1 Introduction

    Micronaut is developed by the creators of the Grails framework and takes inspiration from lessons learnt over the years building real-world applications from monoliths to microservices using Spring, Spring Boot and Grails.

    Micronaut aims to provide all the tools necessary to build JVM applications including:

    • Dependency Injection and Inversion of Control (IoC)

    • Aspect Oriented Programming (AOP)

    • Sensible Defaults and Auto-Configuration

    With Micronaut you can build Message-Driven Applications, Command Line Applications, HTTP Servers and more whilst for Microservices in particular Micronaut also provides:

    • Service Discovery

    • HTTP Routing

    • Client-Side Load Balancing

    At the same time Micronaut aims to avoid the downsides of frameworks like Spring, Spring Boot and Grails by providing:

    • Reduced memory footprint

    • Minimal use of proxies

    • Easy Unit Testing

    Historically, frameworks such as Spring and Grails were not designed to run in scenarios such as server-less functions, Android apps, or low memory-footprint microservices. In contrast, Micronaut is designed to be suitable for all of these scenarios.

    This goal is achieved through the use of Java’s annotation processors, which are usable on any JVM language that supports them, as well as an HTTP Server and Client built on . In order to provide a similar programming model to Spring and Grails, these annotation processors precompile the necessary metadata in order to perform DI, define AOP proxies and configure your application to run in a low-memory environment.

    Many of the APIs within Micronaut are heavily inspired by Spring and Grails. This is by design, and aids in bringing developers up to speed quickly.