Re: [xml-dev] XML processor behavior with unused NS declarations

[Jeff Greif <jgreif@alumni.princeton.edu>]

But note that the XML Canonicalization (used for preparing XML for
crypotographic signatures and transmission to another party that wants
to verify that the XML was not tampered with) will probably remove
those namespace declarations.

Jeff

On Tue, Jul 14, 2009 at 9:58 AM, G. Ken
Holman<gkholman@cranesoftwrights.com> wrote:
> At 2009-07-14 11:38 -0500, Chuck Bearden wrote:
>>
>> Is a namespace-aware XML processor permitted to drop a namespace
>> declaration when no elements or attributes in that namespace are used within
>> the scope of the declaration?  Say, given this example from the RDRa Primer:
>>
>>  <div xmlns:dc="http://purl.org/dc/elements/1.1/";>
>>     <h2 property="dc:title">The trouble with Bob</h2>
>>     <h3 property="dc:creator">Alice</h3>
>>     ...
>>  </div>
>>
>> there's no danger of the processor dropping the 'xmlns:dc' declaration,
>> correct?
>>
>> I looked at the Namespaces in XML recommendation, and it doesn't mention
>> omitting them.  A namespace-unaware processor would treat NS declarations
>> like attributes and hence not drop them, so I reckon that a NS-aware
>> processor should match that behavior as well, but confirmation from the
>> cognoscenti is welcome!
>
> In your example, they are not benign ... in my XSLT processing of the
> attributes I may have a need for de-referencing the prefix I discover in the
> attribute value.  I would use the namespace axis in order to find the URI
> associated with the prefix.  Without it, how would I know that "dc:title" is
> the Dublin Core title?  I doubt I could rely on solely the prefix.
>
> And also the XPath data model needs that information in order to support
> in-scope-prefixes() and other library functions that supply namespace
> information.
>
> Although I cannot find chapter and verse in the namespaces specification, I
> think you are not permitted to drop the namespace declaration in an XML
> processor that will be used for data models such as the XDM.  How would you
> know the context in which your XML processor is being used?  I suppose if
> you choose not to keep the declaration around then you would have to
> advertise that fact so that users of the processor understand the
> limitations.  But I think you just have to keep them around.
>
> I hope this helps.
>
> . . . . . . . . . . . . Ken
>
> --
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