[uf-discuss] A (big) problem with XFN: identity of source and
target not findable
Ryan King
ryan at theryanking.com
Wed Mar 19 16:11:58 PST 2008
This is not a big problem, its mostly solved with [1]
-ryan
1. http://microformats.org/wiki/representative-hcard
On Mar 18, 2008, at 5:31 AM, Costello, Roger L. wrote:
> Hi Folks,
>
> Flickr uses XFN. Here is a sample Flickr page that uses XFN:
> http://www.flickr.com/people/tantek/
>
> At the browser menu select View >> Page Source. Then search for rel=
>
> Here's an example usage of XFN within that Flickr page:
>
> <a href="/photos/24172116 at N08/" rel="contact">
> <img
> src="http://farm3.static.flickr.com/2146/buddyicons/24172116@N08.jpg?
> 12
> 03935044#24172116 at N08"
> alt="Jolene_A" width="48" height="48" /><br />
> Jolene_A
> </a>
>
> Notice the use of XFN: >>> rel="contact" <<<
>
> Metafilter also uses XFN. Here is a sample page that uses XFN:
> http://www.metafilter.com/usercontacts/292
>
> Here's an example usage of XFN within that page:
>
> <a href="/user/10411" rel="colleague" target="_self">40 Watt</a>
>
> Notice the use of XFN: >>> rel="colleague" <<<
>
> Now, suppose that I wanted to create a spider application which crawls
> all social networks that use XFN. Most likely, I would want the
> spider
> to collect:
>
> 1. Who is the source? That is, who is the individual using XFN to
> state a relationship?
>
> 2. What is the relationship? This is, of course, obtained easily from
> the value of the rel attribute on the link.
>
> 3. Who is the target? That is, who is the other individual in the
> relationship?
>
> Examine the above snippets of code. Does 1. and 3. pop out at you?
> That is, do you know who are the individuals that are the source and
> target of the relationship?
>
> That information "can" be found on the Flickr and Metafilter sites,
> but
> each site does it *differently*.
>
> So, the problem with XFN can be stated as this: While XFN does a great
> job of providing a set of relationship values (friend, contact,
> co-worker, etc), it provides no means for the automated discovery of
> the individuals that are the source and target of the relationship.
> Without information about the source and target individuals, the
> relationship information is not very useful.
>
> You might argue: "Well, the XFN *should* be embedded within an hCard,
> then you can discover who the source individual is. And the target
> page should contain an hCard, then you can discover who the target
> individual is." And I agree that is Best Practice. Unfortunately,
> this is not mandated and consequently many people don't do it. For
> example, Flickr and Metafilter don't do it. Nor do any of the other
> social networks do it.
>
> Conversely, consider FOAF. Advogato is a social network that uses
> FOAF. Here an example FOAF on that network:
>
> http://www.advogato.org/person/connolly/foaf.rdf
>
> At the browser menu select View >> Page Source to see the actual FOAF
> document. Notice that the individual who is the source of the
> relationship is clearly listed at the top of the document:
>
> <foaf:name>Dan Connolly</foaf:name>
>
> And the individual who is the target of the relationship is clearly
> identified:
>
> <foaf:knows>
> <foaf:Person
> rdf:about="http://www.advogato.org/person/jtauber/foaf.rdf#me">
> <foaf:nick>jtauber</foaf:nick>
> <rdfs:seeAlso
> rdf:resource="http://www.advogato.org/person/jtauber/foaf.rdf"/>
> </foaf:Person>
> </foaf:knows>
>
> The downside of FOAF is the only built-in relationship is "knows",
> e.g.
> "Dan Connolly knows James Tauber." That is, FOAF doesn't possess the
> richness of expression in terms of relationships. (I know, there are
> extensions of FOAF to express more than "knows," but as far as I can
> tell, no social network is using those extensions)
>
> The upside of FOAF is that all three pieces of information are
> available to a spider application:
>
> 1. The source individual (e.g. Dan Connolly)
>
> 2. The relationship ("knows")
>
> 3. The target individual (e.g. James Tauber)
>
> I don't see any solution to the problem with XFN. As far as I can
> see,
> social networks using XFN cannot be processed by spiders. Only social
> networks that use FOAF can be processed by spiders. Bummer.
>
> Hopefully, I am missing something. I really like the simplicity of
> XFN
> and its rich set of relationships.
>
> /Roger
>
>
>
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