Disclaimer: I am the author of this article. All applications I’ve looked into so far were communicating via a local web server. It wasn’t always WebSockets, o

Disclaimer: I am the author of this article. All applications I’ve looked into so far were communicating via a local web server. It wasn’t always WebSockets, one would also see JSONP or even submitting data to a frame. They typically run the server on a fixed port. Port conflicts are rare in practice, so these applications don’t really care. In one case I’ve seen port probing however: if one port fails, websites will try to connect with subsequent ports. As to best practices: I wouldn’t consider websites communicating with local applications best practice at all, by whatever means. It’s generally something to avoid.