Mapping Hacks

Map Your Friend-of-a-Friend Network #99

Chapter 9, Mapping with Other People

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HACK

push @out, map { Class::RDF::Object->new($_->subject->value) } @n;

}

print Class::RDF->serialise(@out);

We drop this file on a web server somewhere and point the RDFMapper

web service at it. The full instructions, including details on customizing the

display and page layout, are at http://www.mapbureau.com/rdfmapper/.

All the scripts accompanying this hack, and a demo showing the current

state of geo-annotated FOAF world, are at http://mappinghacks.com/

foafworld/.

Identifying People with FOAF

If you have an eye for RDF/XML, you’ll notice that the two Persons in our

first example are not identified by URL, but by temporary nodes that have

temporary IDs relative only to that document—what’s known as a bnode in

RDF terms. In the FOAF world, it can be considered impolite to refer to

people by URLs. I am not a number, nor do I want to be assigned a barcode

from birth (although the FOAF spec does describe a

dna_checksum prop-

erty). Because we can’t, or don’t want to, assign a unique global identifier to

each person, we use a technique called smushing to connect all the informa-

tion we spidered from the FOAF web into one big graph and figure out

which people are actually the same people, mentioned several times.

At http://xmlns.com/foaf/0.1/, the FOAF vocabulary lists the classes and

properties of people (and other “Agents,” ...