Slides from talk given on Tuesday June 12th at the Boulder Java Users Meetup Group and Wednesday June 13th, 2018 at the Denver Java Users Meetup Group. This talk, by Geoff Filippi, will start with an introduction to reactive programming. We will introduce the Reactive Manifesto and explain Non-blocking IO. We will look at some of the new reactive programming features in Java like CompletableFuture and Reactive Streams. Project Reactor, Spring 5 and Spring Boot 2 are helping to make these new features accessible to Java developers. We will also introduce the concept of backpressure to control the flow of data. You will learn how to create a Non-blocking application using Spring Boot 2. We will use start.spring.io to create a new Reactive application. Will will compare the Flux and Mono types and discuss when to use each. About Geoff Filippi: Geoff is a Senior Architect at DISH Network, in the security group. Previously at Dish he served a large group of developers implementing microservices. Prior to his work at DISH, he was an Application Architect at Oildex, an oil and gas data service company. He also spent 12 years at Time Warner Cable, where he was a Senior Engineer. At TWC, he lead the team that built the video streaming web application, TWCTV. Geoff holds BS and MS degrees in Computer Engineering from Virginia Tech. He holds several patents related to high-availability, architecture, wireless networks and cable systems. Geoff is focused on automating security, API design, domain-driven design and cloud-native architectures.

1. Spring 5Spring 5
Project ReactorProject Reactor
/Geoff Filippi @geofffilippi

2. Geoff FilippiGeoff Filippi
Senior ArchitectSenior Architect

3. DISH NetworkDISH Network
Satellite Pay TV provider
Sling TV
Wireless
Spectrum
Narrow Band Internet of Things (NB-IoT)
Network
5G

4. Formerly:
OildexOildex
A cloud service company for oil and gas
2
years

5. Formerly:
Time Warner CableTime Warner Cable
12
years

6. ExperienceExperience
Microservices
Domain-Driven Design
Event-Sourced
Systems
Security

7. ExperienceExperience
Worked on streaming media (Voice over IP), 6
years
5 million phone customers

8. ExperienceExperience
Worked on video and streaming video, 4
years

9. ProjectsProjects
twctv.com
HTML5 Video streaming website
HTML5 Video streaming Set-Top Box (STB) web
application

10. Oildex ProjectsOildex Projects
Rewrite 10+-year-old
apps
Angular 1.4/Angular 2
Scala/Play microservices

11. We will coverWe will cover
Reactive
Project Reactor
Spring Framework
5
Reactive Streams

12. ReactiveReactive

13. Reactive ManifestoReactive Manifesto
Responsive
Resilient
Elastic
Message
Driven

14. ResponsiveResponsive
Respond in a timely
manner

15. ResilientResilient
Stay responsive, even during
failure
Replication
Isolation
Delegation
Contain failures
Circuit Breaker

16. ElasticElastic
Responsive under varying
workload
Scales resources depending on
load
Cost effective

17. Message DrivenMessage Driven
Rely on asynchronous message
passing
Loosely-coupled components
Failures are also messages
Uses message queues
Backpressure
Non-blocking communication

18. Reactive ConceptsReactive Concepts
Synchronous vs.
Asynchronous
Blocking vs. Non-Blocking

19. SynchronousSynchronous
Client makes a request and waits for server to
complete
Server starts a thread per request
Blocks the thread that it runs on
Lots of concurrent requests use lots of threads
Familiar Java APIs

20. AsynchronousAsynchronous
Client makes a request and does not wait for server to
complete
Server handles all requests on the same thread
Does not block the thread that it runs on
Run in an event loop in a single thread
New Java APIs

21. Blocking vs. Non-blockingBlocking vs. Non-blocking

22. BlockingBlocking
Related to synchronous
Thread execution is postponed
Caller waits for the resource to become
available

23. Non-blockingNon-blocking
Related to asynchronous
Thread execution is not postponed
Inform the caller that resource is not immediately
available
Allows the caller to do other work
Notify the caller when results are ready

24. Back PressureBack Pressure
Mechanism to prevent a message producer from
overwhelming a consumer
Consumer signals producer to pause
Should propogate through responsive systems

25. Async Java FeaturesAsync Java Features

26. FutureFuture
Java 7
.get() Blocks
No methods to combine
No methods to handle
errors

27. CompletableFutureCompletableFuture
Java 8
CompletionStage<T>
interface
Equivalent to JavaScript Promise
Single Value
Part of
java.util.concurrent

28. Project ReactorProject Reactor

29. Project ReactorProject Reactor
Reactive Core
Typed Sequences
Non-Blocking IO
Efficient Message Passing
Async
Based on Reactive
Streams

30. MonoMono
0 or 1 async result
Reactive equivalent of
CompletableFuture

31. FluxFlux
Stream of results
Reactive equivalent of
Stream

32. Spring Framework 5Spring Framework 5
Project
Reactor
WebFlux

33. Spring Boot 2Spring Boot 2
Spring 5
spring-boot-starter-
webflux

34. WebFluxWebFlux
Netty
No Servlet
APIs

35. Reactive Spring DataReactive Spring Data
Cassandra
MongoDB
Couchbase
Redis

36. Reactive Spring DataReactive Spring Data
No JPA
JDBC is a fully-blocking API
Asychronous Database Access API (ADBA)
Proposal
Relational Databases are bottlenecks in reactive
systems

37. Spring Boot 2Spring Boot 2
spring-boot-starter-data-mongo-
reactive

38. Reactive StreamsReactive Streams

39. Reactive StreamsReactive Streams
Java 9
Standard for Asynchronous Stream
Processing
java.util.concurrent.Flow
Non-blocking back pressure

40. Reactive Streams Java SpecificationReactive Streams Java Specification
Publisher
Subscriber
Subscription
Processor

41. Reactive Streams ImplementationsReactive Streams Implementations
for Javafor Java
RxJava
Reactor
Akka
Streams
Ratpack
Vert.x

42. Reactive Streams for JavaReactive Streams for Java
1.8
org/reactivestreams
1.9
java.util.concurrent.Flow

43. DemoDemo
Spring Initializr
Josh Long - FluxFlix
Service
Application

44. Questions?Questions?

45. ReferencesReferences

46. Reactive ReferencesReactive References
The Reactive Manifesto
Notes on Reactive Programming Part I: The Reactive
Landscape
Notes on Reactive Programming Part II: Writing Some
Code
Advanced Reactive Java - Operator-fusion (Part 1)
Understanding Reactive types
Design Principles behind Akka Streams

47. Spring Boot 2 ReferencesSpring Boot 2 References
Spring Boot 2
What's new in Spring Boot
2
Josh Long - Flux-Flix
Service
Spring Initializr

48. Spring 5 ReferencesSpring 5 References
Spring Framework 5
Spring WebFlux
WebFlux framework
Reactive Spring 5 and Application Design
Impact
SampleWebFluxApplication
Reacting to Spring Framework 5.0
Going reactive with Spring Data
Spring Messaging with RabbitMQ
Doing Reactive Programming with Spring 5

49. Spring Integrations ReferencesSpring Integrations References
Reactive Streams With Spring Data and
MongoDB
MongoDB Reactive Streams Java Driver
Project Kafka Reference Guide
Reactor Kafka Reference Guide
Kafka 1.0 Documentation
Reactive Kafka
RabbitMQ
RabbitMQ Node Tutorial
Reactor RabbitMQ Reference Guide
Spring Cloud Stream Reference Guide

50. Project Reactor ReferencesProject Reactor References
(Continued)(Continued)
Project Reactor
Intro To Reactor Core
Reactor by Example
Flux
Mono
Reactor 3 Reference Guide
SampleConsumer
Fetch first element which matches
criteria

51. Reactive Streams ReferencesReactive Streams References
What Are Reactive Streams in
Java?
Reactive Streams
Java 9 Reactive Streams

52. VideosVideos
DevOneConf 2018 - Juergen Hoeller and Josh Long -
Reactive Spring
Under the Hood of Reactive Data Access - Mark Paluch
Webinar: Upgrading to Spring Boot 2.0 - Phil Webb
Spring 5 Playlist