[uf-discuss] XFN Relationship types
Julian Bond
a few cases where rel="some other relationship" is being used along with
other qualifiers.
Is there some standard here we should be encouraging like rel="Contact
Acquaintance" or do we expect developers to know that an Acquaintance is
also a Contact? And if it's the second is there some mapping table on a
wiki somewhere?
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Dan Brickley
> I'm seeing a lot of XFN that uses rel="contact". But there's also
> quite a few cases where rel="some other relationship" is being used
> along with other qualifiers.
>
> Is there some standard here we should be encouraging like rel="Contact
> Acquaintance" or do we expect developers to know that an Acquaintance
> is also a Contact? And if it's the second is there some mapping table
> on a wiki somewhere?
Is "X xfn:acquaintance Y" a claim that is considered consistent with the
weaker claim "X contact Y" ?
Some sites I have buddies listed and since that site isn't so well
informed about how well I know those people, they'll emit only 'contact'
links; others have more detail and understand that we have met (and are
acquaintances) or even that we're friends.
The 'friendship (pick at most one)' rule in http://gmpg.org/xfn/11 can
be read in two fundamentally different ways. One is that these are
mutually exclusive states of affairs: call it Reading (A), "If I'm your
friend, then I'm not a contact or acquaintance". This reading takes the
constraint to be a rule about the world. Another, reading (B) is that
"If I claim I'm your friend in some document, I shouldn't also state
that I'm a contact or acquaintance". This reading takes the constraint
to be a rule about document syntax / notation. These two styles roughly
correspond to the comfort zones of RDF vs XML schema languages, btw. RDF
schemas express generalisations about the world; XML schemas
I've tended towards the latter reading; since it fits with the webby
model of scattered, partial information. Last.fm might know that we're
contacts; Flickr might know that we're friends. And missing information
isn't necessarily the same as being broken.
How often is something like 'rel="Contact Acquaintance"' (ie. multiple
from the friendship options together) seen in practice? Does anyone have
a good list of other common values seem alongside the well-known XFN set?
cheers,
Dan
Toby A Inkster
> Is there some standard here we should be encouraging like rel="Contact
> Acquaintance" or do we expect developers to know that an Acquaintance is
> also a Contact? And if it's the second is there some mapping table on a
> wiki somewhere?
The background <http://gmpg.org/xfn/background> document makes it pretty
clear (as does the profile document) that contact, acquaintance and friend
are mutually exclusive.
They can be considered a scale. Choosing a value higher up the scale (e.g.
friend) both forbids the explicit use of one lower down the scale (e.g.
contact), but also implies its meaning. So it's not valid to write, say:
<a href="http://bob.example.net" rel="friend contact">...</a>
but when faced with:
<a href="http://bob.example.net" rel="friend">...</a>
it is acceptable for a parser to conclude that Bob is one of your contacts.
The "co-resident" and "neighbor" values could also be construed in such a
manner.
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Toby A Inkster BSc (Hons) ARCS
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