Gisle,
I will attempt to answer your queries from an Australian viewpoint>
Issue 1:
> I am myself working on an implemention that uses DC 1.0 as a metadata
> "core".
> I also need to be able to add some bits that are specific to my
> application
>
This is our recommended approach. Some subject gateways in Australia use a
combination of DC 1.0, EdNA, and ADMIN. We also make up short names as
required, for example, some elements in our metadata schema for our PADI
service are prefixed with PADI. We add elements rather than change the
meaning of a DC core element. [PADI not yet released, will keep you posted].
Issue 2:
> I would like to hear the arguments (pro et contra) of:
>
> - using a dicrete namespace (FAST.Version), vs.
> - extending DC (DC.Date.Version)
Discrete namespaces are currently supported for schemas in national use by
the DSTC's Reggie, which holds the schema for DC, EdNA, AGLS, IMS, vCard
etc. We generally advocate against using subclasses because it reduces
interoperability and future migration. The latter is especailly significant
because of the significant changes expecetd to subsequent versions of DC for
support of qualifiers. However, australia does have a couple of very
successful implementations of subclasses - see the Business Entry Point
metadata at
http://about.business.gov.au/bep/agencies/provinfo/metadata/metadata.htm.
It succeeds because the use of the metadata is tightly controlled. This will
facilitate future migration.
Issue 3:
> Consequently, we need a registry (e.g. IANA) where one can register
> different RDF/XML namespaces. Anyone picking a prefix can then
> at least check the registry to see that the one they fancy os
> available.
>
Absolutely. We do need a registry so people don't reinvent the wheel. This
has been talked about before, and Reggie at http://metadata.net is a useful
starting point for the southern hemisphere.
Debbie
Metadata Coordinator
Coordination Support Branch
National Library of Australia
ph. 02 6262 1673
fx. 02 6273 2545
e-mail [log in to unmask]
http://www.nla.gov.au/meta
> ----------
> From: Gisle Hannemyr[SMTP:[log in to unmask]]
> Sent: Tuesday, 11 May 1999 11:46 PM
> To: [log in to unmask]
> Subject: Re: DC-Chem
>
> [log in to unmask] wrote:
> > I'm concerned about this whole business of "guerrilla DC". I don't know
> how
> > enforceable this whole thing is, but it seems to me to be unacceptable
> to
> > have specialist groups unilaterally appropriating the DC prefix.
>
> I am concerned about some issues relating to this as well.
>
>
> Issue 1
> -------
>
>
> The solution I've adopted is to use the "DC/dc" prefix for strict DC
> elements, and the prefix "FAST/fast" for application specific elements.
>
> I don't see any problem mixing the two, so I have records like the
> following.
>
> In XML/RDF:
>
> <?xml version="1.0"?>
> <rdf:RDF
> xmlns:rdf="http://www.w3.org/TR/REC-rdf-syntax#"
> xmlns:dc="http://purl.org/dc/elements/1.0/"
> xmlns:fast="http://www.ifi.uio.no/~gisle/fast/meta.html">
> <Description xml:lang="en"
> rdf:about="ftp://ftp.server.edu/bobbas12.zip">
> <dc:creator>Bob Smith</DC:Creator>
> <fast:proglanguage>Java</FAST:Proglanguage>
> </Description>
> </RDF>
>
> Add in HTML:
>
> <LINK rel="schema.DC" href="http://purl.org/dc/elements/1.0/">
> <LINK rel="schema.FAST" href="
> http://www.ifi.uio.no/~gisle/fast/meta.html">
> <META NAME="DC.Creator" CONTENT="Bob Smith">
> <META NAME="FAST.Proglanguage" CONTENT="Java">
>
> Personally, I think this is reasonable.
>
> Comments?
>
>
> Issue 2
> -------
>
> However -- I have had comments from other participants in the metadata
> community who believe that it is _preferable_ to extend DC using
> element qualifiers (type) instread of creating a separate namespace.
>
> For exempel, we have an property to deal with version numbers, named
> "FAST.Version" (in HTML). Some has written to me and suggested that I
> instead create a DC.Date subclass (e.g. "DC.Date.Version") for this
> purpose.
>
> I would like to hear the arguments (pro et contra) of:
>
> - using a dicrete namespace (FAST.Version), vs.
> - extending DC (DC.Date.Version)
>
>
> Issue 3
> -------
>
> In both XML and in HTML namespaces are qualified (by the "xmlns"
> declaration in XML and the "LINK" relationship in HTML).
>
> Currently, I believe that the following is a perfectly valid
> start of an XML/RDF file:
>
> ?xml version="1.0"?>
> <rdf:RDF
> xmlns:rdf="http://www.w3.org/TR/REC-rdf-syntax#"
> xmlns:dc="http://my.site.com/my-dc.html"
> [etc...]
>
> What it does is to dfine a prefix choosen at random (I just happened
> to choose "dc" :-) and to state that this prefix is to be
> associated with the precise namespace defined by the URI
> "http://my.site.com/my-dc.html", (which has nothing whatsoever to do
> with the "Dublin Core").
>
> In _theory_ -- this may be fine. The idea is that whatever software
> it is that processes this record, it would just have to resolve the
> URI, look up the machine readable description of the syntax and
> semantics for the qualified namespace, and from there onwards do "the
> right thing"[tm].
>
> In _practice_ this will not work. There is (AFAIK) no way to capture
> the rich semantics of something like the DC in something machine
> readable. So implementors will train their software to recognize
> the "dc" prefix declaration and to ignore the contents of the URI
> the declaration points to. They can only hope that whatever is
> in the file pointed to by the URI is congurent with whatever they
> have already hardcoded into their software (which it will be as
> long as nobody uses the "dc" for something else out of ignorance
> or because they enjoy looking at the fallout).
>
> I don't think we can ignore the practical side of things.
> Consequently, we need a registry (e.g. IANA) where one can register
> different RDF/XML namespaces. Anyone picking a prefix can then
> at least check the registry to see that the one they fancy os
> available.
>
>
> --
> - gisle hannemyr ( [log in to unmask] - http://home.sol.no/home/gisle/ )
> ------------------------------------------------------------------------
> "Use the Source, Luke. Use the Source." -- apologies to Obi-Wan Kenobi
> ------------------------------------------------------------------------
>
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|