Thursday, December 02, 2004

Persistent Digital Object Identifiers

An open source release of a tool for generating unique persistent digital object names and other identifiers has been made. The tool, called "noid" (nice opaque identifier), can be used as a major piece of an overall identifier strategy no matter which naming scheme you choose (e.g., ARK, DOI, Handle, LSID, PURL, or URN). The documentation, updated Nov 30, is technical on the whole, but it starts with a general overview and a brief tutorial section. This software release is available as open source.

A paper describing the motivation for persistent identifiers and for ARKs (Archival Resource Key).

The "noid" (rhymes with void) tool creates minters, or identifier generators, and accepts commands that operate them. Once created, a minter can produce persistent, globally unique names for documents, databases, images, vocabulary terms, etc.

Properly managed, minted identifiers can be used as long term durable information object references within naming schemes such as ARK, PURL, URN, DOI, and LSID. At the same time, alternative minters can be set up to produce short term names; for example, transaction identifiers and compact web server session keys. These are some of the ways in which the California Digital Library is using noids.

A minter can bind arbitrary metadata to identifiers with individual stored values or rule-based values. Included are instructions for setting up a URL interface and a name resolver. Based on open source Berkeley DB databases, minters are extremely fast, scalable, reliable, and easy to create, and they have a small technical footprint.

Naming and identifying are decisions of what constitutes a work, manifestation or expression and have implications in cataloging.

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