Re: [xml-dev] The limitations of XPath and navigation- A XPath/XQuery

[John Snelson <john.snelson@oracle.com>]

Michael Kay wrote:
> ** > Can you or anyone reading this email duplicate my simple SQL 
> example in XPath 2.0 or XQuery of joining two nonlinear (multi-leg) 
> structures hierarchically together and applying a multi-leg data 
> filtering?  
>  
> I'll be very happy to tackle this if you can express the problem in XML 
> terms. Show us the input XML and the output XML and we'll show you the 
> query. I can't do it if I have to reverse-engineer the problem statement 
> from a solution coded in a different and unfamiliar language, 
> or understand what you mean by the non-XML concepts of "legs" and 
> "nonlinear", or read an academic theory of LCA processing.

I agree. Like Michael, I'm an XQuery implementer and like to think I 
have a reasonable understanding of the technology space, but I'm also 
having a hard time following the opaque terminology you use.

You clearly feel that you have an important message for the XML / XQuery 
community, and I'm willing to put some effort into understanding what 
you're trying to say. What I need is a clear explanation or terms like 
"LCA", "non-linear", "multi-leg" etc. I could so with some examples 
written in XML to illustrate them, and an example of a problem that 
demonstrates the advantages of your query techniques.

I'm not dismissing what you have to say, but I don't exactly get users 
come up to me every day asking when they're going to be able to join two 
non-linear multi-leg structures in XQuery. What's the value proposition 
for XQuery users?

John

-- 
John Snelson, Oracle Corporation            http://snelson.org.uk/john
Berkeley DB XML:        http://www.oracle.com/database/berkeley-db/xml
XQilla:                                  http://xqilla.sourceforge.net