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If we start out by agreeing that we are only talking about the subset of files which serve the purpose of being a "primary" source of information for a person (as in, we're not talking about something like a list of images having descriptions of the persons depicted), there is a way: foaf:topic and/or foaf:page (which is the inverse of foaf:topic). Like this: <rdf:RDF ...> <rdf:Description rdf:about=""> <foaf:topic rdf:nodeID="me"/> </rdf:Description> <foaf:Person rdf:nodeID="me"> <foaf:name>Morten Frederiksen</foaf:name> ... </foaf:Person> </rdf:RDF> This states that the file containing these statements is about "me". For heuristics to apply to files without foaf:topic, see the Topic Finder: http://xml.mfd-consult.dk/foaf/IFP/ Regards, Morten
Morten Frederiksen • 10/24/03; 11:04:47 AM #
The order of things in the file isn't supposed to matter, because this is RDF serialization, meant to be digested into an unordered cloud of triples. An individual file is meant as a fragment of a larger whole in the potential set of all FOAF everywhere. So, it's not really 'weird shit' in the context of FOAF and RDF. One thing you could do is, if you have the email address of the person, or some other identifier, you can match that up with the particular Person to whom the file is said to belong. But! In the context of using URLs to FOAF files as identification and such for social software and things like SEA... yeah, this sucks. How *do* you figure out about whom a particular FOAF file mainly refers, given only the URL to the FOAF? Or, what if you don't even have the URL, but have just a cached copy of the FOAF file?
l.m.orchard • 10/24/03; 2:10:02 PM #
As Morten suggests, you can say who a file is about using foaf:topic, although I suspect this is not in common usage yet. We could recommend it as best practice if this is a usecase though. Releatedly, you can also use foaf:maker to indicate who made the file which might be useful, because then you can tell (if you believe them) when the person who wrote the file is writing about themselves and when about other people. There's an example in my foaf file: http://swordfish.rdfweb.org/people/libby/rdfweb/webwho.xrdf Bear in mind that, as deusx says, the ordering of the xml doesn't matter in a foaf file, and foaf isn't a file format but an RDF vocabulary. This means you should be using an RDF parser to process it - it's not really possible to parse RDF with XML tools like XSLT successfully. This is a pity, but there are some good tools out there like Jena and Redland. If you are having trouble or have technical questions, come and ask us on IRC (irc.freenode.net #foaf) or on the mailing list, rdfweb-dev@vapours.rdfweb.org. We can help!
libby • 10/24/03; 4:00:53 PM #
Yup, it sux! I'd add two entries to Morten's list - foaf:made or foaf:maker establishes a link between a foaf:Person and the document - There's a foaf:Person in the document who never appears on the right hand side of a foaf:knows relationship. (incidentally Marc's own foaf says he knows himself so this one fails!) But what you really need to ask is why you want to know that this file here is mostly about that person and relationship there. If it's because you want to say "Alice asserts that Alice trusts Bob" and tell that this is different from "Bob asserts that Alice trusts Bob", well tough, that doesn't seem to be in RDF or is it not in foaf, or maybe I misunderstood. Or something. Anyway it's hard and doesn't drop straight out of the FOAF that's out there right now with any certainty. Ironically, the machine generated foaf from places like Ecademy or Typepad actually does have this information in it, it's just not in the triples, it's in the existence and structure of the files due to the way it's created. But that's not RDF...
Julian Bond • 10/24/03; 4:00:55 PM #
My apologies, Marc's foaf no longer says he knows himself. So that's alright then.
Julian Bond • 10/24/03; 4:15:59 PM #

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