title: For a push notification, is a websocket mandatory?
body: <p>I have PHP on the server side, and HTML and javascript on the client side.</p>
  
  <p>I am making an app where a stakeholder types a message that is broadcasted to multiple recievers of a group in real time.</p>
  
  <p>I did some research on google and I understand I need to use WebSockets or Comet for real time push notifications.  Is WebSocket or Comet mandatory for sending mass notifications to users?</p>
  
  <p>Is my understanding correct? Any references to start with? </p>