The last stage in our code is to start publishing our real-time stock updates. We're going to implement the letsGetRealtime() function. All this function really needs to do is send a presence stanza to the pubsub server to say that we're online. We'll also need to register a listener for pubsub push events and then add them to the charts.

Let's first write the code that sends the presence stanza:

  var letsGetRealtime = function() { 
    socket.send('xmpp.presence', { to: 'pubsub.localhost' }) 
  } 

That's it! Since presence isn't an IQ type stanza, we don't need to wait for a response, and we can now get on with handling our pushed data:

  socket.on('xmpp.pubsub.push.item', function(item) { 
    stockChart.append( 
      new Date(item.entry.json.timestamp).getTime(), 
      item.entry.json.value 
    ) 
  }) 

In the payload, we are also given details about where (that is, which domain) the payload came from and from, which node...