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Subject: RE: [office] 2009-01-08 Single ODF 1.2 metadata proposal


Thank you for this combined proposal.

I have two concerns.  

First, I wonder whether we are making a simple problem hard.  I appreciate
the care with which the metadata.rdf file is used to provide guidance to
external applications as well as ODF implementations to locate the separate
Zip items that add free-standing RDF (that is, external to the package items
that are subject-matter of the RDF) to the ODF package.  But some aspects of
this seem rather complex.  It would be useful if there were a schema rather
than just the ontology (since I don't think that is a substitute for the
schema, operating at a different level of abstraction, so-to-speak).

Secondly, I am concerned that there is not enough information to understand
how exactly those inter-dependent aspects of RDF/XML, RDFa, OWL, XML 1.0,
xml:id 1.0, and the URI/IRI rfs that are pertinent to the metadata proposal
are profiled against the special requirements and conditions that apply in
the ODF document structure. 

I am not comfortable enough with that complex of interdependencies to
suggest that the difficulties are fatal in any way.  I would hope that there
be some allowance for adjustments that may need to be made in the prose as
part of overall integration into a polished ODF 1.2 committee draft and in
careful review against the specifications that are referenced as somehow

Beside the interaction around XML 1.0, xml:id 1.0 and the use of ID
attributed types, which I will continue to address separately, here are two
examples of the kinds of thing that are part of this second concern:

1. The namespace prefix "xhtml" is assumed to be introduced but the
09-01-18-MetaData-Change-Request.odt uses it without saying what the
namespace is (or I missed it).  I assume that it is
"http://www.w3.org/1999/xhtml"; as mentioned in the "Adaption of W3C RDFa
standard" proposal,

   1.1 I think it would have been better *not* to use "xhtml" as the
illustrative prefix in the ODF 1.2 specification, because we do not mean to
appeal to the entire XHML namespace.  In that respect, assuming (for
illustrative purposes) something like
xmlns:rdfa="http://www.w3.org/1999/xhtml"; might be more useful in
emphasizing that we are using a very specific and limited profile of XHTML
markup (in fact, only a small number of attributes, nothing about XHTML
elements, roots, etc.).  We are still using the XHTML namespace, of course,
but the use of a different prefix is useful in warning readers not to assume
too much.

   1.2 A greater technical concern (rather than one about exposition) that I
have is that using the XHTML namespace, regardless of the prefix used, might
not accomplish the intended technical purpose and the effort required to
investigage that.  I notice in the RDFa specification
(http://www.w3.org/TR/2008/REC-rdfa-syntax-20081014/) that most of the XHTML
attribute names are used without any namespace prefix.  This suggests that
there is no namespace for those attributes, since the default namespace does
not apply to attributes in XML 1.0 (nor in XHTML 1.x).  I thought maybe the
unexplained notation @content, @about, @property, @datatype, etc., might
signify some solution to this, but it is necessary to refer to the XHTML
specification, not just the RDFa specification for resolution of that.  In
the XHTML Modularization W3C Recommendation 8 October 2008 (single file:
tion.html), section 3.1(5),
ation.html#s_conform_document_type>, does state that those attribute names
are also defined as local names of the XHTML namespace although the XHTML
Modularization specification is inapplicable to our use of the
RDFa-augmented XHTML attributes.  In the XHTML 1.0 specification
(http://www.w3.org/TR/2002/REC-xhtml1-20020801/) there is no mention of
attributes with regard to the use of XHTML namespaces (i.e., in section
3.1.2), and there is no indication that the no-namespace attribute names of
XHTML are also local names of the XHTML namespace.

   1.3 BOTTOM LINE: "@" is apparently an undocumented short-hand to refer to
an attribute name in the RDFa specification (it is not used in the XHTML
specification or the XHTML Modularization specification) and the only
suggestion that the XHTML namespace contains the XHTML attribute names as
local names with the significance they have as (extended) attributes in
XHMTL+RDFa is the statement at 3.1(5) in the Modularization specification.
Although the XHTML Namespace URL has a resource that can be dereferenced, it
is no help.  I have not checked the other links in that document to see if
there is anything more specific about this case.  We should not be made to
work so hard to be able to make careful review of the RDF metadata material
in the ODF specification.

2. The idea that the ODF Document must have a physically-resolvable URI goes
too far, especially when the example is of a location on the hard drive of a
computer for which there is no web-resolvable URI in evidence.  

   2.1 The difference between (copies of) document instances and some
understood URI that can be used to refer to features of any such (unaltered
copy of an) instance needs to be allowed for (and this is often recognized
in RDF and demonstrated in W3C RDFa examples, especially but not limited to
the reliance on Dublin Core concepts). Examples of such features are an ISBN
number, the name of the author, bibliographic information about it,
bibliographic information about something mentioned or discussed in it,
assertions about what someone says about it, assertions about what is being
said in the document about what someone says about something, such as in a
book review or literary critique, etc.  

   2.2 The use of URIs as concept identifiers that are never meant to be
resolved is critical in the working of RDF and is the underpinning of the
identification of relations and predicates and properties in RDF.  In many
respects, the document instance is a different entity than a particular
location where a copy of the instance might be located in a physical
repository or on the internet.  It seems clear to me that these prevalent
uses of RDF (illustrate in examples of RDFa) should not be constrained for
RDF annotation of ODF documents.

   2.3. The inter-dependence between the use of CURIEs and the rules for
URIs in ODF packages need to be explained very carefully.  I am assuming
that the ODF 1.2 package rule (section 2.6) for interpreting a URI does
apply after any CURIE expansion to a URI takes place, especially when the
expansion is to a relative URI.  This interdependence does need to be
accounted for, however.   The interdependence also needs to work properly
where, via the CURIE mechanism or not, the resulting URI has a lead string
(or Base URL) that signifies the package but is not an absolute URL that can
be used to access the package part and fragment being mentioned.  On
investigation into RDFa, I notice that reliance on xhtml:base attributes
could have been very useful (and would also need to be reconciled in Package
section 2.6).  There are some open questions in all of this, and I trust
there will be an opportunity to resolve them. 

 - Dennis

-----Original Message-----
From: Svante.Schubert@Sun.COM [mailto:Svante.Schubert@Sun.COM] 
Sent: Thursday, January 08, 2009 10:16
To: OASIS Office
Cc: Svante Schubert
Subject: Re: [office] Single ODF 1.2 metadata proposal

Dear TC members,

Obviously I had skipped one previous revision, but uploaded now a
correction [4]. I apologize for any trouble caused.

As quick summary of this proposal, which is only an enhancement of the
already agreed RDF based metadata proposal.

It was triggered from the feedback of the W3C:
 1) we overtook the now existing RDFa standard. Enable us to use compact
URIs, which for example will save us a lot of space in large spreadsheets.
 2) we provide a GRDDL file to make our metadata easier extractable for
none ODF application (e.g. RDF crawlers)
 3) we dropped boilerplate in connecting the ODF XML world with the RDF
world by simply using relative URLs, making resources behind the IRIs
accessible (like in a web) and better human readable.

Therefore this proposal is pretty much straight forward and I feel
really delighted that we have made this round-trip of refactoring.

PS: BTW XMP is based on RDF and can refer to any ODF resources described
by the new RDF framework. There is no problem.



Svante Schubert wrote:
> Three further remarks:
> 1) I have created and uploaded a W3C GRDDL file (the XSL stylesheet to
> create RDF/XML from RDFa and ODF elements from the meta.xml) [1]
> 2) The namespaces in the proposal have been adapted to the OASIS
> policies pointed out by Mary [2]
> 3) During work on the GRDDL stylesheet it came clear that the RDFa
> properties xhtml:content and xhtml:datatype are exclusive.
> This and the namespaces have been fixed in an updated draft [3].  
> Regards,
> Svante
> [1]
> [2] http://lists.oasis-open.org/archives/office/200812/msg00178.html
> [3]
> Svante Schubert wrote:
>> Dear TC members,
>> I would like to ask the TC to vote on this proposal on the next TC
>> call. If you have any further questions regarding the proposal,
>> please send them to me prior to the call.
>> Regards,
>> Svante
>> Svante Schubert wrote:
>>> Dear TC members,
>>> from my feedback of the W3C Semantic Web Interest group I would like
>>> to combine the previous three existing proposal parts to a single
>>> metadata proposal, consisting of three parts:
>>> Adaption of W3C RDFa standard
>>> Previously RDFa was not a W3C Recommendation and could not be reused
>>> in our spec, now we are able to adapt the official standard.
>>> Usage of W3C GRDDL standard
>>> Meant for non ODF applications to extract the RDF graph from our
>>> content.xml, styles.xml and meta.xml streams via a referenced XSL
>>> stylesheet.
>>> Similar adapted by XHTML files using RDFa standard. The location of
>>> the XSL stylesheet is resolved via the URL of the root namespace
>>> (ie. XHTML use case) or via a GRDDL attribute in the root element
>>> (i.e. ODF use case as namespace is an URN and no URL).
>>> Therefore the only effort for ODF applications is a new root element
>>> attribute, the effect enormous.
>>> (After proposal acceptance I would create the XSL stylesheets and
>>> place it on an OASIS server).
>>> Adaption of RDF mapping to relative URLs
>>> Currently in the new RDF mapping file (manifest.rdf) an arbitrary
>>> URN is being invented for every ODF element described in the RDF
>>> graph. But this creates troublesome URL alias. Instead the standard
>>> will require that a resource (ODF element) will be mapped directly
>>> to its relative URL.
>>> Currently I am finalizing the overall proposal. In case I will be
>>> ready this evening, I would set it on the agenda of the next TC call.
>>> PS: The previous announced ODF 1.2 proposal of fragment identifier
>>> for URLs to ODF mime types is being withdrawn by myself, due to the
>>> amount of proposals that have been requested to be considered for
>>> ODF 1.2.
>>> Regards,
>>> Svante
>>> -- 
>>> Sun Microsystems GmbH           Svante Schubert
>>> Nagelsweg 55                    Software Engineer
>>> 20097 Hamburg                   StarOffice / OpenOffice.org Development
>>> Germany                         Phone: +49(0)40 236 46 500
>>> http://www.sun.com              Svante.Schubert@sun.com
>>> Sitz der Gesellschaft:
>>> Sun Microsystems GmbH, Sonnenallee 1, D-85551 Kirchheim-Heimstetten
>>> Amtsgericht Muenchen: HRB 161028
>>> Geschaeftsfuehrer: Wolfgang Engels, Dr. Roland Boemer
>>> Vorsitzender des Aufsichtsrates: Martin Haering

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