Fusion
The import and export of STL files is for local files. However, you should be able to still accomplish what you want by using other ways to copy the file locally and then import it. And export from Fusion to a local file and then copy to your external system. How you do that will depend on what kind of access you have to the file. For example, is it accessible on the web through a url or is there a web service to access it? It will also depend on which language you're using and what tools it provides. None of that has anything to do with the Fusion API so it would be best to do some general researching online to see what you can find that might work in your case.
