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Hello,

Bernhard Eversberg wrote:
> Am 08.02.2012 12:53, schrieb Karen Coyle:
>>
>> I actually wasn't thinking about readable v. opaque URIs, but that is
>> one topic for best practices. In my experience, you get loud complaints
>> with opaque URIs, but readable URIs are highly problematic.

In ISO TC 46/SC 9 (which develops identifier standards) there is a trend 
towards non-semantic (opaque) identifiers. The main argument in favour 
of this is that any semantics may eventually become meaningless. A 
counterargument is that if the identifier is used as a  URI, semantics 
may provide a hint for locating the correct resolution service(s) from 
the Internet. In this case such hints may not be necessary.

>> I was thinking about things like:
>> - "cool" URIs - hash? or no?

At least some technical experts think that the main weakness of the so 
called cool URIs is the need to maintain the domain name registration 
(and the organizations' inability to carry on with it for decades). See

http://www.ietf.org/mail-archive/web/urn/current/msg01670.html

>> - PURLs v. agency domains

I would prefer persistent identifiers to cool URIs in this case. But the 
PID discussion should not concentrate on PURLs only. There are three 
other persistent identifier systems (DOI, Handle and URN) which are more 
popular and better standardized.

>> - 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
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