I recently started to help out a startup which already had some software in place.<p>The front-end is written in Angular.<p>We wish to track activity of the users, especially how much people are currently active on a page(actually thats a route).<p>Currently we have a polling mechanism in place to update the data on the front-end. So I attached additional logic which creates a REDIS key with with the IP and a cookie, to track each client. Keys are structured in a similar manner:<p>viewing:resource:ip:cookie<p>And there is a TTL on each key. Consecutive call refresh that key. Now I only count the viewing:resource:* keys and I have a number of people on this resource.<p>But the solution is done in an urge of drunken 'brilliance'. How do the big players track concurrent online visitors on webaps?