Very simple example of hierarchical route generation in asp.net web api

gistfile1.cs

// Base route
config.Routes.MapHttpRoute("DefaultApi", "api/{controller}/{id}", new { id = RouteParameter.Optional });

// Nested route (must be distinguishable by param names from above) - Deisgnated by leading _ 
config.Routes.MapHttpRoute("NestedRoute", "_/{controller}/{rootId}");


// Root controller signature:
public class AppDataController : ApiController
{
  public IQueryable<MongoDocument> GetById(long id)
  {
      return this.documentService.Get(id);
  }
}

//Nested controller signature:
public class HistoryController : ApiController, INestedApiController<AppDataController>
{
  // Designate parameter mappings to parent using attributes
  public IQueryable<MongoDocument> Get([RootParamName("id")]long rootId)
  {
    return this.historyService.GetForParent(rootId);
  }
}

/*

So our algorithm goes as follows:

* Identify nested\base controllers using interfaces.
- AppDataController
- HistoryController

* Use Api Explorer to determine potential routes for root controller 
- api/{controller}/{id}

* Use Api Explorer to determine potential routes for nested controller that start with _ 
- _/{controller}/{rootId}

* Take base route and swap out {controller} for our root controller name
- api/AppData/{id}

* Take nested route and swap out {controller} for our nested controller name
- _/History/{rootId}

* Translate parameter names in base route accoring to attributes in nested action signature, and also remove any matching params from the nested route
- api/AppData/{rootId}
- _/History

* Now we create a new route based on a combination of these two, we need to remove the optional flag from any base root params
- api/AppData/{rootId}/History/
  defaults = { controller = "History" }

* Finally, we must ensure to remove any route patterns starting with _ so they will not be present in the runtime routing table


QED!


*/

We will need to do something fancy also to remove extra routes involving querystring params, for example

api/{controller}/{id}

will also create potential route api/{controller}?id={id}