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Micronaut course

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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.

Session 3 will start here

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