Implementing an controller action for Grid paging

I think I might be missing the main documentation.

Is there documentation explaining how to implement an ajax controller handling grid data to be paged? The same for sorting and filtering? It seems like this should be clear in the docs (either here or here), but I don't see it. Am I missing the complete docs?

Basically, I need to know how to write (i.e. what parameters I should accept and what I need to return) an ajax controller action that will handle paging, sorting, and filtering. For example, what page we are on, how many pages are left, filters, etc...

I looked through the walkthrough as well, but didn't see anything handling these issues.

Thanks