Reactive Programming presentation - Dirk Janssen. (13th SPIN meetup)

1. Reactive Programming
Dirk Janssen – Integratie Consultant

2. Reactive Manifesto
“Systems built as Reactive Systems are more flexible, loosely-coupled and scalable. This makes them easier to
develop and amenable to change. They are significantly more tolerant of failure and when failure does occur they
meet it with elegance rather than disaster. Reactive Systems are highly responsive, giving users effective
interactive feedback.”

3. What do they mean?

4. Simplified explanation
“Reactive programming is programming with asynchronous data streams.”

5. Four fundamental effects of programming
One Many
Sync T iterable[T]
Async Future[T] Observable[T]

6. Reactive Components
• Vert.x
• Ratpack
• ReactiveX (C#, Java, Scala, JavaScript, Python, …)
• Akka Streams
• React
• (Reactive) Spring 5
• etc.

7. Vert.x
● Vert.x the plain old jar file
● Event Driven
● Asynchronous
● Non Blocking
● Event Loop

8. Event Loop
● Verticles
● Multi-reactor Pattern.

9. The golden rule
Don’t Block the Event Loop!

10. Why Vert.x for microservices
● TCP, UDP, HTTP clients
● MongoDB, JDBC, SQL, Redis, MySQL/PostgreSQL
● Openshift support
● Camel bridge
● Etc.. (http://vertx.io/docs/)

11. Verticle
● Smallest unit of deployment
● Deploy with Vert.x
● Runs on the event loop
● Types
● Standard;
● Worker verticle;
● Multi-threaded worker verticle.

12. Event-bus
● Messaging between verticles;
● Point to Point
● Publish / subscribe
● Request / Reply
● Polyglot

13. Hello, World!

14. Callback hell

15. RxJava(2)
● ReactiveX
● Observer pattern;
● Event and Data Flows;
● Asynchronous;
● Non blocking.

16. Observable
● Speaker
● (Operator)
● Listener

17. Observable
● Events
● onNext
● onError
● onCompleted
● Subscribe
● Hot vs Cold

18. Observable types
● Observable
● Single
● Maybe
● Flowable
● Completable

19. Operators
● Zip;
● Merge;
● FlatMap;
● Skip;
● Count;
● Filter;
● Etc...

20. (Reminder) Callback hell

21. Composition via Observables

22. Callback hell

23. Marbles
● http://rxmarbles.com/

24. Threading
● Single threaded
● Multi-threaded
● ObserveOn
● SubscribeOn;
● Easy, or not...