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Re: issue-dbooth-10: Does an XML namespace necessarily imply semantics?

From: Harry Halpin <hhalpin@ibiblio.org>
Date: Tue, 19 Jun 2007 18:37:37 -0400
Message-ID: <46785AB1.3040803@ibiblio.org>
To: Harry Halpin <hhalpin@ibiblio.org>
Cc: "Booth, David (HP Software - Boston)" <dbooth@hp.com>, public-grddl-comments@w3.org

Note that I have added the following paragraph to the GRDDL Primer[1],
which I believe satisfies your comment, David:

This sentence  is padding to make it flow with the rest of the primer:

"In this example, the link to the GRDDL transformation was added by
hand. However, as shown in detail in the GRDDL specification [GRDDL]
<http://www.w3.org/2001/sw/grddl-wg/doc29/primer.html#GRDDL>, a
GRDDL-aware agent can also retrieve the namespace document of an XML
dialect to find a GRDDL transformation by "following its nose" from the
namespace on the root element of the GRDDL source document to the
namespace document. "


This is the sentence that I believe addresses your comment:

"The use of a namespace on the root element represents a declaration
that the document conforms to the authoritative definition of that
namespace as defined by the namespace owner, which may include a
transformation from that XML dialect into RDF using GRDDL."

Is your comment satisfied?

[1]http://www.w3.org/2001/sw/grddl-wg/doc29/primer.html


Harry Halpin wrote:
>
> On Tue, 29 May 2007, Booth, David (HP Software - Boston) wrote:
>
>> This is not a significant issue from my perspective, since as DanC
>> pointed out, the TAG has already answered the question.  (I was not
>> aware that it had when I wrote the issue.)
>>
>> In looking over the GRDDL primer editor's draft:
>> http://www.w3.org/2001/sw/grddl-wg/doc29/primer.html
>> I don't see any example of using a namespaceTransformation, and that is
>> the place where it would have been natural to add an explanation of the
>> namespace semantics.  If the primer is expanded to include such an
>> example, then I suggest added text along the lines of: "Use of a
>> namespace on the root element represents a declaration that the document
>> conforms to the semantics of that namespace as defined by the namespace
>> owner" and reference the TAG's decision on this.
>
> Thanks David, if we use such an example in the Primer, we will add
> that text.
>
>>
>> In short, I'm fine with leaving this to the editors' discretion, so this
>> issue can be closed.  I am satisfied with the WG's response.
>>
>> Thanks
>>
>> David Booth, Ph.D.
>> HP Software
>> +1 617 629 8881 office  |  dbooth@hp.com
>> http://www.hp.com/go/software
>>
>>
>>> -----Original Message-----
>>> From: Harry Halpin [mailto:hhalpin@ibiblio.org]
>>> Sent: Friday, May 25, 2007 7:35 PM
>>> To: Booth, David (HP Software - Boston)
>>> Cc: public-grddl-comments@w3.org; Jeremy Carroll; McBride, Brian
>>> Subject: RE: issue-dbooth-10: Does an XML namespace
>>> necessarily imply semantics?
>>>
>>> I am happy to (about to go on 2 week vacation, but when I return) add
>>> warning text to primer if it is thought necessary. If so,
>>> David, please
>>> provide the exact text. Does this satisfy this comment?
>>>
>>> Furthermore, as regards the spec and GRDDL itself, it seems
>>> to implicit in
>>> the very  definition of GRDDL that by using a namespace document.
>>>
>>> "Likewise, by specifying a GRDDL namespace transformation or profile
>>> transformation, the creator of that namespace or profile
>>> states that the
>>> transformation will provide a faithful RDF rendition of a
>>> class of source
>>> documents which relate to that namespace or profile. A
>>> namespace document
>>> or a profile document also provide a means for their authors
>>> to explain in
>>> prose the purpose of the transformation or any policy statements." [1]
>>>
>>> Providing a faithful rendition is another way of hitting upon
>>> the same
>>> issue regarding the use of an XML Vocabulary, as in the  case
>>> of Ralph he
>>> would not be providing a faithful rendition.
>>>
>>> Note that furthermore the TAG has made this decision re the
>>> root node, not
>>> all the nodes. Thus, this does support our decision to postpone any
>>> issues about applying GRDDL transformations to XPath nodes not
>>> specified on on the root node.
>>>
>>> [1]http://www.w3.org/2004/01/rdxh/spec
>>>
>>> ware - Boston) wrote:
>>>
>>>>
>>>> While I was preparing the message below, DanC replied to
>>> Jeremy's query
>>>> on this, saying that the WG and TAG had considered this
>>> question, and an
>>>> XML namespace on the root element *does* imply a certain set of
>>>> semantics:
>>>>
>>> http://lists.w3.org/Archives/Public/public-grddl-wg/2007May/0071.html
>>>>
>>>> FWIW, I agree with the TAG's position on this, so the only remaining
>>>> question for the GRDDL WG is whether the GRDDL spec should include a
>>>> warning about this.  Actually, I think the best approach might be to
>>>> include a brief explanation of this in the GRDDL primer.
>>>>
>>>> David Booth, Ph.D.
>>>> HP Software
>>>> +1 617 629 8881 office  |  dbooth@hp.com
>>>> http://www.hp.com/go/software
>>>>
>>>>
>>>>> -----Original Message-----
>>>>> From: public-grddl-comments-request@w3.org
>>>>> [mailto:public-grddl-comments-request@w3.org] On Behalf Of
>>>>> Booth, David (HP Software - Boston)
>>>>> Sent: Friday, May 25, 2007 11:50 AM
>>>>> To: public-grddl-comments@w3.org
>>>>> Cc: Jeremy Carroll; McBride, Brian
>>>>> Subject: issue-dbooth-10: Does an XML namespace necessarily
>>>>> imply semantics?
>>>>>
>>>>>
>>>>> This is a personal comment -- not on behalf of HP.
>>>>>
>>>>> This is the formal submission of the comment Jeremy already
>>>>> sent to the
>>>>> WG on my behalf:
>>>>>
>>> http://lists.w3.org/Archives/Public/public-grddl-wg/2007May/0061.html
>>>>>
>>>>> Does an XML namespace necessarily imply a certain set of semantics?
>>>>> Suppose Freddy at example.org defines a convenient XML schema for
>>>>> writing a person's legal residence ("a:primaryAddress") a
>>>>> vacation home
>>>>> address ("a:secondaryAddress"), such as:
>>>>>
>>>>> <a:root xmlns:a="http://example.org/AddressSchema.xml">
>>>>>   <a:primaryAddress>25 Park St, Rochester, NY</a:primaryAddress>
>>>>>   <a:secondaryAddress>88 Spring St, Salem, MA</a:secondaryAddress>
>>>>> </a:root>
>>>>>
>>>>> Freddy makes the XML schema definition downloadable from
>>> the namespace
>>>>> URI, and separately provides prose documentation to his users
>>>>> explaining
>>>>> the meaning and purpose of a:primaryAddress and
>>> a:secondaryAddress in
>>>>> his application.  In essence, Freddy's app treats this document as
>>>>> though it had made the following assertions:
>>>>>
>>>>>   foo:_lucy foo:legalResidence "25 Park St, Rochester, NY".
>>>>>   foo:_lucy foo:vacationAddress "88 Spring St, Salem, MA".
>>>>>
>>>>> Later, Ralph needs a schema for billing and shipping
>>> addresses and he
>>>>> notices that Freddy's AddressSchema has the exact form he needs:
>>>>> a:primaryAddress could represent the billing address and
>>>>> a:secondaryAddress could represent the shipping address.  In other
>>>>> words, Ralph wishes to reuse the syntax only.  (This is
>>> analogous to
>>>>> implementation inheritance in OO programming.)  Raph notes
>>> that an XML
>>>>> schema only defines the structure of a document -- not the
>>>>> semantics --
>>>>> and the namespace spec does not seem to say anything about
>>>>> the semantics
>>>>> of a namespace either.  Ralph reuses Freddy's schema by
>>> reference, and
>>>>> provides separate prose documentation to his users
>>> explaining that the
>>>>> syntax (only) of Freddy's schema is being reused but the
>>> semantics are
>>>>> to be the semantics specified by Ralph.  Example:
>>>>>
>>>>> <a:root xmlns:a="http://example.org/AddressSchema.xml">
>>>>>   <a:primaryAddress>123 Winter St, Palo Alto, CA</a:primaryAddress>
>>>>>   <a:secondaryAddress>444 El Camino, San Diego,
>>>>> CA</a:secondaryAddress>
>>>>> </a:root>
>>>>>
>>>>> In essence, Ralph's app treats this document as though it
>>> had made the
>>>>> following assertions:
>>>>>
>>>>>   fum:_desi fum:billingAddress "123 Winter St, Palo Alto, CA".
>>>>>   fum:_desi fum:shippingAddress "444 El Camino, San Diego, CA".
>>>>>
>>>>> Later Freddy decides to update his XML schema document at
>>>>> http://example.org/AddressSchema.xml to declare a GRDDL
>>> transformation
>>>>> in the namespace document such that the above example
>>> would be GRDDL
>>>>> transformed to RDF.  Ralph may have no knowledge of GRDDL
>>> and may be
>>>>> unaware of this change, but suddenly Ralph's documents gain the
>>>>> semantics of Freddy's documents according to the GRDDL spec.
>>>>> Questions
>>>>> Was Ralph wrong to re-use Freddy's namespace and syntax
>>> schema while
>>>>> imparting his own semantics to that schema?  If so, what
>>> spec forbids
>>>>> this?  (Presumably this is a question for the W3C TAG.)
>>>>>
>>>>> My own view at present is that a namespace should be viewed
>>>>> as implying
>>>>> the semantics that its owner declares, regardless of
>>> whether GRDDL is
>>>>> used.  Hence, Ralph should not give his document different
>>> semantics
>>>>> than Freddy somehow specifies via his namespace document.
>>> If Freddy's
>>>>> semantics are not clear to Ralph, then Ralph should not
>>> use Freddy's
>>>>> namespace, due to the risk of guessing wrong.
>>>>>
>>>>> However, since I do not at present see anything in the
>>>>> namespace spec or
>>>>> the WebArch that forbids this kind of syntax-only reuse,
>>> perhaps the
>>>>> GRDDL spec should address the possibility of its allowance.
>>>>> If so, what
>>>>> should the GRDDL spec say?
>>>>>
>>>>> Option 1: Add some warning text in the spec.  This might include
>>>>> suggesting that GRDDL aware agents check last modified times
>>>>> on docs and
>>>>> namespace docs, but this does not seem like it would be reliable.
>>>>>
>>>>> Option 2: Record a postponed issue (possibly to be referred
>>>>> to the TAG).
>>>>>
>>>>> At present I think either option would be okay.
>>>>>
>>>>>
>>>>> David Booth, Ph.D.
>>>>> HP Software
>>>>> +1 617 629 8881 office  |  dbooth@hp.com
>>>>> http://www.hp.com/go/software
>>>>>
>>>>>
>>>>
>>>>
>>>
>>> -- 
>>>                  --harry
>>>
>>>      Harry Halpin
>>>      Informatics, University of Edinburgh
>>>          http://www.ibiblio.org/hhalpin
>>>
>>
>


-- 
		-harry

Harry Halpin,  University of Edinburgh 
http://www.ibiblio.org/hhalpin 6B522426
Received on Tuesday, 19 June 2007 22:37:46 GMT

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