I'm trying to learn express and socket.io and haven't been able to find an answer to my question. I need to reference clients and not sockets, and since I have multiple pages connecting to the server it creates different sockets so I can't keep track of users. What is the proper way to do this? I haven't been able to find a solution that made sense
In essence all I want to do is be able to reference the same client no matter what page they are on with my server. But if I have two separate snippets of code like this to keep track of users it doesn't work
socket.on('set name', function (name) {
console.log("set name My socket id is " + socket.id);
socket.set('username', name);
socket.get('username', function (error, value) {
console.log("set name Socket.username " + value);
});
});
and later
socket.on('getusername', function () {
console.log("getusername My socket id is " + socket.id);
socket.get('username', function (error, value) {
console.log("getusername Socket.username " + value);
});
});
The second code being called from a different page, what are my options to reference the client rather than the sockets?
You can use the concept of rooms in socket.io.
All sockets with same name can going a room.
Something like this:
socket.on('set name', function (name) {
socket.join(name);
});
and later
socket.on('getusername', function () {
// get all the rooms socket is part of and use the
// first room he is in.
var room = io.sockets.manager.roomClients[socket.id][0];
});
You can try set the browser cookie on the client (the one that will be deleted when user closes the browser) and send its value in message payload when you initialize the socket connection.
Related
I am currently creating a websocket server for a mobile front. and in some cases I need to send a json only to a specific user and after several attempts I still haven't managed to get Websocket to work so I can send my json to one client at a time.
i'm using this library : github.com/websockets/ws
To explain my problem i have several products that contain several variables that need to be refreshed in real time. when a user connects to a product he will receive only the json of that product and the other users will receive the json of the other products they are currently on. that's why i want to send a specific json to a user to enable this
I would like to know if any of you know how to fix the problem as I'm starting to block on it.
Thank you very much.
const opp = new WebSocket.Server({port: 10001});
let user = 0;
let lookup = [];
opp.on('connection', function connection(op) {
lookup.push(op.id);
let id = "";
op.on('message', function incoming(message) {
console.log('received: %s', message);
id = message;
query = {
text: "SELECT id,state,users_list_name,user_win,timer_stamp FROM products WHERE id = " + parseInt(id) + " AND circle = 1 ORDER BY CASE WHEN state = \'available\' THEN \'1\' WHEN state = \'soon\' THEN \'2\' WHEN state = \'expired\' THEN \'3\' END",
};
});
client.connect();
const interval = setInterval(function ping() {
client.query(query, (err, res) => {
if (err) {
console.log(err.toString());
console.log(query);
} else {
console.log(lookup);
for (let i = 0; i < lookup.length; i++){
console.log("########################");
lookup[i].send(JSON.stringify(res.rows));
}
}
});
}, 300);
});```
OK. Still trying to understand the actual spec you're shooting for. But, assuming the following (based on your answers to my prior questions):
A client connects using a webSocket.
When they send a message over that webSocket, that message is an id of something that can be looked up in your database and that they want regular updates for.
Those updates for that particular id should be sent only to that specific client that requested it.
If a different client connects and specifies some id, they should get updates for that id only.
When a client sends a new message that specifies a different id, their updates should now be only for that new id.
Updates for the id that one client requested are sent only to that one client (not to the other clients).
If that's what you really want, here's a way to structure that.
const wss = new WebSocket.Server({port: 10001});
// make database connection that all users share
client.connect();
wss.on('connection', function connection(ws) {
// these variables are unique to each ws connection
let interval, query;
// when webSocket closes, stop any current interval timer associated with this webSocket
ws.on('close', function() {
if (interval) {
clearInterval(interval);
}
});
// when we get an id, start querying for updates on that id
ws.on('message', function incoming(id) {
console.log(`received: ${id}`);
query = {
text: "SELECT id,state,users_list_name,user_win,timer_stamp FROM products WHERE id = " + parseInt(id) + " AND circle = 1 ORDER BY CASE WHEN state = \'available\' THEN \'1\' WHEN state = \'soon\' THEN \'2\' WHEN state = \'expired\' THEN \'3\' END",
};
// if interval is not already going, start it
if (!interval) {
interval = setInterval(function() {
client.query(query, (err, res) => {
if (err) {
console.log(err);
console.log(query);
} else {
// send data to just the one client that this timer is for
ws.send(JSON.stringify(res.rows));
}
});
}, 300);
}
});
});
Now, some comments:
Polling the database on a short time interval with a separate polling loop for every single client simply will not scale at all. You will have serious database scale issues. You really need a better design here, but since we don't know the overall requirements and architecture of your application, we don't have enough info to know what to suggest. Probably you want to leverage notifications in a database that tell you when data has changed rather than you polling it on a short interval on behalf of every single client.
I could find no reason for the lookup data structure. Your comments say that you want to send updates to ONE specific client, the one that requested that id. That can be done with ws.send().
This code assumes that the client variable represents a connection to your database that each of the setIntervals for each connected client can all share. That's why that code was moved out of the wss.on('connection', ...) event handler.
I switched to the more common terminology of wss to refer to the server instance and ws to refer to the webSocket for a particular connected client.
ws.send() is how you send to a connected client. I still don't know what you were doing with op.id. Looking at the doc for the ws library, that doesn't appear to be something you can use to send to.
Your code (and this code) creates a separate setInterval() timer for every webSocket client that connects and it uses a very short interval time. This will not scale. At worst, the interval time needs to be lengthened into multiple seconds (depending upon desired target scale). At best, you need to stop polling the database entirely and use some other mechanism in the database for getting notifications when data has been changed.
In docs it is said: "Each Socket in Socket.IO is identified by a random, unguessable, unique identifier Socket#id. For your convenience, each socket automatically joins a room identified by this id."
I am wondering if there is an option to disable such feature.
My solution was:
io.on('connection', function (socket) {
leaveDefRoom(socket);
[...]
}
function leaveDefRoom(socket){
var room = socket.adapter.rooms;
for (var key in room){
if (key.charAt(0) == '/') {
socket.leave(key);
return;
}
}
}
In socket.io. Every time you emit event. socket.io send the event to the client in this room. If you remove user from the room, you cannot send this user messages. Even broadcast will not work.
Anyway, if you really want, you can leave this room, like any other room:
You can change socket.js file and disable this option:
https://github.com/socketio/socket.io/blob/master/lib/socket.js#L289
Socket.prototype.onconnect = function(){
debug('socket connected - writing packet');
this.nsp.connected[this.id] = this;
// You have to remove this line below:
this.join(this.id);
this.packet({ type: parser.CONNECT });
};
I just started learning NodeJS and Socket.io. Until now I have this demo code, from official socket.io site:
http://socket.io/demos/chat/
I am able to get the unique client's ID of each user (socket) which connects, I am still trying to figure out, How can I make my code to only connect with 1 random user at a time when somebody runs the application. I just want to make random chat like Omegle (http://www.omegle.com/).
Only two users should randomly connect and chat with each other till they re-run the app, if they come back they should get connected with someone else who is in the online queue.
What changes do I need to do to have a similar behaviour?
Update
Added Client site code, main.js
$(function() {
var FADE_TIME = 150; // ms
var TYPING_TIMER_LENGTH = 400; // ms
var COLORS = [
'#e21400', '#91580f', '#f8a700', '#f78b00',
'#58dc00', '#287b00', '#a8f07a', '#4ae8c4',
'#3b88eb', '#3824aa', '#a700ff', '#d300e7'
];
// Initialize variables
var $window = $(window);
var $usernameInput = $('.usernameInput'); // Input for username
var $messages = $('.messages'); // Messages area
var $inputMessage = $('.inputMessage'); // Input message input box
var $loginPage = $('.login.page'); // The login page
var $chatPage = $('.chat.page'); // The chatroom page
// Prompt for setting a username
var username;
var connected = false;
var typing = false;
var lastTypingTime;
var $currentInput = $usernameInput.focus();
//Own Global
var room = '';
var socket = io();
function addParticipantsMessage (data) {
var message = '';
if (data.numUsers === 1) {
// message += "there's 1 participant";
// Status Message
message += "Waiting to connect with someone";
} else {
// message += "there are " + data.numUsers + " participants";
//Status message update
message = "You are connected to a stranger! Say Hey!";
}
log(message);
}
// Sets the client's username
function setUsername () {
username = cleanInput($usernameInput.val().trim());
// If the username is valid
if (username) {
$loginPage.fadeOut();
$chatPage.show();
$loginPage.off('click');
$currentInput = $inputMessage.focus();
// Tell the server your username
socket.emit('add user', username);
// Own
socket.emit('login', {'username' : 'Faizan'});
}
}
Although I would close this question because it's too vague, I feel obliged to give you some insight since I worked way too much with websockets in the last years (although not that much with socketio & nodejs). I suppose some simple guide and relevant links could help you. So first,
Kind of relevant intro
You should already know that Socket.io is a WebSocket implementation.
WebSockets (WS) allow server to send data whenever it wants, as long as the connection is still open, as opposed to old way: client querying all the time asking, if there is an update on the server.
You can imagine a woman and a man at the end of a party: "Thanks for tonight, I'd love to repeat it sometimes soon. Would you give me your number?" - asks the old man. "Ughhh, you know what, better give me yours, I promise I will call you!"
If the girl were to give him her number, he'd call a few times a day asking if she'd go somewhere (and she'd reply no). The other way around, she would call him only if she wanted to go and he would go. Of course he would.
I got a bit carried away, but you get the picture. The woman is a server, the guy is a client.
What is important to understand
(Absolute basic, you should know this =>)
When client connect to your server, (s)he should be served a html page and some javascript, which establishes connection to your WS server. In the code you've posted, Express is used as http server. Check this example to see how you should give user html&js.
You'll also notice namespaces and rooms in most of these tutorials. These are used for separating users into subcategories. One server may contain multiple namespaces (by default only one) and each namespace may contain multiple rooms. You probably won't need to bother with namespaces, one is just enough for your case. You will, however, need to understand rooms (more on that later).
Next thing, taken from your code
io.on('connection', function (socket) {
It's important to know, that socket here basically represent one connected client (in one namespace, but possibly in multiple rooms). You can do all sort of stuff with it, most notably:
install event handlers on it (that's what you do when you call socket.on(event, handler(data))
send events to it with socket.emit(event, data)
send broadcast event to all users with socket.broadcast.emit(event, data)
add/remove it to/from room with socket.join(room), socket.leave(room) respectively.
work with it as with an ordinary variable - store it wherever you want and then reuse it
Do you see the definition of numUsers in your code? That's a global variable which is shared with all clients, since nodejs is single-threaded. In the example it is being incremented inside one of the event handlers. Think we could use something like that? YES.
We can define global variable, queue for example. Or Q if you want. Point is, it can be an array used to store sockets, or rather clients, which are not currently in chat room.
At the end of this section I'd like to point out another obvious thing.
io.on('connection', handler); defines an event handler for 'connection' event happening on the io object (WS server). This is triggered each time client makes connection to your WS server (in your case, through javascript ran inside client's browser). Argument to the method is socket and it is this method where you should add event listeners for each client (that you already do in the code, particularly handling events 'new message', 'add user', 'typing', 'stop typing' and 'disconnect').
What events shall you need
That really depends on how complex you want your app to be. In my opinion, the bare minimum would be (note that you can change the event names, but 'disconnect' should stay 'disconnect'):
event name -> data given
Events handled on server side
login -> username (how the user should be called), possibly password if you want to enable registration
message -> text (content of the message being sent)
leave room -> room name
disconnect
Event handled on client side
connect
chat start -> name (second client's name), room (so we can leave it)
chat end -> no data required if you want to allow only one chat at the same time. In case of multiple chats you should also include which chat got closed
disconnect
Last note before we get started
This is only a rough sketch. There are multiple different crossroads along the way and which path you take mostly depends on your idea of the app. If you want to have multiple chats opened at the same time, you'll need to do some modifications. The same goes if you want to have more than two people connected to the same chat. Here I'll describe the simplest case possible, one chat, to people, no registration. Possibly what you want, judging from your post. Could be wrong.
Workflow
User opens your page in their web browser. You serve them html and javascript. The javascript will start new connection to your websocket server. Also, handlers for desired events should be defined at this point.
When the connection is established, this will be happening:
ON SERVER SIDE
io.on('connection', handler) will be fired. Only appropriate handlers for new socket will be installed, not doing anything else at this point.
ON CLIENT SIDE
socket.on('connect', handler) will be fired. Client should at that point have username stored somewhere. If not, no problem. The connection will be alive for quite some time. You can just call socket.emit('login', {'username':name) any time you wish after you are connected (in the example below I set up variable connected, which defaults to false but will be set to true as soon as connection is established.)
After you send login event from client, server registers it and saves it somewhere. Possibilities are endless, in this case I'll create global dictionary which maps socket.id to username. After that, user socket should be either paired with another one or added to queue.
So, if the queue is empty, simply append socket to global variable (it doesn't have to be an array, since we will pair the first available sockets together, however you may want to implement some history of users so they won't get connected to the same person again). If the queue is not empty, we pull one socket out of the Q and add them to the same room. Room name can be random or whatever you want, I'll use (socket1.id+'#'+socket2.id (if you wanted to have more users in one chat, this would have to be changed).
After you add them both, you'll need to notify them that their chat has started and send them the other peer's name. You will emit event 'chat start'.
Clients will catch the event and open new window. After that, whenever user types something and sends it, client emits event 'message' with payload {'message': user_inserted_text}. Server will capture it in the .on('message' handler and broadcast it to the room. Note:
Broadcasting means sending a message to everyone else except for the socket that starts it.
Note: I am really confused about socketio code right now. Look at this and tell me, if socket.rooms is an array or an object (socket.rooms[room] = room; ?? why?)
To avoid dealing with this not-straightforward code, lets create another global object, rooms, which will store the room names for us. We will map socket.id -> roomName there.
So when message comes, we can get name of the room by calling rooms[socket.id]. Then we broadcast the message like this:
socket.broadcast.to(room).emit('message', data);
Where data is what we received from the sender, therefore object {'text': 'some nice message'}. Your peer will then receive it (you won't) and display it (you should display it when you are sending it).
So the chat continues like this for a while, then one of the users decides (s)he wants to leave / chat with somebody else. They will close window and client will emit event 'leave room'. Server will capture it and send to the other party that her/his peer has disconnected. The same should happen if the client disconnects. After everything is closed, add both users to queue (or only one, if the other has disconnected from the server). In my code I will not make sure they won't get paired again. That is for the OP to code (can't be hard).
So, if you read this far, you deserve some actual code. Although I say actual, it's actually untested. But you know, it should work like this.
Some code
Client side
var connected = false;
var username = 'Faizan';
var room = '';
var socket = io('http://localhost');
socket.on('connect', function (data) { // we are connected, should send our name
connected = true;
if (username) socket.emit('login', {'username' : username});
});
socket.on('chat start', function(data) {
room = data.room;
show_chat_window(data.name); // some method which will show chat window
});
socket.on('chat end', function(data) {
hide_chat_window(); // this will close chat window and alert user that the peer ended chat
socket.leave(room); // it's possible to leave from both server and client, hoever it is better to be done by the client in this case
room = '';
});
socket.on('disconnect', function(data) { // handle server/connection falling
console.log('Connection fell or your browser is closing.');
});
var send_message = function(text) { // method, which you will call when user hits enter in input field
if (connected) socket.emit('message', {'text': text});
};
var leave_chat = function() { // call this when user want to end current chat
if (connected) {
socket.emit('leave room');
socket.leave(room);
room = '';
}
};
Server side
Not including initial requires and html/js serving., only global definitions and main io handler.
var queue = []; // list of sockets waiting for peers
var rooms = {}; // map socket.id => room
var names = {}; // map socket.id => name
var allUsers = {}; // map socket.id => socket
var findPeerForLoneSocket = function(socket) {
// this is place for possibly some extensive logic
// which can involve preventing two people pairing multiple times
if (queue) {
// somebody is in queue, pair them!
var peer = queue.pop();
var room = socket.id + '#' + peer.id;
// join them both
peer.join(room);
socket.join(room);
// register rooms to their names
rooms[peer.id] = room;
rooms[socket.id] = room;
// exchange names between the two of them and start the chat
peer.emit('chat start', {'name': names[socket.id], 'room':room});
socket.emit('chat start', {'name': names[peer.id], 'room':room});
} else {
// queue is empty, add our lone socket
queue.push(socket);
}
}
io.on('connection', function (socket) {
console.log('User '+socket.id + ' connected');
socket.on('login', function (data) {
names[socket.id] = data.username;
allUsers[socket.id] = socket;
// now check if sb is in queue
findPeerForLoneSocket(socket);
});
socket.on('message', function (data) {
var room = rooms[socket.id];
socket.broadcast.to(room).emit('message', data);
});
socket.on('leave room', function () {
var room = rooms[socket.id];
socket.broadcast.to(room).emit('chat end');
var peerID = room.split('#');
peerID = peerID[0] === socket.id ? peerID[1] : peerID[0];
// add both current and peer to the queue
findPeerForLoneSocket(allUsers[peerID]);
findPeerForLoneSocket(socket);
});
socket.on('disconnect', function () {
var room = rooms[socket.id];
socket.broadcast.to(room).emit('chat end');
var peerID = room.split('#');
peerID = peerID[0] === socket.id ? peerID[1] : peerID[0];
// current socket left, add the other one to the queue
findPeerForLoneSocket(allUsers[peerID]);
});
});
P.S.
The code above got a bit messy in the end. It can be done better and I encourage you to do better job than I did. Having this material at hand, go through it step by step and try to understand. I think I commented most, if not all of it. Good luck.
Tl;dr
I am not even surprised. Here, read a comic
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I just recently built a chat, it's working pretty well, but I think I need to hook it up to redis.
From what I understand I need redis for scaling and holding some data if a client refreshes or a server goes down.
A core component of the 1on1 chat is that I store the users, and associate a socket.id to those users
var users = {};
io.sockets.on('connection', function (socket) {
// store the users & socket.id into objects
users[socket.handshake.headers.user.username] = socket.id;
});
Now on the client side I can say hey I want to chat with "Jack", as long as that is a valid user then I can pass that data to the server, i.e the user name and message just to jack like so.
var chattingWith = data.nickname; // this is Jack passed from the client side
io.to(users[chattingWith]).emit();
My question is, why should I use redis? What should I store in redis? How should I interact with that data?
I am using an io.adapter
io.adapter(redisIo({
host: 'localhost',
port: 6379,
pubClient: pub,
subClient: sub
}));
Also reading code from an example app I see when a socket connects they save the socket data into redis like so.
// store stuff in redis
redisClientPublish.sadd('sockets:for:' + userKey + ':at:' + room_id, socket.id, function(err, socketAdded) {
if(socketAdded) {
redisClientPublish.sadd('socketio:sockets', socket.id);
redisClientPublish.sadd('rooms:' + room_id + ':online', userKey, function(err, userAdded) {
if(userAdded) {
redisClientPublish.hincrby('rooms:' + room_id + ':info', 'online', 1);
redisClientPublish.get('users:' + userKey + ':status', function(err, status) {
io.sockets.in(room_id).emit('new user', {
nickname: nickname,
provider: provider,
status: status || 'available'
});
});
}
});
}
});
They use it when entering a room, to get information about the room.
app.get('/:id', utils.restrict, function(req, res) {
console.log(redisClientPublish);
utils.getRoomInfo(req, res, redisClientPublish, function(room) {
console.log('Room Info: ' + room);
utils.getUsersInRoom(req, res, redisClientPublish, room, function(users) {
utils.getPublicRoomsInfo(redisClientPublish, function(rooms) {
utils.getUserStatus(req.user, redisClientPublish, function(status) {
utils.enterRoom(req, res, room, users, rooms, status);
});
});
});
});
});
So again, I am asking because I am kind of confused if I need to store anything inside redis/why I need to, for instance we may have a few hundred thousand users and the node.js server "Jack" and "Mike" are chatting on goes down, it then changes to point to a new node.js instance.
Obviously I want the chat to still remember "Jack's" socket id is "12333" and "Mike's" socket id is "09278" so whenever "Jack" says hey I want to send "Mike/09278" a message the server side socket will direct it properly.
Would storing the username as a key and socket ID as a value be a wise use case for redis, would that socket.id still work?
Redis is a pretty good choice as a database for a chat as it provides a couple of data structures that are not only very handy for various chat use cases but also processed in a really performant way. It also comes along with a PubSub messaging functionality that allows you to scale your backend by spawning multiple server instances.
Scaling socket.io with the socket.io-redis adapter
When you want to run multiple instances of your server - be it because of one server not being able to handle increasing users any more or for setting up a high availablility cluster - then your server instances must communicate with each other in order to be able to deliver messages between users who are connected to different servers. The socket.io-redis adapter solves this by using the redis PubSub feature as a middleware. This won't help you if you are using only a single server instance (in fact I assume it will be slightly less performant) but as soon as you spawn a second server this will work out just fine without any headaches.
Want to get a feeling and some insight on how it's working? Monitor your dev redis while using it and you'll see the internal socket.io messages that are pushed through redis.
redis-cli
monitor
Use cases and their according redis data types
Save active conversations in a SET
A redis set is a collection of unique strings. I don't think storing socket.io id's would work out well as you can't assume that a user will get the same id on a reconnect. Better store his rooms and rejoin him on connect. You add every chat room (btw. direct messages can be defined as a room with two participiants so the handling is the same in both cases) that a user enters to their room set. On a server restart, a client reconnect or second client instance you can retrieve the whole set and rejoin users to their rooms.
/* note: untested pseudo code just for illustration */
io.sockets.on('connection', function (socket) {
rooms = await redis.smembers("rooms:userA");
rooms.foreach (function(room) {
socket.join(room);
}
socket.on('leave', room) {
socket.leave(room);
redis.srem("rooms:userA", room);
}
socket.on('join', room) {
socket.join(room);
redis.sadd("rooms:userA", room);
}
}
Save the last 10 messages of a conversation using a redis LIST
A redis list is somewhat of an persistent array of strings. You push a new message into a list and pop the oldest when the list size reaches your threshold. Conveniently the push command returns the size right away.
socket.on('chatmessage', room, message) {
if (redis.lpush("conversation:userA:userB", "Hello World") > 10) {
redis.rpop("conversation:userA:userB");
}
io.to(room).emit(message);
}
To get the message history use lrange:
msgHistory = redis.lrange("conversation:userA:userB", 0, 10)
Save some basic user details in a HASH
A hash is a key/value collection. Use it to store the online status along with avatar urls or whatever.
io.sockets.on('connection', function (socket) {
redis.hset("userdata:userA", "status", "online");
socket.on('disconnect', function () {
redis.hset("userdata:userA", "status", "offline");
}
}
Maintain a "recent conversations" list in a SORTED LIST
Sorted sets are similar to SETs but you can assign a score value to every element and retrieve the set ordered by this value. Simply use a timestamp as score whenever there is an interaction between two users and that's it.
socket.on('chatmessage', room, message) {
io.to(room).emit(message);
redis.zadd("conversations:userA", new Date().getTime(), room);
}
async function getTheTenLatestConversations() {
return await redis.zrange("conversations:userA", 0, 10);
}
References
socket.io-redis: https://github.com/socketio/socket.io-redis
redis PubSub docs: https://redis.io/topics/pubsub
redis data types: https://redis.io/topics/data-types-intro
I'm building a chat app on which, for every client connection, i need to set some attributes to every client instance using socket.io. When i save the attribute, i use:
client.set('name', name, function () {});
client.set('email', email, function () {});
....
and it runs fine.
When i need to get all the client properties, i have not found a better way than this:
client.get("name",function(err,name) {
client.get("email",function(err,email) {
.......
}
}
I need to nest all the "get" to asynchronously get data; but if i had 10 properties to get, do i need to nest all the 10 items? There must be a better way to do it, can anyone help me?
I don't attach attributes to the socket.
io.sockets.on('connection', function(socket) {
var username = "xx";
var email = "xx";
socket.on('doX', function(data) {
socket.emit('ackX', {username: username, email: email});
});
});
I don't know if it's the best solution, but I have seen many examples like that.
EDIT : socket.io - getting more than one field for a socket?
The correct answer may fit your needs