Re: Time dependence/interaction with PURLs was: Re: URL +1, LSID -1

Alan Ruttenberg wrote:
> Two points to make about this. First, the current locations are not 
> hidden - the rewrite rules are accessible, and the agent that follows 
> the redirect can note the actual location.

You're right, and in fact the "Wayback Machine" seems to do that. However, 
if I wanted to make a comment about a specific web page, I'd still prefer 
to attach it to the actual URL than some redirection URL that may in future 
just redirect to some other URL that is seen as equivalent, but not for me.

> Second, how are we to know that this page changes over time, and that we 
> might need to protect ourselves. Making this sort of knowledge available 
> to our agents is another important piece of the puzzle. LSIDs had a 
> single policy identifying that the "data" portion never changes. We've 
> found over time that while this policy works for some cases, it doesn't 
> work for all. I've suggested that we need to define a set of policies 
> that reflect the actual practices and associate a policy with each 
> resource. In order to not box ourselves in, it is desirable that there 
> is an extension mechanism for the policy set so that if new policies 
> become useful we have a way to make agents aware of them.

Explicit support for version numbers is useful: You could assume that a URI 
with a version number is unchangeable, and a URI without is changeable...

Received on Monday, 16 July 2007 09:04:29 UTC