Collection Mirrors

[Josh Reed <jareed@xxxxxxxxxxx>]

Hello all,

I don't know if this is the most appropriate place to ask this, so if  
it isn't excuse my ignorance and point me in the right direction.

I'm working on an application that distributes information/metadata  
about a set of scientific images and data.  I'm using the Atom format  
with liberal use of external namespaces to add additional metadata  
like image orientation, dpi, etc.  Previously I had been using a hand- 
rolled XML file to point to these various Atom feeds of images and  
such.  Now I'm trying to replace that file with an APP Service  
Document as well as bring in other APP capabilities, eventually  
providing a mechanism to post comments and such back to a collection.   
Doing the replacement is pretty straightforward, but one feature that  
I wanted to support is the concept of a mirror (geographically  
dispersed in my case).  I've been trying to grapple with how and where  
this information should be included.  I've been considering two  
approaches:

1) Mirror the files and feeds and specify the mirrors in the service  
document:
	<collection href="http://us.andrill.org/.../atom.xml";>
            <atom:title>Split Core Images</atom:title>
            <accept/>
            <atom:link rel="mirror eu" href="http://eu.andrill.org/.../atom.xml 
"/>
            <atom:link rel="mirror nz" href="http://nz.andrill.org/.../atom.xml 
"/>
        </collection>

All of the mirrored collections would use the same entry ids, but the  
entry content link would point to the mirror-specific URL.

2) Leave the service document alone and push the mirror information  
down into the feed and entries.  So the feed and entries would contain  
the
<atom:link rel="mirror eu" href="http://eu.andrill.org/.../somefile"/>

I'm leaning more towards #1 as it allows to fully distribute things  
without a single point of failure.  #2 is potentially more flexible  
since you can specify mirrors at the individual entry level, but I'm  
afraid that the feed will become needlessly bloated if each entry has  
2-3 extra "mirror" links for it.  Anyhow, I was wondering if anyone  
has tackled this issue already or if there is a preferred way.  I'm  
not expecting other applications to automatically understand the  
mirrors, I just don't want to do anything too orthogonal to the spirit  
of the spec.

Thanks for the time.

Cheers,
Josh

---
Josh Reed
ANDRILL IT Specialist
Tel.: (952) 681-2227
Cell: (612) 308-4011
Email: jareed@xxxxxxxxxxx

ANDRILL Science Management Office
126 Bessey Hall
University of Nebraska-Lincoln
Lincoln, NE  68588-0341
Fax: (402) 472-6723
URL: http://andrill.org