title: Are XMPP PubSub notifications broadcasted simultaneously or queue like?
body: <p>I want to know whether xmpp publish-subscribe functionality send notifications to all subscribers simultaneously(broadcasts) or sends notifications in a queue i.e. one by one.</p>
  
  <p>I want to know the difference between pub-sub and jaxl class which i am using because the jaxl sends push messages in queue that is one user at a time.</p>