Creating Java Microservices

We've seen a lot of theory behind microservice architecture in Chapter 3, Working with Microservices. It's time to do some hands-on practice; we are going to implement our own microservice. This will be a simple REST service, accepting HTTP methods such as GET and POST to retrieve and update entities. There are a couple of choices when developing microservices in Java. In this chapter, we are going to get an overview about two main approaches, probably the most popular will be JEE7, and Spring Boot. We will briefly see how we can code a microservice using JEE JAX-RS. We will also create a microservice running on Spring Boot. In fact, in Chapter 5, Creating Images with Java Applications, we are going to run our Spring Boot microservice from within a Docker container. As we have said in Chapter 3, Working with Microservices, microservices usually communicate with the outside world using REST. Our REST microservice will be as simple as possible; we just need to have something to deploy using Docker and Kubernetes. We will not focus on advanced microservice features such as authentication, security, filters, and so on, as this is outside the scope of this book. The purpose of our examples is to give you an idea of how to develop REST services and then deploy them using Docker and Kubernetes. This chapter will cover the following topics:

• Introduction to REST
• Creating a REST service in Java using Java EE7 annotations
• Creating a REST service using Spring Boot
• Running the service and then calling it with different HTTP clients

At the end of the chapter, we will become familiar with some useful tools- we will use some code generation tools such as Spring Initialzr to quickly bootstrap a Spring Boot service project. Before we start coding our own microservice, let's explain briefly what REST is.