Modern app programming with RxJava and Eclipse Vert.x

With the advent of mobile web and IoT (Internet of Things), today's applications need to handle a lot of concurrent requests while staying responsive and easy to scale. Infrastructure plays a role in achieving these goals, but changing your programming style can help too.

In this presentation, we will make the case for reactive programming, and introduce RxJava in particular. Then we will guide you through the process of building a real-life web application, based on Vert.x 3 and RxJava, communicating with databases, external services and modern datastores. You will learn how Vert.x integrates with RxJava, and why its simplicity makes it a perfect runtime for reactive applications.

Transcript

1. Modern app programming with RxJava & Eclipse Vert.x
2. Who am I? • Thomas Segismont • tsegismont on GitHub, Twitter, Gmail, Freenode... • Vert.x core team since August 2016 • At Red Hat since November 2012 (RHQ and Hawkular)
3. Expectations • Goals – Why should you consider learning Vert.x and RxJava? – What does RxJava look like? Vert.x? – How can I combine them to build scalable, efficient and resilient apps? • Non goals – In-depth study of RxJava or Vert.x
4. http://example.com http://example.com http://example.com Cache Browsers RDBMS Planning Management System Resellers Mobile Devices NoSQL
5. Alexandre Duret-Lutz (CC BY-SA 2.0)
6. ExecutorService to the rescue
7. http://example.com http://example.com http://example.com
8. Thread pools, thread pools EVERYWHERE!
9. Event loops
10. Reactor pattern Single thread
11. Event loop benefits • Mechanical sympathy – Get more from your hardware • Simple concurrency model – No complex multithreaded code bugs • Easier to scale – More predictable behavior under load
12. Vert.x
13. What is Vert.x • Toolkit (lib) • Non blocking • Event-driven • Polyglot (on the JVM) • Fast and lightweight
14. Events • Http server request • Buffer read from a file • Server bound to port • Message from the bus Single thread
15. Multi-Reactor
16. Event Bus • Nervous system of Vert.x • Message passing style • Different messaging paradigms: – Point to point – Publish/Subscribe – Request/Reply • Clustered (browser included!) • Bridges (TCP, Java, Go)
18. Running blocking code • In the real world, most JVM libraries have blocking APIs – JDBC – io.File – Your legacy libs – Heavy computation • With Vert.x you can interact with blocking parts easily • You won’t throw away your code assets!
20. Use cases • Where does it really shine? – API Gateways / Edge Services – Microservices – Cloud (slice of a slice of CPU) – Embedded (IoT)
21. Callback based (reactive imperative)
22. CALLBACK HELL !
23. RxJava A library for composing asynchronous and event-based programs using observable sequences for the Java VM.
24. A bit of history • Started at MSFT with .NET • Provide developers with tools for the apps of 21st century – API economy – Multiple actors – Operating on various systems at different speeds
25. Data and events flows • Everything is a stream! – Mouse clicks – HTTP buffers – EventBus messages – Database rows
26. Push based Observable Observer Subscription • OnNext 0..∞ • Terminal event 0..1 – OnComplete – OnError
27. Backpressure Why do we need it?
28. Reactive pull backpressure Flowable Observer Subscription Request
29. Different flavors Zero One Many Sync void T Iterable<T> Async Completable Single<T> Observable<T> Flowable<T> And in RxJava2 : Maybe (one or none or error)
30. Transforms ReactiveX.io Creative Commons Attribution 3.0 License
31. Composition ReactiveX.io Creative Commons Attribution 3.0 License
32. Coordination ReactiveX.io Creative Commons Attribution 3.0 License
33. Music Store Demo https://github.com/tsegismont/vertx-musicstore
34. http://example.com http://example.com http://example.com https://coverartarchive.org/ Postgres Couchbase App w/ Local Cache
35. Learning http://bit.ly/2i0apir
36. Learning http://red.ht/2pgMEoA
37. Thank you! http://vertx.io Come get your sticker!