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RE: XML query language

• From: Mark Birbeck <Mark.Birbeck@i...>
• To: xml-dev <xml-dev@i...>
• Date: Thu, 1 Apr 1999 16:25:34 +0100

Paul Prescod wrote:
> Mark Birbeck wrote:
> > 
> > Paul Prescod wrote:
> > > And that model has a concept of nodelist -- this is the most
> > > appropriate return value for query results.
> > 
> > What do you mean by nodelist? Does it take into account that result
> > nodes may be returned from different parts of the tree, or even at
> > different depths? 
> 
> Sure. A node list is a list of nodes. No more, no less.

I sort of guessed it might be ;-) I was more getting at the idea of
context. The following is a 'list of nodes':

	<name>Mark</name>
	<name>Tracey</name>
	<name>Jan</name>

But we don't know were they came from. Even if we know what query
generated them, we don't know what depth they came from. If we used the
query:

	//[name='Mark']

we might get:

	<name>Mark</name>
	<name>Mark</name>

But the original source might be:

	<people>
		<authors>
			<author>
				<name>Tracey</name>
				<agent>
					<name>Mark</name>
				</agent>
			</author>
		</authors>
		<nerds>
			<name>Mark</name>
		</nerds>
	</people>

The reason I was suggesting the fragment approach is because it has
within it the notion of context, and it contains a reference to the
actual 'query' - or reference - that yielded those results. We might
return something like:

	<p:package>
		<f:fcs fragbodyref="//[name='Mark']">
			<people>
				<authors>
					<author>
						<name>Tracey</name>
						<agent>
							<f:fragbody
IDREF="1"/>
						</agent>
					</author>
				</authors>
				<nerds>
					<f:fragbody IDREF="2"/>
				</nerds>
			</people>
		</f:fcs>
		<p:page ID="1">
			<name>Mark</name>
		</p:page>
		<p:page ID="2">
			<name>Mark</name>
		</p:page>
	</p:package>

I'm not saying it's ideal for all situations. I'm just interested to see
how context can be encoded in a 'list of nodes'.

Regards,

Mark

Mark Birbeck
Managing Director
Intra Extra Digital Ltd.
39 Whitfield Street
London
W1P 5RE
w: http://www.iedigital.net/
t: 0171 681 4135
e: Mark.Birbeck@i...


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