All file operations, including reading an imported file, use a Windward access provider. Access providers exist for all the common protocols (file servers, basic, digest, OAuth2, etc.). And if you need something different, you can write your own access provider - once. And it then handles any access of files using that protocol. (ref: Ohana)
The key value here is if you need to write your own access provider. If so, you write it once and it is then used anywhere Windward needs to read files using your protocol. And of course, if you use one of the standard protocols, we have it covered.