How should the Registry handle mirrors?

[Ray Plante]

Hi,

First off, anyone who is concerned about these issues should bookmark 
Clive's and Pierre's posts:  Clive's for a good summary of the problem, 
and Pierre's for the real world experience.

Although we have discussed this topic extensively, there's definitely no 
harm in keeping it in everyone's mind since, as Tony points out, we have 
not settled on a solution.  Just to catch up those who haven't been in 
this discussion, I'll briefly summarize some other bits of the discussion 
history.

1. Role of Title, ShortName, and Publisher

On Thu, 24 Jun 2004, Clive Page wrote:
> Is it
> sufficient for the Title element to be identical (so all Vizier clones are
> simply called "Vizier" (or "VizieR"?).  The Identifier (URI) will
> obviously be different, but what about the ShortName, and the Publisher?

Tony answered the main question about how to register mirror status.  I 
just want to add that there no requirements about what the values of Title 
and ShortName should be, other than they are chosen by the provider.  
Thus, applications should *not* rely on them as unambiguous identifiers; 
they are for human consumption.  Publisher is a little different because 
you can attach an identifier.  However, our model is that a mirror of 
resource maintained by a different organization is essentially a 
re-publishing; that is, the new org is the publisher of the mirror.  

2. On Logical Identifiers

An approach from the DL world is to associate a logical identifier 
with a set of resources that is location independent.  Twice we (I) have 
attempted to insert this concept into our XML metadata and both times the 
idea was shelved by the WG as needing more work (for the reasons Tony 
alluded to).  Our current thinking is that we will see how the "mirror-of" 
relationship works for now.  I think this is a wise approach.

3. Who determines mirror status

The "mirror-of" relationship implies two publishers, and it would be nice 
if they both acknowledged this in some way.  However, at the moment, the 
publisher of the mirror is the one that asserts this claim.

cheers,
Ray