W3C home > Mailing lists > Public > public-rdf-dawg@w3.org > April to June 2004

Re: Requirement: queries written as RDF

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Tue, 13 Apr 2004 11:05:52 +0300
Message-Id: <62112BF9-8D21-11D8-8853-000A95EAFCEA@nokia.com>
Cc: "Dirk Colaert" <Dirk.Colaert@quadrat.be>, "Rob Shearer" <Rob.Shearer@networkinference.com>, <public-rdf-dawg@w3.org>, "Eric Prud'hommeaux" <eric@w3.org>
To: "ext Howard Katz" <howardk@fatdog.com>

On Apr 08, 2004, at 17:14, ext Howard Katz wrote:

>>> (2) If queries are represented in XML they can be treated as data
>>> and you can run XQueries over a collection of XQueries.
>> That's interesting. A Query expressed in RDF could be treated as RDF. 
>> It
>> would be easy to do queries about queries. That's an argument for
>> using RDF
>> (or a subset, or a convertible format).
>> All we have to do know is find a use case justifying this
>> requirement... :-)
> It does sound wonderful, doesn't it? I too would like to know what you 
> would
> want to query in a query. Examples anyone ... ?

If one kept a record of submitted queries in a special knowledge
base, one could submit queries against that knowledge base to
generate various statistics about queries having particular
characteristics; e.g.

* terms from particular vocabularies
* use of typed literals
* use of language qualified literals
* 'select' versus description results

Each statistic target would be defined by a query, and the
number of target queries matched would provide the score.

That's just one example.


>> Or do we have a solution without a problem?
>> Dirk
>> -----Original Message-----
>> From: Howard Katz [mailto:howardk@fatdog.com]
>> Sent: mercredi 7 avril 2004 7:08
>> To: Eric Prud'hommeaux
>> Cc: Rob Shearer; public-rdf-dawg@w3.org
>> Subject: RE: Requirement: queries written as RDF
>> I got several responses back from members of the Query wg on the 
>> XQueryX
>> question. I particularly liked this one. I don't know if it'll shed 
>> any
>> light on our own issues, but it's delightfully clear and succinct. The
>> author prefers to remain anonymous.
>> In response to a question on why XQueryX:
>>> (1) An XML-based syntax was considered easier for machines to
>>> generate and exchange than a human-oriented syntax that would
>>> require some sophisticated parsing.
>>> (2) If queries are represented in XML they can be treated as data
>>> and you can run XQueries over a collection of XQueries.
>>> (3) Since XML is known to be an answer to all questions, it must be
>>> an answer to the question "What would be a good format for expressing
>>> queries over XML data"?
>> In response to a question on the technical difficulties that
>> arose once the
>> requirement was formulated:
>>> Once the requirement for an XML query syntax was adopted,
>>> arguments immediately broke out over the level of detail at
>> which a query
>>> should be broken down into XML elements. The working group
>> finally settled
>>> on two separate approaches that represent extreme points on the
>> spectrum:
>>> (a) The whole query is wrapped in a <query> element, and otherwise
>> unchanged.
>>> This approach obviously does not take the XML syntax requirement very
>> seriously.
>>> (b) The query is parsed, and each and every node in the parse tree
>> (including individual
>>> operators, function calls, steps in path expressions, etc.) is
>> represented
>> by its own
>>> element, thus making the query incredibly verbose. This format is
>> obviously useless to humans.
>>> At various times and places, people have attempted to define some
>> intermediate point
>>> between these two extremes. These attempts have always ended in
>> rancor and
>> controversy.
>> Finally, in a follow-up clarification:
>>> I believe that the editor of the XQueryX specification is currently
>> pursuing both approaches
>>> (a) minimal expansion and (b) maximal expansion. Both will be 
>>> defined as
>> valid forms of
>>> XQueryX.
>> Just to close on a personal note, I've always felt that XML is
>> the answer to
>> all questions. I'm now coming to feel increasingly that RDF is
>> even more so!
>> Howard
>>>> On Sun, Apr 04, 2004 at 09:23:14AM -0700, Howard Katz wrote:
>>>    [snip ...]
>>>>> I certainly agree with the sentiments of the second, "human
>> readable"
>>>>> requirement. Interestingly enough, the third, "XML" requirement
>>>> has been the
>>>>> one that's caused the group the most difficulty to my
>>>> knowledge, and at the
>>>>> moment conformance with this requirement has been downgraded to
>>>> optional. I
>>>>> don't know what the major issues have been, but it might be
>>>> interesting to
>>>>> know, if only for the sake of curiosity.
>>>> Can we go beyond the meta-lesson of "that may be hard. it's been 
>>>> hard
>>>> in XQuery" to some of the particular problems that requirement 
>>>> caused
>>>> the XQuery WG? Also, was this requirement born of some compelling 
>>>> use
>>>> cases, or a general notion that it's good practice to express 
>>>> anything
>>>> in XML?
>>> I wasn't trying to impart a particular lesson. My intention, not 
>>> knowing
>>> what DAWG members know or don't know about it, was simply to
>>> provide data on
>>> the experience of the Query wg in the event that might prove
>> useful to the
>>> group. In response to your questions, I've asked several
>> members of the wg
>>> about their XQueryX experience. If they see fit to pass that on
>>> to me, I'll
>>> be happy to share it with the group.
>>> Howard


Patrick Stickler
Nokia, Finland
Received on Tuesday, 13 April 2004 04:25:48 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 17:00:26 UTC