OpenAPI Specification (OAS)

The OpenAPI Specification (OAS) defines a standard, language-agnostic interface to RESTful APIs which allows both humans and computers to discover and understand the capabilities of the service without access to source code, documentation, or through network traffic inspection.

OAS formerly known as Swagger and they donated it to the Linux Foundation to become OpenAPI (Swagger is a better name) . Swagger was version 2.0 and current version of OAS is 3.0.

OAS is a super set of json-schema. In Grails or Spring, OAS describes both the controllers and actions as well the domains. Its uses json-schema, particularly the validation spec to describe the domains.

📝 See here for an example of the Swagger 2.0 spec in action.


There are 2 primary goals of getting OAS and json-schema setup for our Grails Gorm domains

  1. Enable automatic generation of forms with something like Schema Form
  2. Autogenerate docs like some of the examples links below

json-schema docs, specs and examples


https://brandur.org/elegant-apis https://blog.cloudflare.com/cloudflares-json-powered-documentation-generator/


Swagger is a superset of json-schema. See http://editor.swagger.io/#/ for an example And the Swagger site for plenty of examples

Doc Engines

If we have our API defined in Swagger and/or json-schema or yml then we can use something like https://github.com/mermade/widdershins to generate a slate based doc site See http://mikeralphson.github.io/openapi/2016/12/19/oa2s-comparison Example site https://mermade.github.io/shins/#swagger-petstore-v1-0-0

As mentioned in widdershins if we are using a message queue then this is worth looking at for

Other Resources


https://github.com/koumoul-dev/vue-openapi https://github.com/koumoul-dev/openapi-viewer


http://swapi.co/ https://projects.spring.io/spring-restdocs/

Java version of schema validator https://github.com/java-json-tools/json-schema-validator

javadoc to markdown


Using javadocs or annotations

These are some possibilities to generate swagger or docs from javadocs ideally https://wiki.onosproject.org/display/ONOS/Generating+Swagger+documentation+for+the+REST+API

This provides a pretty good overview of 4 options. Swagger(spring fox), Spring REST Docs, RAML, ApiDocJS https://opencredo.com/rest-api-tooling-review/ and Spring Fox looks promising http://springfox.github.io/springfox/docs/current/ there seems to be a version for Grails too, https://github.com/springfox/springfox-grails-integration