OASIS Open Document Format for Office Applications (OpenDocument) TC

  • 1.  RDF metadata as an extension mechanism

    Posted 02-13-2009 15:19 
    Hi all,

in this mail i'd like to share some thoughts on using RDF metadata as an 
extension mechanism.
First, i would like to address an example that Doug Mahugh has posted:

Doug Mahugh wrote:



It seems quite simple to implement this with the current RDF metadata 
support, as specified by ODF 1.2.
Basically, we need to identify the paragraph in content.xml that contains 
the abstract, and annotate it with an RDF property that expresses its, 
umm, "abstract-ness". We assume that our hypothetical CMS wants to keep 
all of the metadata that it is interested in in a separate RDF graph; at 
least, that is what i would recommend. This graph, stored in the stream 
"mymetafile.rdf" in the ODF package, contains the RDF statement which 
annotates the paragraph. In order for the CMS to find its RDF graph, we 
list it in the "manifest.rdf", and declare it to be of a user-defined type 
that the CMS understands.
Spelling things out explicitly, this gives:

Doug's example, implemented with RDF metadata:
(RDF examples are in N3 syntax, because RDF/XML is ... unintuitive)

in manifest.rdf:


  • 2.  Re: [office] RDF metadata as an extension mechanism

    Posted 02-13-2009 16:13 
    Michael Stahl wrote:

> Imho, given that ODF already has a quite powerful mechanism for
> extension (RDF), any other proposed extension mechanisms should be
> closely scrutinized as to whether they actually add some expressive
> power, or merely add additional complexity by introducing different ways

*LOL*

Michael, with respect, proposing to use RDF and few lines of SPARQL
query over XPath oneliner seems like adding complexity to me, not vice
versa.

RDF (and related SemWeb technologies) is what it is. But I don't think
that you can sell it as advantage of ODF 1.2 that you can use few
triplets and few lines of SPARQL instead of just one attribute and one
short XPath expression. This migh attract few SemWeb addicts in the
world, but it will make normal developer quite scary.

It is good that ODF has general metadata mechanism based on RDF. But
mapping everything to RDF datamodel is overkill.

> Having just read a couple of the weblog articles that Doug has posted
> here in another mail about the customXml feature of OOXML, i do not see
> anything that would be obviously impossible to do with RDF metadata.
> The main difference between the two approaches is the data model:
> with customXml, the metadata is an XML tree, while with RDF, it is an
> RDF graph. Granted, some data is expressed more easily with a flexible
> graph, and other data more easily with a strict hierarchy, but i don't
> think that would be a deal-breaker either way.

It is much much easier to query XML tree (be it using customXML or my
private extensions) then to query RDF graph. I don't know any single
language which has integrated SPARQL engine in its standard libraries.
But I know dozen of languages that have integrated XPath.

> Furthermore:
> RDF metadata allow us to specify not only data that describes data (i.e.
> metadata), but we can iterate this another time to get data that
> describes data that describes data.

Surely. One can ever come with ontology to describe ODF documents and
model complete document using only RDF graph without using ODF at all ;-D

				Jirka

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