On Sat, Apr 25, 2009 at 07:16:04PM -0400, Robert Koberg wrote:
Of all the real world applications deployed that use XQuery (I suppose
I could be more specific and say as recommended by Liam, but maybe
probably not necessary), how many do you think would work on more than
one XQuery processor?
I think quite a few, although yes, you generally will have to change
the collection() and document() arguments. Try creating a SQL
database and querying it in Oracle, DB2, MySQL, PostgresQL and you'll
generally find you have to change the code at least a little, but
that does not make SQL completely non-interoperable. It's a case
of managing expectations, and of "the application was ported in
a week" vs "we would need to rewrite millions of lines of code from
scratch".
[...] XQuery as used/promoted by the XML DBs tend to favor their
own extensions in documentation and lists (though there seems to be
more caveats on the lists lately, though).
I don't actually remember which implementations I suggested -- most
likely MarkLogic, Qizx and dbxml, since I've used them. I've not
had major problems moving queries between them, though, once the
files are indexed, which is a separate (although not unfair) question.
We didn't standardise collection() -- at some point you have to
say, "this is the scope of our spec" and stop. Maybe for XQuery 1.1
we could consider an optional directory-of-files-as-collection()
function, but then people would say they needed options to say whether
to re-run indexes, what collation sequences and file encodings to
assume, whether to follow shortcuts and sumbolic links... and pretty
soon it'd be a huge mess. or at least that's been a difficulty in
the past. Relational database schemas aren't entirely portable
either, and neither are filenames (e.g. between MS Windows and
Solaris and OS X the character sets, lengths, and default encodings
differ).
You're right that extension functions are a problem -- that's true
for XSLT as well, of course, and XPath, and for that matter C and
Perl and Python....
Liam
--
Liam Quin, W3C XML Activity Lead, http://www.w3.org/People/Quin/
http://www.holoweb.net/~liam/ * http://www.fromoldbooks.org/
--~------------------------------------------------------------------
XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list
To unsubscribe, go to: http://lists.mulberrytech.com/xsl-list/
or e-mail: <mailto:xsl-list-unsubscribe(_at_)lists(_dot_)mulberrytech(_dot_)com>
--~--