[OAI-implementers] ListMetadataFormats problem

[lagoze@cs.cornell.edu]

Jeff, I think you've got the wrong approach here.  Having spent the last
hour or so staring at the xml schema primer at
http://www.w3.org/TR/xmlschema-0  I found the explanation on importing
types at http://www.w3.org/TR/xmlschema-0/#import.  Using this mechanism
you can pull in types (elements) from another namespace.  E.g., you
could define a schema carlmeta.xsd with a target namespace
http://foo.org/carlmeta with an import of
http://purl.org/dc/elements/1.1.  I quote the primer:

When schema components are imported from multiple namespaces, each
namespace must be identified with a separate import element. The import
elements themselves must appear as the first children of the schema
element. Furthermore, each namespace must be associated with a prefix,
using a standard namespace declaration, and that prefix is used to
qualify references to any schema components belonging to that namespace.
Finally, import elements optionally contain a schemaLocation attribute
to help locate resources associated with the namespaces. 

Don't have time now to experiment with this but coming up with an
example shouldn't be too hard.

Carl

> -----Original Message-----
> From: Young,Jeff [mailto:jyoung@oclc.org]
> Sent: Tuesday, January 30, 2001 4:58 PM
> To: 'lagoze@cs.cornell.edu'
> Subject: FW: [OAI-implementers] ListMetadataFormats problem
> 
> 
> Hi Carl,
> 
> I don't think things are as simple as I'd hoped. I want to 
> check with you
> first, though, before I stir up more confusion in the 
> listserv. Apparently,
> the xsi:schemaLocation element expects namespaces to be 
> paired with schema
> locations. If this is true, then a single schema won't work for the
> application I described below. Is there any reason that 
> schemas can't be
> repeatable as well as namespaces in relation to metadata formats?
> 
> Jeff
> 
> > -----Original Message-----
> > From: Young,Jeff [mailto:jyoung@oclc.org] 
> > Sent: Tuesday, January 30, 2001 4:01 PM
> > To: 'OAI-implementers'
> > Subject: [OAI-implementers] ListMetadataFormats problem
> > 
> > 
> > I'm working on an OAI repository for a group that wants to 
> > define it's own
> > metadata format. The trick is, this format will be a 
> > combination of Dublin
> > Core elements and some new elements yet to be defined. The 
> > examples in the
> > OAI specs, however, all assume that the metadata will consist 
> > of elements
> > from a single namespace. I believe, for the most part, that 
> > the OAI spec
> > doesn't preclude the use of multiple namespaces. For example, 
> > I imagine that
> > the following XML fragment is likely to be acceptable:
> > 
> > <combined xmlns:dc="http://purl.org/dc/elements/1.1/"
> > 	xmlns:myelems="http://www.myelems.com/"
> > 	xmlns:xsi="..."
> > 	xsi:schemaLocation="http://purl.org/dc/elements/1.1/
> > 		http://www.myelems.com/
> > 		http://www.myelems.com/combined.xsd">
> >   <dc:title>This is the title</dc:title>
> >   <myelems:shoesize>12</myelems:shoesize>
> > </combined>
> > 
> > (As far as I can tell, specifying multiple namespaces in the
> > xsi:schemaLocation attribute is perfectly valid.)
> > 
> > Assuming no one sees any problems with this, I do think I see 
> > a problem with
> > ListMetadataFormats.xsd. Now that multiple namespaces are 
> > involved, I expect
> > that ListMetadataFormats will need to accommodate them with multiple
> > metadataNamespace elements. The XML schema for 
> > ListMetadataFormats, however,
> > sets the maxOccurs for metadataNamespace to one. I suspect 
> > this is easily
> > changed to unbounded.
> > 
> > Hopefully, the problem is no more involved than this, but 
> > someone may want
> > to check my assumptions.
> > 
> > Thanks,
> > Jeff
> > 
> > ---
> > Jeffrey A. Young
> > Senior Consulting Systems Analyst
> > Office of Research, Mail Code 710
> > OCLC Online Computer Library Center, Inc.
> > 6565 Frantz Road
> > Dublin, OH   43017-3395
> > www.oclc.org
> > 
> > Voice:	614-764-4342
> > Fax:		614-764-2344
> > Email:	jyoung@oclc.org
> > 
> > 
> > 
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>