Sections 2.2 and 2.3: RTCDtlsTransport

[aboba]

2.2 Operation

A RTCDtlsTransport instance is optionally constructed from an RTCIceTransport object or an RTCIceTransport is automatically constructed.

[BA] Should this be "or an RTCDtlsTransport is automatically constructed"?

2.3 Interface Definition

[Constructor(optional RTCIceTransport transport)]
interface RTCDtlsTransport {
readonly attribute RTCIceTransport transport;
readonly attribute RTCDtlsTransportState state;
RTCDtlsParameters getLocalParameters ();
RTCDtlsParameters? getRemoteParameters ();
void start (RTCDtlsParameters remoteParameters);
void stop ();
attribute EventHandler? onstatechange;
};

Assuming we have a DTLS transport constructed without an ice transport object as an argument, what happens when an app calls start() on the DTLS transport? Is an RTCIceTransport object really an optional argument to the constructor?

[robin-raymond]

I do think it's an optional argument. Start will have to do nothing until it's attached later to an ICE transport. It's kind of in an "awaiting attachment" state. Once attached, it should continue to perform it's operations. If reattached to another ICE transport it should continue its internal state exactly where it left off. If it becomes detached it should freeze its state "as is" and await attachment again to any ICE transport.

[robin-raymond]

The only concern I have is that you move incompatible DTLS sessions. Alice to Bob becomes attached to an Alice to Charles session. It makes no sense in that context. But Alice to Bob being reassigned to a new Alice to Bob ICE session makes sense.

[aboba]

Looks to me that the RTCIceTransport object shouldn't be readonly to allow an Ice Transport to be subsequently assigned.