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Triggered when a WebRTC offer is received through the unified WebSocket connection. WebRTC signaling is sent through the same WebSocket connection as other events, eliminating the need for a separate WebRTC signaling connection.

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Event Properties

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type
string
Event type. Always "webrtc.signaling.offer" for this event.
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data
object
Event data object containing WebRTC offer information.
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data.sdp
object
The SDP (Session Description Protocol) offer object. This is an RTCSessionDescription object that needs to be set as the remote description.Example:
{
  "type": "offer",
  "sdp": "v=0\r\no=- 123456789 123456789 IN IP4 0.0.0.0\r\n..."
}

{
  "type": "webrtc.signaling.offer",
  "data": {
    "sdp": {
      "type": "offer",
      "sdp": "v=0\r\no=- 123456789 123456789 IN IP4 0.0.0.0\r\n..."
    }
  }
}

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Receiving Offer

When you receive a WebRTC offer (typically sent by the server), handle it like this: 
const NavTalkMessageType = Object.freeze({
    WEB_RTC_OFFER: "webrtc.signaling.offer",
    WEB_RTC_ANSWER: "webrtc.signaling.answer",
    WEB_RTC_ICE_CANDIDATE: "webrtc.signaling.iceCandidate",
    // ... other event types
});

// Function to send answer (after receiving offer)
function sendAnswerMessage(sdp) {
    const message = {
        type: NavTalkMessageType.WEB_RTC_ANSWER,
        data: { sdp: sdp }
    };
    socket.send(JSON.stringify(message));
}

// Function to send ICE candidate
function sendIceMessage(candidate) {
    const message = {
        type: NavTalkMessageType.WEB_RTC_ICE_CANDIDATE,
        data: { candidate: candidate }
    };
    socket.send(JSON.stringify(message));
}

async function handleReceivedMessage(data) {
    const nav_data = data.data;
    
    switch (data.type) {
        case NavTalkMessageType.WEB_RTC_OFFER:
            // Create peer connection
            const offer = new RTCSessionDescription(nav_data.sdp);
            peerConnection = new RTCPeerConnection(configuration);
            
            // Set remote description and create answer
            await peerConnection.setRemoteDescription(offer);
            const answer = await peerConnection.createAnswer();
            await peerConnection.setLocalDescription(answer);
            
            // Send answer through unified WebSocket
            sendAnswerMessage(peerConnection.localDescription);
            
            // Set up ICE candidate handler
            peerConnection.onicecandidate = (event) => {
                if (event.candidate) {
                    sendIceMessage(event.candidate);
                }
            };
            break;
    }
}
Key Points:
  • The sdp parameter in data.sdp is an RTCSessionDescription object with:
    • type: "offer"
    • sdp: The SDP string containing the offer description
  • After receiving an offer, you should:
    1. Create an RTCPeerConnection
    2. Set the offer as remote description
    3. Create and send an answer
    4. Set up ICE candidate handler to send candidates
  • When received: The server typically sends the offer when establishing a WebRTC connection
  • What to do: After receiving an offer, create an answer and send it back, then send ICE candidates as they’re generated
  • All WebRTC signaling (offer, answer, ICE candidates) is sent through the unified WebSocket connection using the encapsulated event types. There is no need for a separate WebRTC signaling WebSocket connection.