Using the Channel API on App Engine for instant traffic analysis

In last week's post, we introduced Clio, a system for getting live insight into your site's traffic patterns, and we described how the Prospective Search API lets us filter the site's traffic to get just the records we care about.

This week, we'll cover the other part of the system: delivering results in real-time. For this, we'll be using the Channel API to stream new log entries to admin users in real-time. As with last week's post, where there's differences between our demo implementation and what you'd use in a real-world system, I'll point those out.

The admin interface

First up, we need to provide a simple admin interface to which we'll stream results. Here's the handler for that:

class IndexHandler(webapp.RequestHandler):
  """Serve up the Clio admin interface."""

  def get(self):
    client_id = os.urandom(16).encode('hex')
    channel_key = channel.create_channel(client_id)
    template_path = os.path.join(os.path.dirname(__file__),
                                 'templates', 'index.html')
    self.response.out.write(template.render(template_path, {
        'config': config,
        'client_id': client_id,
        'channel_key': channel_key,

The only thing of significance we do here relates to the Channel API. First, we generate a random client ID by getting some ...