RE: [xquery-talk] Screen-scraping with XQuery

From: Paul Cotton <pcotton@microsoft.com> · Date: Tue, 5 Apr 2005 08:29:27 -0700

XQueryX [1] entered Last Call on April 4.  See general announcement [2].

Could you please submit a Last Call comment with your opinion on what
sort of XML embedding for XQuery you need?

The instructions on how to submit comments are in the Status section of
[1].  

/paulc
Chair, XML Query WG

[1] http://www.w3.org/TR/2005/WD-xqueryx-20050404/ 
[2] http://www.w3.org/News/2005#item44 

Paul Cotton, Microsoft Canada 
17 Eleanor Drive, Nepean, Ontario K2E 6A3 
Tel: (613) 225-5445 Fax: (425) 936-7329 
mailto:pcotton@microsoft.com

> -----Original Message-----
> From: talk-bounces@xquery.com [mailto:talk-bounces@xquery.com] On
Behalf
> Of Erik Bruchez
> Sent: April 1, 2005 8:58 AM
> To: talk@xquery.com
> Subject: Re: [xquery-talk] Screen-scraping with XQuery
> 
> Michael Kay wrote:
> 
>  >><a href="{concat("a", &lt;B>thing&lt;/B>}"/>
>  >>
>  >>Does this make a difference for XQuery?
>  >
>  > Yes, it does. That's not a legal query any more. XQuery only allows
>  > &lt; in character content or in string literals, not in places
where
>  > an operator or element constructor might be expected.
>  >
>  > I guess it's no big deal for XPL if you only support the subset of
>  > XQuery that's well-formed XML. It's easy enough for users to avoid
>  > such constructs (and probably good practice).
> 
> I agree and so far we haven't really had a problem.
> 
>  > More of a practical issue are the operators such as "<", "<=" and
>  > "<<" which in XQuery syntax must be unescaped. It's harder to avoid
>  > using these, although you can always invert the operands and use
>  > ">", ">=", ">>".
> 
> In most cases (not all?) you can use "lt" and "le" for the first two.
> 
>  > (I'm actually trying to write a WG proposal on embedding XQuery in
>  > XML at the moment. XPL is a good use case for it. I'm not happy
with
>  > either XQueryX or the "trivial embedding" where all "<" characters
>  > are escaped. I would like to see something defined along the lines
>  > that XPL uses, but it obviously needs to be specified more
precisely
>  > for a spec than one often does in a product.)
> 
> I agree 100%. We went naturally for this type of XML embedding
> (without being aware of the issues you raise above) because it
> appeared to make the most sense, e.g. a well-formed XML document can
> contain something like:
> 
> <xdb:query collection="/db/orbeon/blog-example/blogs"
> create-collection="true">
>      xquery version "1.0";
>      <categories>
>          {
>          for $i in (/blog[username = 'ebruchez' and blog-id =
> '123'])[1]/categories/category
>          return
>              <category>
>                  <name>{xs:string($i/name)}</name>
>                  <id>{count($i/preceding-sibling::category) + 1}</id>
>              </category>
>          }
>      </categories>
> </xdb:query>
> 
> It would definitely be good if that kind of solution was
> standardized. I can't imagine we will be the only ones desiring
> something like this.
> 
> XqueryX is quite overkill. I can't imagine anybody writing anything
> by hand with that syntax.
> 
> -Erik
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