Syncronizing RSS feeds

I recently picked up a semi-abandoned web-based RSS newsreader. It's a great little project, and I love being able to read, and update all of my incoming feeds from whereever I happen to be physically located (desktop, laptop, cellphone, public terminal, et al.) However, I often find myself in offline situations (plane) where reading from a web-based reader is obviously not an option, and the newly created, and open-source Vienna RSS reader if very slick. But again I end up now having multiple sets of feeds, each in a different "read" state, and I really want to be able to tag/flag feeds for later perusal.

Therefore, I've been thinking about the possiblities for syncronizing feeds across multiple desktop computers as well as with a centralized server. This would allow me to flag, mark read/unread, add feeds, etc. at either the web-based reader or any desktop reader and keep them all syncronized.

The sync interface should be open, allowing any RSS reader to implement and support the interface. Therefore users are not "locked into" a reader just because they have all of their feeds already there. This type of application lock-in is so very totalitarian. People should use software because it fits their needs and be allowed to switch away (or to) without fear of data loss.

There are several simple criteria such an interface should support: added/removed feeds, flagged (multiple methods of flagging/tagging: e.g. interesting, todo, toread, etc), read/unread, last updated, and handle what *version* of a feed item also is marked (assuming updates happen to feed items?).

RSS 2 provides a guid tag. guid stands for globally unique identifier. It's a string that uniquely identifies the item. When present, an aggregator may choose to use this string to determine if an item is new.. Therefore, an syncronization item could look like the following:



http://highearthorbit.com/blog/syncronizing-rss-feeds
read
flagged
Mon, 07 Nov 2005 10:27:33 +0000


However, an important consideration is the fact that there will likely be thousands of feed items to syncronize, and XML is not known for its compactness.

Are there current RSS syncronization standards currently out there that I may have missed?

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Andrew Turner is an advocate of open standards and open data. He is actively involved in many organizations developing and supporting open standards, including OpenStreetMap, Open Geospatial Consortium, Open Web Foundation, OSGeo, and the World Wide Web Consortium. He co-founded CrisisCommons, a community of volunteers that, in coordination with government agencies and disaster response groups, build technology tools to help people in need during and after a crisis such as an earthquake, tsunami, tornado, hurricane, flood, or wildfire.