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RE: xpath vs xql

• From: Jonathan Robie <Jonathan.Robie@S...>
• To: "Christopher R. Maden" <crism@y...>, xml-dev@x...
• Date: Tue, 04 Jul 2000 08:40:46 -0500

At 04:31 PM 7/3/00 -0700, Christopher R. Maden wrote:

>At 12:03 3-07-2000 -0500, Jonathan Robie wrote:
>>There is very little difference between XQL'98 and the abbreviated syntax 
>>of XPath. XQL '98 may best be regarded as a predecessor of XPath.
>
>Can you clarify that statement?  My recollection is that work on the 
>syntax now known as XPath began shortly after the March '98 meeting of the 
>XSL WG, if not sooner.  The July '98 WD of XSL shows the XPath syntax; 
>when was XQL'98 published?  The "QL '98" workshop was in December, but I 
>can't find a pointer to XQL'98.

Work on XQL started in January, 1998, and was largely finished by March, 
1998. It originated when I was working on the DOM and needed a simple query 
language for XML repositories. I showed the original version of the 
language to people at Microsoft and webMethods, and we started working 
together on it, producing a significantly better language than the original 
XQL. Unfortunately, although the original intent was to publish XQL 
quickly, it proved difficult to get all the partners to agree to this.

The people working on XSL Patterns included someone who knew XQL quite 
well, and I think that it is fairly clear that XQL influenced the design of 
XSL Patterns. XQL did not originally support functions, which it adopted 
from XSL.

The language I call XQL'98 is the language defined in the QL '98 workshop 
submission, which is identical to the language defined in the drafts we 
submitted to the XSL WG in September '98, and is referenced in the XPath 
specification. There were two other versions of XQL, the original XQL from 
January 1998 and XQL '99, which has now been abandoned in favor of Quilt.

At any rate, there is *very* little difference between XQL '98 and the 
abbreviated syntax of XPath, and XQL was never blessed by a standards body, 
so most XQL implementations now use the XPath interpretation where the two 
languages differed, e.g. numbering arrays from 1 as in XPath rather than 
from 0 as in the original XQL. Some implementations say they support both 
XQL and a subset of XPath, giving them two acronyms for the price of one.

Jonathan


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• References:
  • RE: xpath vs xql
    • From: Jonathan Robie <Jonathan.Robie@S...>
  • RE: xpath vs xql
    • From: Joshua Allen <joshuaa@m...>
  • RE: xpath vs xql
    • From: "Christopher R. Maden" <crism@y...>

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