# Micronaut course

[toc]

## Learning sessions log

**Session 1 : 04/11/2022**

Daniel - Instructor for the course

Living in Austria - working at technical lead with backend applications. Deploying to aws.

Goal for this course: following it for 45min/day.



**Session 2 : 06/11/2022** - continue with micronaut quickstart, create a hello world endpoint and test it with `@MicronautTest`



## Unit 1 : Introduction

### Spring / Micronaut / Quarkus (09/2020)



Spring - dominating the Java world

- well established
- reactive stack with Spring WebFlux (since v5)
- biggest community
- most integrations
- multi language support
- heavy use of reflection
- support for GraalVM (beta)



Quarkus - cloud native framework

- reactive stack
- minimal memory footprint at startup time
- based on standards and frameworks
- GraalVM / serverless cloud functions
- slower compilation time (AOT)
- smaller community as Spring



**Micronaut** - modern cloud native framework

- reactive stack
- minimal footprint and startup time
- no byte code modidications during compilation
- removes all leves of reflection usage
- GraalVM / serverless cloud functions
- multi language support (Java, Groovy, Kotlin)
- quite similar to Spring framework (good if you have spring background)
- slower compilation time (AOT)
- smaller community as Spring



### Code examples and setup

*Course is compatible with version 3.1*



## Unit 2: Micronaut 3 - quickstart

Cf. https://micronaut.io and https://micronaut.io/launch

Create a first project with:

- Micronaut 3 LTS
- Java 11
- Maven
- Junit

Dependancies: `Netty server`



### Creating our first endpoint

Create a hello world endpoint using annotations.

- create a java class
- add `@Controller("/path")` annotation at class level
- add `@Get(produces = MediaType.TEXT_PLAIN)` at method level

**NOTE**: access http://localhost:8080/hello to see plain text hello world displayed.



### First micronaut test experience

*Let's automate - making sure that written code works*

- create a test class in test folder
- add annotation `@MicronautTest` at class level
- add a class with `@Test` annotation
- create a HttpClient using `@Inject` & `@Client("/")`
- use the `HttpClient client` as a blocking client (for simplicity now) and query the `/hello` endpoint

**NOTE**: by default a `@MicronautTest` is a functionnal test. So to create a unit test simply remove the annotation and use your prefered test framework.



<hr>

***Session 3 will start [here](https://sparkers.udemy.com/course/learn-micronaut/learn/lecture/28896754#overview)***