Wired News has a beautiful new (beta) application for RSS. Give it a search term, and it returns articles that include the term. For example, this feed shows all the articles that contain my name; subscribe to it, and you'll be informed of anything new written about me on Wired News. We used to call this ego surfing, now I have an ego aggregator. As Steve Gillmor says, aggregators are the new desktop, RSS the format that ties together information flows. We call this information routing. Powerful stuff.
They wanted to include some information in their feed that isn't defined by the RSS spec, so they created an extension, also known as module or namespace, with information about the search results. An aggregator that was tuned to work with Wired search results could use the extra info, but the feed will still work with aggregators that don't know about their namespace (like all the ones out there now). Modularity. Coolness. Marc Canter asked me to keep stressing this point. He was right. People should know that RSS is extensible.
I also recently read about a nifty Google-based RSS feed from the popular tracking service Google Alert (www.googlealert.com). This lets you take Ego Surfing to the next level by notifying you anytime your name is mentioned anywhere on the web, as indexed by Google. Results come in emails, HTML or RSS feeds.
I've found it easy to use and very useful.
feedster.com and daypop.com have been doing this for ages.
If an RSS 2.0 feed contains a namespace-qualified element that says "everything in this feed is a joke", how is an aggregator that doesn't know that namespace expected to behave?
That may sound an academic example, but consider what Creative Commons extensions are saying about the feed - should an aggregate/republish tool ignore the copyright agreement just because the spec says it can?
Namespaces only keep names in different spaces, they aren't magic. True extensibility needs help from the core.
>>True extensibility needs help from the core.<<Agreed. However, in this case (RSS 2.0), the core *does* provide help. Specifically, it states: "A RSS feed may contain elements not described on this page, only if those elements are defined in a namespace."
I would agree that RSS 2.0 could have gone furhter, but that does not mean that the extensibility it offers is not useful. It only means that it has some limitations (what doesn't?). The limitation is that extensions are able to add additional information that *can* be ignored by readers that do not recognize the extension; extensions *cannot* modify the interpretation of core elements.
As the architect of MySmartChannels (visit my URL for details), I found this RSS extensibility to be *very* useful. Since MySmartChanels supports item level security, we wanted a way to include permission information in the RSS feed (e.g., can the requesting uses edit this item? delete this item? change permissions for this item? etc.) A reader that understands these extensions can offer UI options appropriate for the user. A reader that does not understand these extensions simply ignores them.