Re: xlink & annotation

At 12:54 AM 11/18/2001 +0100, Danny Ayers wrote:
>Hi,
>Can someone please tell me why the annotation initiative seems to have
>skirted XLink and opted for RDF to supply link semantics?

because there are much richer semantics that other applications
of Annotea will eventually use.  The extensibility of RDF makes
it far more straightforward to add properties refining your own
semantics than the XLink role model permits.

I agree with you that were we only interested in human navigation
links then XLink would have been quite sufficient.  But our ambitions
go well beyond the tiny bit of work you see in Amaya and Annotea
right now.  And even with what we currently represent in Amaya
annotations, we stress what the simpler XLink models express
in their most convenient forms.

You could certainly think of Annotea and its protocol as an example
of what XLink calls an 'external link database'.

Early on in our work we did a whiteboard model of how to express
what we wanted for simple annotations in an 'extended XLink with
locator elements'.  The model turned out to have similar, and in
certain respects a little more, complexity as the plain RDF model
we finally chose for Annotea.  (Note that other people's models
for annotations -- such as the ILRT one -- have refinements over
ours that are even harder to describe in XLink syntax.)  Our early
modelling was the inverse of the exercise described by Ron Daniel
in "Harvesting RDF Statements from XLinks" W3C Note 29 September 2000
http://www.w3.org/TR/2000/NOTE-xlink2rdf-20000929/
though we did our modelling independently of Ron's work.

An interesting exercise would be to repeat the inverse modelling
using the structure in Ron Daniel's NOTE in a more careful
manner.  I wouldd be very happy to review drafts of such work if
someone picks up this exercise.

>(I'm afraid the archive search is "Unable to contact target server
>onatopp.w3.org:11000 after 3 tries.").

We've had major hardware failures on that machine recently
and as a result our system's group has raised the priority of
a complete replacement for our site search facility.

-Ralph

Received on Saturday, 17 November 2001 21:45:27 UTC