Composite datatypes - XML Schema datatype for date+time

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Date: Thu, 29 Jun 2000 20:32:41 +0800
From: Rick JELLIFFE <ricko@geotempo.com>
To: "XML-DEV (E-mail)" <xml-dev@xml.org>
Subject: Re: XML Schema datatype for date+time

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"Petter Nilsen, Systemutvikler 8368" wrote:

> 
> I'm looking at the W3C Schema Part 2: Datatypes document, and I can't find a
> combined date+time datatype.  Doesn't it exist or am I too new to schemas to
> understand the document?

(This is not an answer to your specific question--I'll have to check the
spec first--it is an answer to the general treatment of composite
datatypes in XML Schemas.)
 
There are no composite datatypes in XML Schemas: there are only
  - atomic datatypes of various useful types familiar to database users
  - lists 
  - strings (constrainable by regular expressions)
  - notations (i.e., you do it yourself)

At the current status quo, if you want to have composite data types and
you want to make use of XML Schemas for private validation you must

  1) make up a notation identifier for what you plan to do (i.e. a URL)
     and use XML schemas to say that the element is a notation;
  2) write your own conversion utility which, when it finds some data
     with that notation, parses it into a little XML document
  3) create a mini-schema for that compound type
  4) validate the minidocument against that.

This is all a bit complex, so it may be simpler to 
  -- have two elements or attributes for this, a date and a time
  -- make up some swanky regular expression and make do with lexical
     typing only

Rick Jelliffe

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