For starters, Ratpack is built on the same non blocking, event driven, model as Node.js
This type of non-blocking and asynchronous programming model has become very popular of late
Although, asynchronous programming has many advantages, such as predictive performance behavior under load, it is equally challenging and tricky to implement this style of programming.
Ratpacks value proposition comes from it's ability to abstract some of the complexities associated with asnyc. programming model at the same time provide integration with best in class Java librariries to implement modern day application.
Oracle JDK 9.0.1
I would strongly recommend SDKMan while programming on Linux as it simplifies management of multiple versions of software packages.
Getting started with a helloworld code is two step process and takes under a minute.
start with a gradle file definition
apply plugin: "io.ratpack.ratpack-groovy"
apply plugin: "idea"
import static ratpack.groovy.Groovy.ratpack
render "Hello World!"
render "Hello $pathTokens.name!"
Run Ratle server
This should bring up the server on http://localhost:5050/
Refer official guide for more details on Ratpack programming