W3C home > Mailing lists > Public > www-ql@w3.org > October to December 2001

Re: XQuery and Web services

From: Vadim Draluk <vadim@draluk.net>
Date: Wed, 5 Dec 2001 16:28:13 -0800 (PST)
Message-ID: <20011206002813.6551.qmail@web13501.mail.yahoo.com>
To: www-ql@w3.org
Mark,

thank yoy for your response. Yes, I'm familiar with
both documents you refer to, and the specific use case
of relational database doesn't appear to me to be
similar to one of Web services. There are several
obvious mappings from relational schemas to XML
schemas (the latter in a broad, not technical sense,
so including DTDs, XQuery definitions and such), one
of which is presented in the use case. It is very
different from having an input document encapsulating
the whole semantics of the request.

However, the goal of my posting was more to
sanity-check my judgement, and solicit opinions,
rather than spell out particular requirements. The
most typical lament one hears these days about XQuery
is that of its size/complexity, so adding new
requirements (wich, as I understand, will have to be
considered only for the next version of the language)
might not be the first thing on the agenda.

Cheers

Vadim
--- Mark Needleman - DRA <mneedlem@dra.com> wrote:
> Date: Wed, 5 Dec 2001 16:33:27 -0600 (CST)
> From: Mark Needleman - DRA <mneedlem@dra.com>
> To: Vadim Draluk <vadim@draluk.net>
> Subject: Re: XQuery and Web services
> 
> Vadim
> 
> Im hardly an expert but I am a member of the W3C
> query working group - in
> fact im at a meeting of it right now - have you
> looked at both the
> requirements and use cases documents we have
> published - one of the
> requirements is that the language must support
> querying things that are
> not native xml but can be expressed in xml for the
> purposes of returning
> the result of the query - one of the use cases is
> explicity about how the
> language can be used to query relational databases
> 
> If you have some more specific requirements or use
> cases after reading the
> public documents you can certainly send them in as
> comments for the
> working group to consider
> 
>  
> Mark H Needleman
> Product Coordinator - Standards
> Data Research Associates, Inc.
> 1276 North Warson Road
> P.O. Box 8495
> St Louis, MO 63132-1806
> USA
> 
> Phone: 800 325-0888 (US/Canada)
>        314 432-1100 x318
> Fax: 314 993-8927
>  
> Email: mneedleman@dra.com
>  
> 
> 
> 
> On Wed, 5 Dec 2001, Vadim Draluk wrote:
> 
> > Hello,
> > 
> > I'd like to hear XQuery expert opinions on the
> subject
> > of using the language in the context of Web
> services
> > rather than documents. If possible, it could be
> > potentially vey useful, for example, to create
> > integrated views over several services, pretty
> much
> > the way SQL is used for description of multi-DB
> data
> > views. I'm considering Web services here since
> they
> > seem to be the buzzword of the day, but same
> issues
> > are valid for any synchronous invocation paradigm
> > taking an input XML document and returning an
> output
> > XML document.
> > 
> > The apparent difficulty is in the difference
> between
> > documents and Web services, the latter being
> functions
> > mapping one set of documents into another. There's
> no
> > way I can see in XQuery to explicitly specify
> input
> > documents (hope no one would suggest putting them
> into
> > the URL parameter of the document() function). A
> > possible solution seems to lie with "virtual
> global
> > documents" (VGD), potentially infinite logical
> > documents encompassing all possible outputs of the
> > service. The problem here is then how to map
> elements
> > of a query into input documents to facilitate
> service
> > invocation. It might seem trivial in simple cases
> of
> > basic filtering ("return customer info by customer
> > ID), but tends to turn ugly as soon as input
> documents
> > become richer. UDDI's own querying capabilities
> > provide a good example: while its VGD structure is
> > quite obvious, producing input documents from
> queries
> > expressed in terms of this schema is far from
> simple.
> > 
> > Best regards
> > 
> > Vadim Draluk
> > 
> > __________________________________________________
> > Do You Yahoo!?
> > Send your FREE holiday greetings online!
> > http://greetings.yahoo.com
> > 
> > 
> 


__________________________________________________
Do You Yahoo!?
Send your FREE holiday greetings online!
http://greetings.yahoo.com
Received on Wednesday, 5 December 2001 19:28:13 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Saturday, 22 July 2006 00:10:18 GMT