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RE: XPath conformance? was RE: [xml-dev] storing XML files
- From: Evan Lenz <email@example.com>
- To: "Champion, Mike" <Mike.Champion@SoftwareAG-USA.com>, firstname.lastname@example.org
- Date: Tue, 09 Oct 2001 10:07:46 -0700
Mike Champion wrote:
> I'd submit that a processor that executes legal XPath expressions "is" an
> XPath processor, whatever it's called, and whatever superset of
> XPath syntax
> it also supports.
Because XPath can be extended via an extended function library, a la XSLT
and XPointer, I would disagree with the claim that a processor that supports
an extended *syntax* is in compliance with the XPath specification.
There are parts of the picture that are not standardized--most notably how a
node-set (or even a boolean, for that matter) should be serialized. These
are implementation-dependent (whether the implementation is the XSLT
specification or some XML database vendor).
This leaves vendors much freedom (at the expense of having a standard).
However, they should not feel free to extending the syntax of XPath, i.e.
what the XPath spec *does* standardize.
For example, the following is not in compliance with the XPath spec:
/customer[name ~= "Mike"]
whereas this alternative expression would be perfectly fine: