WebRTC 工作流程

用户A                         服务器                         用户B
上线                                                        上线
emit 'online'  ->                                      <-   emit 'online'
on 'online'
<-   emit 'online'  ->
on 'online'                                                 on 'online'
获得在线用户列表                                               获得在线用户列表
选择用户B
确认要和用户B聊天
emit 'request chat'  ->
on 'request chat'
emit 'request chat'  ->
on 'request chat'
getUserMedia()
<-  emit 'stream ok'
on 'stream ok'
<-  emit 'stream ok'
on 'stream ok'
getUserMedia()
emit 'stream ok'  ->
on 'stream ok'
emit 'stream ok'  ->
on 'stream ok'
createPeerConnection()
pc.createOffer()
pc.setLocalDescription()
<-  emit 'offer'
on 'offer'
<-  emit 'offer'
on 'offer'
createPeerConnection()
pc.setRemoteDescription
pc.createAnswer()
pc.setLocalDescription()
emit 'answer'  ->
on 'answer'
emit 'answer'  ->
on 'answer'
pc.setRemoteDescription()

pc = new RTCPeerConnection(config)
// 向pc中加入需要发送的流
pc.addStream(localStream)
// onicecandidate 处理器会在网络候选可用的时候调用。
pc.onicecandidate = function (event) {
if (event.candidate) {
socket.emit('candidate', requestSocketId, {
type: 'candidate',
label: event.candidate.sdpMLineIndex,
id: event.candidate.sdpMid,
candidate: event.candidate.candidate
});
} else {
console.log('End of candidates.');
}
};
// 如果检测到流媒体流到本地，就把它显示出来，同时把流赋值给 remoteStream
pc.onaddstream = function (event) {
attachMediaStream(remoteVideo, event.stream);
remoteStream = event.stream;
};