Modern app programming with RxJava and Eclipse Vert.x
- 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) #RivieraDev @vertx_project
- 3. Expectations ● Goals – Why is reactive programming important? – What are RxJava and Vert.x? – How can I combine them to build scalable, efficient and resilient apps? ● Non goals – In-depth study of RxJava or Vert.x #RivieraDev @vertx_project
- 4. Back to the late 90s… A hotel room booking engine
- 6. Such apps are mainstream today! ● Microservices ● API economy #RivieraDev @vertx_project
- 7. Alexandre Duret-Lutz (CC BY-SA 2.0)
- 10. New stuff? ● Browser (AJAX, #setTimeout) ● GUI ● Node.js #RivieraDev @vertx_project
- 11. Event loop benefits ● Simple concurrency model ● Mechanical sympathy http://bit.ly/2cJMBsG – Higher throughput – Predictable latency #RivieraDev @vertx_project
- 12. Vert.x
- 13. What is Vert.x ● A toolkit (lib) ● … to build polyglot (on the JVM) – JS, Groovy, Ruby, Scala (3.4), Kotlin (3.4) ● … reactive systems #RivieraDev @vertx_project
- 17. Event Bus ● Nervous system of Vert.x ● Message passing style ● Different messaging paradigms: – Point to point – Publish/Subscribe – Request/Reply #RivieraDev @vertx_project
- 18. Running blocking code ● In the real world, most JVM libraries have blocking APIs – JDBC – io.File – Your legacy libs ● With Vert.x you can interact with blocking parts easily ● You won’t throw away your code assets! #RivieraDev @vertx_project
- 20. Callback based (reactive imperative)
- 21. CALLBACK HELL !
- 22. RxJava
- 23. Data and events flows ● It is great at organizing transformation of data and coordination of events ● It makes most sense when many sources of events are involved (modern apps!) #RivieraDev @vertx_project
- 24. Push based Observable Observer Subscription ● OnNext 0..∞ ● Terminal event 0..1 – OnComplete – OnError #RivieraDev @vertx_project
- 25. Reactive pull backpressure Observable Observer Subscription Request #RivieraDev @vertx_project
- 26. Observable / Single / Completable Zero One Many Sync void T Iterable<T> Async Completable Single<T> Observable<T> #RivieraDev @vertx_project
- 27. Demo Damn simple Rx Verticle
- 29. http://example.com http://example.com http://example.com https://coverartarchive.org/ Postgres Couchbase Vert.x RxJava Vert.x Web Client HTTP Vert.x JDBC Client Couchbase RxJava driver Event Bus Bridge (WebSocket) Vert.x Local Cache
- 30. Observable#map ReactiveX.io Creative Commons Attribution 3.0 License
- 31. Observable#map private Single<JsonArray> findAlbums(SQLConnection sqlConnection, Long artistId) { return sqlConnection.rxQueryStreamWithParams(findAlbumsByArtist, new JsonArray().add(artistId)) .flatMapObservable(SQLRowStream::toObservable) .map(row -> new JsonObject().put("id", row.getLong(0)).put("title", row.getString(1))) .collect(JsonArray::new, JsonArray::add) .toSingle(); } #RivieraDev @vertx_project
- 32. Observable#flatMap ReactiveX.io Creative Commons Attribution 3.0 License
- 33. Single#flatMap public void handle(RoutingContext rc) { dbClient.rxGetConnection().flatMap(sqlConnection -> { return findGenres(sqlConnection).doAfterTerminate(sqlConnection::close); }).flatMap(genres -> { rc.put("genres", genres); return templateEngine.rxRender(rc, "templates/index"); }).subscribe(rc.response()::end, rc::fail); } #RivieraDev @vertx_project
- 34. Single#zip ReactiveX.io Creative Commons Attribution 3.0 License
- 35. Single#zip Single<JsonObject> as = findAlbum(sqlConnection, albumId); Single<JsonArray> ts = findTracks(sqlConnection, albumId); return Single.zip(as, ts, (album, tracks) -> { Map<String, Object> data = new HashMap<>(2); data.put("album", album); data.put("tracks", tracks); return data; }).doAfterTerminate(sqlConnection::close); #RivieraDev @vertx_project
- 36. Observable#observeOn ReactiveX.io Creative Commons Attribution 3.0 License
- 37. Observable#observeOn #RivieraDev @vertx_project albumCommentsBucket.query(Query.parametrized(findRecentCommentsByAlbum, params)) .observeOn(RxHelper.scheduler(rc.vertx())) .flatMap(AsyncQueryResult::rows) .limit(5) .collect(JsonArray::new, (jsonArray, row) -> jsonArray.add(new JsonObject(row.value().toMap()))) .toSingle() .flatMap(data -> { rc.put("comments", data); return templateEngine.rxRender(rc, "templates/partials/album_comments"); }).subscribe(rc.response()::end, rc::fail);
- 39. Thank you! http://vertx.io Come get your sticker! #RivieraDev @vertx_project