XML query language

[Oren Ben-Kiki]

Paul Prescod <paul at prescod.net> wrote:

>Oren Ben-Kiki wrote:
>> I fail to see the benfit in inventing a new format for query results.
>
>It isn't about a format. Query languages do not typically work on formats.
>They have an input data model (i.e. a relational data base) and they have
>an output model (i.e. a set of records). An XML Query Language should also
>work in terms of the XML data model (the information set).


Agreed.

>Let's put it this way: you are saying that the query engine should build a
>list of pointers, build a tree, generate XPointer attributes just so that
>an application can get back the original list of pointers!


I don't follow. You yourself have said:

>The IDL for an XML QL should be something like:
>
>NodeList XMLQuery( DOC doc, String query )

Well, them, what other way is to return a list of XPointers then to store
each in an "element"? This is assuming that you prefer the query engine to
return a list of pointers as a result, which I don't. The one nice thing
about this scheme is that you can add extra data per XPointer - a relevancy
score, for example.

I did mistakenly say:
>> AFAIK all XML QL proposals produce XML as output.
>
>No, XQL goes out of its way to NOT require that the output be XML. "The
>specification does not indicate the output format. The result of a query
>could be a node, a list of nodes, an XML document, an array, or some other
>structure. That is, XQL does not dictate the binary format of the returns,
>but rather the logical returns." The same is true of XSL patterns.


I stand corrected. I think you've phrased it perfectly above - the output
should be defined in the terms of the XML data model.

Have fun,

    Oren Ben-Kiki


xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev at ic.ac.uk
Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ and on CD-ROM/ISBN 981-02-3594-1
To (un)subscribe, mailto:majordomo at ic.ac.uk the following message;
(un)subscribe xml-dev
To subscribe to the digests, mailto:majordomo at ic.ac.uk the following message;
subscribe xml-dev-digest
List coordinator, Henry Rzepa (mailto:rzepa at ic.ac.uk)