> From: Code for Libraries [mailto:[log in to unmask]] On Behalf Of
> Ray Denenberg, Library of Congress
> Sent: Wednesday, April 01, 2009 2:38 PM
> To: [log in to unmask]
> Subject: Re: [CODE4LIB] resolution and identification (was Re:
> [CODE4LIB] registering info: uris?)
> No, not identical URIs.
> Let's say I've put a copy of the schema permanently at each of the
> Three locations, three URIs.
> But the issue of redirect or even resolution is irrelevant in the use
> I'm citing. I'm talking about the use of an identifier within a
> for the sole purpose of identifying an object that the recipient of the
> already has - or if it doesn't have it it isn't going to retrieve 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
> for. (And by the way that should answer Ed's question about a use
> 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
> 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
> its table for each.
> Does that make sense?
Absolute sense to me. Since LC is the "author/creator" of MODS it should
create a Real World Object URI for MODS version 3.3 schema. So LC now
Everyone uses that URI for the SRU recordSchema parameter. What LC has
done is define a URI with the following policy statement:
1) Type of usage: Real World Object (RWO)
2) Persistence: Yes
3) Resolvable: No
As a side issue, one could argue that placing a schema at:
and not having an authorized location is a recipe for disaster. One of
those URIs is an authorized URI the other two are URI aliases. So
according to RFC 2616 you would probably what to have the latter two
URIs either redirect 301/302/307 back to the first URI or have the
latter two return a 200 with a Content-Location header containing
the first URI. Now user agents can figure out which is the authorized
version of the schema and which are URI aliases.