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What are reading lists?

Sunday, May 24, 2009 by Dave Winer.

First an update on today's earlier blog post. Apparently Google Reader does not support reading lists. I think when I asked the question, the 140-character limit on Twitter made it impossible for an accurate answer.  Permalink to this paragraph

No matter what, maybe it would be a good idea now to try to give a complete technical explanation of what a reading list is.  Permalink to this paragraph

1. There are many kinds of "feed consumer" apps, all of them are capable of supporting reading lists, not just feed readers or aggregators. In the rest of this piece I'll use the shorthand "FC" to refer to a feed consumer app. Permalink to this paragraph

2. When you subscribe to a feed you're telling the FC that you want it to periodically read the contents of that feed and somehow act on the new items in the feed.  Permalink to this paragraph

3. A reading list contains a set of feeds. The format of a reading list is exactly the same as the OPML-based subscription list format that's supported by many FCs. Permalink to this paragraph

4. When a FC subscribes to a readling list it does not import the feeds. Permalink to this paragraph

5. When the FC checks for updates, it checks for new items in the feeds in the reading list. Therefore it must keep a record of the feeds in the reading lists it is subscribed to.  Permalink to this paragraph

6. If a new feed appears in the reading list, it does whatever it does for a new feed. Many FCs will consider all the items in the feed as "old" the first time the feed is read, esp if it's a podcatcher. Permalink to this paragraph

7. If a feed that was in the reading list has been removed, then the feed is not read and all record of the feed is erased from FC database, with the following exception. If a feed appears in two or more reading lists, a reference count must be maintained, and the feed is erased only when the reference count goes to zero. Permalink to this paragraph

8. Obviously the user can subscribe to as many reading lists as he or she likes. Permalink to this paragraph

9. The behavior I've described is how the NewsRiver aggregator that runs in the OPML Editor works. I suppose it's possible that other FCs work differently. If so, it would be great to hear about them.  Permalink to this paragraph

I think that pretty much covers it.  Permalink to this paragraph

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A picture named dave.jpgDave Winer, 54, pioneered the development of weblogs, syndication (RSS), podcasting, outlining, and web content management software; former contributing editor at Wired Magazine, research fellow at Harvard Law School, entrepreneur, and investor in web media companies. A native New Yorker, he received a Master's in Computer Science from the University of Wisconsin, a Bachelor's in Mathematics from Tulane University and currently lives in Berkeley, California.

"The protoblogger." - NY Times.

"The father of modern-day content distribution." - PC World.

One of BusinessWeek's 25 Most Influential People on the Web.

"Helped popularize blogging, podcasting and RSS." - Time.

"The father of blogging and RSS." - BBC.

"RSS was born in 1997 out of the confluence of Dave Winer's 'Really Simple Syndication' technology, used to push out blog updates, and Netscape's 'Rich Site Summary', which allowed users to create custom Netscape home pages with regularly updated data flows." - Tim O'Reilly.


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