I am currently having a problem with a small Node.JS application. It is extremely similar to, for example, the Socket.IO sample chat application: whenever an user sends data to the server, I need to process the data and then broadcast it to all users. However, the way data is processed depends on the user that receives it. I tried altering the Socket#emit method (in order to process the data before sending it) for each socket, but the broadcasting doesn't use it. Is there any way I can get this solved?
Thanks in advance.
EDIT
Here is what I'd tried ():
var io = require('socket.io');
io.use(function(socket, next) {
var old_emit = socket.emit;
socket.emit = function() {
// do something with the data (arguments[1] in this case)
// the processing of the data depends on a value that is
// unique to each connection, and can't be sent over to the client
old_emit.apply(socket, arguments);
}
});
I tried the code above because I thought, initially, that broadcasting would call emit somewhere else for each connection.
I am not sure what you want to do,
There is no any "io( )" like function.You are doing it wrong.
BTW, to process data.
From sample chat application,
// when the client emits 'new message', this listens and executes
socket.on('new message', function (data) {
//call a function which you want to process data
var newData = messageProcessingFunc(data);
//and then broadcast it.
// we tell the client to execute 'new message'
socket.broadcast.emit('new message', {
username: socket.username,
message: newData
});
});
Related
I am developing a simple API for a chat application on Node.js Express, and by assignment, it is required to make it possible to communicate between two users using socket.іо. I am faced with the problem that I cannot "safely" transfer information about the current user to the socket in any way. Information about the user with whom the correspondence is conducted can be specified in the socket parameters when connecting, which I do, but what about the current user (me)?
For example, I can do this:
const {receiverId, myId} = socket.handshake.query;
That is, specify both ids when connecting. But this is very unsafe because anyone who will join the socket can specify any id and write anything on behalf of someone else (for example, through Postman WebSockets).
Another option I was considering is making a post request in which a connection to the socket will be created using request.user.id and the request parameter. Then the post request will look like this:
router.post('/chat/:receiver', function (req,res){
const {receiver} = req.params
const socket = io.connect('/')
socket.emit('initMyUserId', {
myId: req.user,
});
})
But this option also did not work, because the file where this function is located and the file where the io variable is initialized are different, and I am not sure that it is generally advisable to transfer and use it in this way. Moreover, this approach will not allow me to check the operation of sockets via Postman, because the connection will occur in a post request, and not manually.
Are there working options to safely transfer the current user id with the ability to test it normally in postman? Or at least just safely pass the current user id if it doesn't work with Postman.
Here is the full code snippet for the socket events handlers:
module.exports = function(io) {
io.on('connection', (socket)=>{
const {id} = socket;
console.log(Socket connected: ${id});
const {idUser} = socket.handshake.query;
console.log(Socket idUser: ${idUser});
socket.on('message-to-user', (msg) => {
msg.type = user: ${idUser};
socket.to(idUser).emit('message-to-user', msg);
socket.emit('message-to-user', msg);
});
socket.on('disconnect', () => {
console.log(Socket disconnected: ${id});
});
});
}
I built a simple API endpoint with NodeJS using Sails.js.
When someone access my API endpoint, the server starts to wait for data and whenever a new data appears, he broadcasts it using sockets. Each client should receive his own stream of data based on his user input.
var Cap = require('cap').Cap;
collect: function (req, res) {
var iface = req.param("ip");
var c = new Cap(),
device = Cap.findDevice(ip);
c.on('data', function(myData) {
sails.sockets.blast('message', {"host": myData});
});
});
The response do not complete (I never send a res.json() - what actually happens is that the browser keep loading - but the above functionality works).
2 Problems:
I'm trying to subscribe and unsubscribe to to this API endpoint from my client (using RxJS). When I subscribe, I start to receive data via sockets - but I can't unsubscribe to the API endpoint (the browser expect the request to be completed).
Each client should subscribe to his own socket room based on the request IP parameter ( see updated code ). Currently it blasts the message to everyone.
How I can create a stream/service-like API endpoint with Sails.js that will emit new data to each user based on his input?
My goal is to be able to subscribe / unsubscribe to this API endpoint from each client.
Revised Answer
Let's assume your API endpoint is defined in config/routes.js like this:
...
'get /collect': 'SomeController.collectSubscribe',
'delete /collect': 'SomeController.collectUnsubscribe',
Since each Cap instance is tied to one device, we need one instance for each subscription. Instead of using the sails join/leave methods, we keep track of Cap instances in memory and just broadcast to the request socket's id. This works because Sails sockets are subscribed to their own ids by default.
In api/controllers/SomeController.js:
// In order for the `Cap` instances to persist after `collectSubscribe` finishes, we store them all in an Object, associated with which socket the were created for.
var caps = {/* req.socket.id: <instance of Cap>, */};
module.exports = {
...
collectSubscribe: function(req, res) {
if (!res.isSocket) return res.badRequest("I need a websocket! Help!");
if (!!caps[req.socket.id]) return res.badRequest("Dude, you are already subscribed.");
caps[req.socket.id] = new Cap();
var c = caps[req.socket.id]; // remember that `c` is a reference to our new `Cap`, not a copy.
var device = c.findDevice(req.param('ip'));
c.open(device, ...);
c.on('data', function(myData) {
sails.sockets.broadcast(req.socket.id, 'message', {host: myData});
});
return res.ok();
},
collectUnsubscribe: function(req, res) {
if (!res.isSocket) return res.badRequest("I need a websocket! Help!");
if (!caps[req.socket.id]) return res.badRequest("I can't unsubscribe you unless you actually subscribe first.");
caps[req.socket.id].removeAllListeners('data');
delete caps[req.socket.id];
return res.ok();
}
}
Basically, it goes like this: when a browser request triggers collectSubscribe, a new Cap instance listens to the provided IP. When the browser triggers collectUnsubscribe, the server retreives that Cap instance, tells it to stop listening, and then deletes it.
Production Considerations: please be aware that the list of Caps is NOT PERSISTENT (since it is stored in memory and not a DB)! So if your server is turned off and rebooted (due to lightning storm, etc), the list will be cleared, but considering that all websocket connections will be dropped anyway, I don't see any need to worry about this.
Old Answer, Kept for Reference
You can use sails.sockets.join(req, room) and sails.sockets.leave(req, room) to manage socket rooms. Essentially you have a room called "collect", and only sockets joined in that room will receive a sails.sockets.broadcast(room, eventName, data).
More info on how to user sails.sockets here.
In api/controllers/SomeController.js:
collectSubscribe: function(req, res) {
if (!res.isSocket) return res.badRequest();
sails.sockets.join(req, 'collect');
return res.ok();
},
collectUnsubscribe: function(req, res) {
if (!res.isSocket) return res.badRequest();
sails.sockets.leave(req, 'collect');
return res.ok();
}
Finally, we need to tell the server to broadcast messages to our 'collect' room.
Note that this only need to happen once, so you can do this in a file under the config/ directory.
For this example, I'll put this in config/sockets.js
module.exports = {
// ...
};
c.on('data', function(myData) {
var eventName = 'message';
var data = {host: myData};
sails.sockets.broadcast('collect', eventName, data);
});
I am assuming that c is accessible here; If not, you could define it as sails.c = ... to make it globally accessible.
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
I'm using Node.js with ws(a socket library) and I'm having a little trouble with finding the socket of a specific user.
when the user connects to my socket server, I'm supposed to keep his socket objct in a big massive object by his userID or socketID like this:
var bigMassiveObject = {};
ws.on('connection', function(socket){
var userID //somehow get the userID
bigMassiveObject[userID] = socket;
// to find the socket
socket = bigMassiveObject[userID];
socket.send("hi");
})
so that later I can send him message by that ID, but isn't it better to just keep his socketID? this way we are not storing all the socket, but only the ID and then somehow(which I don;t know) send him message by that ID
this is what i'm looking for:
var smallObject = {};
ws.on('connection', function(socket){
var userID //somehow get the userID
smallObject[userID] = socketID;
// to find the socket
var socket = generateSocketObjectBySocketID(socketID);
socket.send("tada!");
})
so the question is, is there anyway to generate the socket, by the socketID(or useID)? so that we wouldn't be storing all these big socket objects in memory and there wouldn't be any memory leakage too :)
Simply,
This is what you need :
io.to(socket.id).emit("event", data);
whenever a user joined to the server,socket details will be generated including ID.This is the ID really helps to send a message to particular people.
first we need to store all the socket.ids in array,
var people={};
people[name] = socket.id;
here name is the reciever name. Example:
people["trojan"]=2387423cjhgfwerwer23;
So, now we can get that socket.id with the reciever name whenever we are sending message:
for this we need to know the recievername.You need to emit reciever name to the server.
final thing is:
socket.on('chat message', function(data){
io.to(people[data.reciever]).emit('chat message', data.msg);
});
Hope this works well for you.!!Good Luck
I want to do something like:
//client -> notifies server that client is connected.
//server -> begins fetching information from DB (series of both async and synchronous requests).
//as sets of data become available on server -> server pushes updates to client via res.render()
Basically I have a menu item on the client, and I want to update that menu as the data that the server fetches gets ready. is there any way to do this? I notice I can't do
res.render('something');
// again
res.render('somethingElse');
Because once render is called, then the response is sent, and render cannot be called again
"Error: Can't set headers after they are sent."
Any suggestions?
You might benefit from using WebSockets:
http://en.wikipedia.org/wiki/WebSocket
This post has a little bit of info:
Which websocket library to use with Node.js?
HTTP works via request/response. Typically once the response is sent, the connection is terminated.
To stream data from the server to client, you can use websockets. There is a very popular node.js module called socket.io, which simplifies using websockets.
Using socket.io, the client code would look like this:
var socket = io.connect('http://yourserver.com');
socket.on('data', function (data) {
updateMenu(data);
});
And the server code:
var io = require('socket.io').listen(80);
io.sockets.on('connection', function (socket) {
socket.emit('data', data);
getMoreDataFromDb(function(data){
socket.emit('data', data);
});
// etc..
});
Alternatively, if you want a simpler solution, you can just make multiple small ajax requests to the server, until you get all your data:
(function getData(dataId){
$.ajax({
url:"yourserver.com/getdata",
data: dataId || {},
success:function(data){
updateMenu(data);
if(data) getData({ lastDataReceived: data.lastId }); // server is still returning data, request more
}
});
})();