Interoperability Solutions for European Public Administrations got into the egg nog early:
D7.1.3 – Study on persistent URIs, with identification of best practices and recommendations on the topic for the MSs and the EC (PDF) (I’m not kidding, go see for yourself.)
Five (5) positive rules:
- Follow the pattern: http://(domain)/(type)/(concept)/(reference)
- Re-use existing identifiers
- Link multiple representations
- Implement 303 redirects for real-world objects
- Use a dedicated servive
Five (5) negative rules:
- Avoid stating ownership
- Avoid version numbers
- Avoid using auto-increment
- Avoid query strings
- Avoid file extensions
If the goal is “persistent” URIs, only the “Use a dedicated server” has any relationship to making a URIs “persistent.”
That is that five (5) or ten (10) years from now, a URI used as an identifier will return the same value as today.
The other nine rules have no relationship to persistence. Good arguments can be made for some of them, but persistence isn’t one of them.
Why the report hides behind the rhetoric of persistence I cannot say.
But you can satisfy yourself that only a “dedicated server” can persist a URI, whatever its form.
W3C confusion over identifiers and locators for web resources continues to plague this area.
There isn’t anything particularly remarkable about using a URI as an identifier. So long as it is understood that URI identifiers are just like any other identifier.
That is they can be indexed, annotated, searched for and returned to users with data about the object of the identification.
Viewed that way, that once upon a time there was a resource with the location specified by a URI, has little or nothing to do with the persistent of that URI.
So long as we have indexed the URI, that index can serve as a resolution of that URI/identifier for as long as the index persists. With additional information should we choose to create and provide it.
The EU document concedes as much when it says:
Without exception, all the use cases discussed in section 3 where a policy of URI persistence has been adopted, have used a dedicated service that is independent of the data originator. The Australian National Data Service uses a handle resolver, Dublin Core uses purl.org, services, data.gov.uk and publications.europa.eu are all also independent of a specific government department and could readily be transferred and run by someone else if necessary. This does not imply that a single service should be adopted for multiple data providers. On the contrary – distribution is a key advantage of the Web. It simply means that the provision of persistent URIs should be independent of the data originator.
That is if you read: “…independent of the data originator” to mean independent of a particular location on the WWW.
No changes in form, content, protocols, server software, etc., required. And you get persistent URIs.
Merry Christmas to all and to all…, persistent URIs as identifiers (not locators)!
(I first saw this at: New Report: 10 Rules for Persistent URIs)