In addition to audio-visual media, WebRTC provides a peer-to-peer data channel
- For peer-to-peer file transfer
- To support a chat session
- To support reactions, raise hand, etc.
This is implemented using SCTP, over Datagram Transport Layer Security (TLS) in a secure UDP tunnel: Transparent data channel
- Message-oriented abstraction
- Multiple sub-streams
- Congestion controlled
Makes it straight-forward to build P2P applications with WebRTC This is desirable as it creates the lowest possible Latency.
Some form of signalling protocol must be made to find the peer and establish the path
The control protocol needs to describe the communication session expected:
- Media transport connections required
- Media formats and compression algorithms
- IP addresses and ports to use
- Originator and purpose of session
- Options and parameters
WebRTC doesn’t use QUIC yet as it pre-dates it, however future version are likely to migrate to QUIC, as it is more flexible and highly optimised.