Hi,
Regarding the API documentation, you could refer to the [Javadoc documentation](https://community.denodo.com/docs/html/browse/8.0/vdp/javadoc/index?com/denodo/vdb/engine/storedprocedure/package-summary.html) of the API which explains about the classes and their methods.
Also, to develop a stored procedure/Custom components, you need to add the following jar files to the CLASSPATH of your environment since they contain many helper utilities that can ease the development of the procedures or other custom component:
* <DENODO_HOME>/lib/vdp-server-core/denodo-vdp-server.jar
* <DENODO_HOME>/lib/vdp-client-core/denodo-vdp-parser.jar
You could refer to the sections [Required Libraries to Develop Custom Wrappers](https://community.denodo.com/docs/html/browse/latest/vdp/developer/developing_extensions/developing_custom_wrappers/required_libraries_to_develop_custom_wrappers#required-libraries-to-develop-custom-wrappers) and [Developing Extensions](https://community.denodo.com/docs/html/browse/latest/vdp/developer/developing_extensions/developing_extensions#developing-extensions) of Virtual DataPort Developer Guide for more information.
Hope this helps!!