Acknowledge RabbitMQ message after socket IO event received from React browser - node.js

Question

I have a Node server which consumes messages from a RabbitMQ queue and forwards them to a React frontend as a socket.io event. In the frontend, I have a button click which sends a socket.io event back to the Node server.
Currently, the Node server only logs the receipt of the socket.io event. In addition to logging, I would like to send a message ack to the RabbitMQ server upon receipt of the socket.io event.
The logging is working fine, but I've been struggling with the message acknowledgement part.
My node server looks like this:
server.js
const io = require('./socket');
const amqp = require('amqplib/callback_api');
const CONFIG = require('./config.json');
amqp.connect(`amqp://${CONFIG.host}`, (err, connection) => {
if (err) {
throw err;
}
connection.createChannel((err, channel) => {
if (err) {
throw err;
}
const queue = CONFIG.queueName;
channel.assertQueue(queue, {
durable: true
});
console.log(` [*] Waiting for messages in ${queue}.`);
channel.consume(queue, function(msg) {
console.log(' [x] Request received from RabbitMQ: %s', msg.content.toString());
io.client.emit('sendReview', msg.content.toString());
}, {
noAck: false
});
})
});
socket.js
const io = require('socket.io')();
const port = process.env.PORT || 8000;
module.exports = {
client : any = io.on('connection', (client) => {
console.log(' [*] New client connected with ID: ' + client.id);
client.on('reportReview', (msg) => {console.log(` [x] Response received from browser: ${msg}`)});
client.on('disconnect', () => console.log(` [*] User ${client.id} disconnected.`));
})
};
io.listen(port);
console.log(`Listening on port ${port}`);
My frontend looks like this:
App.js
import React, { Component } from "react";
import * as API from './api';
export default class App extends Component {
constructor(props, context) {
super(props, context);
this.state = {
data: ["Whoops - no reviews available"],
};
this.updateReview = this.updateReview.bind(this);
this.onMessageReceived = this.onMessageReceived.bind(this);
this.handleClick = this.handleClick.bind(this);
}
handleClick() {
API.reportClick(this.state.data[0]);
this.updateReview()
}
updateReview() {
const newArray = this.state.data.slice(1);
if (newArray.length === 0) {
this.setState({data: ["Whoops - no reviews available"]})
} else {
this.setState({data: newArray})
}
}
onMessageReceived(msg) {
console.log(`Request for review received: ${msg}`);
const updatedData = this.state.data.concat(msg);
this.setState({data: updatedData});
if (this.state.data[0] === "Whoops - no reviews available") {
this.updateReview()
}
}
componentDidMount() {
API.subscribe(this.onMessageReceived)
}
render() {
return (
<div className="App">
<p className="App-intro">
Click to confirm review #: {this.state.data[0]}
</p>
<button onClick={this.handleClick}>Click</button>
</div>
);
}
}
Api.js
import clientSocket from 'socket.io-client';
const socket = clientSocket('http://localhost:8000');
function subscribe(onMessageReceived) {
socket.on('sendReview', onMessageReceived);
}
function reportClick(msg) {
socket.emit('reportReview', msg);
}
export { reportClick, subscribe };
As far as I understand, in order to send a message ack I would have to call channel.ack(msg); somewhere on the Node server. However, I am not sure how to pass the channel object to the io module? I have also tried having the socket.io code in server.js so I would have access to the channel object but have not been able to get this to work, either - I have not been able to get the amqp connection and socket.io connection to work together other than using my current approach of having an io module.
Any help would be very much appreciated.

Answer 1

I ended up getting it to work by having the socket code in server.js like this:
const io = require('socket.io')();
function socketIOHandler(callback) {
io.on('connection', (socket) => {
socket.on('error', function(err) {
console.log(err.stack);
});
callback(socket);
});
}
var amqpConn = null;
// start amqp connection to rabbit mq
function start() {
amqp.connect(`amqp://${CONFIG.host}`, (err, connection) => {
if (err) {
throw err;
}
amqpConn = connection;
// start consume worker when connected
startWorker();
});
}
function startWorker() {
socketIOHandler((socket) => {
amqpConn.createChannel((error, channel) => {
... <---- all the bits as before
socket.on('msgSent', (msg) => {
channel.ack(msg);
});
})
});
io.listen(port);
}
start();