Sample code for real-time comments using http://indiewebcamp.com/webmention, Redis and Websockets.

browser.js

var commentContainerSelector = '.references ul';

if($(commentContainerSelector).length > 0 && "WebSocket" in window) {
  var ws = new WebSocket(window.location.origin.replace("http","ws")+":8077");
  ws.onopen = function(event) {
    // Send the current window URL to the server to register to receive notifications about this URL
    ws.send(window.location);
  };
  ws.onmessage = function(event) {
    // Whatever comes back from the websockets connection is rendered in the list
    $(commentContainerSelector).append(event.data);
  };
}

server.js

var WebSocketServer = require('ws').Server;
var Redis = require('redis');

var port = 8077;

var wss = new WebSocketServer({port: port});

wss.on('connection', function(ws) {
  console.log("New websockets connection");
  ws.on('message', function(message) {
    var redis = Redis.createClient(6379, 'localhost');
    var channel = 'replies::' + message;
    redis.subscribe(channel);
    // console.log('Listening for comments on channel ' + channel);
    redis.on('message', function (channel, message) {
      ws.send(message);
    });
    ws.on('close', function(){
      // console.log('Killing listener for channel ' + channel);
      redis.unsubscribe();
      redis.end();
    });
    ws.on('error', function(){
      // console.log('Killing listener for channel ' + channel);
      redis.unsubscribe();
      redis.end();
    });
  });
});

console.log("WebSocket Server Listening on port "+port);

webmention.php

<?php
/*
 * When a new Webmention is received, broadcast the rendered HTML of the comment to any websocket listeners
 */

    // ... Normal webmention processing code above

    ob_start();
    Site::displayComment($this->sourceURL); // Renders the comment HTML
    $html = ob_get_clean();
    redis()->publish('replies::' . $this->targetURL, $html);
?>