How do push notifications work?

Question

I\'m trying to implement push notifications on my PHP-based website. The goal is to make something similiar to what Stackoverflow and other sites have which notify a user in

Answer 1

I just wanted to share the actual implementation I went with. I decided to go with a great SAAS, Pusher, since there are many challenging issues in implementing Push notifications, as I realized in reading the links in @Virendra's excellent answer, that Pusher solves for you.

What I was most impressed with is how little code you have to write to make this work. See below. My server-side is in PHP (Pusher has libraries in many languages).

require('/application/thirdParty/pusher-html5-realtime-push-notifications/lib/squeeks-Pusher-PHP/lib/Pusher.php');
require('/application/thirdParty/pusher-html5-realtime-push-notifications/config.php');
$pusher = new Pusher(APP_KEY, APP_SECRET, APP_ID);

foreach($recipients as $row){                   
  $channel='my-channel'.$row->recipient_id;
  $pusher->trigger($channel, 'notifications', 
    array('message' => $row->message,
          'notification_id' => $row->notification_id) 
  );
}

Here's the HTML/JS (don't be overwhelmed, most of this code is just to populate the little circle and the list with the incoming notification as Stackoverflow and others do it):