[uf-discuss] Proposal: Mandatory connection of a XFN to a"source" hCard and a "target" hCard

[Scott Reynen]

On Mar 19, 2008, at 10:02 AM, Costello, Roger L. wrote:

>> 1. All people in an XFNetwork MUST be identified via
>> hCard somewhere within the network.
>
> How about allowing the parties involved in an XFN-relationship be
> identified by either hCard or a FOAF document or an OpenID? (I must
> confess ignorance of OpenID.  Is the id specified in its own document,
> like FOAF, or is it embedded within HTML?)

I think it's good to keep it as flexible as possible for publishers.   
I didn't mean to suggest my support for MUST vs. SHOULD or something  
else.  I was just trying to show that the subject of a given document  
is not necessarily identified directly in the document itself.  But in  
all of the examples, it is identified directly in the document itself  
(see below), so my point there may not be particularly relevant.

> [Scenario] You are a robot.  Your mission is to create a social graph
> using every XFN you can find. You've just arrived at a web page with
> this URL: http://www.flickr.com/photos/13886259@N03/.  As you parse  
> the
> page you encounter a link containing XFN: <a
> href="/photos/24172116 at N08/" rel="contact">  How do you determine the
> identity of the source and target of this relationship?

Here's my thinking on this:

The source and target of the relationship are the subjects of the  
documents at either end of the link.  So I think the question is more  
simply: how do you determine which person is the subject of a  
document?  I think <h#> headings are good for identifying a subject,  
and hCard is good for identifying people, so we could easily combine  
those two to determine which person is the subject.

I'm further convinced this is a workable solution after looking at the  
sites mentioned that use XFN, which are for the most part already  
doing what I've described above (combining <h#> with hCard to indicate  
a person as a subject).  Of the 6 sites mentioned that use XFN:

- 5 use <h#> tags around the person who is the subject of the page  
(the other, Twitter, uses class="about vcard").
- 4 (all but MetaFilter and Last.fm) use hCards.
- 3 (Flickr, Magnolia, and Pownce) already combine the two to clearly  
indicate a person as a subject.

So I'd say start the robot on those 3, encourage MetaFilter and  
Last.fm to add hCard, and encourage Twitter to use a heading (<h#>)  
intersecting with the existing hCard.

Peace,
Scott