Have you ever struggled with the saturation of thread pools when you’re dealing with thousands of requests at a time? This problem of synchronous request processing is common with traditional MVC applications. This is where Spring WebFlux enters the picture. It empowers you to build applications with a reactive programming paradigm in an asynchronous, non-blocking, and event-driven manner. This webinar will deal with this concept and help you leverage the principles of reactive programming to develop microservices with the Spring WebFlux framework. The agenda of the webinar will be as follows - ~ Introduction to reactive programming with Java ~ Build a microservice with Spring Webflux and writing unit test cases for it. ~ Using WebClient to leverage external services

1. Building Reactive
Microservices with
Spring Webflux
Presented By: Vinisha Sharma
Software Consultant
Knoldus Inc.

2. About Knoldus
Knoldus is a technology consulting firm with focus on modernizing the digital systems
at the pace your business demands.
DevOps
Functional. Reactive. Cloud Native

3. 01 Evolution of Programming
02 Reactive Programming
03 Spring Webflux (CRUD)
04 WebClient
05 Writing Unit Test for Reactive Application
Our Agenda

4. EVOLUTION OF PROGRAMMING
Few years ago
- Monolithic applications
- Run in App server
- Doesn’t embrace distributed
systems
Today
- Microservices
- Run in cloud
- Embrace distributed
systems

5. TRADITIONAL THREAD PER REQUEST MODEL

6. TRADITIONAL THREAD PER REQUEST MODEL

7. REACTIVE PROGRAMMING
● Programming paradigm oriented around - data flows and
propagation of change.
● Asynchronous and Non Blocking.
● Data flow as an Event/Message Driven stream

8. REACTIVE MANIFESTO

9. REACTIVE STREAMS
● Represents the Data
source
● Database
● External Service, etc…..
● Represents consumer
of stream data
● request()
● cancel()
● represents a
processing
stage—which is both
a Subscriber and a
Publisher.

10. REACTIVE STREAMS

11. SPRING WEBFLUX
● Reactive Stack web Framework
● Embraces Reactive Streams
● Supports Spring 5
● Asynchronous
● Non-Blocking
● Event-Driven
● Supported by Project Reactor

12. SPRING WEBFLUX
Non-blocking
client

13. REACTIVE DATA TYPES : MONO
● Publisher<T> that emits at most one item
● Optionally terminates with an onComplete signal or an onError signal.

14. REACTIVE DATA TYPES : FLUX
● Publisher<T> that emits 0 to n items
● Optionally terminates with an onComplete signal or an onError signal.

15. REACTIVE DATA TYPES : MONO AND FLUX
Mono<Student> Flux<Student>

16. CREATING REST API WITH SPRING WEBFLUX
Two approaches:
○ Annotation Based Programming Model (@Controller)
○ Functional Programming Model (Handler Functions)
We will be exploring on annotation based programming model in this
webinar

17. CREATING REST API WITH SPRING WEBFLUX
Let’s start creating a simple CRUD Microservices with
Spring Webflux

18. SPRING WEBCLIENT
● Interface representing the main entry point for performing web requests
● Non-blocking
● Replacement of RestTemplate
Let’s see how to use it for hitting external services

19. UNIT TEST CASES
● WebTestClient
● Project reactor-test dependency
Let’s use them in the code to write unit test cases

20. Thank You!
vinisha.sharma@knolds.com