Java Modules in Practice with Spring Boot

This project contains the source of the demo application used for my talk about migration your Spring Boot application to Java modules. What you're looking at right now are the sources of the application after migration. For the state of the application before migration, see the tag before-migration.

Talk abstract

Java Modules have been around for a little while now and most of know deep inside that we need start doing something with them. Yet most developers are waiting for the momentum to take off. You've probably heard the theory a couple of times already, but putting it into practice sounds like mummy forcing you to eat your veggies. Actually I love my veggies, so I’ll gladly help you out here. In this session I will demonstrate how you can start using the power of modules in your own application. A Spring Boot application. Because despite the adoption in libraries is not yet great, you can already perfectly make your own application modular. I will guide you through a step-by-step approach to making your application modular. No magic or module-fu is required to achieve this result. Just everyday technologies we have at our disposal in the Java ecosystem. And as a bonus, it even works with Kotlin....

Application details

The application essentially consists of 6 modules: domain, persistence, rest-api, bgg-client, security and application.

• domain is at the root of the dependency graph and essentially has no dependencies (outside the Java and Kotlin platform).
• peristence implements the persistence layer using Spring Data JPA and with PostgreSQL. Depends on domain.
• rest-api implements the REST API using Spring Web. Depends on domain
• bgg-client implements a client to the BoardGameGeek XML API using JAX-B and OpenFeign. Depends on domain.
• security implements the security configuration using Spring Security and jjwt. Has no internal dependencies.
• application is the module that pulls it all together. Depends on all other modules and Spring Boot. This is the main module.

Building and running the application

To build the application from the command line, simply run Maven from the root of the repository.

mvn package

After this you can either build the Docker image separately or use docker-compose to run both the application and the PostgreSQL database. A setup for this is included in the /local folder. You can start the database and the application by running docker-compose in the /local folder.

cd local
docker-compose up -d

Conferences

This talk was given at the following conferences:

Conference	Date	Session details
Devoxx UK	10 May 2019	Session details
Spring I/O	16 May 2019	Session details
Oracle Code One	17 September 2019	Session details
Java Global Summit	1 August 2020	Session details
JavaLand	17 March 2021	Session details