详解WebRTC-网页实时通信技术

function createConnection() {  sendButton.disabled = true;  megsToSend.disabled = true;  var servers = null;  bytesToSend = Math.round(megsToSend.value) * 1024 * 1024;  // 创建连接，servers可以传入一些描述信息，由于这个demo不需要验证连接信息，在同一个页面上可以直接连接，该参数传null即可  localConnection = localConnection = new RTCPeerConnection(servers);  //打印log  trace('Created local peer connection object localConnection');  var dataChannelParams = {ordered: false};  if (orderedCheckbox.checked) {    dataChannelParams.ordered = true;  }  //创建数据通道 语法：dataChannel = RTCPeerConnection .createDataChannel（label [，options ]）;，lable：通道的名称；optins：是个可选参数，传入数据通道配置参数，有很多参数可选，例子中的ordered:true表示有序模式，false即为无序模式，还有其他参数maxPacketLifeTime 、maxRetransmits等等  sendChannel = localConnection.createDataChannel(      'sendDataChannel', dataChannelParams);  sendChannel.binaryType = 'arraybuffer';  trace('Created send data channel');  //绑定onopen、onclose、onicecandidate（当RTCPeerConnection被createPeerConnection()成功创建时触发，回调会返回待连接端的配置信息）  sendChannel.onopen = onSendChannelStateChange;  sendChannel.onclose = onSendChannelStateChange;  localConnection.onicecandidate = function(e) {    onIceCandidate(localConnection, e);  };  //创建呼叫实例  localConnection.createOffer().then(    gotDescription1,    onCreateSessionDescriptionError  );  //创建远端接收连接实例  remoteConnection = remoteConnection = new RTCPeerConnection(servers);  trace('Created remote peer connection object remoteConnection');  remoteConnection.onicecandidate = function(e) {    onIceCandidate(remoteConnection, e);  };  //当一个RTC数据通道已被远端调用createDataChannel()添加到连接中时触发  remoteConnection.ondatachannel = receiveChannelCallback;}function receiveChannelCallback(event) {  trace('Receive Channel Callback');  receiveChannel = event.channel;  receiveChannel.binaryType = 'arraybuffer';  //接收到数据时触发  receiveChannel.onmessage = onReceiveMessageCallback;  receivedSize = 0;}function onReceiveMessageCallback(event) {  receivedSize += event.data.length;  receiveProgress.value = receivedSize;  if (receivedSize === bytesToSend) {    closeDataChannels();    sendButton.disabled = false;    megsToSend.disabled = false;  }}function onSendChannelStateChange() {  var readyState = sendChannel.readyState;  trace('Send channel state is: ' + readyState);  if (readyState === 'open') {    sendGeneratedData();  }}function sendGeneratedData() {  sendProgress.max = bytesToSend;  receiveProgress.max = sendProgress.max;  sendProgress.value = 0;  receiveProgress.value = 0;  var chunkSize = 16384;  var stringToSendRepeatedly = randomAsciiString(chunkSize);  var bufferFullThreshold = 5 * chunkSize;  var usePolling = true;  if (typeof sendChannel.bufferedAmountLowThreshold === 'number') {    trace('Using the bufferedamountlow event for flow control');    usePolling = false;    // 缓冲区大小限值    bufferFullThreshold = chunkSize / 2;    // 缓冲区大小控制    sendChannel.bufferedAmountLowThreshold = bufferFullThreshold;  }  // bufferedamountlow 事件处理  var listener = function() {    sendChannel.removeEventListener('bufferedamountlow', listener);    sendAllData();  };  var sendAllData = function() {    // 把一堆数据排队进行处理，在数据通道被填满时停止，这里不建议每次发送后设置Timeout，这样会降低吞吐量    while (sendProgress.value < sendProgress.max) {      if (sendChannel.bufferedAmount > bufferFullThreshold) {        if (usePolling) {          setTimeout(sendAllData, 250);        } else {          sendChannel.addEventListener('bufferedamountlow', listener);        }        return;      }      sendProgress.value += chunkSize;      // send方法发送数据，RTCDataChannel的语法跟WebSocket语法非常相似，都有message事件和sand方法      sendChannel.send(stringToSendRepeatedly);    }  };  setTimeout(sendAllData, 0);}

'use strict';var os = require('os');var nodeStatic = require('node-static');var http = require('http');var socketIO = require('socket.io');var fileServer = new(nodeStatic.Server)();var app = http.createServer(function(req, res) {  fileServer.serve(req, res);}).listen(8080);var io = socketIO.listen(app);io.sockets.on('connection', function(socket) {  // 打印日志功能  function log() {    var array = ['Message from server:'];    array.push.apply(array, arguments);    socket.emit('log', array);  }  socket.on('message', function(message) {    log('Client said: ', message);    // 本示例使用广播方式，真实项目中应该是指定房间号（Socket.IO适用于学习WebRTC信号，因为它内置了'房间'的概念）    socket.broadcast.emit('message', message);  });  socket.on('create or join', function(room) {    log('Received request to create or join room ' + room);    var clientsInRoom = io.sockets.adapter.rooms[room];    var numClients = clientsInRoom ? Object.keys(clientsInRoom.sockets).length : 0;    log('Room ' + room + ' now has ' + numClients + ' client(s)');    if (numClients === 0) {      socket.join(room);      log('Client ID ' + socket.id + ' created room ' + room);      socket.emit('created', room, socket.id);    } else if (numClients === 1) {      log('Client ID ' + socket.id + ' joined room ' + room);      io.sockets.in(room).emit('join', room);      socket.join(room);      socket.emit('joined', room, socket.id);      io.sockets.in(room).emit('ready');    } else { // 最多两个客户端      socket.emit('full', room);    }  });  socket.on('ipaddr', function() {    var ifaces = os.networkInterfaces();    for (var dev in ifaces) {      ifaces[dev].forEach(function(details) {        if (details.family === 'IPv4' && details.address !== '127.0.0.1') {          socket.emit('ipaddr', details.address);        }      });    }  });});