User finds HTML link to PID
User clicks on link and should get back something that makes sense in a browser - either the thing identified or some document about the thing or about access to the thing.
User finds PID in non-linked form
Perhaps less and less common but in various areas of scholarship printed material is still very important. User should be able to recognize that identifier is resolvable, be able to copy/type into browser and then get something useful. Brings in notions of recognizability and brevity/copyability (e.g. long string of digits hard to copy accurately).
Web indexing
We will want resources identified and linked with PIDS to be indexed in popular search engines (Google, Yahoo!, msn, etc.). The URL that the resource is indexed under should be the PID and not the final server (true?). What requirements for redirection etc. should be fulfilled? I think this means that 302 redirect would be appropriate.
Play nicely with the Semantic Web (should we consider this?)
A client makes a request for a resource identified with a PID indicating that it wants data (RDF/XML) in the Accept header. Should this be supported at the resolver level (return via 303 some description of the resource, its ids and any public metadata in the resolver?) or should we consider this not a function of the resolver and instead leave metadata query to some other interface? The potential value of this is not limited to Semantic Web applications - what is described is similar to the OAI getcapabilities request.
Or should the resolver pass the request header to the permanent resource and let the permanent resource respond with data? We may have 2 use cases here – one a request for the metadata of the PID itself and the other for data from the identified resource.
Retrofitting a CUL web site with PID's
A website manager is asked to change all the links on a site to PID's. He or she can follow a defined workflow for assigning PID's to links, for modifying location references, and for replacing referenced URL's with PID's.
We need a solution for legacy websites incapable of being modified to store the PIDs created; the resolver must be able to assume that the original URL provided for the resource will continue to function, or that some alternative will be provided when the legacy website ceases to respond. This becomes a matter of policy rather than technology.