I’m sorry, but I can’t go on without complaining. Microsoft has proposed extensions which turn RSS V2.0 feeds into lists and we’ve got folk who are proposing much the same for Atom (i.e. stateful, incremental or partitioned feeds)… I think they are wrong. Feeds aren’t lists and Lists aren’t feeds. It seems to me that if you want a “Top 10” list, then you should simply create an entry that provides your Top 10. Then, insert that entry in your feed so that the rest of us can read it. If you update the list, then just replace the entry in your feed. If you create a new list (Top 34?) then insert that in the feed along with the “Top10” list.
What is the problem? Why don’t folk see that lists are the stuff of entries – not feeds? Remember, “It’s about the entries, Stupid…”
I think the reason we’ve got this pull to turn feeds into Lists is simply because we don’t have a commonly accepted “list” schema. So, the idea is to repurpose what we’ve got. Folk are too scared or tired to try to get a new thing defined and through the process, so they figure that they will just overload the definition of something that already exists. I think that’s wrong. If we want “Lists” then we should define lists and not muck about with Atom. If everyone is too tired to do the job properly and define a real list as a well defined schema for something that can be the payload of a content element, then why not just use OPML as the list format?
What is a search engine or a matching engine supposed to return as a result if it find a match for a user query in an entry that comes from a list-feed? Should it return the entire feed or should it return just the entry/item that contained the stuff in the users’ query? What should an aggregating intermediary like PubSub do when it finds a match in an element of a list-feed? Is there some way to return an entire feed without building a feed of feeds? Given that no existing aggregator supports feeds as entries, how can an intermediary aggregator/filter return something the client will understand?
You might say that the search/matching engine should only present the matching entry in its results. But, if you do that what happens is that you lose the important semantic data that comes from knowing the position the matched entry had in the original list-feed. There is no way to preserve that order-dependence information without private extensions at present.
I’m sorry but I simply can’t see that it makes sense to encourage folk to break important rules of Atom by redefining feeds to be lists. If we want “lists” we should define what they look like and put them in entries. Keep your hands off the feeds. Feeds aren’t lists – they are feeds.