OSP protocol split

[backkem]

I opened this ticket to continue the exploration of splitting the OSP protocol up into parts: a Connection spec and a Messaging spec.

OSP Connection (OSP-C)
The connection spec would contain mDNS discovery and the authentication step to exchange TLS.

It may be worth exploring if the OSP-C protocol can be defined independent from OSP use. Pushing all OSP specific pieces to the OSP-M spec, such as the values used for _openscreen._udp.local mDNS queries.

OSP Messaging (OSP-M)
The messaging spec would contain the CBOR message delivery, presentation, remote playback and streaming protocols. The spec should probably define a normative way of layering OSP-M on top of OSP-C + QUIC. Likewise, this spec would likely define how a potential OSP-over-Matter is wired up.

OSP stack overview
I made an overview of what the stack may look like after such a split:

Local Peer-to-Peer (LP2P) considerations
Since the group is exploring synergies with the Local Peer-to-Peer proposal, I wanted to quickly touch on that. One way to see the LP2P proposal is also in two pieces: A connection establishment between devices and a transport/messaging API. This is quite similar to the above. I explore this below.

Browser P2P connection
I made an overview of what the stack may look like after such a split:

Browser P2P networking
I made an overview of what the stack may look like after such a split:

For this overview I used the suggestion from ibelem/local-peer-to-peer#11 to use the WebTransport API and layered a simple messaging protocol on top for ease-of-use.

Sidenote: I think it would be great if the QUIC + WebTransport approach extended to WebRTC as once proposed by p2p-webtransport.