Extensions on the registry

[Tony Linde]

> If "query" means "extract metadata from resource documents, 
> transform and present to user as XHTML", then clearly a given 
> registry can't do this properly for unknown extensions. 
> (Nominating XSLT stylesheets in processing instructions might help.)

No - registry does not 'present' the data in any way.

> If "query" means "return the resource document matching a 
> given IVOID" then that works with or without extensions.

Yes.

> If "query" means "return XML fragments extracted from 
> resource documents according to some query language such as 
> XQuery or ADQL" then it's less clear.

No - any such function would need to be extra functionality offered by a
registry (e.g. by offering an XQuery interface).

Cheers,
Tony. 

> -----Original Message-----
> From: owner-registry at eso.org [mailto:owner-registry at eso.org] 
> On Behalf Of Guy Rixon
> Sent: 13 April 2005 09:53
> To: Ray Plante
> Cc: registry at ivoa.net
> Subject: Re: Extensions on the registry
> 
> On Tue, 12 Apr 2005, Ray Plante wrote:
> 
> > On Tue, 12 Apr 2005, KevinBenson wrote:
> > > Does everybody agree that we should be able to on Full Registries 
> > > store all Resources including extension Resources?
> >
> > My current take, personally, is that Full registries *should* store 
> > all records, even though they contain extensions; however, I'm not 
> > sure I would go as far as "must", since this has potentially 
> > substantial implementation issues.  The next question is, what does 
> > this do to the meaning of "Full"?  If a registry does not include 
> > extensions, is it allowed to declare itself full, or can we 
> live with a fuzzier definition?
> >
> > > Would it be okay if certain Full Registries would not be able to 
> > > query on them and possibly never query on them (them being the 
> > > extension part of the schema's)?
> >
> > Yes.
> 
> Doesn't it depend on what you mean by query?
> 
> If "query" means "extract metadata from resource documents, 
> transform and present to user as XHTML", then clearly a given 
> registry can't do this properly for unknown extensions. 
> (Nominating XSLT stylesheets in processing instructions might help.)
> 
> If "query" means "return the resource document matching a 
> given IVOID" then that works with or without extensions.
> 
> If "query" means "return XML fragments extracted from 
> resource documents according to some query language such as 
> XQuery or ADQL" then it's less clear.
> My guess is that an XQuery or XPath query would work even on 
> resources-with-extensions and that an ADQL/SQL query might 
> have problems.
> 
> I think we should mandate the 
> return-entire-document-matching-IVOID query for all 
> registries even in the presence of extended documents. (I'd 
> also prefer XQuery over ADQL for the structured query, but 
> that's a separate issue.)
> 
> Cheers,
> Guy
> 
> Guy Rixon 				        gtr at ast.cam.ac.uk
> Institute of Astronomy   	                Tel: +44-1223-337542
> Madingley Road, Cambridge, UK, CB3 0HA		Fax: 
> +44-1223-337523
>