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Why my socketio is not connecting with my socketio-client?

i am working on a chatapp project that needs a real time chatting so i have used socketio in my server side which is written in nodejs and than used socketio-client in my main chatapp react-native project.
But now a problem is coming my socket is not initializing. I'm not able to connect my server with my main app. I am using socketio and socketio client my both the socket version are same 4.5.1 but it's not even connecting. I have tried to use old version of socket but its also not working and I have also tried to change my localhost port to 4000 but it's also not working.
My server code:
const express = require('express');
var bodyParser = require('body-parser');
const app = express();
const http = require('http');
const server = http.createServer(app);
const { Server } = require("socket.io");
const io = new Server(server);
const port = process.env.PORT || 3000;
require('./src/config/database')
const user_routes = require('./src/user/users.routes');
app.use(bodyParser.urlencoded({extended: true}))
app.use(express.json())
app.get('/', (req, res) => {
res.sendFile(__dirname + '/index.html');
});
app.use('/User', user_routes)
io.on('connection', (socket) => {
console.log('a user connected');
socket.on('send_message',(data)=>{
console.log("received message in server side",data)
io.emit('received_message',data)
})
socket.on('disconnect', () => {
console.log('user disconnected');
});
});
server.listen(port, () => {
console.log( `Server running at http://localhost:${port}/`);
});
My app socketservice file code:
import io from 'socket.io-client';
const SOCKET_URL = 'http://localhost:3000'
class WSService {
initializeSocket = async () => {
try {
this.socket = io(SOCKET_URL, {
transports: ['websocket']
})
console.log("initializing socket", this.socket)
this.socket.on('connect', (data) => {
console.log("=== socket connected ====")
})
this.socket.on('disconnect', (data) => {
console.log("=== socket disconnected ====")
})
this.socket.on('error', (data) => {
console.log("socekt error", data)
})
} catch (error) {
console.log("scoket is not inialized", error)
}
}
emit(event, data = {}) {
this.socket.emit(event, data)
}
on(event, cb) {
this.socket.on(event, cb)
}
removeListener(listenerName) {
this.socket.removeListener(listenerName)
}
}
const socketServcies = new WSService()
export default socketServcies
Where I have marked it should be connected = true but it's false in the dev console I have done console log so check that it's connecting or not and I can see that it's not connecting. How to make it connect?
There is no error in my app or server I have checked many times and my server is also running when I am running my app.

Answering my own question
The problem was i was using android emulator and android in an emulator can't connect to localhost you need to use the proxy ip so when i add http://10.0.2.2:3000 in const SOCKET_URL = 'http://10.0.2.2:3000' than its working fine
credit goes to gorbypark who told me this in discord

I'm assuming that your front and back runs in localhost. The documentation says that if the front-end is in the same domain as the back-end, you don't need to use the URL. Since you have the options parameter declared, you can use the default argument window.location in first place:
class WSService {
initializeSocket = async () => {
try {
this.socket = io(window.location, {
transports: ['websocket']
})
console.log("initializing socket", this.socket)
this.socket.on('connect', (data) => {
console.log("=== socket connected ====")
})
this.socket.on('disconnect', (data) => {
console.log("=== socket disconnected ====")
})
this.socket.on('error', (data) => {
console.log("socekt error", data)
})
} catch (error) {
console.log("scoket is not inialized", error)
}
}
emit(event, data = {}) {
this.socket.emit(event, data)
}
on(event, cb) {
this.socket.on(event, cb)
}
removeListener(listenerName) {
this.socket.removeListener(listenerName)
}
}

Don't specify the host/port for socket-io to connect to. It can figure it out on its own.
Per documentation, it tries to connect to window.location if no URL is specified as an argument.
So instead of
this.socket = io(SOCKET_URL, {
transports: ['websocket']
})
Just do
this.socket = io()
I am not sure it works with other arguments. You could try like this
this.socket = io(undefined, {
transports: ['websocket']
})

How do I use express.js with truffle contracts?

I was following a tutorial on Youtube on making a decentralized voting app on truffle: https://youtu.be/3681ZYbDSSk.
The source code is as follows: https://github.com/dappuniversity/election/tree/2019_update
The system has a backend with lite-server, the same as the official pet-shop tutorial and a simple frontend where users vote for their candidates.
This is fine until I wanted to add a login and sign up feature into the system. After some research, I found out that lite-server is not able to send Mysql queries like express.js or php, so I tried to implement this feature in express.js.
I created a new dir, init truffle, npm install express, then put everything from the original project to the new one. I created index.js, which I run as the server
var express = require("express");
var app = express();
const path = require("path");
app.use(express.json());
app.use(express.urlencoded({ extended: true }));
app.use(express.static(path.join(__dirname, "public")));
app.use(express.static(path.join(__dirname, "build")));
// http://localhost:3000/
app.get("/", function (request, response) {
// Render login template
response.sendFile(path.join(__dirname + "/index.html"));
});
app.listen(3000);
I hope to include the compiled contracts using app.use(express.static(path.join(__dirname, "build")));, however somehow it can't recognize it, so I was forced to move the compiled contract into the public dir. Then I nodemon index.js again.
The system failed to render the candidates detail, so it's blank. This is how it should have look like.
In the app, the client-side app.js makes call to the web3.js api to get the details of candidates deployed on the blockchain. In my express app, it can only get the blockchain address but not the details. Here is the app.js (which can also be found on the github link above).
App = {
web3Provider: null,
contracts: {},
account: "0x0",
hasVoted: false,
init: function () {
return App.initWeb3();
},
initWeb3: function () {
// TODO: refactor conditional
if (typeof web3 !== "undefined") {
// If a web3 instance is already provided by Meta Mask.
App.web3Provider = web3.currentProvider;
web3 = new Web3(web3.currentProvider);
} else {
// Specify default instance if no web3 instance provided
App.web3Provider = new Web3.providers.HttpProvider(
"http://localhost:7545"
);
web3 = new Web3(App.web3Provider);
}
console.log("We are in initWeb3");
return App.initContract();
},
initContract: function () {
$.getJSON("Election.json", function (election) {
// Instantiate a new truffle contract from the artifact
App.contracts.Election = TruffleContract(election);
// Connect provider to interact with contract
App.contracts.Election.setProvider(App.web3Provider);
App.listenForEvents();
return App.render();
});
},
// Listen for events emitted from the contract
listenForEvents: function () {
App.contracts.Election.deployed().then(function (instance) {
// Restart Chrome if you are unable to receive this event
// This is a known issue with Metamask
// https://github.com/MetaMask/metamask-extension/issues/2393
instance
.votedEvent(
{},
{
fromBlock: 0,
toBlock: "latest",
}
)
.watch(function (error, event) {
console.log("event triggered", event);
// Reload when a new vote is recorded
App.updateCounts();
});
});
},
render: function () {
var electionInstance;
var loader = $("#loader");
var content = $("#content");
console.log("In render");
loader.show();
content.hide();
// Load account data
web3.eth.getCoinbase(function (err, account) {
if (err === null) {
App.account = account;
$("#accountAddress").html("Your Account: " + account);
}
});
// Load contract data
App.contracts.Election.deployed()
.then(function (instance) {
electionInstance = instance;
console.log(electionInstance.candidatesCount());
return electionInstance.candidatesCount();
})
.then(function (candidatesCount) {
var candidatesResults = $("#candidatesResults");
candidatesResults.empty();
var candidatesSelect = $("#candidatesSelect");
candidatesSelect.empty();
for (var i = 1; i <= candidatesCount; i++) {
electionInstance.candidates(i).then(function (candidate) {
var id = candidate[0];
var name = candidate[1];
var voteCount = candidate[2];
// Render candidate Result
var candidateTemplate =
"<tr><th>" +
id +
"</th><td>" +
name +
"</td><td id='vc_" +
id +
"'>" +
voteCount +
"</td></tr>";
candidatesResults.append(candidateTemplate);
// Render candidate ballot option
var candidateOption =
"<option value='" + id + "' >" + name + "</ option>";
candidatesSelect.append(candidateOption);
});
}
return electionInstance.voters(App.account);
})
.then(function (hasVoted) {
// Do not allow a user to vote
if (hasVoted) {
$("form").hide();
}
loader.hide();
content.show();
})
.catch(function (error) {
console.warn(error);
});
},
updateCounts: function () {
$("#content").hide();
$("#loader").show();
App.contracts.Election.deployed()
.then(function (instance) {
electionInstance = instance;
return electionInstance.candidatesCount();
})
.then(function (candidatesCount) {
for (var i = 1; i <= candidatesCount; i++) {
electionInstance.candidates(i).then(function (candidate) {
var id = candidate[0];
var voteCount = candidate[2];
var cell = document.getElementById("vc_" + id);
if (cell != null) {
cell.innerHTML = voteCount;
}
});
}
return electionInstance.voters(App.account);
})
.then(function (hasVoted) {
// Do not allow a user to vote
if (hasVoted) {
$("form").hide();
}
});
$("#content").show();
$("#loader").hide();
},
castVote: function () {
var candidateId = $("#candidatesSelect").val();
App.contracts.Election.deployed()
.then(function (instance) {
return instance.vote(candidateId, { from: App.account });
})
.then(function (result) {
// Wait for votes to update
$("#content").hide();
$("#loader").show();
})
.catch(function (err) {
console.error(err);
});
},
};
$(function () {
$(window).load(function () {
App.init();
console.log("Init success");
});
});
I noticed that web3.eth.getCoinbase works perfectly because the address is correctly shown, but somehow at the line App.contracts.Election.deployed(), it cannot get the details from the contract.
My question is, how do I fix my code so it can correctly show the details of the candidates? Because the sign up and login system can only work if the basic voting component is in place. Plus, how do I put it correctly so express.js can recognize my contracts in build/contracts?
Or are there other ways to make it work such as configuring lite-server to send mysql queries, or implementing this on xampp then use php to connect to mysql? Thank you very much.
P.S. I've tried to use express-box for this project. For whatever reasons, it cannot work. Whenever I tried to truffle compile, the vs code pops up and truffle did nothing, so I turned to creating a new express project instead.

After a series of painstaking trial-and-error experiments. I've finally found the solution. On the line " $.getJSON("Election.json", function (election)", it sends out a http get request to the server asking for "Election.json". This compiled contract resides in build/contracts, so the server has to serve this json if the voting system has to work, otherwise, it would turn up a blank section for candidates.
The solution is simply add one more line in index.js that imports the json. Then, add one more endpoint that just serves that json when requested. The final code would look like this
var express = require("express");
var app = express();
const path = require("path");
var json = require("./build/contracts/Election.json");
app.use(express.json());
app.use(express.urlencoded({ extended: true }));
app.use(express.static(path.join(__dirname, "public")));
// http://localhost:3000/
app.get("/", function (request, response) {
// Render login template
response.sendFile(path.join(__dirname + "/index.html"));
});
app.get("/Election.json", function (request, response) {
response.send(json);
});
app.listen(3000);
Now the system can find the json it needs to let user see the votes and vote as well.
If you have a better solution, please let me know!

SO_REUSEADDR in NodeJs using net package

I have two backends. Backend A and Backend B.
Backend B sends and receives info using a socket server running at port 4243.
Then, with Backend A, I need to catch that info and save it. But I have to also have a socket server on Backend A running at port 4243.
The problem is that, when I run Backend A after running Backend B I receive the error "EADDRINUSE", because I'm using the same host:port on both apps.
If, for Backend A I use Python, the problem dissapear because I have a configuration for sockets that's called SO_REUSEADDR.
Here we have some examples:
https://www.programcreek.com/python/example/410/socket.SO_REUSEADDR
https://subscription.packtpub.com/book/networking-and-servers/9781849513463/1/ch01lvl1sec18/reusing-socket-addresses
But, I want to use JavaScript for coding my Backend A, so I was using the net package for coding the sockets, and I can't get it to work, because of the "EADDRINUSE" error.
The NodeJS documentation says that "All sockets in Node set SO_REUSEADDR already", but it doesn't seem to work for me...
This is my code so far:
// Step 0: Create the netServer and the netClient
console.log(`[DEBUG] Server will listen to: ${HOST}:${PORT}`);
console.log(`[DEBUG] Server will register with: ${AGENT_ID}`);
const netServer = net.createServer((c) => {
console.log('[netServer] Client connected');
c.on('message', (msg) => {
console.log('[netServer] Received `message`, MSG:', msg.toString());
});
c.on('*', (event, msg) => {
console.log('[netServer] Received `*`, EVENT:', event);
console.log('[netServer] Received `*`, MSG:', msg);
});
}).listen({
host: HOST, // 'localhost',
port: PORT, // 4243,
family: 4, // ipv4, same as socket.AF_INET for python
});
// Code copied from nodejs documentation page (doesn't make any difference)
netServer.on('error', function (e) {
if (e.code == 'EADDRINUSE') {
console.log('Address in use, retrying...');
setTimeout(function () {
netServer.close();
netServer.listen(PORT, HOST);
}, 1000);
}
});
const netClient = net.createConnection(PORT, HOST, () => {
console.log('[netClient] Connected');
});
// Step 1: Register to instance B of DTN with agent ID 'bundlesink'
netClient.write(serializeMessage({
messageType: AAPMessageTypes.REGISTER,
eid: AGENT_ID,
}));
With this code, I get the following output in the terminal:
But, with the Python code, the socket connects successfully:
I don't know what to do :(
I hope I get some help here.
Edit 1
By the way, the lsof command, throws me this output for the JavaScript backend:
And this other output for the Python backend:
Edit 2
It really seems to be a problem with JavaScript. I also found this snippet:
var net = require('net');
function startServer(port, host, callback) {
var server = net.createServer();
server.listen(port, host, function() {
callback(undefined, server);
});
server.on('error', function(error) {
console.error('Ah damn!', error);
callback(error);
});
}
startServer(4000, '0.0.0.0', function(error, wildcardServer) {
if (error) return;
startServer(4000, '127.0.0.1', function(error, localhostServer) {
if (error) return;
console.log('Started both servers!');
});
});
From this post:
https://medium.com/#eplawless/node-js-is-a-liar-sometimes-8a28196d56b6
As the author says:
Well, that prints “Started both servers!” which is exactly what we don’t want.
But for me, instead of printing that, I get an error:
Ah damn! Error: listen EADDRINUSE: address already in use 127.0.0.1:4000
at Server.setupListenHandle [as _listen2] (node:net:1319:16)
at listenInCluster (node:net:1367:12)
at doListen (node:net:1505:7)
at processTicksAndRejections (node:internal/process/task_queues:84:21) {
code: 'EADDRINUSE',
errno: -98,
syscall: 'listen',
address: '127.0.0.1',
port: 4000
}
I really cannot make it to run and print "Started both servers!".
Because that's what I want my code to do.
Edit 3
This is the Python server socket: https://gitlab.com/d3tn/ud3tn/-/blob/master/tools/aap/aap_receive.py
This is the important part:
addr = (args.tcp[0], int(args.tcp[1])) # args.tcp[0] = "localhost", args.tcp[1] = "4243"
with AAPTCPClient(address=addr) as aap_client:
aap_client.register(args.agentid) # args.agentid = "bundlesink"
run_aap_recv(aap_client, args.count, args.verify_pl)
It creates an AAPTCPClient, and the only thing that AAPTCPClient does, is the following:
def __init__(self, socket, address):
self.socket = socket
self.address = address
self.node_eid = None
self.agent_id = None
def register(self, agent_id=None):
"""Attempt to register the specified agent identifier.
Args:
agent_id: The agent identifier to be registered. If None,
uuid.uuid4() is called to generate one.
"""
self.agent_id = agent_id or str(uuid.uuid4())
logger.info(f"Sending REGISTER message for '{agent_id}'...")
msg_ack = self.send(
AAPMessage(AAPMessageType.REGISTER, self.agent_id)
)
assert msg_ack.msg_type == AAPMessageType.ACK
logger.info("ACK message received!")
def send(self, aap_msg):
"""Serialize and send the provided `AAPMessage` to the AAP endpoint.
Args:
aap_msg: The `AAPMessage` to be sent.
"""
self.socket.send(aap_msg.serialize())
return self.receive()
def receive(self):
"""Receive and return the next `AAPMessage`."""
buf = bytearray()
msg = None
while msg is None:
data = self.socket.recv(1)
if not data:
logger.info("Disconnected")
return None
buf += data
try:
msg = AAPMessage.parse(buf)
except InsufficientAAPDataError:
continue
return msg
I don't see any bind, and I don't understand why the python code can call "socket.recv", but in my JavaScript code I can't do "netServer.listen". I think it should be the same.

There are things to clarify.
1.) The client uses the bind syscall where the kernel selects the source port automatically.
It does so by checking sys local_portrange sysctl settings.
1.) If you want to bind the client to a static source port, be sure to select a TCP port outside the local_portrange range !
2.) You cannot subscribe to event "*", instead you've to subscribe to the event "data" to receive messages.
For best practice you should also subscribe to the "error" event in case of errors !
These links will get you started right away:
How do SO_REUSEADDR and SO_REUSEPORT differ?
https://idea.popcount.org/2014-04-03-bind-before-connect/
So, for all beginners, who want to dig deeper into networking using node.js…
A working server example:
// Step 0: Create the netServer and the netClient
//
var HOST = 'localhost';
var PORT = 4243;
var AGENT_ID = 'SO_REUSEADDR DEMO';
var net = require('net');
console.log(`[DEBUG] Server will listen to: ${HOST}:${PORT}`);
console.log(`[DEBUG] Server will register with: ${AGENT_ID}`);
const netServer = net.createServer((c) => {
console.log('[netServer] Client connected');
c.on('data', (msg) => {
console.log('[netServer] Received `message`, MSG:', msg.toString());
});
c.on('end', () => {
console.log('client disconnected');
});
c.on('error', function (e) {
console.log('Error: ' + e.code);
});
c.write('hello\r\n');
c.pipe(c);
}).listen({
host: HOST,
port: PORT,
family: 4, // ipv4, same as socket.AF_INET for python
});
// Code copied from nodejs documentation page (doesn't make any difference)
netServer.on('error', function (e) {
console.log('Error: ' + e.code);
if (e.code == 'EADDRINUSE') {
console.log('Address in use, retrying...');
setTimeout(function () {
netServer.close();
netServer.listen(HOST, PORT);
}, 1000);
}
if ( e.code = 'ECONNRESET' ){
console.log('Connection reset by peer...');
setTimeout(function () {
netServer.close();
netServer.listen(HOST, PORT);
}, 1000);
}
});
The Client:
/* Or use this example tcp client written in node.js. (Originated with
example code from
http://www.hacksparrow.com/tcp-socket-programming-in-node-js.html.) */
var net = require('net');
var HOST = 'localhost';
var PORT = 4243;
var client = new net.Socket();
client.setTimeout(3000);
client.connect(PORT, HOST, function() {
console.log("Connected to " + client.address().address + " Source Port: " + client.address().port + " Family: " + client.address().family);
client.write('Hello, server! Love, Client.');
});
client.on('data', function(data) {
console.log('Received: ' + data);
client.end();
});
client.on('error', function(e) {
console.log('Error: ' + e.code);
});
client.on('timeout', () => {
console.log('socket timeout');
client.end();
});
client.on('close', function() {
console.log('Connection closed');
});
Best Hannes

Steffen Ullrich was completely right.
In my JavaScript code, I was trying to create a server to listen to the port 4243.
But you don't need to have a server in order to listen to some port, you can listen with a client too! (At least that's what I understood)
You can create a client connection as following:
const netClient = net.createConnection(PORT, HOST, () => {
console.log('[netClient] Connected');
});
netClient.on('data', (data) => {
console.log('[netClient] Received data:', data.toString('utf8'));
});
And with "client.on", then you can receive messages as well, as if it were a server.
I hope this is useful to someone else.

SSH into remote machine and execute commands in Node.js

I'm looking for a way to SSH into a virtual machine and then execute certain scripts inside the virtual machine using Node.js
So far I've created the shell script that automate the login to the virtual machine but i'm unable to figure out how to move forward.
My shell script for login to remote server
spawn ssh root#localhost
expect "password"
send "123456"
send "\r"
interact
This is my server.js
var http = require('http');
var execProcess = require("./exec_process.js");
http.createServer(function (req, res) {
res.writeHead(200, {'Content-Type': 'text/plain'});
execProcess.result("sh sshpass.sh", function(err, response){
if(!err){
res.end(response);
}else {
res.end("Error: ", err);
}
});
}).listen(3000);
console.log('Server listening on port 3000');
exec_process.js
var exec = require('child_process').exec;
var result = function(command, cb){
var child = exec(command, function(err, stdout, stderr){
if(err != null){
return cb(new Error(err), null);
}else if(typeof(stderr) != "string"){
return cb(new Error(stderr), null);
}else{
return cb(null, stdout);
}
});
}
exports.result = result;
Any help is appreciated thanks

Why dont you use simple-ssh ?
I made a simple example of how to load a file with a list of commands and execute them in chain.
exampleList : (commands must be separated in new lines)
echo "Testing the first command"
ls
sshtool.js : (it can be buggy, example: if any command contains \n)
const _ = require("underscore");
//:SSH:
const SSH = require('simple-ssh');
const ssh = new SSH({
host: 'localhost',
user: 'username',
pass: 'sshpassword'
});
//example usage : sshtool.js /path/to/command.list
function InitTool(){
console.log("[i] SSH Command Tool");
if(process.argv[2]){AutomaticMode();}
else{console.log("[missing argument : path to file containing the list of commands]");}
}
//:MODE:Auto
function AutomaticMode(){
const CMDFileName = process.argv[2];
console.log(" ~ Automatic Command Input Mode");
//Load the list of commands to be executed in order
const fs = require('fs');
fs.readFile(process.argv[2], "utf8", (err, data) => {
if(err){console.log("[!] Error Loading Command List File :\n",err);}else{
var CMDList = data.split("\n"); // split the document into lines
CMDList.length = CMDList.length - 1; //fix the last empty line
_.each(CMDList, function(this_command, i){
ssh.exec(this_command, {
out: function(stdout) {
console.log("[+] executing command",i,"/",CMDList.length,"\n $["+this_command+"]","\n"+stdout);
}
});
});
console.log("[i]",CMDList.length,"commands will be performed.\n");
ssh.start();
}
});
}
//:Error Handling:
ssh.on('error', function(err) {
console.log('[!] Error :',err);
ssh.end();
});
InitTool();
It uses underscore for looping through the command list.

How to stop webdriver without crashing node js

is it possible to stop the selenium webdriver without stopping node?
I have following issue:
I try to create a API tool that does some web automation when getting a get request. So I am basically running selenium webdriver on a get request to /start via Express. I want the tool to check for different elements and when it somehow fails I want it to stop selenium but NOT the node instance (since a new get request could be send).
This is my code so far:
"use strict";
const webdriver = require('selenium-webdriver'),
Express = require('express'),
By = webdriver.By,
until = webdriver.until,
Keys = webdriver.Key,
app = new Express();
app.get("/automate", (req, res) => {
start(res);
});
function start(res) {
const driver = new webdriver.Builder().forBrowser('chrome').build();
driver.get('https://www.google.com/');
// # --- foo --- #
let errMessage = {pos: "FOO", message: "Ooops friendly robot has some troubles!"}
checkStep("#foo", errMessage);
driver.findElement(By.id("foo"))
.sendKeys("fooz");
// # --- bar --- #
errMessage = {pos: "BAR", message: "Ooops friendly robot has some troubles!"}
checkStep("#bar", errMessage);
driver.findElement(By.id("bar"))
.sendKeys("baz");
// etc…
function checkStep(selector, errMessage) {
driver.findElement(By.css(selector))
.then(() => {
console.log(`${selector} => found`);
})
.catch(err => {
console.log(`Error: ${err}`);
res.send(errMessage);
driver.quit();
});
}
}
app.get("*", (req, res) => {
res.send("Hello World");
});
// start the server
const port = process.env.PORT || 3000;
const env = process.env.NODE_ENV || 'production';
app.listen(port, err => {
if (err) { return console.error(err); }
console.info(`Server running on http://localhost:${port} [${env}]`);
});
it is actually working so far that when selenium do not find the element the response from the API is correct. In Selenium I get back:
{
"pos": "FOO",
"message": "Ooops friendly robot has some troubles!"
}
So far all good.
BUT unfortunately stopping selenium is also stopping Node from running.
The error I get is following:
throw error;
^
WebDriverError: no such session
(Driver info: chromedriver=2.30.477690 (c53f4ad87510ee97b5c3425a14c0e79780cdf262),platform=Ma
c OS X 10.12.5 x86_64)
at WebDriverError
Please help, thank you!
ps: I am not using webdriverio as you can see I use this package: https://www.npmjs.com/package/selenium-webdriver

Ok, I got this working. It’s a bit difficult solution but it works:
Using Child Processes
Basically, every time the app gets a get request to /automate it will now create a child process in node which runs the selenium scripts (a child process is kind of like using another thread. Here is a very good tutorial on child processes):
index.js
"use strict";
const Express = require('express');
const { spawn } = require('child_process');
const data = require('./data.json');
const app = new Express();
app.get("/automate", (req, res) => {
const child = spawn(
process.execPath,
[`${__dirname}/test.js`, JSON.stringify(data)],
{ stdio: ['inherit', 'inherit', 'inherit', 'pipe'] }
);
child.stdio[3].on('data', data => {
const response = JSON.parse(data.toString());
res.send(response);
console.log(response);
child.kill();
});
});
app.get("*", (req, res) => {
res.send("Hello World");
});
const port = process.env.PORT || 3000;
const env = process.env.NODE_ENV || 'production';
app.listen(port, err => {
if (err) { return console.error(err); }
console.info(`Server running on http://localhost:${port} [${env}]`);
});
test.js
"use strict";
// hook with argument 3, that is "pipe" from parent
const Net = require('net'),
pipe = new Net.Socket({ fd: 3 });
const data = JSON.parse(process.argv[2]);
const webdriver = require('selenium-webdriver'),
By = webdriver.By,
until = webdriver.until,
Keys = webdriver.Key;
function start() {
const driver = new webdriver.Builder().forBrowser('chrome').build();
driver.get('https://www.google.com/');
// # --- foo --- #
let errMessage = {pos: "lst-ib", message: "Ooops friendly robot has some troubles!"}
checkStep("#lst-ib")
.sendKeys("fooz");
driver.get('https://www.facebook.com/');
driver.get('https://www.google.com/');
driver.get('https://www.facebook.com/');
// # --- bar --- #
errMessage = {pos: "BAR", message: "Ooops friendly robot has some troubles!"}
checkStep("#bar")
.sendKeys("baz");
function checkStep(selector) {
driver.findElement(By.css(selector))
.then(() => {
console.log(`${selector} => found`);
})
.catch(err => {
console.log(`${selector} => not found`);
publish(errMessage);
driver.quit();
});
}
}
function publish(message) {
pipe.write(JSON.stringify(message));
}
start();
It is working like a charm: on each request opening a new child process and killing that child process if it sends some message while also responding with the message to the client. Like this you can easily have several selenium instances simultaneously.
You’re welcome.
ps: If you hate all this asyncron stuff from Selenium webdriver-sync seems like a good choice. It basically wraps the selenium code to be syncon instead of asyncron. Like that I am able to use try {} catch {} and to driver.quit(); without any errors for code that comes later. (But this comes with a disadvantage: it is actually blocking your other nodejs code.)