Why identifiers? To access resources To cite resources To unambiguously identify a resource –To register it as intellectual property –To record changes in ownership

How we identify objects now ftp://ftp.is.co.za/rfc/rfc1808.txt gopher://spinaltap.micro.umn.edu/00/Weather/New%20York/ Ithaca

URLs Service instructions for accessing an object Oriented toward access/location vs. identification –Essentially, an address Most likely ephemeral service, protocol machine/host namelocal file location

Good Identifiers Globally unique Persistent | permanent –Even when the identified resource ceases to exist or is no longer available Independent of location

Good Identifier Schemes Scalable Extensible Support for legacy schemes –ISBNs, ISSNs, etc.

Uniform Resource Identifiers URL URN

URNs urn: :<Namespace Specific String Identifies an object Nothing about access mechanism, little about location Requires resolution services and registries –Indirection

URNs urn:issn: X urn:dwr:myOrganizations:theirMembers

Naming schemes Handle System –cnri.dlib/june98-powell DOI – /october2002-hitchcock ARK –ark://some.host/1234/ –ark:1234/

As (potential) URNs urn:hdl:cnri.dlib/june98-powell urn:doi: /october2002-hitchcock urn:ark://some.host 1234/

PURLs A persistent URL –Using indirection Temporary solution? Still identify a service, not an object –Not an actual “name” –Dependent on that service (HTTP)

In the interim Likely depend on proxy services for resolution to Cornell’s “doorstep” –urn:cul:... –urn:hdl:cul.rmc:... But inside our doors? –How do we manage identifiers within Cornell and/or Cornell University Library?

Identifiers and semantics Semantic identifiers –Perhaps intelligent to people –cnri.dlib/june98-powell Non-semantic identifiers –Not meaningful to people – /abc123456