An interesting debate was started by André Luís last month on the microformats-discuss mailing list on the benefits of hAtom. I didn’t have time to read it in details at the time, but read the discussion today and here’s my summary.
For those not familiar with hAtom, it is an XHTML microformat for RSS-like feeds.
Great, but why would someone want to do that, given that blogging platforms already generate the RSS/Atom feed for you? Are there use cases for providing hAtom in addition to the Atom feed?
Zhang Zhen pointed to the WebSlice upcoming IE8 feature, which reuses hAtom syntax and will allow users to subscribe to a portion of a webpage. This pointer is interesting, but not quite exactly hAtom.
Toby Inkster mentioned that hAtom could help avoid the use of blogging software by essentially allowing the Atom feed to be generated by a service (but as André noted, this wasn’t really his question):
<link rel="service.feed" type="application/atom+xml" href="hatom2atom.php?uri=http://example.org/page.html" mce_href="hatom2atom.php?uri=http://example.org/page.html"/>
Brian Suda explained that hAtom could be used by Web crawlers to extract valuable metadata, and by browser plugins to provide a better user experience as a user is reading Web content.
While all these were valid benefits, the one that captured the attention of the group was the use of hAtom and rel='next' or rel='prev' for pagination of microformats, i.e. linking microformat entries listed on multiple pages together.
Let’s say you have a collection of hCalendar entries or hCard entries on your Web site, you could mark these up as hAtom and use a link between them, so that a microformat parser could navigate the site and generate a single collection of hCalendar and hCard entries.