactor.io/docs
- 30. CONFIDENTIAL 30