I've just started learning how to do module development.  I've worked through Clinton Patterson's tutorial and am looking to try developing my own module.

I notice there are various C# DNN (e.g DotNetNuke.Web) libraries that can be used, but haven't found where they are documented.  Similarly there are various SQL tables, but I'm not sure whether they can be queried by developers either.

In particular I'd like to retrieve menu data, ideally through a webservice providing json, or if one doesn't exist writing my own webservice.  Is that feasible or am I going about this in the wrong way? What I would like to get is the complete menu structure; top-level plus sub-levels.