I believe the key is in the part that says The client connects. The client initiates the TCP connection (thus traversing NAT), which stays alive like any other

I believe the key is in the part that says The client connects. The client initiates the TCP connection (thus traversing NAT), which stays alive like any other HTTP 1.1 connection (which has a Content-length header). The server produces the requests, however. I suspect that in order to traverse proxies, the client establishes the original connection via the quasi-standard HTTP CONNECT method which is otherwise used for proxying HTTPS. This is conjecture, however, as I've yet to research RHTTP. EDIT: it seems my instinct on proxying was incorrect, other posts imply that the 'Upgrade' header is used. I'm a little surprised that this is widely supported by proxies. I suppose the proxy just keeps the connection open if there's no specified Content-length. Timeouts spring to mind as a potential issue.