At Thu, 2 Apr 2009 19:29:49 +0100,
Rob Sanderson wrote:
> All I meant by that was that the info:doi/ URI is more informative as to
> what the identifier actually is than just the doi by itself, which could
> be any string. Equally, if I saw an SRW info URI like:
> that's more informative than some ad-hoc URI for the same thing.
> Without the external knowledge that info:doi/xxx is a DOI and
> info:srw/cql-context-set/2/ is a cql context set administered by the
> owner with identifier '2' (which happens to be me), then they're still
> just opaque strings.
Yes, info:doi/10.1111/xxx is more easily recognizable (‘sniffable’) as
a DOI than 10.1111/xxx, both for humans and machines.
If we don’t know, by some external means, that a given string has the
form of some identifier, then we must guess, or sniff it.
But it is good practice to use other means to ensure that we know
whether or not any given string is an identifier, and if it is, what
type it is. Otherwise we can get confused by strings like go:home. Was
that a URI or not?
That said, I see no reason why the URI:
is more informative than the URI:
As you say, both are just opaque URIs without the additional
information. This information is provided by, in the first case, the
info-uri registry people, or, in the second case, by the organization
that owns srw.org.
> I could have said that http://srw.cheshire3.org/contextSets/rel/ was the
> identifier for it (SRU doesn't care) but that's the location for the
> retrieval documentation for the context set, not a collection of
> abstract access points.
> If srw.cheshire3.org was to go away, then people can still happily use
> the info URI with the continued knowledge that it shouldn't resolve to
If srw.cheshire3.org goes away, people can still happily use the http
URI. (see below)
> With the potential dissolution of DLF, this has real implications, as
> DLF have an info URI namespace. If they'd registered a bunch of URIs
> with diglib.org instead, which will go away, then people would have
> trouble using them. Notably when someone else grabs the domain and
> starts using the URIs for something else.
The original URIs are still just as useful as identifiers, they have
become less useful as dereferenceable identifiers.
> Now if DLF were to disband AND reform, then they can happily go back to
> using info:dlf/ URIs even if they have a brand new domain.
The info:dlf/ URIs would be the same non-dereferenceable URIs they
always were, true. But what have we gained?
The issue of persistence of dereferenceablity is a real one. There are
solutions, e.g, other organizations can step in to host the domain;
the ARK scheme; or, we can all agree that the diglib.org domain is too
important to let be squatted, and agree that URIs that begin
http://diglib.org/ are special, and should by-pass DNS. 
> > I think that all of us in this discussion like URIs. I can’t speak
> > for, say, Andrew, but, tentatively, I think that I prefer
> > <info:doi/10.1111/xxx> to plain 10.111/xxx. I would just prefer
> > <http://dx.doi.org/10.1111/xxx>
> info URIs, In My Opinion, are ideally suited for long term
> identifiers of non information resources. But http URIs are
> definitely better than something which isn't a URI at all.
Something we can all agree on! URIs are better than no URIs.
1. Take with a grain of salt, as this is not something I have fully
thought out the implications of.
;; Erik Hetzner, California Digital Library
;; gnupg key id: 1024D/01DB07E3