Re: Pondering RDF Path

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Libby Miller <Libby.Miller@bristol.ac.uk> writes:

> On Fri, 5 Sep 2003, Sean B. Palmer wrote:
>
>>
>> > Damian Steer has come up with an implementation of
>> > an RDF path syntax as an addition to Saxon:
>>
>> That's interesting, especially in that it doesn't appear to conflate
>> nodes and arcs since it uses RDF/XML's striping. But I wonder how it
>> handles stuff such as
>> <foaf:Person><foaf:knows><foaf:Person/></></>--will it make the
>> internally nested Person available from the root, or does one have to
>> //foaf:Person to get it? And if so, would //rdf:type match rdf:type as
>> a node or an arc, or both? (I've not got Java on this box... will test
>> shortly; I looked at the "README", which made some things clearer).

See below. I haven't implemented the descendant axis yet because it
may turn nasty :-).

> I hope Damian will reply to this - he has more documentation in
> progress.

Two day old draft at:

<http://rdfweb.org/people/damian/treehugger/index1.html>

Hope this makes things clearer. I've added a bit about XPath -> RDF
Query at the end. I see it as an efficiency thing, but you can see
there's a close relationship. One thing I should note is that Squish
is more useful than a single XPath expression. You can pick off useful
bits using SELECT. XPath just returns a nodeset. But using XSLT makes
it useful.

>>
>> > I really like the idea of an RDF path syntax, because I think
>> > that it might enable the huge community of XSLT users to
>> > get to grips with RDF quickly without dealing with the syntax,
>> > and using the XML tools they are used to.
>>
>> Absolutely!
>>

Yeah, this is the idea behind RDFTwig and TreeHugger. They 'subvert'
XPaths for RDF use. I hope my draft makes this clear. I intially
thought that TreeHugger would be a useful 'crutch' for XML people
using RDF, but I'm finding it pretty useful myself. Read into that
what you will :-)

>
> I agree. I guess I was thinking that it would be interesting to attatch
> the paths to a database. I use queries even for api-level stuff when it
> comes to databases in my own implementation, so I'm kind of query
> obsessed :)
>

Indeed. I've been messing about with squish to make it my ideal api
(too many iterators in normal apis). I'll post my increasingly silly
additions here when I've finished the write up.

Damian
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Received on Friday, 5 September 2003 07:36:45 UTC