* some other web server accepts the WebSocket connection from the client
* the web server then starts acting as a proxy and relaying the connection to reSIProcate
* Apache proxy mode doesn't really support WebSocket at all (tested: it strips the Upgrade header)
* maybe some other kind of reverse proxy can be used to multiplex the connections between the SIP server and apache based on the URL path it sees from the client
* Apache has a module that can proxy WebSocket connections to TCP:
* can't just treat it as a regular SIP over TCP connection
* how to indicate the WS message size over a non-WS TCP connection? Maybe send the messages over a message queue?
* how to pass client attributes (e.g. source IP, client cert params, cookies)? Maybe send as headers in an AMQP message?
* Apache module must recognise the SIP subprotocol
* can clients send URL paths? Is this meaningful?