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Re: RDF syntax 'improvements'?

From: Dan Brickley <danbri@w3.org>
Date: Fri, 4 Aug 2000 10:15:42 -0400 (EDT)
To: "'www-rdf-interest@w3.org'" <www-rdf-interest@w3.org>
Message-ID: <Pine.LNX.4.20.0008040900590.24015-100000@tux.w3.org>
[disclaimer: this is my personal take and not any kind of W3C 
 pronouncement on the matter...]



  Lee Jonas <lee.jonas@cakehouse.co.uk> asks:
> Is it too soon after the RDF recommendation to suggest future
> 'improvements'?  Should we just try to live with RDF as is?

I have the long-rumoured 'RDF developer issues' list near the top of my
todo list now. There are known bugs in the RDF syntax that need
addressing. Quite how these are dealt with is something that we should be
discussing in the RDF Interest Group. I've been going through the
www-rdf-comments archive while preparing a report on the RDF Schema CR
period; to pre-summarise this, one finding is that there are a few cases
in which Schema, Model and Syntax issues become tangled. For example,
primitive datatyping and RDF container constructs (Seq/Alt/Bag/etc), so
summarising feedback on the RDF CR has involved summarising syntax etc
issues too.


I do not believe the RDF Model and Syntax errata document to reflect all
the clear-cut 'syntax bugs' known to the community. Distinguishing
clear-cut from 'up for discussion' is something we should be doing here. I
intend to have some documents to fuel such discussion out within the
month. We have had too much 'open issue churn' on this list. It would be
good to put these issues behind us and get on with building things on top
of the RDF core...


Here are some things that could happen. We could/should bring the errata
document for RDF M&S up to date with the experience of RDF implementors,
and make available answers to FAQs where these seem clear, and writeup
summaries for topics (eg. the xmlns prefix pairing business) that are
perhaps not so clear. We could explore possibility of new work on a
'better' rdf syntax, either as a W3C Working Group as an informal effort
amongst RDF implementors on this list, with the intention of publishing
either a new 'better syntax' REC (which would be a substantial piece of
work) or an informational W3C Note outlining an alternative XML syntax
for RDF models. ('we' being the RDF implementor community, ie. RDF IG)

It could be that RDF Model and Syntax 1.0 plus cleaned up errata plus
issue list and FAQ would remove much of the impetus for a Working Group
activity in this area. At some point the errata needs to be rolled into a
revision of the RDF Syntax document; this should be a largely mechanical
affair. I don't think this is the same hypothetical work item as the
ceation of a new alternate syntax for RDF (eg. the so-called 'by property'
syntaxes that Sergey and TimBL have sketched). 

I'm not personally convinced that a new alternate RDF syntax is a 
priority right now, though I'd like to hear arguments to the contrary.
The XSLT / Semantic Web Screenscraping threads on this
list have shown how we can extract RDF models from all manner of well
managed XML data. There are a fair number of RDF 1.0 parsers now, and
significant effort has gone into creating these. I would rather see our
time go on developing interoperability tests for these to get them up to
production grade, learning through doing so about any grey areas in the
syntax spec. 

In addition, XML Schema is not yet a REC; when we get such a thing,
RDF syntaxes will be able to help themselves to more machinery
(eg. datatyping, qnames in attribute values etc) than the original RDF
Syntax WG had available. I do believe that we _will_ see some alternative
strategies for encoding RDF-like data graphs in XML (eg. see the various
papers from Andrew Layman and others, the SOAP submission etc); I'm not
sure doing this as an RDF specific activity is a good use of
resources. I'd rather see a good web data /graph syntax done for XML as a
whole, and make sure this meets RDF's needs. Some have suggested XLink
might even provide this; I'd like to see some feedback from implementors
on feasibility of this.

I'd also (and this is totally personal opinion as an RDF developer) rather
see effort go into a clearly phrased discussion paper
outlining the issues w.r.t. XML encoding of Web data graphs, summarising
experience with deployment of RDF 1.0 syntax, contrast with alternate
proposals (TimBL's, Sergey's, SOAP) for graphs-over-XML. Only once we had
such a paper, something digestable by the mainstream XML world, would I
feel comfortable proposing a major effort to define a better syntax for
RDF. In other words, I'd rather go the route of working out a requirements
document that says something of what RDF asks of a serialisation syntax,
than to go immediately heads-down on defining some such syntax. My gut
expectation is that after doing this, we'd realise that the thing we're
after has a lot in common with non-RDF XML apps, and that a broader effort
might make more sense. 

So... we should step back and ask for characterisations of what we
want from an XML syntax for RDF. What are the must-haves?  What would the goals
be for any effort to provide a 'better' syntax? ie. what would make it
better...? And then we need to ask who amongst us has time to commit to
the projects sketched above. If the time, inclination and effort are
there amongst W3C Members and the wider RDF world, then let's do it...

IMHO etc.,

Dan

--
mailto:danbri@w3.org
Received on Friday, 4 August 2000 10:15:43 GMT

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