An Archival Resource Key (ARK) is a Uniform Resource Locator (URL) that is a multi-purpose persistent identifier for information objects of any type. An ARK contains the label ark: after the URL's hostname, which sets the expectation that, when submitted to a web browser, 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. The ARK and its inflections ('?' and '??') gain access to three facets of a provider's ability to provide persistence. Implicit in the design of the ARK scheme is that persistence is purely a matter of service and not a property of a naming syntax. Moreover, that a "persistent identifier" cannot be born persistent, but an identifier from any scheme may only be proved persistent over time. The inflections provide information with which to judge an identifier's likelihood of persistence. ARKs can be maintained and resolved locally using open source software such as Noid (Nice Opaque Identifiers) or via services such as EZID and the central N2T (Name-to-Thing) resolver.
1 Structure 2 Name Assigning Authority Numbers (NAANs) 3 Generic Services
3.1 Access Service (access, location) 3.2 Policy Service (permanence, naming, etc.) 3.3 Description Service
4 See also 5 Notes and references 6 External links
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, and to variants (versions, languages, formats) of components.
Name Assigning Authority Numbers (NAANs)
A complete NAAN registry is maintained by the California Digital
Library and replicated at the
Bibliothèque Nationale de France
12025: National Library of Medicine 12148: Bibliothèque Nationale de France 13030: California Digital Library 13038: World Intellectual Property Organization 13960: Internet Archive 14023: Revista de Arte, Ciência e Comunicação 14365: Colectica 15230: Rutgers University 17101: Centre for Ecology & Hydrology 20775: University of California, San Diego 21198: University of California Los Angeles 26678: Frantiq 25031: University of Kansas 25593: Emory University 25652: École nationale supérieure des mines de Paris 26677: Library and Archives Canada 27927: Portico/Ithaka Electronic-Archiving Initiative 28722: University of California Berkeley 29114: University of California San Francisco 32150: University of Durham 35911: IEEE 39331: National Library of Hungary 45487: Russian Linguistic Bulletin (Российский Лингвистический Бюллетень) 48223: UNESCO 52327: Bibliothèque et Archives Nationales du Québec 61001: University of Chicago 62624: New York University 64269: Digital Curation Centre 65323: University of Calgary 67531: University of North Texas 78319: Google 78428: University of Washington 80444: Northwest Digital Archives 81055: British Library 88435: Princeton University 87925: University College Dublin
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). 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.
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.
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.
Digital object identifier
Notes and references
^ Hierarchy qualifiers begin with a slash character. ^ Variant qualifiers begin with a dot character. ^ Name Assigning Authority Number registry
ARK (Archival Resource Key), California Digital Library Towards Electronic Persistence Using ARK Identifiers, California Digital Library The ARK Identifier Scheme, Internet Engineering Task Force Name-to-Thing Resolver Noid (Nice Opaque Identifiers) open source software EZID