I need to perform a load testing on our websocket service.
Is there a way to open multiple websocket connections from a single workstation?
I already tried npm ws and websocketmodules to launch them with NodeJS. It works fine with a single connection, but when I try to open them in a for-loop it throws an exception or uses only last open client.
If you want to do it from a single workstation, you can use child processes :
app.js :
var cp = require('child_process');
var children = [];
var max = 10; // tweak this to whatever you want
for(var i = 0; i<max; i++){
children[i] = cp.fork('./child.js');
.on('error', function(e) {
console.log(e);
}).on('message',function(m){
console.log(m)
}).on('exit', function(code) {
console.log('exit with code',code);
});
}
then in child.js, just have a script that starts a connection. you can also send messages between parent and child, using the child process API
Related
With the following code i open a stream connection to the Binance crypto exchange:
let adress = 'wss://stream.binance.com:9443/ws/btcusdt#kline_1h';
const ws = new WebSocket(adress);
If i make this call for different crypto currencys then i have later a few streams open, i want to know how can i check the current open streams, is there something like a function or parameter where i can see for which currencys i have a open stream running?
because i also have the problem that it looks like streams are stopping sometimes and i dont have a good solution for checking which streams have stop and how to receonnect them. My idea is now to first find a way how to check which streams are running and then maybe if one streams is stop i will just send the connection request again.
In javascript there is a websocket events thing, so all you need is to
ws.onclose = function(event) {
ws = new WebSocket(adress);
//just reopen it
};
Or, for more safety, you can
ws.onclose = function(event) {
if (event.wasClean) {
ws = new WebSocket(adress);
} else {
console.log('Connection error!');
//or whatever u want
}
};
Sorry for this stupid styling, I'm newbie there
If you have your ws variable, then checking whether the websocket is open and alive is done with
if(ws && ws.readyState === 1){
// is opened
}
For other states of the websocket, see the docs.
If you want to receive push messages from the server, you need to keep the ws connection open. If not, you can close the ws after a query and reopen it then for another query. You should wait for the closed state ws.readyState === 3 before reopening.
If you need to keep all ws connections open, then you need a list of ws Objects. You push new objects to the list:
let ws_list = [] // global list of ws objects
let create_connection = function(url){
try{
ws_list.push(new WebSocket(url));
} catch(err){
console.log(err, url);
}
}
let do_something = function(){
for(let ws of ws_list){
// do something with the ws object
}
}
I've two node apps/services that are running together,
1. main app
2. second app
The main app is responsible to show all the data from diffrent apps at the end. Now I put some code of the second app in the main app and now its working, but I want it to be decoupled. I mean that the code of the secnod app will not be in the main app (by somehow to inject it on runtime )
like the second service is registered to the main app in inject the code of it.
the code of it is just two modules ,is it possible to do it in nodejs ?
const Socket = require('socket.io-client');
const client = require("./config.json");
module.exports = (serviceRegistry, wsSocket) =>{
var ws = null;
var consumer = () => {
var registration = serviceRegistry.get("tweets");
console.log("Service: " + registration);
//Check if service is online
if (registration === null) {
if (ws != null) {
ws.close();
ws = null;
console.log("Closed websocket");
}
return
}
var clientName = `ws://localhost:${registration.port}/`
if (client.hosted) {
clientName = `ws://${client.client}/`;
}
//Create a websocket to communicate with the client
if (ws == null) {
console.log("Created");
ws = Socket(clientName, {
reconnect: false
});
ws.on('connect', () => {
console.log("second service is connected");
});
ws.on('tweet', function (data) {
wsSocket.emit('tweet', data);
});
ws.on('disconnect', () => {
console.log("Disconnected from blog-twitter")
});
ws.on('error', (err) => {
console.log("Error connecting socket: " + err);
});
}
}
//Check service availability
setInterval(consumer, 20 * 1000);
}
In the main module I put this code and I want to decouple it by inject it somehow on runtime ? example will be very helpful ...
You will have to use vm module to achieve this. More technical info here https://nodejs.org/api/vm.html. Let me explain how you can use this:
You can use the API vm.script to create compiled js code from the code which you want run later. See the description from official documentation
Creating a new vm.Script object compiles code but does not run it. The
compiled vm.Script can be run later multiple times. It is important to
note that the code is not bound to any global object; rather, it is
bound before each run, just for that run.
Now when you want to insert or run this code, you can use script.runInContext API.
Another good example from their official documentation:
'use strict';
const vm = require('vm');
let code =
`(function(require) {
const http = require('http');
http.createServer( (request, response) => {
response.writeHead(200, {'Content-Type': 'text/plain'});
response.end('Hello World\\n');
}).listen(8124);
console.log('Server running at http://127.0.0.1:8124/');
})`;
vm.runInThisContext(code)(require);
Another example of using js file directly:
var app = fs.readFileSync(__dirname + '/' + 'app.js');
vm.runInThisContext(app);
You can use this approach for the conditional code which you want to insert.
You can create a package from one of your apps and then reference the package in the other app.
https://docs.npmjs.com/getting-started/creating-node-modules
There are several ways to decouple two applications. One easy way is with pub/sub pattern (in case you don't need a response).
(Now if you have an application that is very couple, it will be very difficult to decouple it unless you do some refactoring.)
zeromq offers a very good implementation of pub/sub and is very fast.
e.g.
import zmq from "zmq";
socket.connect('tcp://127.0.0.1:5545');
socket.subscribe('sendConfirmation');
socket.on('message', function (topic, message) {
// you can get the data from message.
// something like:
const msg = message.toString('ascii');
const data = JSON.parse(msg);
// do some actions.
// .....
});
//don't forget to close the socket.
process.on('SIGINT', () => {
debug("... closing the socket ....");
socket.close();
process.exit();
});
//-----------------------------------------
import zmq from "zmq";
socket.bind('tcp://127.0.0.1:5545');
socket.send(['sendConfirmation', someData]);
process.on('SIGINT', function() {
socket.close();
});
This way you could have two different containers (docker) for your modules, just be sure to open the corresponding port.
What i don't understand, is why you inject wsSocket and also you create a new Socket. Probably what I would do is just to send the
socket id, and then just use it like:
const _socketId = "/#" + data.socketId;
io.sockets.connected[socketId].send("some message");
You could also use another solution like kafka instead of zmq, just consider that is slower but it will keep the logs.
Hope this can get you an idea of how to solve your problem.
You can use npm link feature.
The linking process consists of two steps:
Declaring a module as a global link by running npm link in the module’s root folder
Installing the linked modules in your target module(app) by running npm link in the target folder
This works pretty well unless one of your local modules depends on another local module. In this case, linking fails because it cannot find the dependent module. In order to solve this issue, one needs to link the dependent module to the parent module and then install the parent into the app.
https://docs.npmjs.com/cli/link
I had built interception calls in the socket.io file located under node_modules/socket.io/lib/client.js with version 1.3.7 (at least I think so, however I have to update to 1.4.5 because of other requirements). These changes allowed spoof information coming from the sender socket and they were done before continuing to send the data to the receiver socket.
Before (around 1.3.7), the method ran before sending a packet was the following:
Client.prototype.packet = function(packet, preEncoded, volatile){
var self = this;
var sockets = this.sockets[0]; //this helds the socket object
but now (1.4.5) socket.io changed its call to the following
Client.prototype.packet = function(packet, opts){
var sockets = this.sockets[0]; //gives undefined
I tried to look throughout the given objects but couldn't find the sockets of the receiver user.
Back in 1.3.7 I was able to effortlessly give properties to a socket object (e.g: socket.some-property = 1; in the .js file ran by nodejs in the root of the server) and later be able to get this some-property back in node_modules/client.js whenever the receiver got some packet so I could intercept the call but now it does not work and I would like to apply my old code to this new context in order for it all to function again.
var socketObject = {};
io.sockets.on('connection', function (client) {
socketObject[client.id] = {socket: client};
client.on('data', function (somedata) {
socketObject[client.id].data = someData;
});
client.on('disconnect', function() {
delete socketObject[client.id];
});
});
This is my server side websocket script:
var clients = [ ];
//sample request: ****:8080/?steamid=123456789
var connection;
var aqsteamid = getParameterByName("steamid",request.resource);
connection = request.accept(null, request.origin);
connection.ID = aqsteamid;
connection.balRefreshes = 0;
connection.clientIndex = clients.push(connection) - 1;
//check if this user is already connected. If yes, kicks the previous client ***====EDITED====***
for(var i = 0; i < clients.length; i++)
{
if(clients[i].ID === aqsteamid){
var indx = clients.indexOf(clients[i]);
clients[indx].close();
}
}
console.log('ID',connection.ID,' connected.');
socket.on('close', function(webSocketConnection, closeReason, description){
try{
console.log('ID',webSocketConnection.ID,'disconnected. ('+closeReason+';'+description+')');
webSocketConnection.balRefreshes = 0;
webSocketConnection.spamcheck = false;
clients.splice(webSocketConnection.clientIndex, 1);
}catch(e)
{
console.log(e);
}
});
Basically what I want is to kick all connections with same ID (for example, connecting with multiple browser tabs).
But, instead of kicking the old client, it kicks both clients or in some cases both clients remain connected with same ID.
Is there any other way or is there any mistakes in my script?
Thanks
using an object instad of Array to key the clients pool makes it faster and simpler:
var clients = {};
//sample request: ****:8080/?steamid=123456789
var connection;
var aqsteamid = getParameterByName("steamid",request.resource);
connection = request.accept(null, request.origin);
connection.ID = aqsteamid;
connection.balRefreshes = 0;
clients[aqsteamid]=connection;
socket.on('close', function(webSocketConnection, closeReason, description){
try{
console.log('ID',webSocketConnection.ID,'disconnected. ('+closeReason+';'+description+')');
webSocketConnection.balRefreshes = 0;
webSocketConnection.spamcheck = false;
delete clients[aqsteamid];
}catch(e)
{
console.log(e);
}
});
//check if this user is already connected. If yes, kicks the previous client
if(clients[aqsteamid]) clients[aqsteamid].close();
console.log('ID',connection.ID,' connected.');
With an object pool, we can remove all the array pool looping and comparing logic, and our index will never get out of sync.
It sounds like multiple connections with the same ID could be part of a genuine workflow with multiple tabs (unlike, say, malicious users that intentionally scrape data w/multiple threads...)
Rather than "kicking" the users from other tabs and then having to deal with them re-connecting, a more elegant solution would be to introduce an orchestration layer across multiple tabs.
You can rely on localstorage api to elect a master tab that will handle communications with the server (doesn't really matter if it's websocket or ajax) and share responses with other tabs - again, through localstorage. It doesn't really matter if you have 1 or 20 tabs open when you can share that data since you care about same message notifications, or stock ticker updates, or whatever.
From another stackoverflow answer:
The storage event lets you propagate data between tabs while keeping a
single SignalR connection open (thereby preventing connection
saturation). Calling localStorage.setItem('sharedKey', sharedData)
will raise the storage event in all other tabs (not the caller):
$(window).bind('storage', function (e) {
var sharedData = localStorage.getItem('sharedKey');
if (sharedData !== null)
console.log(
'A tab called localStorage.setItem("sharedData",'+sharedData+')'
);
});
Given the code above, if sharedKey value is already available when the page is loaded, assume a master tab is active and get shared values from localstorage. You can check if a master tab re-election is needed (i.e. that browser tab has been closed or navigated away) with an interval or relying on something more sophisticated like page visibility api.
Note you're not limited to sharing "same" data across multiple tabs but instead batch any requests over a shared channel.
I have made small reasearch about patterns supported by zeromq. I would like to describe problem with PUB/SUB pattern, but probably I discover this problem in my recent project also in PUSH/PULL pattern. I use NodeJS zeromq implementation.
I prepare two examples (server.js & client.js). I recognized that first message from server.js is lost every time I restart server (message is send every 1 second). client.js doesn't get first message. It is probably caused by to short time before sending messages. When I start sending messages after some time (e.g. 1 second) everything works fine. I thing that zmq needs some time for initialization connection between publisher and subscriber.
I would like to know when producer (server) is ready to sending messages for subscribed clients. How get this information?
I don't understand why client.js connected and subscribed for messages doesn't get it, because server is not ready for support subscriptions after restart.
Maybe it works like this by design.
server.js:
var zmq = require('zmq');
console.log('server zmq: ' + zmq.version);
var publisher = zmq.socket('pub');
publisher.bindSync("tcp://*:5555");
var i = 0;
var msg = "get_status OK ";
function sendMsg () {
console.log(msg + i);
publisher.send(msg + i);
i++;
setTimeout(sendMsg, 1000);
}
sendMsg();
process.on('SIGINT', function() {
publisher.close();
process.exit();
});
client.js:
var zmq = require('zmq');
console.log('client zmq: ' + zmq.version);
var subscriber = zmq.socket('sub');
subscriber.subscribe("get_status");
subscriber.on('message', function(data) {
console.log(data.toString());
});
subscriber.connect("tcp://127.0.0.1:5555");
process.on('SIGINT', function() {
subscriber.close();
process.exit();
});
In the node zmq lib repo you have stated the supported monitoring events. Subscribing to this will allow you to monitor your connection, in this case the accept event. However don't forget that you'll also have to call the monitor() function on the socket to activate monitoring.
You should end up with something like:
var publisher = zmq.socket('pub');
publisher.on('accept', function(fd, ep) {
sendMsg();
});
publisher.monitor(100, 0);
publisher.bindSync("tcp://*:5555");