我如何构建一个简单的节点js服务器来发送和接收到客户端？

Question

I have a node js server, and a html/javascript client.

I simply want to allow the client to send a json-string to the node.js server, the server process's that string and returns a result string back to the client.

I started by setting up the html-client to call like so :

var msg = 
        {
            type: "message",
            text: "Hello"
        };

        function CallWebSocket()
        {
            var socket = new WebSocket("ws://127.0.0.1:8080","test");
            socket.onopen = function (event)
            {
                alert(JSON.stringify(msg));
                socket.send(JSON.stringify(msg)); 
            };
            socket.onmessage = function(event)
            {
                alert(event.data);
            }
        }

and node.js :

var net = require('net');
var server = net.createServer(function(socket)
{
    // do what you need
    socket.setEncoding("utf8");
    socket.on('data', function(data)
    {
        var jsonData = JSON.parse(data);
        socket.write(jsonData.text);
        socket.end();
        process.exit(0);
    });
});
server.listen(8080);

but on the server I get this error :

    undefined:1
``GET / HTTP/1.1
    ^
    SyntaxError: Unexpected token G
        at Object.parse (native)
        at Socket.<anonymous> (/home/jay/projects/nodejs/test/json-server.js:8:23)
        at Socket.EventEmitter.emit (events.js:95:17)
        at Socket.<anonymous> (_stream_readable.js:746:14)
        at Socket.EventEmitter.emit (events.js:92:17)
        at emitReadable_ (_stream_readable.js:408:10)
        at emitReadable (_stream_readable.js:404:5)
        at readableAddChunk (_stream_readable.js:165:9)
        at Socket.Readable.push (_stream_readable.js:127:10)
        at TCP.onread (net.js:526:21)

Any help is much appreciated.

---

UPDATE

The updated server code :

var WebSocketServer = require('websocket').server;
var http = require('http');

var server = http.createServer(function(request, response) {
    console.log((new Date()) + ' Received request for ' + request.url);
    response.writeHead(404);
    response.end();
});
server.listen(8080, function() {
    console.log((new Date()) + ' Server is listening on port 8080');
});

wsServer = new WebSocketServer({
    httpServer: server,
    // You should not use autoAcceptConnections for production
    // applications, as it defeats all standard cross-origin protection
    // facilities built into the protocol and the browser.  You should
    // *always* verify the connection's origin and decide whether or not
    // to accept it.
    autoAcceptConnections: false
});

function originIsAllowed(origin) {
  // put logic here to detect whether the specified origin is allowed.
  return true;
}

wsServer.on('request', function(request) {
    if (!originIsAllowed(request.origin)) {
      // Make sure we only accept requests from an allowed origin
      request.reject();
      console.log((new Date()) + ' Connection from origin ' + request.origin + ' rejected.');
      return;
    }

    var connection = request.accept('echo-protocol', request.origin);
    console.log((new Date()) + ' Connection accepted.');
    connection.on('message', function(message) {
        if (message.type === 'utf8') {
            console.log('Received Message: ' + message.utf8Data);
            connection.sendUTF(message.utf8Data);
        }
        else if (message.type === 'binary') {
            console.log('Received Binary Message of ' + message.binaryData.length + ' bytes');
            connection.sendBytes(message.binaryData);
        }
    });
    connection.on('close', function(reasonCode, description) {
        console.log((new Date()) + ' Peer ' + connection.remoteAddress + ' disconnected.');
    });
});

This solved my problem and I am now getting the message back.

Answer 1

A websocket is not a plain TCP socket. That is basically the core of your problem.

The websocket protocol looks like a modified HTTP protocol that allows two way communication using a single (TCP) socket. Read the RFC for more info on how the websocket protocol actually works: http://tools.ietf.org/html/rfc6455#section-1.2

You have two options if you want to use websockets with node servers:

1. Read the RFC and write a function to handle the websocket protocol so you can pass that function to socket.on.

2. Use a websocket server module that someone else have written. Go to npm and search for "websocket server" or google "websocket server npm" . There are lots of modules out there. Pick one you like best.

There is a third alternative. Use socket.io . Socket.io is a library that communicates between client and server using websocket if possible (preferred) but is able to degrade to other transports such as Flash and ajax on older browsers.