Book Image

Building Applications with Spring 5 and Kotlin

By : Miloš Vasić
Book Image

Building Applications with Spring 5 and Kotlin

By: Miloš Vasić

Overview of this book

Kotlin is being used widely by developers because of its light weight, built-in null safety, and functional and reactive programming aspects. Kotlin shares the same pragmatic, innovative and opinionated mindset as Spring, so they work well together. Spring when combined with Kotlin helps you to reach a new level of productivity. This combination has helped developers to create Functional Applications using both the tools together. This book will teach you how to take advantage of these developments and build robust, scalable and reactive applications with ease. In this book, you will begin with an introduction to Spring and its setup with Kotlin. You will then dive into assessing the design considerations of your application. Then you will learn to use Spring (with Spring Boot) along with Kotlin to build a robust backend in a microservice architecture with a REST based collaboration, and leverage Project Reactor in your application. You’ll then learn how to integrate Spring Data and Spring Cloud to manage configurations for database interaction and cloud deployment. You’ll also learn to use Spring Security to beef up security of your application before testing it with the JUnit framework and then deploying it on a cloud platform like AWS.
Table of Contents (12 chapters)

Adding an @Service component

We will continue our work by introducing a Service component. So, what is a Spring service exactly? An @Service annotated class is Service, originally defined by domain-driven design. That is an operation offered as an interface that stands alone in the model, with no encapsulated state.

Spring offers the following commonly used annotations:

  • @Component
  • @Controller
  • @Repository
  • @Service

Let's explain the difference between them.

  • @Component is a generalization stereotype for any component managed by Spring Framework.

The following specializations are available: @Repository, @Service, and @Controller. Each is specialized for a different use:

  • @Repository annotation is a marker for any class that fulfills the role of a Data Access Object (DAO) of a repository. It also offers the automatic translation of exceptions. We will explain its usage soon...