Pre negotiated dataChannel?

[jimmywarting]

Would it make it easier if dataChannel where pre negotiated somehow?

pc.createDataChannel(channelName, {
  negotiated: true,
  id: something  
})

Mostly thinking of other torrent client that integrating webrtc, would make it possible to skip the onDatachannel. step.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.

[feross]

@jimmywarting I'm afraid I don't understand what the purpose of this would be. Could you explain a bit more about what use case this suggestion solves?

[jimmywarting]

The purpose would be to create a dataChannel initially (out of band) on both sides. with an agreed-upon id. Without having to worry about state, what side you’re on, or what condition the connection is in.

• Dose removing the need of having to wait for the other person to send a dataChannel. and be able to skip the hole pc.ondatachannel setup
• You wouldn't have to care so much if you are a initiator or not.
• you can configure the datachannel.onmessage earlier
• you would then use the same codebase more or less
• you don't have to listen so much to the any of the RTCPeerConnection events.

i know simple-peer takes care of lots of logic for you. but not every torrent client is going to use simple-peer

[feross]

Interesting. What are the reasons one would want to use an agreed-upon id? When a peer connects to you, you don't really know anything about them.

[jimmywarting]

Interesting. What are the reasons one would want to use an agreed-upon id? When a peer connects to you, you don't really know anything about them.

the agreed-upon id could be based of on the peerID who starts or something else

the difference would be that you could have a datachannel right away where as it's now you would have to wait for some extra callback to wait for some dataChannel and setup things afterwards.

To demonstrate with an simple example, peer2 (not the initiator) would have to wait until he receives a dataChannel, you would need a bit more callbacks here and there before you can start playing with it or adding him to some list of connected peers

var pc = new RTCPeerConnection();
if (initiator) {
  setupData({ channel: pc.createDataChannel('testchannel') })
} else {
  pc.ondatachannel = setupData
}

function setup({ channel }) {
  channel.onmessage = startAcceptingMessages
}

with this example both peer1 and peer2 can start to fiddle with the datachannel right away

var pc = new RTCPeerConnection();
var dc = pc.createDataChannel('testchannel', {
  negotiated: true,
  id: from_peer_id_who_started()
})

dc.onmessage = startAcceptingMessages

[feross]

If you're the initiator, then I see how you might know the peer ID of the peer you are connecting to. In that case, as the initiator you can just create the data channel and start using it. But does the non-initiating peer actually know the peer ID of the remote peer?

[jimmywarting]

But does the non-initiating peer actually know the peer ID of the remote peer?

I think so...? dose not the tracker sends the peer_id of who sent the initial offer to the non-initiator?