2006/12/2, Antone Roundy:
Now that this has sunk in, it makes a lot of sense--the @rel value says "you can subscribe to that",
Why would I subscribe? is it an alternate representation of what I'm looking at? or the feed containing the article I'm looking at? or a totally distinct resource that might interest me if I'm interested in what I'm looking at (think about blogrolls and the "people who bought this also bought that and that" links)? By saying "you can subscribe to that", you're not describing a relation. Maybe you're describing a facet of the resource the link points to, but is this objective or subjective? If it's meant to be objective, then the media type is enough (am I *able* to subscribe to such a thing), or maybe there's a need for another kind of metadata (I proposed a new 'subscribable' attribute on the WHATWG list).
The media type helps the user agent figure out whether it has the capability to do those things. For example, a feed reader that only handles RSS could ignore subscription links to resources of type "application/atom+xml" (ie. not present the subscription option to the user).
And if an UA has the capability to subscribe to something, why couldn't it provide a mean to subscribe, whichever the relationship? What would be important is to reflect the relationship on the UI so the user have all the information available to choose whether he *wants* to subscribe.
The "subscribe to hAtom feed" case where @type is "text/ html" might be a little difficult to make a decision on, because there's no indication of what microformat is being used by the "feed" (or even if there's a microformat in use at all--maybe it really is just an HTML page, and "subscribing" to it just means "watch for changes to the entire document").
...or it's an HTML5 page making use of the new <article> element...
One problem that I hadn't really thought clearly about till right now is that understanding the nature of the think linked TO may require some understanding of the nature of the thing linked FROM. For example, an "alternate" link from a typical blog homepage to its feed really does point to the same thing in an alternative format. Both are live documents in which new data gets added to the top, and old data drops off the bottom. But if you don't know that the webpage is a live document, you wouldn't know whether the link pointed to a static or live document. "alternate" is perfectly accurate, but it's not helpful enough. "subscribe" would be much more explicit.
Why should it be automated? When you go read a web site every morning because you know it's "live", it's not automated. What you could automate is how to go read that site (e.g. use it as your browser's "start page", or include it in a bunch of bookmarks you "open in tabs" every morning). There's not always a need to automate everything. Things like "whether it'd be interesting to subscribe to something" are better handled by humans than computers. -- Thomas Broyer
