Background Info
I want to integrate a javascript single-page web application with a 3rd party desktop windows application. I'm working with the 3rd party vendor to try to figure out the best way to set up the integration. The plan is to call URIs from the web application, and have the desktop application handle them to perform various actions. Right now, the URI's use the localhost scheme (i.e. they look like "http://localhost:8888/..."
The Questions
1) Attempting to make a get request to the URI from javascript results in the desktop app taking the desired action, but an error is returned to the browser due to cross-origin policy. I assume this is something that can be handled with CORS like any other cross origin request. Is this true? Or are URI requests to the OS "special" in some way?
2) We might instead want to use a custom URI scheme so that our URL can look like "myapp:..." instead of localhost. Will this suffer from the same cross-origin issues as the above? Will it run into any additional restrictions in major browsers? Would users need to manually muck with their browser settings to get it to work correctly, or is it even possible at all? Is there anything different from a browser security/permission standpoint between a "standard" URI using localhost and a custom URI scheme?