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RE: XQuery and DTD/Schema?

• To: "Uche Ogbuji" <uche.ogbuji@f...>,"Jonathan Robie" <jonathan.robie@d...>
• Subject: RE: XQuery and DTD/Schema?
• From: "Dare Obasanjo" <dareo@m...>
• Date: Wed, 3 Jul 2002 14:36:35 -0700
• Cc: "Simon St.Laurent" <simonstl@s...>,<xml-dev@l...>
• Thread-index: AcIi1y092ZlGHHkuRxyf7ciWvYG3uAAANcew
• Thread-topic: XQuery and DTD/Schema?

> -----Original Message-----
> From: Uche Ogbuji [mailto:uche.ogbuji@f...] 
> Sent: Wednesday, July 03, 2002 1:48 PM
> To: Jonathan Robie
> Cc: Simon St.Laurent; xml-dev@l...
> Subject: Re:  XQuery and DTD/Schema? 
> 
> a) There is no reason it has to be static.  

  i.) Static types improve performance and help catch errors in many
cases. However, the XQuery type systemin some cases costs more than the
benefits it brings, 

 ii.) If you don't like static types then don't use a schema or static
type related constructs. The problem however is that if static types are
made mandatory then queries which may work such as 

	/foo[@bar < 5] 

will fail at compile time which may be rather unsatisfactory. 
 
> so how do I 
> express my dynamic constraints in an XQuery function definition?

What dynamic constraints would you like to express? 
 
> b) There is no reason it has to be named types.  

You need a mechanism to specify constraints on the arguments to various
functions and operators. Whether you decide to name them or keep them
anonymous doesn't make much of a difference although I'd prefer named
types for usability reasons. 

> 
> c) Even if one were to say "XQuery requires static, named 
> types"   Why mandate that these come 
> from the PSVI?

This is not mandated. This is why there is a mapping from the PSVI to
the XQuery data model in the first place. 


-- 
PITHY WORDS OF WISDOM 
Lynch's Law: When the going gets tough, everyone leaves.

This posting is provided "AS IS" with no warranties, and confers no
rights. 

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