I've observed with janus-gateway 0.7.4 that the first response to a message transaction may not always be a synchronous (ACK) response; it may respond with an event containing the SDP answer before ACKing the reception of the SDP offer, which is weird but OK.
https://github.com/michaelfranzl/minnie-janus/blob/625120f13327602036f43be0b2a5240f47f17a0f/src/session.js#L141
I've observed with janus-gateway 0.7.4 that the first response to a message transaction may not always be a synchronous (ACK) response; it may respond with an event containing the SDP answer before ACKing the reception of the SDP offer, which is weird but OK.