Kevin's Easy-to-Understand Spring Reactive Web Applications: Reactor Part 2

Section 1: Creating a new sequence

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.

Section 2: Filtering a sequence

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.

  
  

Section 3: Transforming an existing sequence

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.

Section 4: Peeking into a sequence

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.

Section 5: Working with time

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.

Section 6: Handling errors

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.

  
  

Section 7: Splitting a Flux

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.

  
  

Section 8: Multicasting a Flux to several Subscribers

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.

  
  

Kevin's Complete Course on Spring Reactive Web Applications: Easy to Understand

• 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.)

Learning Materials

• 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.

  • Collection of lecture materials by section

• All example codes explained in class are available on GitHub and can be downloaded from the address below.

  • Original example source code

• 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.

Player Knowledge and Precautions

• 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.