Re: When and how are xs:anyURI references made absolute?

Hi,

FWIW, the example with the namespace-rename step I think has a few 
aspects that were not taken into account, see below:

Imagine this was a built-in step, it makes sense to have such a step 
probably as a built-in step, what type you would have used for its 
options? Not xs:anyURI for sure, because it will not work for exactly 
the reasons you mentioned, the local URI reference is resolved for 
built-in steps.

In my reading of the namespaces spec, the empty string in a namespace 
declaration is an empty string and not an empty relative URI, and it 
means no namespace:

https://www.w3.org/TR/xml-names/#ns-decl
***
The attribute's normalized value MUST be either a URI reference — the 
namespace name identifying the namespace — or an empty *string*.
***

This leads me to the conclusion that the implied type for managing both 
no namespace and specific namesapces is a reunion of URI references and 
(empty) string, therefore the appropriate type to use for a namespace 
rename step options is probably string and not anyURI.

XML Schema uses '##local' to mean no namespace in some contexts, for 
example:
https://www.w3.org/TR/xmlschema-1/#element-anyAttribute
***
namespace = ((##any | ##other) | List of (anyURI | (##targetNamespace | 
##local)) )  : ##any
***

Also xs:schema/@targetNamesapce does not use an empty value to mean no 
namespace, it models that with an absent attribute:
https://www.w3.org/TR/xmlschema-1/#ag-target_namespace
***
{target namespace}
     Either ·absent· or a namespace name, as defined in [XML-Namespaces].
***
and
https://www.w3.org/TR/xml-names/#iri-use
***
The empty string, though it is a legal URI reference, cannot be used as 
a namespace name.
***


Best Regards,
George
--
George Cristian Bina
<oXygen/> XML Editor, Schema Editor and XSLT Editor/Debugger
http://www.oxygenxml.com

On 6/27/25 10:46, Norm Tovey-Walsh wrote:
> Earlier, I said that the proposed change in behavior had no effect on my test suite results. That’s because I implemented it incorrectly. On further attempts to implement it, about 30 tests fail. And some steps are effectively no longer usable.
> 
> Consider:
> 
>    <p:namespace-rename to="http://example.com/ns"/>
> 
> That step changes the namespace name of elements in no namespace so that they’re in the http://example.com/ns namespace. It’s the same as:
> 
>    <p:namespace-rename from="" to="http://example.com/ns"/>
> 
> And “from” is declared as xs:anyURI. So with the proposed change, it becomes, if not impossible, certainly wildly impractical, to pass the empty string as an xs:anyURI value.
> 
> I also tried to investigate the actual meaning of the xs:anyURI type. The XML Schema definition of xs:anyURI has no facet for storing the base URI, but explicitly says that the “value can be absolute or relative, and may have an optional fragment identifier”. At the data type level, a relative URI is free floating with no notion of its “inherent” base URI.
> 
> And, just to be sure, I tested the behavior of XSLT (I mean, I *knew* what the behavior was, but I wrote the test anyway because that’s safer.)
> 
> If the behavior change proposed is extended beyond options to any occurrence of an xs:anyURI (including, for example, in a p:variable), then we’ll have behavior that is markedly different than XSLT:
> 
> <?xml version="1.0" encoding="utf-8"?>
> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
>                  xmlns:xs="http://www.w3.org/2001/XMLSchema"
>                  exclude-result-prefixes="xs"
>                  version="3.0">
> 
> <xsl:output method="xml" encoding="utf-8" indent="no"/>
> 
> <xsl:variable name="file"
>                xml:base="http://example.com/path/"
>                select="xs:anyURI('file.xml')"/>
> 
> <xsl:template name="xsl:initial-template">
>    <xsl:call-template name="mytemplate">
>      <xsl:with-param name="file" select="$file"/>
>    </xsl:call-template>
> </xsl:template>
> 
> <xsl:template name="mytemplate">
>    <xsl:param name="file" as="xs:anyURI"/>
>    <doc>
>      <file><xsl:sequence select="$file"/></file>
>      <abs><xsl:sequence select="resolve-uri($file)"/></abs>
>    </doc>
> </xsl:template>
> 
> </xsl:stylesheet>
> 
> That stylesheet produces <file>file.xml</file> and
> <abs>file:/tmp/file.xml</abs> (because the stylesheet was in /tmp so that’s the static-base-uri() of the stylesheet.)
> 
> Having the same behavior as XSLT is in no way a technical requirement, but it is reasonable to argue that it’s “what users will expect.”
> 
> I’m coming around to the uncomfortable position that George is right about what the spec says, but it doesn’t say what we meant. Certainly, the p:namespace-rename case is strong evidence that resolving a relative URI against a base URI was intended to be selective, not universal.
> 
>                                          Be seeing you,
>                                            norm
> 
> --
> Norm Tovey-Walsh <ndw@nwalsh.com>
> https://norm.tovey-walsh.com/
> 
>> The lasting pleasures of contact with the natural world are not reserved for scientists but are available to anyone who will place himself under the influence of the earth, sea and sky and their amazing life.--Rachel Carson
>

Received on Friday, 27 June 2025 12:38:21 UTC