I wrote a code for broadcasting a message to all users:
// 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;
...
Please notice:
I don't have any user reference but only a connection .
All users connection are stored in an array.
Goal: Let's say that the Node.js server wants to send a message to a specific client (John). How would the NodeJs server know which connection John has? The Node.js server doesn't even know John. all it sees is the connections.
So, I believe that now, I shouldn't store users only by their connection, instead, I need to store an object, which will contain the userId and the connection object.
Idea:
When the page finishes loading (DOM ready) - establish a connection to the Node.js server.
When the Node.js server accept a connection - generate a unique string and send it to the client browser. Store the user connection and the unique string in an object. e.g. {UserID:"6", value: {connectionObject}}
At client side, when this message arrives - store it in a hidden field or cookie. (for future requests to the NodeJs server )
When the server wants to send a message to John:
Find john's UserID in the dictionary and send a message by the corresponding connection.
please notice there is no asp.net server code invloced here (in the message mechanism). only NodeJs .*
Question:
Is this the right way to go?
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.
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 ws. 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.
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
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
}
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,
Related
I have used methods socket.on and io.emit, And i got response to all users. But, i want to get response for particular user.
But my application contains login functionality and i followed this post on stackoverflow, and they are saying we need unique userId and socketId in an object for a particular user to emit an event for a particular user.
But i am getting the userId after login, But we want it when user connect to app.
So can anyone please help me with the same?
In your node.js, create a global array 'aryUser', each element contains the socketid and loginid.
node.js onConnect (new connection), add a new element to the array with the socketid and set loginid = empty.
after the user login, emit an event from client to the server, e.g:
socket.emit('userloginok', loginid)
in node.js, define a function:
socket.on('userloginok', loginid)
and in this function, search the aryUser with the socketid and replace the empty loginid inside the array element with the parm loginid.
in node.js, define the function:
socket.on('disconnect')
and in this function, search the aryUser, use aryUser.splice(i,1) to remove the user just disconnected.
that means, aryUser contains all users connected, some of them logined, some of them not logined. And you can use the socketid of the array to send message to particular user, and/or all users.
Example Source Code:
server.js
http://www.zephan.top/server.js
server.html
http://www.zephan.top/server.html.txt
rename server.html.txt to server.html, put server.html and server.js in the same directory, and run:
node server.js
Yes, you definitely need socketId in order to send and receive messages between two specific users.
UserId is required just to keep track of socketId associated with the particular user or you can manage it with some other way as well that's up to you.
As per your question, you have userId of the user and you need socketId of that user! So, in this case, you can pass userId when that particular connects to a socket server from the client side as shown in below snippet,
const socket = io(this.SOCKET_SERVER_BASE_URL, { query: `userId=${userId}` });
And you can read this user on nodejs server like this,
const userId= socket.request._query['userId'],
const socketId= socket.id
Now store this socketId in somewhere, for example, Redis or some sort of caching mechanism again up to you, just make sure fetching and retrieval should be fast.
Now while sending a message just pull the socketId from your cache and emit the message on that socketId by using below code,
io.to(socket.id).emit(`message-response`, {
message: 'hello'
});
I have written a complete blog post on this topic on both Angular and AngularJs, you can refer those as well.
Edit 1:
Part 1 =>
When your user completes the login request, then make the connection to the socket server.
Assuming you are using React Or Angular After a successful login you will redirect your user to home component(page). On the Home component(page) make the socket server connect by passing the userId just like this,
const socket = io(SOCKET_SERVER_BASE_URL, { query: `userId=${userId}` });
P.S. you can get userID from URL or maybe using a cookie that is up to you.
Once you receive this socket connection request on the server, then you can read the userID query and you can get socketId associated with it and store it in cache like this,
io.use( async (socket, next) => {
try {
await addSocketIdInCache({
userId: socket.request._query['userId'],
socketId: socket.id
});
next();
} catch (error) {
// Error
console.error(error);
}
});
Part 2 =>
Now, let's say you have a list of the users on the client side, and you want to send a message to particular users.
socket.emit(`message`, {
message: 'hello',
userId: userId
});
On the server side, fetch the socketId from the cache using UserId. Once you get the socketId from cache send a specific message like this,
io.to(socketId).emit(`message-response`, {
message: 'hello'
});
Hope this helps.
My problem is that the current solution I have for sending a specific socket using the library "ws" with node.js is not good enough.
The reason is because if I connect with multiple tabs to the websocket server with the same userid which is defined on the client-side, it will only refer to the latest connection with the userid specified.
This is my code:
// Server libraries and configuration
var server = require("ws").Server;
var s = new server({ port: 5001});
// An array which I keep all websockets clients
var search = {};
s.on("connection", function(ws, req) {
ws.on("message", function(message){
// Here the server process the user information given from the client
message = JSON.parse(message);
if(message.type == "userinfo"){
ws.personName = message.data;
ws.id = message.id;
// Defining variable pointing to the unique socket
search[ws.id] = ws;
return;
}
})
})
As you can see, each time a socket with same id connects, it will refer to the latest one.
Example If you did not understand:
Client connect to server with ID: 1337
search[1337] defined as --> websocket 1
A new connection with same ID: 1337
search[1337] becomes instead a variable refering to websocket 2 instead
Websockets provide a means to create a low-latency network "socket" between a browser and a server.
Note that the client here is the browser, not a tab on a browser.
If you need to manage multiple user sessions between the browser and server, you'll need to write code to do it yourself.
I am creating customer service chat application that get data from client website to node.js server then send this data to agent and the agent reply to the client..
Server code:
var ws = require("nodejs-websocket");
var clients = [];
var server = ws.createServer(function(conn){
console.log("New Connection");
//on text function
conn.on("text", function(str){
var object = JSON.parse(str);
conn.sendText("Message send : " + object);
console.log("User ID: " + object.id);
clients.push(object.id);
var unique=clients.filter(function(itm,i,a){
return i==a.indexOf(itm);
});
/*
conn.on('message', function("test") {
console.log('message sent to userOne:', message);
unique[0].send("Message: " + message);
});
*/
console.log("Number of connected users : " + unique.length);
//closing the connection
conn.on("close", function(){
console.log("connection closed");
});
});
}).listen(process.env.PORT, process.env.IP);
Everything works perfectly and I have each client ID but the
I want to reply with a message to that client ID..
What I have tried:
I have tried to reply to the client using conn.send("message", callBackFunction) but it send to all not with a specified user ID.
Disclaimer: co-founder of Ably - simply better realtime
You have two problems there I suspect. Firstly, if you ever need to scale to more than one server you've got problems as you will need to figure out how to pass messages between servers. Secondly, you have no way of maintaining state between disconnections which will happen as part of normal behaviour for clients.
The industry typically approaches this type of problem using the concept of channels as it scales, it decouples the publisher from the subscriber, and it's quite a simple concept to work with. For example, if you had a channel called "client:1" and you published to that channel, and your subscriber was listening on that channel, then they would receive the message. You can find out more about how we have designed our realtime service around channels, I would suggest you do consider that pattern in your system.
Matt, co-founder, Ably
I'm new to stakoverflow, but I swear that I really searched a lot before ask here. In short, I've two browsers opened, and two PHP sessions, redis takes care of the session, but when I try to refresh the page the online user that refreshed the node.js server take the (maybe socket id?) of the refreshed one, and if I do a logout on the not refreshed one, the connection will close as the refreshed one.
I know, it's messy. I have to set a socket id array with also session together?
Currently, I am storing each new connection in a room (to have private sockets), but I become to think that maybe I've to change something for make all work properly.
How you handle a refreshed page? Also because can happen that a user open another tab of same website, or a friend give a link and you visit that link, and you need the session id (ok) the saved user (ok) and the socket io socket (wrong in my case?). Maybe its because I don't know how to get the cookie outside this:
socket.on('connection', function(client) {
cookieManager = new co.cookie(client.request.headers.cookie);
clientSession.get("sessions/"+cookieManager.get("PHPSESSID"), function(error, result) {
if (error) {
console.log("error : "+error);
}
if (result != "") {
// if (result.toString() != "") {
console.log("PHP session id: " + cookieManager.get("PHPSESSID"));
//console.log(result.toString());
//console.log("print result: " + result); //warning! this will parse entire session, test only!
userData = JSON.parse(result);
}
}
}
By default, the nodejs server does not send back the php cookie.
When I used php + redis + socket.io, i used the configuration present in this answer: here (edit: I used memcache & a custom class, now I use redis + publish/subscribe to broadcast events!)
to connect, i read the cookie with javascript from the page and sent it in the beginning of the connection.
/** C "cookie" function, gets the cookie string.
* #param {string} [k] - key, the cookie to get
*/
function C(k){return(document.cookie.match('(^|; )'+k+'=([^;]*)')||0)[2]}
s = io.connect("//io."+ window.location.host +"/", {query: "id=" + C('PHPSESSID')});
from the nodejs side:
io.sockets.on("connection", function (socket) {
var cookie = socket.handshake.query.id;
...
});
I stored the data formatted in json in the redis database, with phpsessid as key.
Hope it helps!
I'm new to node.js and I'm making a simple chat app to get started. I'm a bit confused with the socket.set and socket.get methods.
The way the app works, is - first the client sets its username (pseudo):
function setPseudo() {
if ($("#pseudoInput").val() != "")
{
socket.emit('setPseudo', $("#pseudoInput").val());
$('#chatControls').show();
$('#pseudoInput').hide();
$('#pseudoSet').hide();
}
}
On the server, the pseudo is fetched with:
socket.on('setPseudo', function (data) {
socket.set('pseudo', data);
});
If I understand correctly, the server sets the pseudo variable with data received from this particular client. The server can later get that variable with socket.get. The following code broadcasts a message from a client to all clients:
socket.on('message', function (message) {
socket.get('pseudo', function (error, name) {
var data = { 'message' : message, pseudo : name };
socket.broadcast.emit('message', data);
console.log("user " + name + " send this : " + message);
})
});
What I don't understand is, why can't the client itself use socket.get to fetch its own pseudo? Using socket.get('pseudo') gives an error saying socket.get is not a function. Or am I overcomplicating this, and it would be better to just store the pseudo in a hidden field on the client or something similar? It just feels strange that a client should have to get its own username from the server.
EDIT:
Upon clicking Send, this code displays the sent message on the client itself. However, the displayed username is "Me". How can I modify it to show the client's username from the server?
addMessage($('#messageInput').val(), "Me", new Date().toISOString(), true);
function addMessage(msg, pseudo) {
$("#chatEntries").append('<div class="message"><p>' + pseudo + ' : ' + msg + '</p></div>');
}
You have to realize that although socket is a name used by both the server and the client, and interfaces are similar these are two independent things. (i.e. server socket and client socket) describing two ends of one connection.
If server sets some data on a socket what it actually does is it saves some data in its own memory and remembers that this data is associated with the socket. So how would client read something from server's memory? How can machine A read data from machine's B memory? Well, the only (reasonable) possibility is to send that data over network and this is actually what happens.
As for the other question: it's actually natural for the client to get its own name from the server or at least validate that name. Consider this scenario: two clients connect to the server and use the same name. This would lead to a conflict so it is up to the server to solve the problem. Basically you would tell one of the clients "sorry, this name is already being used, use something else".