Question

我是Nodejs的新手，并试图熟悉它。那么，目前，我正在尝试在Web浏览器上推送通知，如果数据库中发生任何更改。我有一段代码，我一直用于测试目的。以下代码可以在数据库表内容更改时向浏览器发送更新：

Server.js

var app = require('http').createServer(handler).listen(8000),
  io = require('socket.io').listen(app),
  fs = require('fs'),
  mysql = require('mysql'),
  connectionsArray = [],
  connection = mysql.createConnection({
    host: 'localhost',
    user: 'root',
    password: '',
    database: 'nodejs',
    port: 3306
  }),
  POLLING_INTERVAL = 3000,
  pollingTimer,
  pollingTimer_2;


// If there is an error connecting to the database
connection.connect(function(err) {
  // connected! (unless `err` is set)
  console.log(err);
});


// on server started we can load our client.html page
function handler(req, res) {
  fs.readFile(__dirname + '/client.html', function(err, data) {
    if (err) {
      console.log(err);
      res.writeHead(500);
      return res.end('Error loading client.html');
    }
    res.writeHead(200);
    res.end(data);
  });
}




/*
 * This function loops on itself since there are sockets connected to the page
 * sending the result of the database query after a constant interval
 *
 */

var pollingLoop = function() {

  // Doing the database query
  var query = connection.query('SELECT * FROM users'),
    users = []; // this array will contain the result of our db query

  // setting the query listeners
  query
    .on('error', function(err) {
      // Handle error, and 'end' event will be emitted after this as well
      console.log(err);
      updateSockets(err);
    })
    .on('result', function(user) {
      // it fills our array looping on each user row inside the db
      users.push(user);
    })
    .on('end', function() {
      // loop on itself only if there are sockets still connected
      if (connectionsArray.length) {
        pollingTimer = setTimeout(pollingLoop, POLLING_INTERVAL);

        updateSockets({
          users: users
        });
      }
    });

};


// creating a new websocket to keep the content updated without any AJAX request
io.sockets.on('connection', function(socket) {

  console.log('Number of connections:' + connectionsArray.length);
  // starting the loop only if at least there is one user connected
  if (!connectionsArray.length) {
    pollingLoop();

  }

  socket.on('disconnect', function() {
    var socketIndex = connectionsArray.indexOf(socket);
    console.log('socket = ' + socketIndex + ' disconnected');
    if (socketIndex >= 0) {
      connectionsArray.splice(socketIndex, 1);
    }
  });

  console.log('A new socket is connected!');
  connectionsArray.push(socket);

});

var updateSockets = function(data) {
  // adding the time of the last update
  data.time = new Date();
  // sending new data to all the sockets connected
  connectionsArray.forEach(function(tmpSocket) {
    tmpSocket.volatile.emit('notification', data);
  });
};

Client.html

<html>
    <head>

        <title>Push notification server streaming on a MySQL db</title>
        <style>
            dd,dt {
                float:left;
                margin:0;
                padding:5px;
                clear:both;
                display:block;
                width:100%;

            }
            dt {
                background:#ddd;
            }
            time {
                color:gray;
            }
        </style>
    </head>
    <body>
        <time></time>
        <div id="container">Loading ...</div>
    <script src="socket.io/socket.io.js"></script>
    <script src="http://code.jquery.com/jquery-latest.min.js"></script>
    <script>

        // create a new websocket
        var socket = io.connect('http://localhost:8000');
        // on message received we print all the data inside the #container div
        socket.on('notification', function (data) {
        var usersList = "<dl>";
        $.each(data.users,function(index,user){
            usersList += "<dt>" + user.user_name + "</dt>\n" +
                         "<dd>" + user.user_desc + "\n" +
                            "<figure> <img class='img-polaroid' width='50px' src='" + user.user_img + "' /></figure>"
                         "</dd>";
        });
        usersList += "</dl>";
        $('#container').html(usersList);

        $('time').html('Last Update:' + data.time);
      });
    </script>
    </body>
</html>

现在，您可以看到当前服务器正在监听port 8000。我只是想知道我怎么能改变它来听一个特定的网址？因为如果我要在服务器项目上实现，那么我不会使用url来侦听端口？相反，我想将它用作普通的Url，因为如果有任何用户连接到特定网址，我可以顺利发送通知吗？

任何帮助？

Answer 1

如果您希望节点服务器响应URL http://www.example.com/updates，则使服务器侦听端口80（如果未列出端口且协议为“http”，则为默认端口）。然后，您让服务器响应"/updates"路由。

服务器侦听特定IP地址的特定端口。他们不听路径或URL。浏览器使用DNS在URL中获取主机的IP地址。如果URL中有端口号，则使用该端口。如果不是，则使用特定协议的默认端口。然后，它与该端口上的该IP地址建立TCP连接。然后，如果协议是http，它会在该连接上发送请求并包含路径。

因此，服务器接收传入连接，然后作为HTTP协议的一部分，它接收动词（GET，POST，DELETE等等）和路径，然后是服务器工作决定什么到根据传入的命令/路径做。

聆听特定网址而不是端口

1 个答案: