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From Andreas Veithen <andreas.veit...@gmail.com>
Subject Re: Redundant names space removal when Serializing - AXIOM
Date Tue, 22 Nov 2011 13:06:52 GMT
Well, the problem is that that specification actually contradicts what
you are saying. You can find the relevant quote in section 2.1 "Data
Model":

"An element E has namespace nodes that represent its namespace
declarations as well as any namespace declarations made by its
ancestors that have not been overridden in E's declarations, the
default namespace if it is non-empty, and the declaration of the
prefix xml."

Removing a redundant namespace declaration therefore doesn't change
the data model because that declaration is "restored" by virtue of the
second part of that definition. Therefore the output of the
canonicalization (and hence the signature) doesn't change.

Andreas

Note: the superfluous namespace declarations implied by this
definition are eliminated by the following rule specified in section
2.3 "Processing Model":

"A namespace node N is ignored if the nearest ancestor element of the
node's parent element that is in the node-set has a namespace node in
the node-set with the same local name and value as N. Otherwise,
process the namespace node N in the same way as an attribute node,
except assign the local name xmlns to the default namespace node if it
exists (in XPath, the default namespace node has an empty URI and
local name)."

On Tue, Nov 22, 2011 at 13:31, Sanjiva Weerawarana
<sanjiva@opensource.lk> wrote:
> http://www.w3.org/TR/xml-c14n
>
> On Tue, Nov 22, 2011 at 5:59 PM, Sanjiva Weerawarana <sanjiva@opensource.lk>
> wrote:
>>
>> Please look at the C14N spec.
>>
>> On Tue, Nov 22, 2011 at 4:00 PM, Andreas Veithen
>> <andreas.veithen@gmail.com> wrote:
>>>
>>> Sanjiva,
>>>
>>> Can you substantiate these claims by references to the spec or
>>> concrete examples?
>>>
>>> Andreas
>>>
>>> On Tue, Nov 22, 2011 at 03:51, Sanjiva Weerawarana
>>> <sanjiva@opensource.lk> wrote:
>>> > Thanks for the clear writeup Andreas.
>>> > On Tue, Nov 22, 2011 at 12:41 AM, Andreas Veithen
>>> > <andreas.veithen@gmail.com> wrote:
>>> >>
>>> >> removal of redundant namespace declarations? I don't know the C14N
>>> >> specs well enough to answer that question, but I've seen that these
>>> >> specs make provisions to preserve the namespace context of the element
>>> >> and also define an algorithm to remove redundant namespace
>>> >> declarations (search for "superfluous" or "unnecessary" namespace
>>> >> declarations through the specs).
>>> >
>>> > Simple answer is that yes the spec is sensitive to any nodes being
>>> > removed,
>>> > including seemingly redundant namespace nodes. As Alek noted, with the
>>> > advent of XPath, its now possible for a namespace declaration that
>>> > looks
>>> > redundant to an XML parser to actually be required. However this case
>>> > is
>>> > simpler- the element is signed and removing the node breaks the
>>> > signature.
>>> > I think we need to have a way to say "don't mess with the XML
>>> > serialization
>>> > AT ALL" .. that is what we want in the case of Synapse is not just an
>>> > infoset preserving serialization but rather the EXACT serialization.
>>> > Sanjiva.
>>> > --
>>> > Sanjiva Weerawarana, Ph.D.
>>> > Founder, Director & Chief Scientist; Lanka Software Foundation;
>>> > http://www.opensource.lk/
>>> > Founder, Chairman & CEO; WSO2; http://wso2.com/
>>> > Founder & Director; Thinkcube Systems; http://www.thinkcube.com/
>>> > Member; Apache Software Foundation; http://www.apache.org/
>>> > Visiting Lecturer; University of Moratuwa; http://www.cse.mrt.ac.lk/
>>> >
>>> > Blog: http://sanjiva.weerawarana.org/
>>> >
>>>
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>>> To unsubscribe, e-mail: dev-unsubscribe@ws.apache.org
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>>>
>>
>>
>>
>> --
>> Sanjiva Weerawarana, Ph.D.
>> Founder, Director & Chief Scientist; Lanka Software Foundation;
>> http://www.opensource.lk/
>> Founder, Chairman & CEO; WSO2; http://wso2.com/
>> Founder & Director; Thinkcube Systems; http://www.thinkcube.com/
>> Member; Apache Software Foundation; http://www.apache.org/
>> Visiting Lecturer; University of Moratuwa; http://www.cse.mrt.ac.lk/
>>
>> Blog: http://sanjiva.weerawarana.org/
>
>
>
> --
> Sanjiva Weerawarana, Ph.D.
> Founder, Director & Chief Scientist; Lanka Software Foundation;
> http://www.opensource.lk/
> Founder, Chairman & CEO; WSO2; http://wso2.com/
> Founder & Director; Thinkcube Systems; http://www.thinkcube.com/
> Member; Apache Software Foundation; http://www.apache.org/
> Visiting Lecturer; University of Moratuwa; http://www.cse.mrt.ac.lk/
>
> Blog: http://sanjiva.weerawarana.org/
>

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