As we transition to the new Hyland Community, some post links may be temporarily disrupted as we finalize redirects. We apologize for the inconvenience and are working to resolve this as quickly as possible. Details.
just could not find in the API document
Yes, the swagger (open api spec) definition is available from Activiti version 6 onwards - Activiti/activiti.json at 6.x · Activiti/Activiti · GitHub. There is currently no RAML files available for the community version.
If you are using Alfresco Process Services (enterprise version) the swagger & raml files of the enterprise apis are also available in the product.