RSS, OPML and the XML platform.
Copyright 2012 World Readable
I'll reproduce the Q&A between Blake and myself here.
Is it possible for online content producers to charge a nominal fee for RSS? Yes! In fact, this can be done today, by simply authenticating the RSS URL. Unfortunately, the implementation is extremely problematic.
First, many, possibly most RSS clients cannot handle authenticated RSS. My Reblinks surely doesn't, mainly because it's a security nightmare. Accidentally pulishing credentials could create an undesirable liability.
Second, nothing would stop these credentials from being used by multiple users. This would prove impossible to control for the both the publisher and aggregator. If two users subscribed via Reblinks to the same feed using the same credentials, the publisher would have little clue to this violations, since the aggregator need not present a different behavior than if only one user was subscribedd. Further, what happens when two users susbscribe to an aggregator with different credentials? Do you poll once or twice?
Although feasible, the implementation is uncontrollable. Is there another possible implementation? Certainly! And it's already in wide use.
The solution is to provide a public unauthenticated feed with summary content. This is actively being done by hundreds, if not thousands of existing pulishers. The user is presented with a brief summary and link that entices them to click thru. When the user clicks thru the link, he is requested to authenticate. Without existing credentials, he pays a subscription fee to view the full content. Of course, the content has to be very compelling if the user is gonna give you his PayPal or Visa numbers.
Unfortunately, it won't always be two people sharing one subscription. It'll quite often be dozens, possibly hundreds. Paid RSS subscriptions doesn't seem feasible. But as I mentioned, partial feeds that entice clicks and subscriptions are likely the desired solution.