Call socket event from router page in Node

Question: How to send socket notification from Node API/Router?

1. In App file (like index.js OR app.js)

   //Express setup
   var express = require('express');
   var app = express();
   
   //socketsetup setup
   var io = require('socket.io')(https);    
   app.set('io', io); //IMP this will let available io in router file
   

2. In Router or Controller file

   exports.sendnotify = function(req, res) {
       var io = req.app.get('io');
       io.sockets["in"]('room_446').emit('session_end_notify', {vid:100,event_type:'live'});   //Send the Notification
       res.send('node is working fine');
   };
   
   

Question: How decrypt a text which is encoded with base64?

let buff = Buffer.from('ENCRYPTED_TXT', 'base64');
print buff.toString('ascii');