RE: XQuery -- Reinventing the Wheel?

[Evan Lenz <elenz@xyzfind.com>]

Thomas B. Passin wrote:
> Oh, no, I don't see this at all.  I see it in a very different
> way.  XQuery is
> built on a model that includes a graph-like  info set, a system
> to navigate
> around the graph, a system to specify and evaluate expressions of
> a type not
> included in XPath/XSLT, a type system, and a query algebra.  Only the
> navigation part is like XPath (it virtually IS XPath).  And this is as it
> should be - if you need a tree or "forest" navigational system, use XPath
> (extended if need be).

I suggest that you dig a little deeper; you will find that the overlap is
real, not imagined. The "navigation part" is only a small part of the
overlap. The result construction mechanisms, the flow control mechanisms,
the variable binding mechanisms--these are all virtually indistinguishable
(other than syntax) from XSLT's mechanisms for doing the same. I demonstrate
all of this in my paper.

The introduction of datatypes is making its way not only into XQuery but the
XPath 2.0 and XSLT 2.0 requirements. Regardless of whether datatypes are
only part of query or are part of both query and transformations, there
should be a common semantic and syntactic core for XSLT and XQuery, rather
than an invention of an entirely new syntax.

> Me, I like a lot of what I see in the draft XQuery documents.  I'm really
> puzzled, though, by what seems to be invalid XML illustrated in several
> places.

That's because XQuery is not expressed in XML, though there supposedly will
be an XML syntax for it.

Evan Lenz
XYZFind Corp.