Develop Reference

Problem in communicating with Binance exchange in NodeJS web socket

When I execute the following piece of code in the app.js file
const WebSocket = require('ws');
const ws = new WebSocket('wss://stream.binance.com:9443/ws/!miniTicker#arr');
ws.on('message', function (data){
//const result = JSON.parse(data);
console.log(data);
});
I get the following error and I cannot receive data.

10.10.34.34 (what your DNS server resolved stream.binance.com to) is a local IP address! You are not even reaching Binance. It's probably a captive portal or some firewall.
Open that IP address in the browser and check whether you get some sort of web interface that gives you a clue about what is blocking your request. You can also try changing your DNS server to Google (8.8.8.8) or some other public DNS server instead of relying on your router.
Update:
In your comment you mentioned your DNS server is 178.22.122.100 (i.e., shecan.ir). If I try to resolve the domain with that server, I also get nonsensical results (10.10.34.34 and d0::11). According to this book, this is part of Iranian censorship, and your ISP would handle this IP address to show a page about this domain being blocked if you'd open it in a browser.
So, an alternative public DNS server without censorship such as 8.8.8.8, 1.1.1.1 or 9.9.9.9 should help. If this doesn't work then those DNS servers are also blocked by your ISP and you would need to use a VPN or other means of bypassing government censorship.

Web application using websockets “Could not establish connection. Receiving end does not exist."

Java server, javascript client, no special libraries, plain text HTTP/1.1 and websocket connections.
Server side written (in Eclipse) using JDK 16 and a websocket jar found in Tomcat, version 10.0.2. (Many permutations of other JDKs and websocket jars have also been tried.)
Two web applications. Tomcat 10.0.2 on PC, 10.0.7 on server. Both apps run on Windows 10. Deployed to a Ubuntu 20.04 server. Both programs display the initial HTTP data. One program gets a websocket connection and works, the other fails to get the websocket connection. Both use the same code to calculate the target URL for the websocket connection:
window.onload = function() {
var target = "ws://" + location.host + "/[context]/[endpoint]";
console.log("target: " + target);
try {
if ('WebSocket' in window) {
socket = new WebSocket(target);
} else if ('MozWebSocket' in window) {
socket = new MozWebSocket(target);
} else {
alert('WebSocket is not supported by this browser.');
return;
}
} catch (e) {
console.log("websocket connection exception: " + e.description);
}
...
Where only [context] and [endpoint] differ. Recall that these URLs work on a PC. I believe they are “well-formed”/valid.
Results for the web app that fails:
Firefox:
uncaught exception: Could not establish connection. Receiving end does not exist.
GET ws://35.xxx.xx.xx:8080/Memory/MemoryEndpoint[HTTP/1.1 404 70ms]
Firefox can’t establish a connection to the server at ws://35.xxx.xx.xx:8080/Memory/MemoryEndpoint.
Chrome:
Error handling response: TypeError: Cannot read property 'encrypt' of undefined
at Object.13 (chrome-extension://bkdgflcldnnnapblkhphbgpggdiikppg/public/js/content-scripts/autofill.js:1427:33)
. . .
game.js:31 WebSocket connection to 'ws://xxx.xx.xx.xx:8080/Memory/MemoryEndpoint' failed:
Chrome continues for many lines regarding the 'encrypt' undefined issue. I have no idea what that is about but it might be very relevant. The last line above implies that some reason for the failure might be given on the next line, but it is empty.
Neither browser logs the expected exception text beginning with: "websocket connection exception:".
Tomcat log files are all clean except for some curious entries in localhost__access_log such as:
209.90.225.218 - - [11/Jul/2021:00:43:33 +0000] "HEAD /robots.txt HTTP/1.0" 404 -
And others mentioning /invoker/readonly, /login, /jenkins/login, /nifi/.
The fact that both programs do return results from the Tomcat server tells me that permissions on ports etc are all sufficient. I've also dug into netstat results and the like, reviewed firewall settings, read many many articles and requests for help. (Probably irrelevant because Tomcat does return expected HTTP/1.1 data.) No luck.
I need this program to work. I would pay a cash reward for a solution to this by 07-16-2021, though I don't know how to discretely negotiate that. :-(

Problem resolved, though I don't understand the cause. Recall: the web application ran fine on development PC deployed to Tomcat version 10.0.2, for various JDKs, websocket libraries (including one found in the Tomcat 10.0.7 that had been installed on the VM). The app failed on the Ubuntu VM. A friend installed Tomcat 10.0.8 in the VM. Presto! websockets work.

Check telnet connection with server IP and Port number in JScript

I need to test telnet connection to the server in my local pc. My pc don't have any server side languages like PHP, NodeJS,.. I want to do this in basic JavaScript or chrome extension from latest chrome. I have checked with websocket HTML5. But, it was not working. Here's my code,
<script>
var connection = new WebSocket('ws://10.0.30.1:80');
connection.onopen = function () {
connection.send('Ping'); // Send the message 'Ping' to the server
};
</script>
Lets explain what's my mistake and give me a solution if any other possible.

You can't. Unless you set up a proxy server, a websocket can only communicate with a websocket server.

Faye and Nodejs Issue

Hi currently I'm trying to do a notification feature on a webapp and I decided to use Faye in order to make them live notifications. Now the feature works fine on my local computer, but when somebody else tries to connect to my network, they get a connection refused and faye doesn't work.
Current code working on my local machine:
var http = require('http');
var faye = require('faye');
var server = http.createServer();
var bayeux = new faye.NodeAdapter({mount: '/faye', timeout: 45});
bayeux.attach(server);
server.listen(8000);
I managed to read some other questions related to this issue, and people said to make the server listen to all interfaces by adding: '0.0.0.0' to the server.listen call. When I do this it even stops working on my local machine. Any help will be appreciated!, Nodejs is not the only server running on my machine but the port is open so thats not an issue. I get a get failed request towards the faye message request.

Chrome websockets, readystate always on 0

I'm trying to use websockets on a website, so first I developed a small and very simple websocket page just to test it.
I have a websocket server running on my localhost, it is based on the python Tornado "Chat" demo. For some reason the chat demo app runs perfectly but I can't seem to use the websocket with my own page although some form of connection is made.
I am testing this using the latest Chromium version, so implementing websockets version 13, which is supported by the Tornado implementation.
So here is the problem:
Load page, js executes and Upgrade request is sent to the server
Server receives request and answers
So here in my understanding Chrome should set readyState = 1 and I should be able to send messages from my page.
Only for some reason it doesn't work, readyState remains 0 and of course if I try to send a message I receive an INVALID_STATE_ERR.
Here are the Headers :
Request:
GET ws://127.0.0.1:8000/chatsocket HTTP/1.1
Origin: http://127.0.0.1
Cookie: _xsrf=9f73731fc2d544df864ce777bef0775a
Connection: Upgrade
Host: 127.0.0.1:8000
Sec-WebSocket-Key: pkwlpY+TtxfgUrm3M4WtTQ==
Upgrade: websocket
Sec-WebSocket-Version: 13
Response:
HTTP/1.1 101 Switching Protocols
Connection: Upgrade
Upgrade: websocket
Sec-WebSocket-Accept: ur9KL2jBhYB38e2SgwOkjyBlQXk=
Any help is appreciated :)
--- EDIT ---
So I figured it out in the end, if you run into the same problem here is the reason:
WebSocket's readyState is updated when the Thread ENDS !
So running a code like:
var ws = new WebSocket(stuff);
while(ws.readyState==0){};
Will send the browser in an infinite loop...
Running code like:
var ws=new WebSocket(stuff);
do_other_stuf();
Might work, but you wont be able to use WS.
If the code that is supposed to run after the socket opens uses the socket this is the way it will have to be written:
var ws=new WebSocket(stuff);
ws.onopen = new function(){
// some code that need WS to be open
}
// rest of the code that doesn't require WS to be open
A better way to do this would be to let the thread end by using an asynchronous call:
var ws = new WebSocket(stuff);
setTimeout(whatever,500);
function whatever(){
if(ws.readyState==1){
// The code you want to run after WS is open
}
else
setTimeout(whatever,500);
}

In order to trigger some functionality when WebSockets are connected please use callbacks:
var socket = new WebSocket(...);
socket.onopen = function() {
// socket is connected
};
socket.onerror = function() {
// some error happened
};
socket.onmessage = function(evt) {
// you get a message: evt.data
};
Using readyState is well bad thing to do in such case, especially if you have to ask it multiple times (is just unnecessary).
Additionally take in account that each vendor of browsers implements WebSockets with very slight differences (unfortunately), so make sure you test it in most browsers.