This is one of the clearest articulations of the problem I've heard in a long while.
We know how to deal with simple string values, and how to qualify them
(subproperties and datatypes, in RDF-ese). We don't know yet how to
preserve widearea interoperability and data re-use as we move from this
realtively well understood realm towards more complex, highly strucured
multi-namespace data exchange. It's OK, that's a difficult problem for
everyone...
Dan
On Sat, 9 Mar 2002, Andy Powell wrote:
> On Fri, 8 Mar 2002, Carl Lagoze wrote:
>
> > Andy, is there any reason in your mind why we should NOT allow xHTML
> > in the values of the simple schema. My first reaction is that it
> > opens the door sufficiently to allow things like MathML but does not
> > push it wide open into unrestricted land.
>
> I'm not really sure... but my feeling is that 'simple DC' means simple
> literal string values and *nothing* else.
>
> Here's my thinking...
>
> We need to have a shared understanding of what we mean by a 'simple DC'
> application.
>
> Currently, that understanding has to work across applications that are not
> based on XML. I'm thinking here about applications that carry metadata
> using non-XML encodings such as HTML4/meta, Z39.50/GRS-1, Z39.50/MARC, ...
>
> Any two 'simple DC' applications should be able to exchange all their
> metadata. Anything encoded in one 'simple DC' application, should be able
> to be encoded in another with no loss of data.
>
> 'Simple DC' is our most dumbed-down form of metadata. It provides our
> base level of interoperability between different services. (Simple DC is
> the equivalent of the plain text rendered by, say, lynx - not the (X)HTML
> page on which that rendering is based).
>
> XHTML carried in DC element values does *not* feel like 'simple DC' to me.
> I completely agree that it would be a useful thing to be able to do (and
> at least one of the services I'm involved in would like to be able to do
> it!) - but I wouldn't call it 'simple DC' and I don't think support for it
> should appear in a 'simple DC' XML schema.
>
> Finally, as an aside...
>
> It seems to me that the problems associated with trying to embed
> structured content within DC element values is the aspect of DC that we
> understand least currently. I think we now have a good understanding of
> qualified DC in terms of element refinement and encoding schemes. But we
> still don't know how to handle structured content very well. For example,
> we have the rather messy situation in which it is not clear if the DCMI
> Box encoding scheme is a 'formatted string' or an 'XML application' or
> both. I think this stems from an acknowledgement that we can do some
> things in XML-based applications that we can't do in text-based
> applications but without being quite sure how to handle that properly in
> practice.
>
> Andy.
>
> > > -----Original Message-----
> > > From: Roland Schwaenzl
> > > [mailto:[log in to unmask]]
> > > Sent: Friday, March 08, 2002 1:17 PM
> > > To: [log in to unmask]
> > > Subject: Re: Public Comment on DC-simple XML Schema declaration within
> > > OAI
> > >
> > >
> > > > From [log in to unmask] Fri Mar 8 16:30 MET 2002
> > > > content-class: urn:content-classes:message
> > > > MIME-Version: 1.0
> > > > X-MimeOLE: Produced By Microsoft Exchange V6.0.5762.3
> > > > Thread-Topic: Re: Public Comment on DC-simple XML
> > > Schema declaration
> > > > within OAI
> > > > Thread-Index: AcHGrDpz/EG80hNpQAmDGuSf4riG1QACWQMg
> > > > Date: Fri, 8 Mar 2002 10:30:05 -0500
> > > > From: Carl Lagoze <[log in to unmask]>
> > > > Subject: Re: Public Comment on DC-simple XML Schema
> > > declaration within OAI
> > > > Comments: cc: Herbert Van de Sompel <[log in to unmask]>
> > > > To: [log in to unmask]
> > > > Content-Transfer-Encoding: 8bit
> > > > X-MIME-Autoconverted: from quoted-printable to 8bit by
> > > scarlett.mathematik.Uni-Osnabrueck.DE id QAA20116
> > > >
> > > > Roland,
> > > >
> > > > Regarding point 1: The prohibition as you state it sound
> > > pretty draconian; seems like some of the people originally
> > > motivated OAI (eprints folks) would want mathML. Remind me
> > > again, is there a solution that allows things like mathML but
> > > forbid arbitrary other XML?
> > >
> > > >
> > >
> > > Sure, you could (!) do that. W3C's xml-schema-primer has an
> > > example, with content restricted to XHTML:
> > > http://www.w3.org/TR/xml-schema-0 sec.5.5. It's the example
> > > preceding the textType example.
> > > In particular table 4 in that section is quite useful as
> > > summary of built in facilities.
> > > There's a similar technique with attributes.
> > >
> > > One could try: http://www.w3.org/1998/Math/MathML for a namespace URI.
> > >
> > > There's some use of MathML embedded into XHTML -
> > > (cf. processContents="skip" in the example cited above)
> > >
> > >
> > > rs
> > >
> > >
> > >
> > > > Carl
> > > >
> > > > I've copied to Herbert Van de Somple because the MathML
> > > thing might be of concern to him also.
> > > >
> > > >
> > > >
> > > > > -----Original Message-----
> > > > > From: Roland Schwaenzl
> > > > > [mailto:[log in to unmask]]
> > > > > Sent: Friday, March 08, 2002 9:19 AM
> > > > > To: [log in to unmask]
> > > > > Subject: Re: Public Comment on DC-simple XML Schema
> > > declaration within
> > > > > OAI
> > > > >
> > > > >
> > > > > Dears,
> > > > >
> > > > > with us it's now the time for reports rather than development.
> > > > > I'll not be able to follow this discussion the coming week.
> > > > >
> > > > >
> > > > > Let me try to summarize, what i understand currently from
> > > the dc-xml
> > > > > discussion.
> > > > >
> > > > >
> > > > > 1. In OAi the use of dc:elements with the xml- simple
> > > > > dataType "string" will (continue to) be required in
> > > > > the mandatory part of OAi.
> > > > > It could be, that OAi allows a dataType extension by
> > > > > the xml:lang attribute.
> > > > >
> > > > > [In particular no mark-up from W3C's MathML or Ruby will
> > > be allowed in
> > > > > oai-dc records].
> > > > >
> > > > > 2. There are mixed views on (details of) requirements, design
> > > > > and coding
> > > > > for dcmi supported "plain-xml"-schemes.
> > > > >
> > > > >
> > > > > Please correct me on mistaken points.
> > > > >
> > > > >
> > > > > Best,
> > > > > rs
> > > > >
> > > >
> > >
> >
>
> Andy
> --
> Distributed Systems, UKOLN, University of Bath, Bath, BA2 7AY, UK
> http://www.ukoln.ac.uk/ukoln/staff/a.powell +44 1225 383933
> Resource Discovery Network http://www.rdn.ac.uk/
>
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