Exploring the Power of Micronaut

The Game-Changing JVM Framework for Agile Microservices

Created using Imagine.art

Micronaut is a JVM-based framework for building modular, lightweight applications. It offers a unique approach to building microservices by using ahead-of-time (AOT) compilation to pre-compute the framework’s dependencies and minimize runtime overhead. This approach enables faster startup time and lower memory consumption compared to traditional JVM-based frameworks. Micronaut to compile applications ahead of time, resulting in faster startup times and lower memory consumption. In this article, we will talk about what Micronaut is and what is the motive behind using the new framework. We will go through a simple ‘Hello World’ example and what more to explore in Micronaut.

Micronaut

What Makes Micronaut a Game-Changer?

Micronaut is a cutting-edge framework designed to simplify the development of microservices. While Micronaut shares some features with existing frameworks like Spring, it also introduces innovative capabilities that distinguish it. Additionally, with support for Java, Groovy, and Kotlin, it provides developers with a versatile range of options to create applications.

The low overhead of the runtime is achieved through compile-time complete dependency injection and an Aspect-Oriented Programming (AOP) API that avoids the use of reflection. This is a major concern in frameworks that rely on reflection during the Inversion of Control (IoC) process, as it results in the loading and caching of every field, method, and constructor. However, in the case of Micronaut, the load time and memory consumption are not directly proportional to the size of the codebase.

Micronaut provides an HTTP server that allows it to expose APIs to be consumed by HTTP clients. The HTTP client can be built declaratively using annotations, which are implemented at compile-time, resulting in reduced memory consumption. With these capabilities, one can develop various APIs and connect to SQL databases such as PostgreSQL with Hibernate, as well as Redis, MongoDB, GraphQL, and Cassandra databases.

Micronaut with Google Cloud Platforms

Micronaut offers several features including service discovery (Eureka), client-side load balancing, circuit breaker, configuration sharing (Consul, with planned support for AWS/GCP), distributed tracing tools (such as Zipkin), and support for serverless computing with AWS Lambda. In summary, Micronaut provides a programming model similar to Spring Boot and Grails, but with reduced load time and memory consumption.

Why Micronaut?

Do you want something similar to Spring Boot for creating microservices with APIs, but with faster boot time and lower memory consumption? Well, Micronaut is the perfect choice! Not only is Micronaut faster and more efficient, but it also doesn’t rely on reflection, making it more secure and less prone to security breaches. Additionally, Micronaut offers excellent support for cloud-native environments, making it a go-to choice for building microservices that can run on platforms like Kubernetes.

But that’s not all! Micronaut also supports traditional JVM-based environments, allowing developers to build microservices that can run in the cloud, on-premises, or even in hybrid environments with ease.

One of the key features of Micronaut is its support for reactive programming. Reactive programming is a programming paradigm that focuses on asynchronous data streams and the propagation of data changes. This can significantly improve the performance and scalability of microservice applications, as it enables them to handle a large number of concurrent requests without encountering memory or CPU constraints.

Overall, Micronaut is a powerful and efficient framework for building microservice applications. With its support for reactive programming, cloud-native environments, and AOT compilation, it becomes an excellent choice for creating scalable and high-performance microservices.

Examples for Micronaut

You will need the following:

• A decent editor or IDE.
• JDK 1.8 or greater installed with JAVA_HOME configured appropriately.
• Install Micronaut ($sdk install micronaut).

Now let's look at creating a simple HTTP server application. To start, we'll use SDKMAN! to create a project.

$mn create-app example.micronaut.micronautguide - build=gradle - lang=java

This will create a new Micronaut java project using gradle in a directory named hello-world-server. Inside this directory, we’ll find our main application source code, build.gradle file, and other support files for the project.

Add Launch Class

public class ServerApplication {
  public static void main(String[] args) {
   Micronaut.run(ServerApplication.class); 
  } 
}

In the above snippet, you can see the simple main method to launch the Micronaut application, this is the same launch class you see in the spring boot application.

Add Controller

Here we are adding a simple controller which you can find similarly in Spring Boot as well. The controller will be having to get and post methods to showcase the examples of Micronaut.

@Controller("/greet") 
public class GreetController { 

  @Inject 
  private GreetingService greetingService;

  @Get("/{name}")
  public String greet(String name) {
   return greetingService.getGreeting() + name; 
  } 

  @Post(value = "/{name}", consumes = MediaType.TEXT_PLAIN)
  public String setGreeting(@Body String name) { 
    return greetingService.getGreeting() + name; 
  }
}

In the above snippet, you can see we have created a controller, And the HTTP GET method will return the String with the name provided in the path variable. HTTP POST method does the same thing it returns the string with a name but here is the difference, it would accept the request body instead of the path variable. Now you can write service and return the response. By default, a Micronaut response uses application/json as Content-Type. We are returning a String, not a JSON object, so we set it to text/plain.

Add Service

Here we will be adding a simple service, The controller invokes the services.

@Primary
@Singleton
public class GreetingService {
    public String getGreeting() {
        return "Hello ";
    }
}

The class GreetController invokes the method named getGreeting() from the service class GreetingService and the method returns the string ‘Hello’.

Comprehensive Support Material

Micronaut has provided extensive and well-documented materials to read and get hands-on experience with it. The official website of Micronaut offers various documents, ranging from installation guides to examples for different use cases. You can find the installation process outlined in the documentation. Additionally, you can explore documents covering topics such as Micronaut with GraphQL, and this is just the tip of the iceberg in the vast ocean of Micronaut possibilities.

Summary

Historically, frameworks such as Spring and Grails were not designed to run in scenarios such as serverless functions, Android apps, or low-memory footprint microservices. In contrast, Micronaut is designed to be suitable for all of these scenarios. The article is just the tip of the iceberg called Micronaut. Micronaut makes 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 Netty. To provide a similar programming model to Spring and Grails, these annotation processors precompile the necessary metadata to perform DI, define AOP proxies, and configure your application to run in a low-memory environment. Micronaut is heavily inspired by Spring and has many similarities in terms of usability; developers with knowledge of Spring should pick up things quickly. See you next time, Happy Micronauting!