These pages give some foundational knowledge about the building blocks of the App SDK - plugins and events:
Describes the plugins - the building blocks in a V-Ray scene.
Describes the parameter types, how to manipulate parameters, default values and other details.
Describes the categories to which plugins can belong. Plugins can be Lights, Materials, Textures, etc.
Describes how to handle events and gives notes about performance and thread safety.
Describes some aspects of the plugins, classes and categories API in Python and Node.js