My overall goal is to generate a stream of random numbers in a JavaScript file (which is run using node) and send them to a python script in asynchronous time intervals. Once the numbers are in python, the script will determine if the numbers are even, or not. If they are, the numbers are sent back to the JavaScript file. My main focus is to get the communication between JavaScript and Python.
Once I begin the JavaScript file and python server, they will continue running until I stop them.
Currently, I have been working off the tutorial located here (https://tutorialedge.net/python/python-socket-io-tutorial/). The tutorial uses socket io for JS and aiohttp for python.
I manipulated the html code into a JS code (index.js), which is below:
// index.js
var socket = require('socket.io-client')('http://localhost:8080');
socket.on('connect', function(){});
function generateNumber() {
let n = Math.floor(Math.random() * 50);
let json = {
'number': n
}
console.log(json);
return json;
}
(function loop() {
var rand = Math.round(Math.random() * (3000 - 500)) + 500;
setTimeout(function() {
generateNumber();
loop();
}, rand);
}());
function sendMsg() {
socket.emit("message", generateNumber());
}
socket.on("message", function(data) {
console.log(data);
});
I created a function (generateNumber) to produce random numbers outputted in JSON format. I am using JSON because I believe it will allow for data to be easily converted into lists and integers when the numbers reach the python script. The loop function allows the numbers to be created at random intervals continuously and was taken from here: Randomize setInterval ( How to rewrite same random after random interval)
The python server (server.py) shown below, was taken from the tutorial (https://tutorialedge.net/python/python-socket-io-tutorial/):
# server.py
from aiohttp import web
import socketio
# creates a new Async Socket IO Server
sio = socketio.AsyncServer()
# Creates a new Aiohttp Web Application
app = web.Application()
# Binds our Socket.IO server to our Web App
# instance
sio.attach(app)
# we can define aiohttp endpoints just as we normally
# would with no change
async def index(request):
with open('index.html') as f:
return web.Response(text=f.read(), content_type='text/html')
# If we wanted to create a new websocket endpoint,
# use this decorator, passing in the name of the
# event we wish to listen out for
@sio.on('message')
async def print_message(sid, message):
# When we receive a new event of type
# 'message' through a socket.io connection
# we print the socket ID and the message
print("Socket ID: " , sid)
print(message)
# We bind our aiohttp endpoint to our app
# router
app.router.add_get('/', index)
# We kick off our server
if __name__ == '__main__':
web.run_app(app)
As of now, when I run node index.js, random numbers are continuously generated at random intervals and the output can be seen in the terminal. But I am not getting a response on the server side.
I believe the problem is related to the following 2 issues:
First, my current JS code (index.js) was originally a html script that sent a message with a button click hosted on “http://localhost:8080.” I adjusted the script to be a JS script, as well as adding additional functions. So there may be an issue in the following lines of index.js where I setup socket io:
var socket = require('socket.io-client')('http://localhost:8080');
socket.on('connect', function(){});
For clarity, here is the original html code (index.html) that index.js is based off:
<!-- index.html -->
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<meta http-equiv="X-UA-Compatible" content="ie=edge" />
<title>Document</title>
</head>
<body>
<button onClick="sendMsg()">Hit Me</button>
<script src="https://cdnjs.cloudflare.com/ajax/libs/socket.io/2.2.0/socket.io.js"></script>
<script>
const socket = io("http://localhost:8080");
function sendMsg() {
socket.emit("message", "HELLO WORLD");
}
</script>
</body>
</html>
I also asked a previous question related to the html to JS conversion (Syntax error when trying to convert HTML file to JavaScript containing socket io, SyntaxError: Unexpected token <)
Second, because the tutorial originally used a html file rather than JS, I believe the python script (server.py) is still waiting on output from a html script, so I think these lines in server.py need to be changed:
async def index(request):
with open('index.html') as f:
return web.Response(text=f.read(), content_type='text/html')
But I am unsure how to make the proper changes, I am having issues finding references to my question on the aiohttp site (https://aiohttp.readthedocs.io/en/stable/), or I may be unsure as to what I am looking for.
Both server.py and index.js currently run without errors, but they are not communicating.
Overall, the JS file (index.js) will be sending data to a python server (server.py) using socket io, and the python server, using aiohttp, will be sending back the analyzed data to the same JS script. This will happen continuously until one of the scripts is stopped manually.
If any clarification is needed on anything, please feel free to ask.
