No,  not identical URIs.

Let's say I've put a copy of the schema permanently at each of the following 

Three locations, three URIs.

But the issue of redirect or even resolution is irrelevant in the use case 
I'm citing.   I'm talking about the use of an identifier within a protocol, 
for the sole purpose of identifying an object that the recipient of the URI 
already has - or if it doesn't have it it isn't going to retrieve it, it 
will just fail the request.   The purpose of the identifier is to enable the 
server to determine whether it has the schema that the client is looking 
for.  (And by the way that should answer Ed's question about a use case.)

So the server has some table of schemas, in that table is the row:

["mods schema]   [ <URI identifying the mods schema>]

It recieves the SRU request:
identifying the mods schema>

If the "URI identifying the MODS schema" in the request matches the URI in 
the table, then the server know what schema the client wants, and it 
proceeds.  If there are multiple identifiers then it has to have a row in 
its table for each.

Does that make sense?


----- Original Message ----- 
From: "Ross Singer" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, April 01, 2009 2:07 PM
Subject: Re: [CODE4LIB] resolution and identification (was Re: [CODE4LIB] 
registering info: uris?)

> Ray, you are absolutely right.  These would be bad identifiers.  But
> let's say they're all identical (which I think is what you're saying,
> right?), then this just strengthens the case for indirection through a
> service like  Then it doesn't *matter* that all of these are
> different locations, there is one URI that represent the concept of
> what is being kept at these locations.  At the end of the redirect can
> be some sort of 300 response that lets the client pick which endpoint
> is right for them -or arbitrarily chooses one for them.
> -Ross.
> On Wed, Apr 1, 2009 at 1:59 PM, Ray Denenberg, Library of Congress
> <[log in to unmask]> wrote:
>> We do just fine minting our URIs at LC, Andy. But we do appreciate your
>> concern.
>> The analysis of our MODS URIs misses the point, I'm afraid. Let's forget
>> the set I cited (bad example) and assume that the schema is replicated at
>> several locations (geographically dispersed) all of which are planned to
>> house the specific version permanently. The suggestion to designate one 
>> as
>> cannonical is a good suggestion but it isn't always possible (for various
>> reasons, possibly political). So I maintain that in this scenario you 
>> have
>> several *location* none of which serves well as an identifier. I'm not
>> arguing (here) that info is better than http (for this scenario) just 
>> that
>> these are not good identifiers.
>> --Ray
>> ----- Original Message ----- From: "Houghton,Andrew" <[log in to unmask]>
>> To: <[log in to unmask]>
>> Sent: Wednesday, April 01, 2009 1:21 PM
>> Subject: Re: [CODE4LIB] resolution and identification (was Re: [CODE4LIB]
>> registering info: uris?)
>>>> From: Code for Libraries [mailto:[log in to unmask]] On Behalf Of
>>>> Karen Coyle
>>>> Sent: Wednesday, April 01, 2009 1:06 PM
>>>> To: [log in to unmask]
>>>> Subject: Re: [CODE4LIB] resolution and identification (was Re:
>>>> [CODE4LIB] registering info: uris?)
>>>> The general convention is that "http://" is a web address, a location.
>>>> I
>>>> realize that it's also a form of URI, but that's a minority use of
>>>> http.
>>>> This leads to a great deal of confusion. I understand the desire to use
>>>> domain names as a way to create unique, managed identifiers, but the
>>>> http part is what is causing us problems.
>>> http:// is an HTTP URI, defined by RFC 3986, loosely I will agree that
>>> it is a web addresss. However, it is not a location. URIs according
>>> to RFC 3986 are just tokens to identify resources. These tokens, e.g.,
>>> URIs are presented to protocol mechanisms as part of the dereferencing
>>> process to locate and retrieve a representation of the resource.
>>> People see http: and assume that it means the HTTP protocol so it must
>>> be a locator. Whoever initially registered the HTTP URI scheme could
>>> have used "web" as the token instead and we would all be doing:
>>> <web://>. This is the confusion. People don't understand
>>> what RFC 3986 is saying. It makes no claim that any URI registered
>>> scheme has persistence or can be dereferenced. An HTTP URI is just a
>>> token to identify some resource, nothing more.
>>> Andy.