Archival Resource Key

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Archival Resource Key (ARK) is a Uniform Resource Locator (URL) that provides a multi-purpose identifier given to information objects of any type. ARKs contain the label ark: in the URL, which sets the expectation that the URL terminated by '?' returns a brief metadata record, and the URL terminated by '??' returns metadata that includes a commitment statement from the current service provider.

While ARKs have application in identifier persistence, the ARK scheme sees persistence as purely a matter of service and not a property of a naming syntax. The ARK inflections '?' and '??' are designed to permit service providers to convey to users some sense of their ability to provide persistence.

Contents

[edit] Structure

[http://NMAH/]ark:/NAAN/Name[Qualifier]
  • NAAN: Name Assigning Authority Number - mandatory unique identifier of the organization that originally named the object
  • NMAH: Name Mapping Authority Host - optional and replaceable hostname of an organization that currently provides service for the object
  • Qualifier: optional string that extends the base ARK to support access to individual hierarchical subcomponents of an object[1], and to variants (versions, languages, formats) of components[2].

[edit] Name Assigning Authority Numbers (NAANs)

A complete NAAN registry[3] is maintained by the California Digital Library and replicated at the Bibliothèque Nationale de France and the US National Library of Medicine. In 2011 it contained over 80 entries, some of which appear below.

[edit] Generic Services

Three generic ARK services have been defined. They are described below in protocol-independent terms. Delivering these services may be implemented through many possible methods given available technology (today’s or future).

[edit] Access Service (access, location)

  • Returns (a copy of) the object or a redirect to the same, although a sensible object proxy may be substituted (for instance a table of contents instead of a large document).
  • May also return a discriminated list of alternate object locators.
  • If access is denied, returns an explanation of the object’s current (perhaps permanent) inaccessibility.

[edit] Policy Service (permanence, naming, etc.)

  • Returns declarations of policy and support commitments for given ARKs.
  • Declarations are returned in either a structured metadata format or a human readable text format; sometimes one format may serve both purposes.
  • Policy subareas may be addressed in separate requests, but the following areas should be covered:
    • object permanence,
    • object naming,
    • object fragment addressing, and
    • operational service support.

[edit] Description Service

  • Returns a description of the object. Descriptions are returned in either a structured metadata format or a human readable text format; sometimes one format may serve both purposes.
  • A description must at a minimum answer the who, what, when, and where questions concerning an expression of the object.
  • Standalone descriptions should be accompanied by the modification date and source of the description itself.
  • May also return discriminated lists of ARKs that are related to the given ARK.

[edit] See also

[edit] Notes and references

  1. ^ Hierarchy qualifiers begin with a slash character.
  2. ^ Variant qualifiers begin with a dot character.
  3. ^ Name Assigning Authority Number registry [1]

[edit] External links


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