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Hello,

Karen Coyle wrote:

> Juha, thanks for the info regarding IETF activity. The issue I see with 
> URNs is not the structure but the minting: should libraries begin to 
> link their data I see a need for thousands or even tens of thousands of 
> identifiers (hundreds of thousands?) when we figure out a way to make 
> library holdings available to the linked data space. Surely we'll need 
> at least an identifier for each library. At least URIs piggy-back on the 
> domain system, which already exists.

Yes, a lot of identifiers will be needed. And if someone prefers to use 
URNs for this purpose, RFC 3188bis (the revised namespace registration 
request for National Bibliography Numbers, NBNs) makes it clear that 
these identifiers can be assigned to data elements as well.

Where these URN:NBNs resolve to and what kind of services they will be 
able to support will depend on the technical infrastructure available.
> 
> Definitely, this gives us something to think about, and I have no doubt 
> that we could develop some kind of naming/identifying system to carry 
> this data. Obviously the first step is to figure out what we need to 
> identify, a kind of requirements study.

Yes; and in addition we may need to consider what kind of services the 
identified things require.

> What I dislike about the persistent identifier is that you lose the link 
> to the originating agency that you have in the URI. That might be just a 
> "human thing" - that I feel better when looking at the URI that I can 
> see WHO is responsible. 

A persistent identifier may show the originating agency as well. Whether 
they do or don't, depends on the identifier system used. With URN:NBN 
the namespace specific string (the identifier part of the URN) may be 
semantic, if that is the preference of the organization assigning those 
identifiers. But in the long run it may not be a good idea to include 
the originating agency into the identifier, since organisations (and 
even more so, their domain names) may be more short-lived than the 
things they create. Cool URIs, just like semantic identifiers, may tell 
who originated the resource, but there is a good chance that they do not 
tell who is currently responsible for keeping the resource available. A 
different method for finding this out must be available.

ARKs, of course, give you both, at least in
> theory. Is anyone using the "?" feature of ARKs that lets you query for 
> that information? Should such info be part of our best practices?

I don't know if the "?" and "??" features of ARK are in use, and if so, 
by whom. John Kunze may be able to tell that. But I do think that 
providing this functionality in a PID system is a good idea, and will 
"lend" it into the URN system (in case John doesn't mind ;-)). Although 
the practical implementation in the URN system will probably be an 
option of retrieving preservation metadata / rights metadata about the 
resource.

Revised version of the URN syntax (RFC2141bis) allows the use of <query> 
and <fragment>. <query> will never be part of the URN, but it could be 
used to carry service-related information. For example, this base URN:

http://urn.fi/URN:ISBN:978-952-10-7612-1

provides the user the default service (splash page describing the 
resource, and providing a link to the book), but this URN:

http://urn.fi/URN:ISBN:978-952-10-7612-1?I2C

will supply descriptive metadata about the resource in the default 
format, provided that the resolution service knows how to deal with the 
service request in <query> (I2C = URI to resource description).

In the context of linked data, we might be interested in enabling for 
instance retrieval of the definition of a concept in the chosen language 
(?ENG for English, ?SWE for Swedish, and so on). Whatever linking 
mechanisms are used (PIDs, cool URIs or something else) they should 
enable us to do whatever needs to be done.

Links are an essential feature in linked data, and we should plan 
carefully the implementation of this functionality - and not take for 
instance the functionality cool URIs are currently providing as the 
predetermined basis for our work.

All the best,

Juha
> 
> kc
> 
>>
>>>> - what should the URI resolve to?
>>
>> URN-related RFCs are currently being revised (see
>> http://datatracker.ietf.org/wg/urnbis/). I am currently writing a new
>> version of RFC 2483, which specifies the resolution services URN can
>> provide. In the present RFC 2483 the list of services is fixed. RFC
>> 2483bis will be based on the idea that IANA should establish a registry
>> of informal and formal resolution services. Then URN user communities
>> could register new services at will (and parameters to these services,
>> for instance for requesting descriptive metadata about the resource in
>> different formats).
>>
>> Existing persistent identifier systems provide a diverse set of
>> services. With ARK, for instance, it is possible to check the
>> preservation commitment of the organisation holding a resource. I don't
>> know if the PID systems will become more homogeneous in this respect in
>> the future.
>>
>> Nobody knows what the URIs utilized within this initiative should
>> resolve to, but I am sure that the mechanism to be built should be
>> flexible so that it can be adjusted to meet the future needs we don't
>> foresee yet.
>>
>> Best regards,
>>
>> Juha
>>
>>>>
>>>> That kind of thing.
>>>>
>>>
>>> Does anyone know an answer to any of these questions? Therefore, I
>>> think, no URI is better than no URI at all. Use brief and simple and
>>> easily memorized codes for vocabularies like the terms in 337-338, and
>>> use IDnumbers for names and subjects and titles.
>>> Any implementation can easily relate them to all sorts of URIs that may
>>> be in current use or follow best practice or resolve to something
>>> useful for the purpose at hand. Verbal terms need changes and are
>>> language-bound, URLs are perishable, only codes and numbers are robust,
>>> easy to handle, and versatile.
>>>
>>> B.Eversberg
>>
> 

-- 

  Juha Hakala
  Senior advisor, standardisation and IT

  The National Library of Finland
  P.O.Box 15 (Unioninkatu 36, room 503), FIN-00014 Helsinki University
  Email [log in to unmask], tel +358 50 382 7678