Reactive Programming in Modern Java using Project Reactor

Learn to write fast performing Asynchronous and NonBlocking code using the Reactive Programming principles and Reactor.

What you'll learn:
What is Reactive Programming?
When to use Reactive Programming ?
Write Reactive Code using Project Reactor
Different Operators that are part of Project Reactor
Reactive Streams Specification
Build Non Blocking Rest Clients using Spring WebClient
Unit Test the Reactive Code using JUnit5
Reactive Types Flux/Mono

Requirements
Prior Java Experience is mandatory
Experience writing test cases using JUnit
Experience working with Intellij or any other IDE

Description
Reactive Programming is a new programming paradigm that's well suited for applications that are required to perform better under heavy load.

Reactive Programming is built on the foundation of reactive streams specification. Project Reactor is an implementation of Reactive Streams Specification.

Code that's written using Reactive programming has these qualities:

Fundamentally Asynchronous

Non Blocking

Functional Programming Style of code

Backpressure support

This course is designed to provide both theoretical and practical knowledge about reactive programming using Project Reactor. This is a pure hands-on oriented course and all the concepts are explained by writing code.

Course Curriculum:

Section 1: Getting Started With the Course

This section covers the course objectives and the prerequisites that are needed to make the most out of this course.

Section 2: Introduction to Reactive Programming

In this section, I will introduce you to reactive programming and its related concepts. The following topics are covered in this section

Why Reactive Programming?

What is Reactive Programming?

Introduction to Reactive Streams

Section 3: Getting Started with Project Reactor

In this section, I will introduce you to the reactive library project reactor, and the reactive types Flux and Mono that forms the foundation for Project Reactor

Introduction to Project Reactor

Reactor Reactive Types - Flux and Mono

Section 4: Setting up the Project for this course

In this section, I will set up the base project that will be used for the rest of this course.

Section 5: Functional Programming in Modern Java

In this section, I will explain Functional Programming and the benefits that are tied with this programming style

Imperative Style vs Functional Style

Section 6: Let's create our very first Flux and Mono

In this section, I will code and explain the reactor types Flux and Mono using simple examples

The following topics are covered as part of this lecture:

Let's write our very first Flux

Let's write our very first Mono

Reactive Stream Events

Testing Flux using JUnit5

Section 7: Transforming Flux and Mono

In this section, I will code and explain different operators that can be used to transform data from one form to another using project reactor

The following topics are covered as part of this section:

Transforming Data Using Operators in Project Reactor

Transform using map() Operator

Reactive Streams are Immutable

Filter using filter() Operator

Advanced transform using the flatMap() Operator

Asynchronous Operations using flatMap() Operator

Advanced transform using the concatMap() Operator

flatMap( ) operator in Mono

flatMapMany( ) operator in Mono

Transform using the transform() Operator

Handling empty data using defaultIfEmpty and switchIfEmpty() Operators

Section 8: Combining Flux and Mono

In this section, I will code and explain different operators that can be used to combine the reactive streams using project reactor

The following topics are covered as part of this section:

Introduction to Combining Reactive Streams

Combining Reactive Streams using merge() and mergeWith() Operators

Combining Reactive Streams using mergeSequential() Operators

Combining Reactive Streams using zip and zipWith() Operators

Section 9: Build Movie ReactiveService using Project Reactor

In this section, we will build the Reactive MovieService using all the skills that we have acquired so far

Overview of this MovieService

Retrieve all of the MovieInfo

Retrieve MovieInfo by movieId

Section 10: doOn* CallBacks - Peeking into a Sequence

In this section, I will code and explain the techniques to peek into the individual events that's emitted by the publisher

Section 11: Exception/Error Handling in Flux and Mono

In this section, I will cover the different exception handling strategies that are part of the Project reactor

The following topics are covered as part of this section:

Exceptions in Reactive Streams

Introduction to Exception Handling Operators

onErrorReturn() : Exception Handling Operator

onErrorResume() : Exception Handling Operator

onErrorContinue() : Exception Handling Operator

onErrorMap() : Exception Handling Operator

doOnError() : Catching Exceptions and Throw the error

Error Handling Operators in Mono

Section 12: Implement Exception Handling in Movies Reactive Service

In this section, I will implement the exception handling in the MoviesReactiveService.

Exception Handling in MoviesReactiveService using onErrorMap

Test Exception in MoviesReactiveService using Mockito

Section 13 : Retry, Repeat using retry(), retryWhen(), repeat()

In this section, I will code and implement different techniques to retry the exceptions in the Reactive Streams using Project Reactor

The following topics are covered as part of this section:

Retry Exceptions using retry() and retry(n)

Retry Specific Exceptions using retryWhen()

Repeat a Sequence using repeat() and repeat(n)

Repeat a Sequence repeatWhen()

Section 14: Reactors Execution Model - Schedulers, Threads, and Threadpool

In this section, I will explain the threads and the execution model behind the project reactor

The following topics are covered as part of this section:

Reactor Execution Model

Switching Threads using publishOn()

Switching Threads using subscribeOn()

Section 15: Making Blocking Calls in MovieReactiveService

In this section, we will add an enhancement to the MoviesReactive Service by adding a blocking call in to the pipeline.

Making Blocking calls in MovieReactiveService

In this lecture, we will code and learn about how to make blocking calls using project reactor

Section 16: BackPressure

In this section, I will explain the concept of backpressure in reactive programming

The following topics are covered as part of this section:

Introduction to BackPressure

Let's implement BackPressure

Write a JUnit test for BackPressure

Handling Backpressure using onBackpressureDrop()

Handling Backpressure using onBackpressureBuffer()

Handling Backpressure using onBackpressureError()

Section 17: Explore Data Parallelism in Project Reactor

In this section, I will explain about introducing parallelism into the reactive pipeline

The following topics are covered as part of this section:

Parallelism using parallel() and runOn() operators

Parallelism using flatmap() operator

Parallelism using flatMapSequential() operator

Section 18: Cold & Hot Streams

In this section, I will explain about cold and hot streams in Reactive Programming

The following topics are covered as part of this section:

Cold & Hot Streams

Cold Streams

Hot Streams - ConnectableFlux and different options

Section 19: JUnit Testing using VirtualTimeScheduler

In this section, I will explain the use of VirtualTimer to decrease the execution time of test cases.

StepVerifier using VirtualTimeScheduler

Section 20: Build NonBlocking RestClient using WebClient

In this section, we will write a nonblocking rest client using Spring WebClient

The following topics are covered as part of this section:

Overview of the Reactive Movie API

Build the non-blocking MovieInfoService RestClient

Build the non-blocking Review RestClient

Build getAllMovies non-blocking MovieReactiveService Client

Build getMovieById non-blocking MovieReactiveService Client

Integrate WireMock for Integration Tests

Section 21: Programmatically Creating a Flux

In this section, I will code and explain the techniques that are available to create a flux programmatically.

The following topics are covered as part of this section:

Create a Flux using create()

Create a Flux using push()

Section 22: Debugging in Project Reactor

In this section, I will demonstrate different approaches that are available when it comes to debugging reactor error messages.

The following topics are covered as part of this section:

Debug Exceptions using "checkpoint" operators

Debug Exceptions using Hooks.onOperatorDebug()

Production-ready Global Debugging using "ReactorDebugAgent"

By the end of this course, you will have a complete understanding of Reactive Programming, write code using the Reactive Programming Principles, and when to use them in your project.

Who this course is for
Any Java Developer who is interested in exploring Reactive Progrmming
Any Java Developer who has the need to write fast performing code under heavy load
Any Java Developer who is interested in learning all the features of the "Reactor" Reactive Programming Library