An Archival Resource Key (ARK) is a multi-purpose URL suited to being a persistent identifier for information objects of any type. It is widely used by libraries, data centers, archives, museums, publishers, and government agencies to provide reliable references to scholarly, scientific, and cultural objects. In 2019 it was registered as a Uniform Resource Identifier (URI).[1]
A URL that is an ARK is distinguished by 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.[incomprehensible] The ARK and its inflections ('?' and '??') provide 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.
History
Throughout the 1990s, the Internet Engineering Task Force and other organizations developed standards for persistent identifiers for web resources, including URN, PURL, Handle, and DOI. In each of these standards, indirect identifiers would resolve to URLs, which themselves changed over time. Many believed that such systems would contribute to the persistence of web resources over time. [2]
In 2001, John Kunze of the University of California and R. P. Channing Rodgers of the United States National Library of Medicine released the first draft of “The ARK Persistent Identifier Scheme,” designed in response to the needs of their two organizations, as an IETF working document.[3] In explaining their motivations for creating a new system, Kunze later wrote that “each [persistent identifier] system had specific problems.” In contrast to the decentralized structure of the web, with many independent publishers, Handle and DOI were related centralized systems which charged for inclusion; they were “antithetical,” according to Kunze, “to an implicit principle that Internet standards must not endorse control by any one entity, over access to the networked resources of another entity.” URNs were free, but lacked a resolver discovery services, and, wrote Kunze, “it seemed to me that the IETF community lost interest in creating a whole new Internet indirection infrastructure that would add little to existing web and DNS mechanisms, especially in light of the small part that indirection plays in keeping links from breaking.”[2]
In contrast to these other systems, the ARK scheme proposed that “persistence is purely a matter of service,… neither inherent in an object nor conferred on it by a particular naming syntax.” The most an identifier could do to solve the problem of persistence, then, was to indicate an organization’s commitment. Accordingly, in the ARK standard, identifiers would refer not only to a web resource, but also to “a promise of stewardship” and metadata about the resource. If a web server was queried with an ARK, it should return the resource itself or some surrogate for it, such as “a table of contents instead of a large complex document.” If a question mark was appended to the ARK, though, it should return a description—metadata—instead, which “must at minimum answer the who, what, when, and why questions concern an expression of the object.” (The scheme also included a guide to Electronic Resource Citations, a simple format for structuring this metadata.) If two question marks were appended, the server should return the provider’s policies regarding “object persistence, object naming, object fragment addressing, and operational service support.”[3]
California Digital Library began using ARKs in 2002, and released the Noid (Nice Opaque IDentifiers) software for managing ARKs and other identifiers in 2004. Other early adopters of ARKs included Portico, the Internet Archive, and the Bibliothèque nationale de France, the first of several francophone institutions to adopt the scheme.
In 2018, the California Digital Library and DuraSpace announced a collaboration, initially named ARKs-in-the-Open and then the ARK Alliance, to build an international community around ARKs and their use in open scholarship. By 2021, over 800 institutions registered to use ARKs.[2]
Structure
https://NMA/ark:/NAAN/Name[Qualifier]
NAAN: Name Assigning Authority Number - mandatory unique identifier of the organization that originally named the object
NMA: Name Mapping Authority - 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,[4] and to variants (versions, languages, formats) of components.[5]
ARKs may be assigned to anything digital, physical, or abstract. Below are examples, as reported (2020) to the ARK Alliance by the linked organizations.
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.
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.
The Dublin Core, also known as the Dublin Core Metadata Element Set (DCMES), is a set of fifteen main metadata items for describing digital or physical resources. The Dublin Core Metadata Initiative (DCMI) is responsible for formulating the Dublin Core; DCMI is a project of the Association for Information Science and Technology (ASIS&T), a non-profit organization.
A Uniform Resource Identifier (URI) is a unique sequence of characters that identifies a logical or physical resource used by web technologies. URIs may be used to identify anything, including real-world objects, such as people and places, concepts, or information resources such as web pages and books. Some URIs provide a means of locating and retrieving information resources on a network ; these are Uniform Resource Locators (URLs). A URL provides the location of the resource. A URI identifies the resource by name at the specified location or URL. Other URIs provide only a unique name, without a means of locating or retrieving the resource or information about it; these are Uniform Resource Names (URNs). The web technologies that use URIs are not limited to web browsers. URIs are used to identify anything described using the Resource Description Framework (RDF), for example, concepts that are part of an ontology defined using the Web Ontology Language (OWL), and people who are described using the Friend of a Friend vocabulary would each have an individual URI.
The Resource Description Framework (RDF) is a World Wide Web Consortium (W3C) standard originally designed as a data model for metadata. It has come to be used as a general method for description and exchange of graph data. RDF provides a variety of syntax notations and data serialization formats, with Turtle currently being the most widely used notation.
A Uniform Resource Name (URN) is a Uniform Resource Identifier (URI) that uses the urn scheme. URNs are globally unique persistent identifiers assigned within defined namespaces so they will be available for a long period of time, even after the resource which they identify ceases to exist or becomes unavailable. URNs cannot be used to directly locate an item and need not be resolvable, as they are simply templates that another parser may use to find an item.
A digital object identifier (DOI) is a persistent identifier or handle used to uniquely identify various objects, standardized by the International Organization for Standardization (ISO). DOIs are an implementation of the Handle System; they also fit within the URI system. They are widely used to identify academic, professional, and government information, such as journal articles, research reports, data sets, and official publications. DOIs have also been used to identify other types of information resources, such as commercial videos.
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Webcal is a uniform resource identifier (URI) scheme for accessing iCalendar files. WebCal allows you to create and maintain an interactive events calendar or scheduling system on a Web site or app.
A web resource is any identifiable resource present on or connected to the World Wide Web. Resources are identified using Uniform Resource Identifiers (URIs). In the Semantic Web, web resources and their semantic properties are described using the Resource Description Framework (RDF).
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In IETF specifications, a Uniform Resource Characteristic (URC) is a string of characters representing the metadata of a Uniform Resource Identifier (URI), a string identifying a Web resource. URC metadata was envisioned to include sufficient information to support persistent identifiers, such as mapping a Uniform Resource Name (URN) to a current Uniform Resource Locator (URL). URCs were proposed as a specification in the mid-1990s, but were never adopted.
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