[rdfweb-dev] Re: XSLTs for FOAF, Spring v1.3.1 and plans for FOAF spec improvements

Morten Frederiksen mof-rdf at mfd-consult.dk
Tue Jun 24 16:35:46 UTC 2003

Dan Brickley <danbri at w3.org> wrote:
>So, (i) is inevitable. Nothing is mandatory in FOAF, although it is probably 
>polite/sensible to minimally mention your foaf:name, and typically mailboxes
>(hashed?) and homepage and maybe an image. So that sort of variety we can't do 
>much about. Just as nobody says what you can write in your homepage, nobody 
>gets to dictate what you write in your machine-readable homepage, ie. your 
>FOAF file.
I agree that there should be no hard requirements, but some
recommendations would be fine.

I see the minimal useful standalone FoaF "fragment" as being foaf:name
and at least one inverseFunctionalProperty, prefering foaf:mbox_sha1sum
over foaf:mbox and foaf:homepage. (If only the rdfweb database would
accept the mbox_sha1sum for queries - Libby?)

Anything "extra" is just added bonus, with foaf:homepage or foaf:weblog
and a rdfs:seeAlso pointing to a "primary" FoaF document topping my
list of wishes.

>Re (ii), vocabulary stability and confusion, I have a plan(!). Rather than 
>worry whether FOAF itself is 'stable' or not, I intend to tag each vocabulary 
>item with 'stable','unstable','testing'. For eg., 'foaf:homepage' is stable;
>'foaf:surname' is unstable; much of the rest is 'testing'. More on this in due
>course. I hope this should clear up some concerns folk have w.r.t. deployability
>of different bits of FOAF vocab.
This sounds reasonable, although I'm not quite sure how you'd implement
those "tags"?

>  http://xml.mfd-consult.dk/foaf/explorer/ is currently XSLT-based, and quite 
>  widely used. 
>  Morten, could you comment on any robustness issues, tips, 
>  problems etc you have encountered?
Short version: It's a mess.

Longer version: It's a hard...

Long version: The permissible variations in RDF/XML syntax is nice for
authoring, but parsing (with XSLT) is getting difficult. I have done
only small improvements over the last months, since anything I do is
bound to break something.

>  Do these various approaches work for 100% of RDF/XML FOAF docs out there?
>  Maybe 80% Quite likely 100% of those files built by foaf-a-matic?
Most of the FoaF-specific XSLT I've seen out there handles perhaps 75%,
with my FoaF Explorer weighing in at 95%. :-)
But yes, the Foaf-a-Matic output is quite parsable.


Morten Frederiksen
After three days without programming, life becomes meaningless.
<URL: http://xml.mfd-consult.dk/foaf/explorer/?foaf=morten.rdf >

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