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my notes on our group discussion today on RDF Query via XQuery, in WWW-2003 BOF on RDF Query&Rules

From: Benjamin Grosof <bgrosof@MIT.EDU>
Date: Thu, 22 May 2003 08:21:19 -0400
Message-Id: <5.1.0.14.2.20030522081522.01d345c0@po12.mit.edu>
To: www-rdf-rules@w3.org, eric@w3.org, connolly@w3.org

% notes from WWW-2003 BOF discussion on relating RDF-Query to XQuery
% by Benjamin Grosof 5/22/03

Here are the notes I took.  Not "official", please post 
corrections/additions to the www-rdf-rules list.

Benj, EricP, Andy Seaborne, DanC, general consensus:  worth looking at
how to do RDF-Q stuff in XQuery:

EricP:  XQuery has lots of nice stuff

Benj and various: can reduce lots of RDF-Q stuff to XQuery, front end XQuery
engines with more RDF-specific query lang and then do some
query/result reformulation (incl. later for optimization); even keep
track of; graph vs. tree will matter sometimes; can infer in rule-ish
manner using ability to return / be constructive in head of query

Nick Gibbons:  RDF has aspects of model-theoretic semantics we need to support
Brian McBride:  probably OK usually to ignore whether stuff is ground or not
DanC:  want to do some inference about what's true

Me:  e.g., use rules for RDFS stuff (e.g., subclassof)

TimBL:  there's a FLOWER pattern (Forall Let Where) in XQuery queries
which is often unnecessarily complex for RDF querying, and probably hurts
ability to optimize getting at triple stores

Andy Seaborne: want to replace the XPath part of XQuery by something
more RDF-specific; good to leverage on XQuery aspects that support
things like XML-Schemas

DanC:  want to have test cases that show what XQuery can't do that
we need for RDF-Q

EricP and TimBL:  let's have and RDF-Path for simpler stuff, then
another RDF thing

TimBL:  let's also look at having a canonical XML syntax for RDF,
lots of people want that

Benj:  in TimBL's keynote story about lots of XML data being put into
RDF to be shared, the expressiveness needed will probably not be
more, or much more, than XQuery supports, so we could get a lot of
leverage from the above; then for stuff that starts out in life as
RDF, we do things using other more RDF-powerful query lang/engines

TimBL:  interesting to keep track of what started out as RDF vs. as XML


ff-up meeting:  Fri eve
- see by Fri noon:  look on message point, EricP

also see WIKI (shared webspace):
http://esw.w3.org/topic/



________________________________________________________________________________________________
Prof. Benjamin Grosof
Web Technologies for E-Commerce, Business Policies, E-Contracting, Rules, 
XML, Agents, Semantic Web Services
MIT Sloan School of Management, Information Technology group
http://ebusiness.mit.edu/bgrosof or http://www.mit.edu/~bgrosof
Received on Thursday, 22 May 2003 08:20:30 UTC

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