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Dynamic Context Discovery Functions

From: Tom Bradford <tbradford@openlinksw.com>
Date: Wed, 15 Dec 2004 16:00:34 -0500
Message-ID: <41C0A5F2.9050003@openlinksw.com>
To: public-qt-comments@w3.org

I posted this on my blog, and got a lot of responses saying that it 
would be an extremely good thing to have, particularly for XSLT 
processing rather than XQuery itself.  I was wondering if these 
functions could be considered for inclusion in the XPath function set.

As they're functions, they don't represent a change to the language 
syntax, and they also could be essentially stubbed out for 
implementations that don't support them.

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XQuery and XPath operate against the notion of a dynamic context, where 
the concepts of current collection, and document set are knowns, yet 
there are no functions available for exposing those variables. As a 
person who pretty much lives XML database technology, I find that 
information incredibly important from an implementation standpoint, if 
only to minimize reliance on APIs such as the XML:DB API in order 
perform repository discovery.

Therefore I propose that the following functions be added that expose 
additional aspects of the dynamic context:

fn:default-collection() as xs:anyURI
Returns a URI to the default Collection.

fn:child-collections(xs:anyURI) as xs:anyURI*
Returns a sequence of URIs to for the specified URI. Return an empty 
sequence if there are none, or an error if the underlying store does not 
support this functionality.

fn:child-collections() as xs:anyURI*
Same as the child-collections(xs:anyURI) form, but executed against the 
default collection.

fn:collection-documents(xs:anyURI) as xs:anyURI*
Returns a sequence of URIs identifying the document resources that are 
associated with the specified collection URI. Return an empty sequence 
if there are none, or an error if the underlying store does not support 
this functionality.

fn:collection-documents() as xs:anyURI*
Same as the collection-documents(xs:anyURI) form, but executed against 
the default collection.

-- 
Tom Bradford - Virtuoso Technology Evangelist
OpenLink Software: http://www.openlinksw.com/
Personal Web Log:  http://www.tbradford.org/
Received on Thursday, 16 December 2004 10:49:53 GMT

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