Getting started with webrtc: 12 Rtendpoint and webrtcendpoint under kurento

In the previous chapter , do kms When the cluster of , Introduced RtpEndpoint, This is a new class , What we used before was WebrtcEndpoint, What is the difference between the two classes ？ If you use it directly WebrtcEndpoint, Can the cluster be connected .

Let's see , There are several important in the document Endpoint, The inheritance diagram is as follows ：

But from the detailed documentation ,RtpEndpoint and WebrtcEndpoint They are all inherited. BaseRtpEndpoint Of .

From the documentation ,RtpEndpoint and WebrtcEndpoint There should be little difference , Because it has a common base class BaseRtpEndpoint.

Compare the difference between the two documents ：

RtpEndpoint：
WebRtcEndpoint：

From the documentation ,RtpEndpoint and WebrtcEndpoint The difference is that RtpEndpoint You can go directly through SDP You can connect with each other ,WebrtcEndpoint To connect , It's not just necessary SDP It also needs to be ICE.

That is to say RtpEndpoint In design , You can go through SDP Establishing a connection , So in SDP It must contain IP And port information .

In source code kms_sdp_agent_create_offer_impl You can see the generated SDP, Exist in the corresponding IP And port information .

v=0
o=- 3864705878 3864705878 IN IP4 192.168.100.130
s=Kurento Media Server
c=IN IP4 192.168.100.130
t=0 0
m=audio 5198 RTP/AVPF 96 0 97
a=setup:actpass
a=extmap:3 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time
a=rtpmap:96 opus/48000/2
a=rtpmap:97 AMR/8000
a=rtcp:5199
a=sendrecv
a=mid:audio0
a=ssrc:1665516295 cname:[email protected]
m=video 1420 RTP/AVPF 102 103
a=setup:actpass
a=extmap:3 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time
a=rtpmap:102 VP8/90000
a=rtpmap:103 H264/90000
a=fmtp:103 level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=42e01f
a=rtcp:1421
a=sendrecv
a=mid:video0
a=rtcp-fb:102 nack
a=rtcp-fb:102 nack pli
a=rtcp-fb:102 goog-remb
a=rtcp-fb:102 ccm fir
a=rtcp-fb:103 nack
a=rtcp-fb:103 nack pli
a=rtcp-fb:103 ccm fir
a=ssrc:2557383214 cname:[email protected]

These two RtpEndpoint You can negotiate the connection .

and WebrtcEndpoint Generated in the SDP, Not included IP And port information , This can be followed up kms_sdp_agent_create_offer_impl, See why . Such an agreement , It's a browser webrtc All the same .

Then if you use WebrtcEndpoint Can you implement cluster ？ It should be possible , But rather than RtpEndpoint Naturally, it will be more complicated , Because he involves ICE The steps are .

If you also need , It can be implemented with the following code .

  private synchronized void presenter(final WebSocketSession session, JsonObject jsonMessage)
      throws IOException {
    
    if (presenterUserSession == null) {
    
      presenterUserSession = new UserSession(session);

      pipeline = kurento.createMediaPipeline();
      presenterUserSession.setWebRtcEndpoint(new WebRtcEndpoint.Builder(pipeline).build());

      WebRtcEndpoint presenterWebRtc = presenterUserSession.getWebRtcEndpoint();
      
      pipeline_B = kurento.createMediaPipeline();

      presenterUserSession.setWebRtcEndpoint_A(new WebRtcEndpoint.Builder(pipeline).build());
      WebRtcEndpoint presenterWebRtc_A = presenterUserSession.getWebRtcEndpoint_A();
      
      presenterUserSession.setWebRtcEndpoint_B(new WebRtcEndpoint.Builder(pipeline_B).build());
      WebRtcEndpoint presenterWebRtc_B = presenterUserSession.getWebRtcEndpoint_B();

      presenterUserSession.getWebRtcEndpoint().connect(presenterWebRtc_A);

      String offerString = presenterWebRtc_A.generateOffer();
      String sdpAnswerViewer = presenterWebRtc_B.processOffer(offerString);
      presenterWebRtc_A.processAnswer(sdpAnswerViewer);
      log.info(offerString); 

      presenterWebRtc_A.addIceCandidateFoundListener(new EventListener<IceCandidateFoundEvent>() {
    
        @Override
        public void onEvent(IceCandidateFoundEvent event) {
    
		log.info("presenterWebRtc_A.addIceCandidateFoundListener");
		presenterWebRtc_B.addIceCandidate(event.getCandidate());
          }
      });

      presenterWebRtc_B.addIceCandidateFoundListener(new EventListener<IceCandidateFoundEvent>() {
    
        @Override
        public void onEvent(IceCandidateFoundEvent event) {
    
		log.info("presenterWebRtc_B.addIceCandidateFoundListener");
		//presenterWebRtc_A.addIceCandidate(event.getCandidate());
          }
      });

      presenterWebRtc.addIceCandidateFoundListener(new EventListener<IceCandidateFoundEvent>() {
    

        @Override
        public void onEvent(IceCandidateFoundEvent event) {
    
          JsonObject response = new JsonObject();
          response.addProperty("id", "iceCandidate");
          response.add("candidate", JsonUtils.toJsonObject(event.getCandidate()));
          try {
    
            synchronized (session) {
    
              session.sendMessage(new TextMessage(response.toString()));
            }
          } catch (IOException e) {
    
            log.debug(e.getMessage());
          }
        }
      });

      String sdpOffer = jsonMessage.getAsJsonPrimitive("sdpOffer").getAsString();
      String sdpAnswer = presenterWebRtc.processOffer(sdpOffer);

      JsonObject response = new JsonObject();
      response.addProperty("id", "presenterResponse");
      response.addProperty("response", "accepted");
      response.addProperty("sdpAnswer", sdpAnswer);

      synchronized (session) {
    
        presenterUserSession.sendMessage(response);
      }
      presenterWebRtc.gatherCandidates();
      presenterWebRtc_A.gatherCandidates();
      presenterWebRtc_B.gatherCandidates();


    } else {
    
      JsonObject response = new JsonObject();
      response.addProperty("id", "presenterResponse");
      response.addProperty("response", "rejected");
      response.addProperty("message",
          "Another user is currently acting as sender. Try again later ...");
      session.sendMessage(new TextMessage(response.toString()));
    }
  }