R – How Feedburner knows number of subscribers to a RSS Feed


Feedburner(http://feedburner.google.com) provides statistics about RSS feed of subscribers and reaches. This is interesting.

It is easy to understand that Feedburner can count visits (reaches) to a RSS feed. But, how does Feedburner get to know subscribers to a RSS feed.

In my understanding, each requests to RSS Feed URI is independent. There are no cookies or identity validation. So, how does feedburner know how many subscribers to a RSS feed?

Best Solution

The easy part is Google tell it the number of Google Readers, and so do the other Reader/Aggregators.

For individual users polling the RSS/Atom feed, there are http headers involved in the request, so users are tracked by IP address, and when behind proxies, a number of proxies include original IP in header, this helps sort between proxied sources.

Failing that you could read the FeedBurner help on that topic.

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