r2dbc-postgresql VS initializr

Now that we have an application, let's turn it into a reactive application. For this, we will replace Spring Web dependency with Spring WebFlux, Spring Data JPA with Spring Data R2DBC. We will also add R2DBC dependency for our H2 database. R2DBC works with a reactive driver so it will integrate nicely with the rest of our application to allow us database access in a non-blocking way.

However, if you really expect a lot of users (especially concurrent ones) to use your API, you should delve into the world of reactive programming. Use tools like RxJS (JS/TS) or Project Reactor (Java) in such a case, preferably in combination with a broker like Kafka or RabbitMQ. R2DBC is also great for a data store. Then of course if you want to go one step further, there also exists the less popular but very interesting Actor model which Akka easily has ported into Java.

The best way, for generating a ready-to-run application in Java you can use the Spring Boot Initializr tool.

curl --location 'https://start.spring.io/starter.zip?type=maven-project&language=java&bootVersion=3.2.2&baseDir=ms-xcoffee&groupId=com.xcoffee&artifactId=ms-xcoffee&name=ms-xcoffee&description=Demo%20project%20for%20Spring%20Boot&packageName=com.xcoffee.ms-xcoffee&packaging=jar&javaVersion=21&dependencies=webflux%2Clombok%2Cvalidation' | tar -xzvf -

In this segment we will create a basic Spring boot app from Spring Initializer. Add the below dependencies:

Add the following MongoDB dependencies in your pom.xml or use spring initializer and select the Spring Data MongoDB dependency:

I created all of these applications using start.spring.io's REST API and HTTPie.

An easy way to create the skeleton project is to visit Spring Initializr, I set the Project to Gradle - Groovy, Language to Java, and add Spring Web dependency. Then it's just to generate the project and unpack it.

Create a new Spring Boot application using the Spring Initializr. You can use the web version or the curl command below. Use the default for most of the options. For the dependencies, select web, and okta. For the build tool, select Gradle.

I will start with a simple example of a cloud function, which is the same as a rest endpoint in the classical spring boot web application. You can create a project from your favorite IDE or from Spring Initliazr.