https://github.com/nurkiewicz/reactor-workshop

Spring Reactor hands-on training (3 days)
https://github.com/nurkiewicz/reactor-workshop

concurrency java reactor spring spring-boot webflux

Last synced: 3 months ago
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Spring Reactor hands-on training (3 days)

• Host: GitHub
• URL: https://github.com/nurkiewicz/reactor-workshop
• Owner: nurkiewicz
• License: gpl-3.0
• Created: 2018-08-28T20:33:10.000Z (over 6 years ago)
• Default Branch: master
• Last Pushed: 2023-07-21T04:58:09.000Z (over 1 year ago)
• Last Synced: 2024-10-14T15:27:37.432Z (4 months ago)
• Topics: concurrency, java, reactor, spring, spring-boot, webflux
• Language: Java
• Homepage: https://nurkiewicz.com/slides/reactor-workshop
• Size: 1.12 MB
• Stars: 135
• Watchers: 8
• Forks: 41
• Open Issues: 14
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Reactor training

[![Java CI master](https://github.com/nurkiewicz/reactor-workshop/actions/workflows/gradle.yml/badge.svg)](https://github.com/nurkiewicz/reactor-workshop/actions/workflows/gradle.yml) [![Java CI solutions](https://github.com/nurkiewicz/reactor-workshop/actions/workflows/gradle.yml/badge.svg?branch=solutions)](https://github.com/nurkiewicz/reactor-workshop/actions/workflows/gradle.yml)

Spring [Reactor](https://projectreactor.io) hands-on training (3 days)

See also [workshop notes](https://nurkiewicz.com/slides/reactor-workshop).

## Day 1: Introduction

- What is reactive programming

- Crash course to `CompletableFuture` and thread pools

- Introducing Reactor

- How to create a stream?

  - `just()`, `generate()`, `create()`, `fromCallable()`, `fromStream()`

- Laziness

  - Hot vs. cold

- Basic operators

  - `map()`, `filter()`, `filterWhen()` `flatMap()`, `handle()`, `take()`, `skip()`

  - `doOn*()` operators

  - `window()`, `buffer()`, `distinct()`

  - `cast()`, `ofType()`, `index()`

  - `timestamp()`, `elapsed()`

  - `zip()`, `merge()`

- Error handling

  - `timeout()`, `retry*()`, `retryBackoff()`

  - `onError*()`

- Blocking and reactive, back and forth

- Concurrency with blocking code and thread pools

  - `subscribeOn()`, `parallel()`

- Unit testing

## Day 2: Reactor advanced

- Concurrency with non-blocking code

- Advanced error handling and retries

- `transform()` vs. `transformDeferred()`

- Advanced operators

  - `groupBy()`, `window()`

  - `reduce()`, `scan()`

  - `expand*()`

- Backpressure

  - `onBackpressure*()`

- `Processor` API

  - `Unicast`, `Emitter`, `Replay`

- Advanced testing with virtual time

- `Context`

- Speculative execution example

- [RxJava](https://github.com/ReactiveX/RxJava) interoperability

## Day 3: Practical

- Comparison to blocking and asynchronous servlets

- Refactoring existing application to Reactor

- [Spring Boot](https://spring.io/projects/spring-boot)

  - Reactive database access

  - Reactive controllers

  - `WebFilter`

  - Global error handling

  - Payload validation

  - Web sockets

- Streaming data in and out

- Troubleshooting and debugging

  - `checkpoint()`, `onOperatorDebug()`, `doOn*()`

## Reference materials

1. [Reactor 3 Reference Guide](https://projectreactor.io/docs/core/release/reference/)

2. [Web on Reactive Stack](https://docs.spring.io/spring/docs/current/spring-framework-reference/web-reactive.html#spring-webflux) in [Spring Framework Documentation](https://docs.spring.io/spring/docs/current/spring-framework-reference/index.html)

3. [The "Spring WebFlux Framework"](https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-developing-web-applications.html#boot-features-webflux) in [Spring Boot Reference Guide](https://docs.spring.io/spring-boot/docs/current/reference/html/)

## Troubleshooting, tips and tricks

### IntelliJ test runner

In IntelliJ it's much faster to run tests directly, rather than through Gradle.

Go to `Preferences` -> `Build, Execution, Deployment` -> `Build Tools` -> `Gradle` and select `IntelliJ IDEA` from `Run Tests Using` drop-down.

### Error `Can not connect to Ryuk at localhost:...`

Add this environment variable:

```

TESTCONTAINERS_RYUK_DISABLED=true

```

See: [Disabling Ryuk](https://www.testcontainers.org/features/configuration/#disabling-ryuk)

### Reusing containers in testcontainers

In `.testcontainers.properties` in your `$HOME` folder put the following line:

```

testcontainers.reuse.enable=true

```