使用 webSocket 向特定连接的用户发送消息？

我编写了一个代码，用于向 所有用户广播信息:

// websocket and http servers
var webSocketServer = require('websocket').server;


...
...
var clients = [ ];


var server = http.createServer(function(request, response) {
// Not important for us. We're writing WebSocket server, not HTTP server
});
server.listen(webSocketsServerPort, function() {
...
});


var wsServer = new webSocketServer({
// WebSocket server is tied to a HTTP server.
httpServer: server
});


// This callback function is called every time someone
// tries to connect to the WebSocket server
wsServer.on('request', function(request) {
...
var connection = request.accept(null, request.origin);
var index = clients.push(connection) - 1;
...

请注意:

  • 我没有任何用户参考，只有一个连接。
  • 所有用户连接都存储在 array中。

目标 : 假设 Node.js 服务器想要向特定的客户机(John)发送消息。NodeJs 服务器如何知道 John 有哪个连接？Js 服务器根本不认识 John。它看到的只是联系。

所以，我相信现在，我不应该只存储用户的连接，相反，我需要存储一个对象，这将包含 userId和 connection对象。

想法:

  • 当页面完成加载(DOM 就绪)时，建立到 Node.js 服务器的连接。

  • 当 Node.js 服务器接受连接时——生成一个惟一的字符串并将其发送到客户端浏览器。将用户连接和唯一字符串存储在对象中。例如 {UserID:"6", value: {connectionObject}}

  • 在客户端，当此消息到达时-将其存储在一个隐藏字段或 cookie 中。(用于以后对 NodeJs 服务器的请求)

当服务器希望向 John 发送消息时:

  • 在字典中查找 john 的 UserID 并通过相应的连接发送消息。

  • 请注意，这里没有涉及 asp.net 服务器代码(在消息机制中)

问题:

Is this the right way to go?

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小开
最佳答案

This is not only the right way to go, but the only way. Basically each connection needs a unique ID. Otherwise you won't be able to identify them, it's as simple as that.

Now how you will represent it it's a different thing. Making an object with id and connection properties is a good way to do that ( I would definitely go for it ). You could also attach the id directly to connection object.

Also remember that if you want communication between users, then you have to send target user's ID as well, i.e. when user A wants to send a message to user B, then obviously A has to know the ID of B.

小开

Here's a simple chat server private/direct messaging.

package.json

{
"name": "chat-server",
"version": "0.0.1",
"description": "WebSocket chat server",
"dependencies": {
"ws": "0.4.x"
}
}

server.js

var webSocketServer = new (require('ws')).Server({port: (process.env.PORT || 5000)}),
webSockets = {} // userID: webSocket


// CONNECT /:userID
// wscat -c ws://localhost:5000/1
webSocketServer.on('connection', function (webSocket) {
var userID = parseInt(webSocket.upgradeReq.url.substr(1), 10)
webSockets[userID] = webSocket
console.log('connected: ' + userID + ' in ' + Object.getOwnPropertyNames(webSockets))


// Forward Message
//
// Receive               Example
// [toUserID, text]      [2, "Hello, World!"]
//
// Send                  Example
// [fromUserID, text]    [1, "Hello, World!"]
webSocket.on('message', function(message) {
console.log('received from ' + userID + ': ' + message)
var messageArray = JSON.parse(message)
var toUserWebSocket = webSockets[messageArray[0]]
if (toUserWebSocket) {
console.log('sent to ' + messageArray[0] + ': ' + JSON.stringify(messageArray))
messageArray[0] = userID
toUserWebSocket.send(JSON.stringify(messageArray))
}
})


webSocket.on('close', function () {
delete webSockets[userID]
console.log('deleted: ' + userID)
})
})

Instructions

To test it out, run npm install to install ws0. Then, to start the chat server, run node server.js (or npm start) in one Terminal tab. Then, in another Terminal tab, run wscat -c ws://localhost:5000/1, where 1 is the connecting user's user ID. Then, in a third Terminal tab, run wscat -c ws://localhost:5000/2, and then, to send a message from user 2 to 1, enter ["1", "Hello, World!"].

Shortcomings

This chat server is very simple.

  • Persistence

    It doesn't store messages to a database, such as PostgreSQL. So, the user you're sending a message to must be connected to the server to receive it. Otherwise, the message is lost.

  • Security

    It is insecure.

    • If I know the server's URL and Alice's user ID, then I can impersonate Alice, ie, connect to the server as her, allowing me to receive her new incoming messages and send messages from her to any user whose user ID I also know. To make it more secure, modify the server to accept your access token (instead of your user ID) when connecting. Then, the server can get your user ID from your access token and authenticate you.

    • I'm not sure if it supports a WebSocket Secure (wss://) connection since I've only tested it on localhost, and I'm not sure how to connect securely from localhost.

小开

I would like to share what I have done. Hope it doesn't waste your time.

I created database table holding field ID, IP, username, logintime and logouttime. When a user logs in logintime will be currect unixtimestamp unix. And when connection is started in websocket database checks for largest logintime. It will be come user logged in.

And for when user logs out it will store currect logouttime. The user will become who left the app.

Whenever there is new message, Websocket ID and IP are compared and related username will be displayed. Following are sample code...

// when a client connects
function wsOnOpen($clientID) {
global $Server;
$ip = long2ip( $Server->wsClients[$clientID][6] );


require_once('config.php');
require_once CLASSES . 'class.db.php';
require_once CLASSES . 'class.log.php';


$db = new database();
$loga = new log($db);


//Getting the last login person time and username
$conditions = "WHERE which = 'login' ORDER BY id DESC LIMIT 0, 1";
$logs = $loga->get_logs($conditions);
foreach($logs as $rows) {


$destination = $rows["user"];
$idh = md5("$rows[user]".md5($rows["time"]));


if ( $clientID > $rows["what"]) {
$conditions = "ip = '$ip', clientID = '$clientID'


WHERE logintime = '$rows[time]'";
$loga->update_log($conditions);
}
}
...//rest of the things
}
小开

interesting post (similar to what I am doing). We are making an API (in C#) to connect dispensers with WebSockets, for each dispenser we create a ConcurrentDictionary that stores the WebSocket and the DispenserId making it easy for each Dispenser to create a WebSocket and use it afterwards without thread problems (invoking specific functions on the WebSocket like GetSettings or RequestTicket). The difference for you example is the use of ConcurrentDictionary instead of an array to isolate each element (never attempted to do such in javascript). Best regards,

小开

For people using ws version 3 or above. If you want to use the answer provided by @ma11hew28, simply change this block as following.

webSocketServer.on('connection', function (webSocket) {
var userID = parseInt(webSocket.upgradeReq.url.substr(1), 10)

webSocketServer.on('connection', function (webSocket, req) {
var userID = parseInt(req.url.substr(1), 10)

ws package has moved upgradeReq to request object and you can check the following link for further detail.

Reference: https://github.com/websockets/ws/issues/1114


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