
Kevin's Easy-to-Understand Java Developer Roadmap Story
Kevin
Kevin's Easy-to-Understand Java Developer (Web Developer) Roadmap Story
Beginner
Java
Reactor, one of the core technologies of Spring WebFlux-based reactive applications, and Reactor Operator, which can be said to be the most important part of Reactor, if you want to make it yours, take the `Kevin's Easy-to-Understand Spring Reactive WebApplications: Reactor Part 2` lecture.
358 learners
Level Basic
Course period Unlimited


Reviews from Early Learners
5.0
보키
I started listening to the WebFlux Part 1 lecture on July 20th and finished Part 2 on September 5th! Personally, I followed along with Java as well as Kotlin in 2 sets, and I listened to other lectures alternately, so it took a long time.ㅎㅎ I really enjoyed the lecture! I look forward to the Part 3 lecture using Spring + WebFlux next. Thank you.
5.0
Matthew
I'm glad you explained it so easily :)
5.0
김세진
There aren't many webflux lectures, but this is okay!
How to use Operators to create Reactor Sequences
How to use Operators to filter data in Reactor Sequence
How to use an Operator to transform data emitted from a Reactor Sequence
How to use the Operator to check the internal operation of the Reactor Sequence
How to use time-related operators
How to use an operator to handle errors that occur in a reactor sequence
How to use Operators to split data emitted from a Reactor Sequence
Kevin, who opened Kevin's easy-to-understand RxJava course, is back with a reactive programming series in Inflearn lectures and books after three years!

There is one thing that is most easily overlooked by those who want to develop web applications based on Spring WebFlux.
That is, they want to learn Spring WebFlux right away without properly learning about Operator, which is the core of reactive programming.
We understand your desire to quickly implement Spring WebFlux-based applications.
Many people move on to Spring WebFlux without having a solid understanding of Reactor's Operators, but they often end up hitting a wall called Operator and having to relearn Operators.
In order to avoid these trial and errors, in the second lecture , we will cover the core of Reactor, which is ⭐
We only cover Operators so that you can focus on learning how to use them.
I am confident that this lecture will be the key that will open the door to Reactor, and especially the Operator, which is called the flower of Reactor.
Part 2 of the lecture focuses solely on Reactor's Operators.
To better understand how an Operator works, we will use a marble diagram corresponding to the Operator.
Understand the basic concepts of Operators with example code to understand the basic concepts of a specific Operator.
After understanding the basic concepts, we will explain example code to help you gain insight into how to utilize specific operators.
It explains how to utilize each operator through 97 example codes for a total of 60 operators.
In Section 1, we learn about Operators that create new Reactor Sequences.

justOrEmpty : Learn how to use justOrEmpty Operator to create a single value or an empty Sequence from a Reactor Sequence.
fromIterable: Learn how to create a Sequence from data contained in a Collection in Java.
fromStream : Learn how to create a Sequence from a Java Stream using the fromStream Operator.
range : Learn how to create a sequence of integers within a specified range using range operator.
defer : Let's understand how to delay data emission until the Subscriber subscribes using defer operator.
using : Learn how to create a Sequence that includes the process of acquiring and releasing resources using the using Operator.
generate, create : Learn how to programmatically generate data using generate and create operators.
In Section 2, we learn Operators that filter data in Reactor Sequence.

filter : Learn how to filter data in a Reactor Sequence using the filter Operator.
skip : Learn how to skip data in a sequence using the skip operator.
skip extension Operator : skipLast , skipUntil , skipUntilOther ,
Learn how to skip data in different ways using skipWhile .
take : Learn how to use the take Operator to retrieve only the data you need from the data emitted from a Sequence.
take extension Operator : takeLast , takeUntil , takeUntilOther ,
Learn how to use takeWhile to retrieve only the data you need from data emitted in various ways .
next : Let's look at a method to obtain only the first data among the emitted data.
In Section 3, we learn about Operators that transform data in Reactor Sequences.

map : Learn how to transform data in a Sequence using the map Operator.
flatMap : Take the time to understand how to transform the emitted data using the flatMap Operator and what flattening means.
Learn various flattening methods using the flatMap extension operator : FlatMapIterable , FlatMapMany , and FlatMapSequential .
concat : Learn how to concatenate multiple Sequences using the concat Operator.
merge : Understand how to merge multiple Sequences using the merge Operator.
zip : Learn how to combine source data from multiple Sequences using the zip operator.
and, when : Learn how to check the termination of a Reactor Sequence based on conditions using the and , when Operators.
then : Learn then Operator to perform tasks sequentially .
collectList, collectMap : Learn how to collect emitted data into a List or Map and emit it downstream all at once.
In Section 4, we will learn about Operators, which allow us to look inside Reactor Sequence.

doOnXXXX : Let's understand the life cycle of Sequence by looking into the internals of Sequence using doOnSubscribe , doOnRequest , doOnNext , doOnComplete , etc.
In Section 5, we learn time-related operators among the operators provided by Reactor Sequence.
delayElements : Learn about delayElements , which allows you to emit data at regular intervals.
delaySubscription vs delaySequence : Understand how delaySubscription and delaySequence work and the differences between them.
timeout : Learn about the timeout Operator, which raises an error if data is not emitted within a given time.
In Section 6, we will learn about Operators used to handle errors that occur in Reactor Sequences.

error : Learn how to explicitly throw errors in a Reactor Sequence using the error Operator.
onErrorReturn, onErrorResume : Learn how to emit alternative values or start an alternative Sequence when an error occurs using onErrorReturn and onErrorResume Operators.
onErrorContinue : Learn how to use the onErrorContinue Operator to keep a Sequence running even if an error occurs.
onErrorMap : Learn how to convert errors that occur in a Sequence into a new exception type using the onErrorMap Operator.
retry : Learn how to retry a Sequence if an error occurs using the retry Operator.
In Section 7, we learn an Operator that splits the data emitted from the Reactor Sequence.

window : Learn how to divide emitted data into a certain number of windows and emit them using the window operator.
buffer, bufferTimeout : Learn how to emit data by storing it in a buffer using buffer and bufferTimeout operators.
groupBy : Learn how to group emitted data according to specific criteria using groupBy Operator.
In Section 8, we learn about an Operator that multicasts data to multiple Subscribers with a single Flux.

publish : Learn how to multicast data on a Sequence using the publish Operator.
autoConnect : Learn how to automatically connect to an upstream source when a subscription occurs using the autoConnect Operator.
refCount : Learn how to automatically connect to the upstream source when a subscription occurs using the refCount Operator, and automatically disconnect from the upstream source when the subscription is canceled.
replay : Learn how to re-emit data on a Sequence when a new subscription occurs using the replay Operator.
Part 1 covers the concepts of reactive programming and Project Reactor , which plays a central role in Spring Reactive Web Applications.
Part 2 focuses solely on Project Reactor's Operators , which were not covered in Part 1. Operators play a crucial role among Reactor's various components. Furthermore, this course is structured as a separate course so that those familiar with reactive programming can learn about Operators separately.
Part 3 will focus on example projects that will teach you how Spring WebFlux works and then build reactive web applications . (It's scheduled to open in 2024.)
You can download and review the PPT lecture materials used in each class. While you can download the PPT lecture materials for each class during class, if you find them difficult to view because they are broken down by class, we recommend accessing the integrated lecture materials by section in the Github Repository below.
All example codes explained in class are available on GitHub and can be downloaded from the address below.
All lessons consist of videos ranging from 5 to 20 minutes long.
Please note that some of the video recordings from the first part of the lecture production process are included, so the package structure in some of the lecture videos may appear different from the original example source code.
Java proficiency is a must.
If you have any experience learning Reactor, you do not need to take Part 1.
If you have no experience learning Reactor or are new to the concept of reactive programming, we recommend studying Part 1.
If you use the example code on a blog or other site, please indicate the source.
The marble diagram images used in the lecture (excluding images from the official Reactor website) are copyrighted and cannot be used on other sites such as blogs.
Who is this course right for?
Junior developers who want to learn reactive programming
Developers who want to learn the basics of Project Reactor
If you are having trouble figuring out how to learn the Operator of Project Reactor
Anyone who wants to gain insight into using the Operator in Project Reactor
Anyone who wants to develop a reactive web application based on Spring
Need to know before starting?
Java
Basic knowledge about Project Reactor
Career Verified
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4.8
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Courses
Main languages or technologies: Java, Spring Framework, RxJava, Reactor, Spring WebFlux
Worked as a Backend Developer at Penta Security Inc. (From 2015.07 To 2022.01)
Worked as a Senior Educational Software Engineer (Backend) at Code States Co., Ltd. (https://www.codestates.com)
(From 2022.03 To 2024.01.31)
- Working as a freelance developer and instructor (Since 2024.02)
- Author of
Hello, I'm Kevin. ^^
I am very happy to meet you all as an instructor here on Inflearn.
As is the case in any field, I believe that for a software developer in particular, constantly honing one's skills to keep up with ever-changing trends is the only way to survive. I am one of those developers who enjoys developing software while maintaining a mindset of always learning.
I started my courses on Inflearn with the hope that my knowledge and experience could be of even a little help to others.
I will continue to reach out to students through various courses that provide practical help. Thank you.
Questions and feedback are always welcome, so please feel free to reach out via email (it.village.host@gmail.com).
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5
I started listening to the WebFlux Part 1 lecture on July 20th and finished Part 2 on September 5th! Personally, I followed along with Java as well as Kotlin in 2 sets, and I listened to other lectures alternately, so it took a long time.ㅎㅎ I really enjoyed the lecture! I look forward to the Part 3 lecture using Spring + WebFlux next. Thank you.
Thank you for your hard work studying. I hope your skills have improved, Boki. Thank you!
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