Example of createSignalingChannel in HTML5

Web RTC required peer-to-peer communication between browsers. This mechanism required signalling, network information, session control and media information. Web developers can choose different mechanism to communicate between the browsers such as SIP or XMPP or any two way communications. An example of createSignalingChannel():

var signalingChannel = createSignalingChannel();
var pc;
var configuration = ...;

// run start(true) to initiate a call
function start(isCaller) {
   pc = new RTCPeerConnection(configuration);
   // send any ice candidates to the other peer
   pc.onicecandidate = function (evt) {
      signalingChannel.send(JSON.stringify({ "candidate": evt.candidate }));
   };
   
   // once remote stream arrives, show it in the remote video element
   pc.onaddstream = function (evt) {
      remoteView.src = URL.createObjectURL(evt.stream);
   };

   // get the local stream, show it in the local video element and send it
   navigator.getUserMedia({ "audio": true, "video": true }, function (stream) {
      selfView.src = URL.createObjectURL(stream);
      pc.addStream(stream);
      if (isCaller)
         pc.createOffer(gotDescription);
      else
         pc.createAnswer(pc.remoteDescription, gotDescription);
      function gotDescription(desc) {
         pc.setLocalDescription(desc);
         signalingChannel.send(JSON.stringify({ "sdp": desc }));
      }
   });
}
signalingChannel.onmessage = function (evt) {
   if (!pc)
      start(false);
      var signal = JSON.parse(evt.data);
      if (signal.sdp)
      pc.setRemoteDescription(new RTCSessionDescription(signal.sdp));
   else
      pc.addIceCandidate(new RTCIceCandidate(signal.candidate));
};