resource identifiers

[Tony Linde]

Hi Ray,

(10 min break :) )

> As I've said, this breaks uniformity for refering to parts.  
> This also means we cannot allow a "#..." corresponding to a 
> RecordKey in the URI form since it cannot be unambigously 
> converted back to the XML form.  

This would be uniform for SIA where it matters. And if SIA says that
ImageKey follows the '#' then it is easily converted back.

> I guess I'm not grasping why.  I've argued that the RecordKey 
> does not break the model of an identifier (it is 
> fundementally the same problem, I think), and it incurs 
> minimal cost to consumers.  The benefit is that we have a 
> uniform solution of identifying parts that will surely be 
> useful beyond SIA.

The key (groan!) point is that RecordKey is not needed as part of the
ResourceID to uniquely identify a resource. Identifying *parts* of a
resource is nothing to do with the registry and solely to do with how that
resource is used. If users of a type of resource (eg SIA types) want to
standardise on some way of identifying parts then they are free to do so and
to create a namespaced schema.

And if you want to create a 'generalised' part identifier which includes
ResourceID and RecordKey then go for it - personally I'd argue that it is
better for the users of resource types to define their own since nothing is
served by having one common such identifier, but I'm not overly bothered.

Cheers,
Tony. 

> -----Original Message-----
> From: Ray Plante [mailto:rplante at poplar.ncsa.uiuc.edu] 
> Sent: 28 May 2003 15:55
> To: registry at ivoa.net
> Subject: RE: resource identifiers
> 
> 
> Hi Tony,
> 
> On Wed, 28 May 2003, Tony Linde wrote:
> > I think that at heart I am really uncomfortable with having the 
> > ResourceID including a component that never gets used in 
> the registry.
> 
> ...
> 
> > <SiaImageID>
> >   <ResourceID>
> >     <AuthorityID>www.ncsa.uiuc.edu</AuthorityID>
> >     <ResourceKey>ADIL/SIA/targeted</ResourceKey>
> >   </ResourceID>
> >   <ImageKey>95.DR.01.01.fits</ImageKey>
> > </SiaImageID>
> 
> As I've said, this breaks uniformity for refering to parts.  
> This also means we cannot allow a "#..." corresponding to a 
> RecordKey in the URI form since it cannot be unambigously 
> converted back to the XML form.  (I don't think the URI form 
> can be effectively extended later because non-supporters of 
> <SiaImageID> won't know what to do with it.)
> 
> If <RecordKey> cannot be part of the <ResourceID>, then I 
> think the only 
> solution is to drop Req. (4).
> 
> > The ResourceID should be used solely to describe a resource 
> registered 
> > within the VO and this requires only the AuthorityID and the 
> > ResourceKey.
> 
> I guess I'm not grasping why.  I've argued that the RecordKey 
> does not break the model of an identifier (it is 
> fundementally the same problem, I think), and it incurs 
> minimal cost to consumers.  The benefit is that we have a 
> uniform solution of identifying parts that will surely be 
> useful beyond SIA.
> 
> I appreciate your desire to keep the role of IDs "lean and 
> mean", which is 
> why I think its good to frame this in terms of requirements.  
> 
> cheers,
> Ray
>