Created question in FIWARE Q/A platform on 26-03-2023 at 17:03
Please, ANSWER this question AT https://stackoverflow.com/questions/75849244/fail-subscription-to-orion-change-contest-from-node-server

Question:
Fail subscription to Orion change contest from Node Server

Description:
I am developing a simple project in which I made a list of entities that I put on Orion-LD. Now I would like to make a server that allows to receive notifications whenever the state of an entity attribute changes. i chose to use Node.JS Express for ease but it is not mandatory.
I am leaving here the simple code used to implement my server.
const express = require('express');
const request = require('request');

const app = express();
const PORT = 3000;

//Subscription on batteryLevel changes of device 9845A
app.get('/subscribe', (req, res) => {
const data = {
"description": "Subscription",
"subject": {
"entities": [

],
"condition":

},
"notification": {
"http": {
"url": `http://localhost:$

`)
});

The problem is that if I subscribe to an existing entity properly, it reports a "status": "failed" in the subscription and therefore I cannot receive notifications about the status. Reading the Orion LD logs, it seems that it can't communicate with my server at port 3000, but I can't figure out why. Can anyone help me with this?