Subscribe is not a Function Angular / Socket.IO - node.js

Question

I'm writing a chat app and I'm using a Node server and socket.io server side and Angular and socket.io-client client side. Unfortunately I get a "this.socketService.getMessage(...).subscribe is not a function" error when I run it. Everything else seems to work.
app.component.ts:
import { Component, OnInit, OnDestroy } from '#angular/core';
import { SocketService } from './socket.service';
import { Observable } from 'rxjs';
#Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css']
})
export class AppComponent implements OnInit {
title = 'chat';
registered = false;
username: string;
constructor(public socketService: SocketService) {
}
ngOnInit(): void {
this.socketService
.getMessage()
.subscribe(msg => {
if (msg === 'Registered') {
this.registered = true;
console.log(this.registered)
}
});
}
register(username: string): void {
console.log(username)
this.username = username;
this.socketService.sendMessage('register', username);
}
send(message: string): void {
this.socketService.sendMessage('message', message);
}
}
socket.service.ts:
import { Injectable } from '#angular/core';
import { io } from 'socket.io-client';
import { Observable } from 'rxjs';
#Injectable({
providedIn: 'root'
})
export class SocketService {
socket;
constructor() {
this.socket = io('http://localhost:3000/');
}
getMessage(): Observable<any> {
return this.socket.on('message', msg => {
console.log(msg);
});
}
sendMessage(type: string, words: any): void {
console.log(type, words);
this.socket.emit(type, words);
}
}

Answer 1

this.socket.on doesn't returns an Observable so you can't .subscribe() as you would do with an observable.
It returns a Socket as described into the docs : https://socket.io/docs/v3/client-api/#socket-on-eventName-callback