REST - Representational state transfer
The light platform provides a plugin architecture and dozens of middleware handlers to address cross-cutting concerns in general. When you decide to build an API or service, you have to choose from different styles and the corresponding framework to get started.
Chances are you are building a public Web API and want to follow RESTful style to make sure everyone can understand and consume it.
Light-rest-4j is a framework that is designed to speed up RESTful API development and deployment. On top of light-4j, it has several middleware handlers designed explicitly around Swagger 2.0 and OpenAPI 3.0 specifications. There are completely two different frameworks to support Swagger 2.0 and OpenAPI 3.0 as later is not backward compatible.