I have an existing asp.net-mvc web site and now I need to expose of a few of my calls to external applications that are only used within my site right now. This is all happening within an intranet within my company.

I have read [this page](http://www.binaryintellect.net/articles/7bfdd512-91e3-49a4-865d-6dd03ace73fb.aspx) which explains Web API versus controller actions as well [as this SOF question](https://stackoverflow.com/questions/10479055/consuming-asp-net-mvc-action-methods) which seems to have a similar issue but the answers seem a bit outdated. So I am trying to determine given the latest available functionality what is the simplest solution to meet my requirement.

In my case, since I already have the same controller actions used within my current website then WEB API doesn't really make sense but if I google anything around asp.net-mvc authentication or security I only see articles around web API. 

Given that, I am trying to figure out best practice for exposing my controller action to another application.