Exposing RSS Comments

UPDATE: Since publication, this recommendation has been incorporated into many RSS feeds. You can read the semi-official docs for the wfw:commentsRss element on rssboard.org.

So far, comments have gotten a lot of play in the RSS space:

• The RSS 2.0 element to expose a link for a browser-based UI to view/add comments
• The extension element to expose the number of comments current made on an item
• The extension element to expose the URL endpoint for posting comments via the CommentAPI

However, what’s missing is the ability to pull out a list of comments associated with an item. Instead, folks like Sam publish their comments as a separate feed, and then feed readers thread the comments with the content by comparing the elements from the type feeds (as well as all of the other feeds). That works for most standard-sized RSS sites, but what about sites that exposes hundreds of thousands of entries like msdn.com? Cached per site comment feeds don’t scale as well as on-demand per-item comment feeds. Towards that end, I’d like to propose another element to the well-formed web’s CommentAPI namespace: commentRss.

The commentRss element would be a per-item URL for an RSS feed of comments. It looks very like the wfw:comment element:

<wfw:commentRss xmlns:wfw="http://wellformedweb.org/CommentAPI/"> 
  http://bitworking.org/news/commentsRss/52
</wfw:commentRss>

With wfw:commentRss, the RSS reader can pull the comments down on demand, merging them in with the cross-references from other blogs as it does now. In addition, an extension to RSS like this would allow feed readers to subscribe to comments for a particular item, either manually for conversations in which the user is interested or automatically when the user posted a comment for an item.

Comments?