SFU: simple forwarding unit

Protocol

For receiving

url = protocol, host, path, query

protocol = 'ws', ['s'], '://'
 
hostname = <whatever valid character for a domain/IP address>, ':', { digit }

path = <whatever valid character for paths>

query = <whatever valid character for query>

The query MUST contain the following parameters:

• keyid
• id
• kind

All strings.

kind is especially important.

If the local RTCPeerConnection gets a track whose kind does not match kind, then the client can safely ignore it.