Building a Simple Employee Management Application Using Micronaut

Last Updated : 23 Sep, 2024

In this article, we will demonstrate how to create a simple RESTful Employee Management Application using Micronaut. This article will guide you through saving employee information in a database and handling HTTP requests using Micronaut's powerful features. We will compare Micronaut with Spring Boot to highlight key differences and use cases.

What is Micronaut?

Micronaut is a JVM-based framework designed for developing lightweight, modular applications. Developed by Oracle Cloud Infrastructure (OCI), it simplifies the process of building microservices by offering faster startup times, reduced memory usage, and more efficient performance compared to other frameworks like Spring Boot.

Key Features of Micronaut:

Compile-Time Dependency Injection: Dependency injection happens at compile-time instead of runtime, leading to faster startup times and reduced memory consumption since no reflection is used.
Modular and Lightweight: Micronaut is highly modular, letting developers include only the necessary components, reducing the application's memory footprint.
Cloud-Native Support: It supports cloud-native features such as service discovery and distributed configuration.
Serverless-Friendly: Micronaut’s fast startup times and minimal resource consumption make it ideal for serverless architectures.
Built-in Security: Micronaut includes built-in support for validation, authentication, and authorization.

Use Cases for Micronaut:

Micronaut shines in specific environments, and here are a few key scenarios where it excels:

Microservices Architecture: Due to its fast startup times, low memory consumption, and modular design, Micronaut is ideal for building and managing microservices.
Serverless Computing: Micronaut's efficient memory usage and fast startup make it perfect for serverless applications where you need to reduce cold start latency.
Cloud-Native Applications: Micronaut simplifies the deployment of applications in cloud environments by providing built-in support for distributed configuration and cloud providers like AWS, Google Cloud, and Azure.

Implementation to Create an Employee Management System Using Micronaut

This example walks through building a simple Employee Management API that allows users to save employee details in a database.

Step 1: Create a Micronaut Project

Go to Micronaut Launch and create a Micronaut project. Download the ZIP file, extract it, and open it in IntelliJ IDEA or your preferred IDE.

Open Micronaut Project in Intellij IDEA IDE.

Step 2: Employee Domain Class

Java

// Domain package for the Employee entity
package com.emp.domain

// Import necessary annotations and JPA packages
import groovy.transform.Canonical
import groovy.transform.CompileStatic
import jakarta.persistence.Entity
import jakarta.persistence.GeneratedValue
import jakarta.persistence.GenerationType
import jakarta.persistence.Id

// Mark this class as a JPA Entity
@Entity
@CompileStatic
@Canonical
class Employee {

    // Define the primary key for the Employee entity
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    Long id

    // Define other attributes of the Employee
    String name
    String email
    String city
    Long salary
}

This domain class represents the Employee entity, which will be used to map the employee data to the database.

Step 3: Create Repository

Java

// Define repository package for Employee
package com.emp.repository

import com.emp.domain.Employee
import io.micronaut.data.annotation.Repository
import io.micronaut.data.jpa.repository.JpaRepository
import jakarta.inject.Singleton

// Define a repository interface for Employee using Micronaut Data JPA
@Singleton
@Repository
abstract class EmployeeRepository implements JpaRepository<Employee, Long> {
}

The EmployeeRepository provides basic CRUD operations for the Employee entity by extending JpaRepository.

Step 4: Create DTO for Payload

Java

// Define a DTO for Employee data transfer
package com.emp.dto.request

import groovy.transform.Canonical
import groovy.transform.CompileStatic
import io.micronaut.core.annotation.Introspected
import io.micronaut.serde.annotation.Serdeable

@Introspected
@CompileStatic
@Canonical
@Serdeable.Deserializable
class EmployeeDto {
    String name
    String email
    String city
    Long salary
}

This DTO (Data Transfer Object) is used to receive the employee information from the client in the API request.

Step 5: Create Response DTO

Java

// Response class to send a result back to the client
package com.emp.dto.response

import com.fasterxml.jackson.annotation.JsonIgnoreProperties
import groovy.transform.Canonical
import groovy.transform.CompileStatic
import io.micronaut.core.annotation.Introspected

@Introspected
@CompileStatic
@Canonical
@JsonIgnoreProperties(ignoreUnknown = true)
class EmployeeResp {
    String name
    String email
    String city
    Long salary
}

This DTO is used to send the employee data back as a response after saving the employee to the database.

Step 6: Service Class

Java

// Define the service to handle business logic
package com.emp.service

import com.emp.domain.Employee
import com.emp.dto.request.EmployeeDto
import com.emp.dto.response.EmployeeResp
import com.emp.repository.EmployeeRepository
import groovy.transform.CompileStatic
import jakarta.inject.Singleton

@Singleton
@CompileStatic
class EmployeeService {

    private final EmployeeRepository employeeRepository

    // Constructor-based dependency injection
    EmployeeService(EmployeeRepository employeeRepository) {
        this.employeeRepository = employeeRepository
    }

    // Method to save an employee
    EmployeeResp saveEmployee(EmployeeDto employeeDto) {
        Employee employee = convertToDomain(employeeDto)
        employeeRepository.save(employee) // Save employee to DB
        return convertResponse(employee)
    }

    // Convert DTO to Domain entity
    private static Employee convertToDomain(EmployeeDto employeeDto) {
        new Employee(
            name: employeeDto?.name,
            email: employeeDto?.email,
            city: employeeDto?.city,
            salary: employeeDto?.salary
        )
    }

    // Convert Domain entity to Response DTO
    private static EmployeeResp convertResponse(Employee employee) {
        new EmployeeResp(
            name: employee?.name,
            email: employee?.email,
            city: employee?.city,
            salary: employee?.salary
        )
    }
}

The service class handles the business logic, such as converting the DTO to an entity and saving it to the database.

Step 7: Create Controller

Java

// Define the controller for the API
package com.emp.controller

import com.emp.dto.request.EmployeeDto
import com.emp.dto.response.EmployeeResp
import com.emp.service.EmployeeService
import io.micronaut.http.annotation.Body
import io.micronaut.http.annotation.Controller
import io.micronaut.http.annotation.Post

@Controller("/api/employee/")
class EmployeeController {

    private final EmployeeService employeeService

    // Constructor-based dependency injection
    EmployeeController(EmployeeService employeeService) {
        this.employeeService = employeeService
    }

    // Endpoint to save an employee
    @Post("save")
    EmployeeResp saveEmployee(@Body EmployeeDto employeeDto) {
        return employeeService.saveEmployee(employeeDto)
    }
}

The EmployeeController class defines the API endpoint /api/employee/save to handle HTTP POST requests for saving employee details.

Step 8: Testing the API

Run the application and test the API using Postman. Use a POST request with the following URL:

http://localhost:8080/api/employee/save

Provide the employee details in JSON format in the request body and check the response.

Output:

Difference Between Micronaut And Spring Boot

Features	Micronaut (AOT Compilation)	Spring Boot (Runtime Reflection)
Startup Time	Faster, due to compile-time dependency injection	Slower, as it relies on runtime reflection
Memory Footprint	Smaller	Larger
Dependency Injection	Compile-time	Runtime reflection
Reactive Programming	Natively supported	Supported, but with more setup complexity
Configuration	Less verbose, simpler setup	Requires extensive annotations and configurations.
Performance	Highly optimized for microservices	Optimized but heavier due to runtime ops
Community	Smaller community	Larger community
Documentation	Well-written records	Outstanding record-keeping

In this article, we have created a simple employee management API using Micronaut with a detailed comparison of its features against Spring Boot. Micronaut's fast startup times and low memory usage make it a great choice for microservices, serverless, and cloud-native applications.

Employee Management System Project using Spring Boot

kevalpatoliya

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Article Tags :

Building a Simple Employee Management Application Using Micronaut

What is Micronaut?

Key Features of Micronaut:

Use Cases for Micronaut:

Implementation to Create an Employee Management System Using Micronaut

Step 1: Create a Micronaut Project

Step 2: Employee Domain Class

Step 3: Create Repository

Step 4: Create DTO for Payload

Step 5: Create Response DTO

Step 6: Service Class

Step 7: Create Controller

Step 8: Testing the API

Output:

Difference Between Micronaut And Spring Boot

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