The Web, Naturally!

hFoaf (Hypertext Friend of a Friend) has recently been updated to version 0.3, this one has been an important update because basically the XSLT needed a lot of tidying, refining, which also gave me an opportunity to add a few more actions such as being able to extract things that a user has made or authored, and a more complete expansion of XFN rel="me".

What may be a good idea now would be to give you some clues on how to build hFoaf in a quick and dirty howto, but first... hFoaf is not a microformat or a proposed one, although it does rely heavily on microformats to determine the output of a FOAF RDF document.

The first step is to create a hcard, then add an id="" to the hcard and a class="url" with the XFN relationship rel="me"

Example:

1. <div class="vcard" id="weborganics">
2. <p class="fn n">
3. <span class="given-name">Martin</span>
4. <span class="family-name">McEvoy</span>
5. </p>
6. <p><img alt="weborganics" src="http://weborganics.co.uk/images/me.jpg" class="photo"/></p>
7. <p>Contact: <a class="email" href="mailto:weborganics@googlemail.com"
8. id="sha1:3cc1a719a5023e9087ced9c74610b66cfbb58d54">weborganics@googlemail.com</a></p>
9. <p>Web: <a rel="me" class="url" href="http://weborganics.co.uk/">WebOrganics</a></p>
10. <div class="geo">
11. <p>Location: <abbr title="53.7552" class="latitude">N 53.7552</abbr>,
12. <abbr title="-2.3675" class="longitude">W -2.3675</abbr><p>
13. </div>
14. </div>

hCard classes and how they map to FOAF are as follows...

• "vcard" => foaf:Person
• "fn" => foaf:name
• "given-name" => foaf:givenname
• "family-name" => foaf:family_name
• "email" => foaf:email
• "url" => foaf:homepage
• "url org" => foaf:workplaceHomepage
• "photo" => foaf:img

The geo component of hcard maps to foaf:based_near and defined using the WGS84 Geo Positioning RDF vocabulary...

• "geo" => geo:Point
• "latitude" => geo:lat
• "longitude" => geo:long

Lastly The value of foaf:mbox_sha1sum uses the id="" of class email prefixed with "sha1:"

XFN relationship values are also expanded and added to your FOAF output. rel="me" values that are links to popular social networking sites are mapped to foaf:holdsAccount, although not all rel me links are added to the output, a list of supported sites are as follows...

• twitter
• flickr
• digg
• ma.gnolia
• last.fm
• delicious
• pownce
• youtube

Example:

1. <a rel="me" href="http://delicious.com/weborganics">delicious</a>

All XFN relationships are defined as foaf:knows, foaf:Person, foaf:name and foaf:weblog along with its XFN value eg: xfn:met.

Example:

1. <a rel="friend met" href="http://www.djkippax.com/" title="James Kippax">James Kippax</a>

Interests and things that have been made or authored by a user are simply defined as foaf:interest maps to hAtom rel="bookmark".

And thats it, easy eh? There is a Demo of how to use hFoaf With GRDDL along with some copy and paste code and some example output available at hFoaf Demo and also a webservice available at TransFormr that extracts a FOAF document