socket.io not emitting event from server to client on connection - javascript

I have a very basic setup with socket.io but am having trouble getting my server to send back a message once the connection has been established.
When a connection is established to my server, I want the server to send back a message to the client. I've tried to accomplish this with the following code:
Server
// Modules
var fs = require('fs');
var https = require('https');
// Certificate
var options = {
pfx: fs.readFileSync('<my cert>')
};
// Create Server
httpsServer = https.createServer(options);
// Create websocket
var io = require('socket.io')(httpsServer);
// Listen on a port
httpsServer.listen(4000,function() {
console.log('listening on *:4000');
});
io.on('connection', function(socket) {
console.log('a user connected');
socket.emit('test','you connected');
});
Client
var socket = io('https://<my server>:4000');
When I execute this code, the websocket gets established and my server console shows the message "a user connected". However, the message ['test','you connected'] does not get emitted through the socket.
The only way I've been able to get this to work is to use setTimeout() to wait 500ms before emitting the event, in which case it does work.
Why is that? How can I configure my server to automatically respond with a message as soon as the user connects?

You need to listen to the emitted event, using socket.on(event, callback);
<script src="https://cdn.socket.io/socket.io-1.4.5.js"></script>
<script>
var socket = io('https://localhost:4000');
//test is the emitted event.
socket.on("test", function(data){
console.log(data); //"you connected"
});
</script>

Related

Client not receiving message from server

Hi i have a node js server and im using sockets to communicate.
Index:
<script src="socket.io/socket.io.js"></script>
Client JS:
var socket = io.connect("http://localhost:8081");
socket.on('hi', function(data){
console.log("g");
console.log(data);
});
So it seems to connect just fine to the server. I have a socket called 'hi' waiting for any incoming messages. I added 2 console logs incase data was null, it would still print something to the console.
Server:
var express = require("express");
var app = express();
var server = require("http").Server(app);
var io = require("socket.io")(server);
var mazeGenerator = require("generate-maze");
app.use(express.static("public"));
io.on("connection", function(socket) { // EDITED
console.log("A player has connected - sending maze data...");
socket.emit("hi", "hi");
});
So when i refresh the page, the client connects and in my CMD i see the "A player has connected..." console log. From then on, its blank from the server or client, I can keep refreshing and it will keep saying a player has connected by the clients console stays blank
Since the connection is proven to be established, I suspect this is an issue of a way you emit the data. Your second parameter hi may not be taken as a data to be transmitted, according to
https://socket.io/docs/server-api/#socket-emit-eventname-args-ack
In my understanding, socket.io emit Object instead of String so can you try this?
io.on("connection", function(socket) {
console.log("A player has connected - sending maze data...");
socket.emit("hi", {data: "hi"});
});

Does socket IO need to serve HTML to work?

So, I am quite puzzled. I have a socket IO server that runs OK, and the HTML web client does connect to it. But, I can't emit anything. I'm using xampp to serve webpages, but does socket IO need to serve content for it to receive and send data? It's weird that I connect OK,but that's it, no emit function works.
Here's my code..
var io = require('socket.io')();
io.on('connection', function(client){ console.log("Connected OK."); io.emit('message',"data"); });
io.on('message', function(client){ console.log(client); });
io.listen(8080);
HTML
<script src="http://localhost:8080/socket.io/socket.io.js"></script>
<script>
// Create SocketIO instance, connect
var socket = io.connect('http://localhost:8080');
// Add a connect listener
socket.on('connect', function() {
alert('Client has connected to the server!');
});
socket.on('message', function(event) {
console.log('Received message from client!', event);
});
</script>
The code above prints "Connected OK" to the NPM console, and it alerts "Client has connected to the server!", but that's it. So my question is, does the NPM server need to serve the HTML to work, or am I doing things wrong?. I use xampp because of PHP and MySQL.
UPDATE:## The server sends to client just fine, and the client tries to send data back, and the server receives the packet. But then it reports: " engine:polling transport discarded - closing right away +0ms". Is this normal?

Can I connect to socket.io server using generic method?

I have a node.js server and I attached socket.io listener to it. The code is like this.
const server = new Hapi.Server();
server.connection({
"port": config.port
});
let io = socketio(server.listener);
io.on("connection", function(socket) {
console.log("A user connected");
socket.on("disconnect", function(){
console.log("A user disconnected");
});
// receive message from client
socket.on("client-server", function(msg) {
console.log(msg);
});
});
// somewhere to emit message
io.emit("server-client", "server to client message");
Normally I use the standard way to connect to the websocket server. An example is like this:
<!DOCTYPE html>
<html>
<head><title>Hello world</title></head>
<script src="http://localhost:3000/socket.io/socket.io.js"></script>
<script>
var socket = io();
socket.on('server-client', function(data) {document.write(data)});
socket.emit('client-server', 'test message');
</script>
<body>Hello world</body>
</html>
It works without issue. Now, my colleague wants to connect to the websocket server from his FME server. Based on his research, the only way he can use to connect to a websocket server is using a url like this:
ws://localhost:3000/websocket
My question is: is there a way to connect to socket.io server listener using this type of string?
If not, is there a way to create a websocket server with ws://host:port url and also attach it to my node.js server?
Or, is there a way to connect to socket.io listener in FME server?
To tell Socket.IO to use WebSocket only, add this on the server:
io.set('transports', ['websocket']);
And on the client add this:
var socket = io({transports: ['websocket']});
Now you can only connect to the WebSocket server using ws protocol.

socket.io authentification not working on first connection

I have a NodeWebkit client which connects to a nodejs server using the socket.io library (JavaScript).
The client launches the connect procedure on the application start but the server does not acknoledge any connections... Though the client's socket has the connected attribute to "true".
You should know that I am using socketio-jwt to authentificate the connection.
Github: https://github.com/auth0/socketio-jwt
I know that the connection does work in a way because if I add :
io.sockets.on('connection', function(){console.log("hello");})
It prints hello !
So it seems that event though the connection is somehow made it doesn't want to do the auth part with the library, resulting in... Well... Nothing.
But that's not all !!
Because if I reboot the app (not the server) then the auth works most of the time ! It acts like a race condition... But I dont see how it could possibly be one... Every line of code is geting executed appart of the success callback of authentification.
I tried connecting to a remote server and on my localhost.
I also tried with an other library of socket auth but I've got the same probleme.
This is the server code:
var session = require('express-session');
var app = require('express')();
var http = require('http').Server(app);
var io = require('socket.io')(http);
var socketioJwt = require('socketio-jwt');
io.sockets.on('connection', socketioJwt.authorize({
secret: 'some secret',
timeout: 15000 // 15 seconds to send the authentication message
})).on('authenticated', function (socket) {
console.log('[Info]: A user connected to socket = ', socket.decoded_token);
});
});
http.listen(5000, function () {
console.log('listening on *:5000');
});
And now the client code:
this.socket = io.connect('http://' + that.hostName +':' + that.port);
var token = jwt.sign({email: "someEail", pwd: "somePwd"}, fromServerSecret);
this.socket.on('connect', function () {
that.socket.emit('authenticate', {token: token}) //send the jwt
.on('authenticated', function () {
console.log("[Info]: Socket login successfull");
})
.on('unauthorized', function (msg) {
console.log("[Warning]: Socket unauthorized: " + JSON.stringify(msg.data));
throw new Error(msg.data.type);
});
});
The server side log "A user connected to socket" is never shown.
If you have an idear ! Thanks for your time.
Why is there a 'that' on socket.emit (client)? I think you should handle it within the same instance of socket.io - using same 'this' as above

using Socket.io with iOS via the socket.io Swift client

I've been trying to do basic communication between an app and my server but no matter what I do I can't seem to get it to work.
Below is my js code
var app = require('express')();
var http = require('http').Server(app);
var io = require('socket.io')(http);
io.on('connection', function(socket){
console.log('a user connected');
io.emit("hello");
socket.on('disconnect', function() {
console.log('a user disconnected');
});
socket.on('response', function(message){
console.log(message);
});
});
http.listen(3000, function(){
console.log('listening on *:3000');
});
This should in theory be alerted when a user connects, output a message saying the user has connected and then emit an event "hello"
below the on disconnect part I am trying to communicate with the server from my iOS app. I emit a event called "response" with a string called "I got your response".
I get the "a user connected" message in the console but the message I send from the iOS app never gets printed in the console.
This the code in my app.
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
let socket = SocketIOClient(socketURL: "192.168.0.3:3000")
socket.on("hello") {data, ack in
socket.emit("response", "I got your response")
}
socket.connect()
}
As you can see my server side code emits the event "hello". This should trigger the socket.on("hello") and make the app emit the event "response" which makes the server print out the string sent with it.
None of this is happening apart from the message that gets printed in the console when a user connects.
An help would be greatly appreciated.
the Github repo for the framework is below
https://github.com/socketio/socket.io-client-swift
Declare and initiate your socket variable in the top of the class. As previous comments said, I think the variable is lost in the scope otherwise.
class HostSocketHandler {
let socket = SocketIOClient(socketURL: urlString)
init(){
socket.connect();
}
}

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