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Triggered when a WebRTC ICE candidate is received through the unified WebSocket connection. ICE candidates are used to establish the optimal network path for WebRTC media streaming.

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Event Properties

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type
string
Event type. Always "webrtc.signaling.iceCandidate" for this event.
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data
object
Event data object containing ICE candidate information.
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data.candidate
object
The RTCIceCandidate object containing candidate information for network path discovery.Example:
{
  "candidate": "candidate:1 1 UDP 2130706431 192.168.1.1 54321 typ host",
  "sdpMLineIndex": 0,
  "sdpMid": "0"
}

{
  "type": "webrtc.signaling.iceCandidate",
  "data": {
    "candidate": {
      "candidate": "candidate:1 1 UDP 2130706431 192.168.1.1 54321 typ host",
      "sdpMLineIndex": 0,
      "sdpMid": "0"
    }
  }
}

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Sending ICE Candidate

When ICE candidates are generated by your RTCPeerConnection, you need to send them immediately. Here’s how to send ICE candidates: 
const NavTalkMessageType = Object.freeze({
    WEB_RTC_ICE_CANDIDATE: "webrtc.signaling.iceCandidate",
    // ... other event types
});

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

// Set up ICE candidate handler - send candidates as they're generated
peerConnection.onicecandidate = (event) => {
    console.log('onicecandidate:', event.candidate ? 'new candidate' : 'gathering complete');
    if (event.candidate) {
        // event.candidate is an RTCIceCandidate object
        sendIceMessage(event.candidate);
    }
};
Message Structure: When sending an ICE candidate, the message structure should be: 
{
  "type": "webrtc.signaling.iceCandidate",
  "data": {
    "candidate": {
      "candidate": "candidate:1666409998 1 udp 2122129151 192.168.1.81 64301 typ host generation 0 ufrag lwyK network-id 1",
      "sdpMid": "0",
      "sdpMLineIndex": 0,
      "usernameFragment": "lwyK"
    }
  }
}
RTCIceCandidate Object Properties: The candidate object should have the following properties:
  • candidate (string): The candidate string, e.g., "candidate:1666409998 1 udp 2122129151 192.168.1.81 64301 typ host generation 0 ufrag lwyK network-id 1"
  • sdpMLineIndex (number, optional): The SDP media line index, typically 0 for video or 1 for audio
  • sdpMid (string, optional): The SDP media identification tag, typically "0" for video or "1" for audio
  • usernameFragment (string, optional): The ICE username fragment (ufrag)
Key Points:
  • The candidate parameter in data.candidate should be an RTCIceCandidate object (or equivalent plain object)
  • Send ICE candidates immediately when they’re generated in the onicecandidate event handler
  • Only send candidates when event.candidate is not null (when it’s null, ICE gathering is complete)
  • You may receive multiple ICE candidates - send each one as it’s generated

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Receiving ICE Candidate

When you receive an ICE candidate, handle it like this: 
async function handleReceivedMessage(data) {
    const nav_data = data.data;
    
    switch (data.type) {
        case NavTalkMessageType.WEB_RTC_ICE_CANDIDATE:
            const candidate = new RTCIceCandidate(nav_data.candidate);
            await peerConnection.addIceCandidate(candidate);
            console.log('ICE candidate added');
            break;
    }
}
Complete Example: 
// Set up peer connection
const peerConnection = new RTCPeerConnection(configuration);

// Send ICE candidates as they're generated
peerConnection.onicecandidate = (event) => {
    console.log('onicecandidate:', event.candidate ? 'new candidate' : 'gathering complete');
    if (event.candidate) {
        sendIceMessage(event.candidate);
    }
};

// Handle received ICE candidates
async function handleReceivedMessage(data) {
    const nav_data = data.data;
    
    switch (data.type) {
        case NavTalkMessageType.WEB_RTC_ICE_CANDIDATE:
            const candidate = new RTCIceCandidate(nav_data.candidate);
            await peerConnection.addIceCandidate(candidate);
            console.log('ICE candidate added');
            break;
    }
}
  • When to send: Send ICE candidates immediately when they’re generated in the peerConnection.onicecandidate event handler
  • What to send: Send event.candidate (which is an RTCIceCandidate object) as the candidate value
  • Multiple candidates: You may receive multiple ICE candidates - send each one as it’s generated
  • ICE candidates are sent through the unified WebSocket connection