Though Java EE is perfect for microservices, there are other options using the same bases and that may be a little lighter in some scenarios.

One of them is KumuluzEE (https://ee.kumuluz.com/). It's based on Java EE and has many microservice must-have features, such as service discovery. It won a Duke Choice Awards prize, which is huge!

The other one is Payara Micro (https://www.payara.fish/payara_micro). Payara is the company that owns a commercial implementation of GlassFish, the Payara Server, and from the Payara Server, they created the Payara Fish. The cool thing about it is that it is just a 60 MB JAR file that you start using the command line and boom! Your microservice is running.

Finally, the awesome thing about these two projects is that they are aligned with the Eclipse MicroProfile project (http://microprofile.io/). MicroProfile is defining the path and the standards for microservices in the Java EE ecosystem  right now, so it is worth following.

One last note about the code covered in this recipe: it would be nice in a real-world solution to use a DTO to separate the database representation from the service one.