gist.cpp

// This function is called when the websocket connection is established 
void MediaManagerInterface::OnConnected()
	{
    // _signaling is the object of sending signaling through websocket 
		_signaling->AsyncRequest("getRouterRtpCapabilities", nlohmann::json(), [this](nlohmann::json jMsg) {
			createFactory(); // Create webrtc threads, etc.
			mediasoupclient::PeerConnection::Options op;
			op.factory = _peerConnectionFactory;
			if(!_device->IsLoaded()) {
				_device->Load(jMsg["data"], &op);
			}

      // sctpCapabilities is added for datachannel
			nlohmann::json j1 = { 
				{ "forceTcp", false },
				{ "producing", true },
				{ "consuming", false },
				{ "sctpCapabilities", _device->GetSctpCapabilities() } 
			};
			nlohmann::json r1 = _signaling->SyncRequest("createWebRtcTransport", j1);
			{
				nlohmann::json jData = r1["data"];

				auto* sendTransportListener = new SendTransportListener(_signaling);
				// This will block the current thread until completion.
				mediasoupclient::PeerConnection::Options op;
				op.factory = _peerConnectionFactory;
				_sendTransport.reset(_device->CreateSendTransport(
				  sendTransportListener,
				  jData["id"],
				  jData["iceParameters"],
				  jData["iceCandidates"],
				  jData["dtlsParameters"],
				  jData["sctpParameters"],
				  &op));
			}

			nlohmann::json j2 = { { "forceTcp", false },
				          { "producing", false },
				          { "consuming", true },
				          { "sctpCapabilities", _device->GetSctpCapabilities() } };
			nlohmann::json r2 = _signaling->SyncRequest("createWebRtcTransport", j2);
			{
				nlohmann::json jData = r2["data"];
				mediasoupclient::PeerConnection::Options op;
				op.factory                  = _peerConnectionFactory;
				auto* recvTransportListener = new RecvTransportListener(_signaling);
				_recvTransport.reset(_device->CreateRecvTransport(
				  recvTransportListener,
				  jData["id"],
				  jData["iceParameters"],
				  jData["iceCandidates"],
				  jData["dtlsParameters"],
				  jData["sctpParameters"],
				  &op));
			}

			// join room
			nlohmann::json j = { 
				{ "displayName", _myName },
				{ "device", "windows" },
				{ "rtpCapabilities", _device->GetRtpCapabilities() },
				{ "sctpCapabilities", _device->GetSctpCapabilities() } 
			};
			_signaling->AsyncRequest("join", j, [this](nlohmann::json jMsg) {
				createLocalProducer(); // This method will create a DataProducer for chat
			});
		});
	}