Internet Engineering Task Force E. Zierau, Ed. Internet-Draft The Royal Danish Library Intended status: Informational December 7, 2017 Expires: June 10, 2018 A Persistent Web IDentifier (PWID) URN Namespace draft-pwid-urn-specification-00 Abstract This document specifies a Uniform Resource Name (URN) for Persistent Web IDentifiers to web material in web archives using the 'pwid' namespace identifier. The purpose of the standard is to support general, global, sustainable, humanly readable, technology agnostic, persistent and precise web references for web materials. The PWID URN can assist in two ways: First, by providing potential resolvable precise and persistent reference scheme for documents, which is not sufficiently covered by existing web reference practices. Second, by providing a standardized way to specify web elements in a web collection also known as web corpus. Definitions of web collections are often needed for extraction of data used in production of research results, e.g. for evaluations in the future. Current practices today are not persistent as they often use some CDX version, which vary for different implementations. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on June 10, 2018. Zierau Expires June 10, 2018 [Page 1] Internet-DraftA Persistent Web IDentifier (PWID) URN NamespDecember 2017 Copyright Notice Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 2. Namespace Registration Template . . . . . . . . . . . . . . . 3 3. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11 4. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 4.1. Normative References . . . . . . . . . . . . . . . . . . 11 4.2. Informative References . . . . . . . . . . . . . . . . . 12 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 13 1. Introduction The purpose of the PWID URN is to represent general, global, sustainable, humanly readable, technology agnostic, persistent and precise web archive resource references - in a way that can be used for technical solutions. The motivation for defining a PWID namespace is the growing challenge of references to web resources, - both regarding referencing web resources from papers and regarding definition of web collection/ corpus - calls for action now, which can be provided with PWID as a URN, allthough the prefixing with "urn:" is not ideal. In deatail the challenges are: o Citation guidelines generally do not cover general and persistent referencing techniques for web resources that are not registered by Persistent Identifier systems (like DOI [DOI]). However, an increasing number of references point to resources that only exist on the web, e.g. blogs that turned out to have a historical impact. In order to obtain persistency for a reference, the target need to be stable. As the live web is 'alive' and in constant change, persistency can only be obtained by referring to Zierau Expires June 10, 2018 [Page 2] Internet-DraftA Persistent Web IDentifier (PWID) URN NamespDecember 2017 archived snapshots of the web. The PWID URN is therefore focused on referencing archived web material in a technology agnostic way (research documented in [IPRES] and [ResawRef]). o There are many different requirements for construction of collection definitions for web material besides precision and persistency. Recent research have found that various legal and sustainability issues leads to a need for a collection to be defined by references to the web parts in the collection. The PWID URN is needed in such definitions in order to fulfil these requirements and to enable a collection to cover web materials from more archives (Research documented in and [ResawColl]). For the sake of usability and sustainability, the definition of the PWID URN is focused on only having the minimum required information to make a precise identification of a resource in an arbitrary web archive. Resent research have found that this is obtain by the following information [ResawRef]: o Identification of web archive o Identification of source: * Archived URI or identifier * Archival timestamp o Intended coverage (page, part, subsite etc.) The PWID URN represents this information in an unambiguous way, and thus enabling technical solutions to be defined in this URN. 1.1. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. 2. Namespace Registration Template Namespace Identifier: PWID Version: 1 Zierau Expires June 10, 2018 [Page 3] Internet-DraftA Persistent Web IDentifier (PWID) URN NamespDecember 2017 Date: 2017-12-08 Registrant: Eld Maj-Britt Olmuetz Zierau The Royal Danish Library Soeren Kierkegaards Plads 1 1219 Copenhagen Denmark ph: +45 9132 4690 email: elzi@kb.dk Purpose: The purpose of the PWID URN is to represent general, global, sustainable, humanly readable, technology agnostic, persistent and precise web archive resource references - in a way that can be used for technical solutions. The standard is needed to address web materials meeting precision and persistency issues on par precision in with traditional references for analogue material. The scope and applicability of the PWID URN is both references to archived web resources from literature as well as basis for defining parts of a archived web collection. Strict unambiguous syntax is needed in order to ensure that it can be used for computational purposes. This is relevant for web collection definitions, which will need a strict syntax in order to be a basis for automatic extraction. Furthermore, readers of research papers are today expecting to be able to access a referenced resource by clicking an actionable URI, therefore a similar facility will be expected for references to available archived web material. The interest for this new PWID has already been shown, a paper about the invention of the PWID "Persistent Web References - Best Practices and New Suggestions" [IPRES] was accepted for the iPres 2016 conference and nominated as best paper. At the RESAW 2017 conference there are two related papers: One on referencing practices [ResawRef] and one on research data management practices [ResawColl]. The interest for the PWID so far indicates that this is a recognized issue, and that the PWID can fill a gap. The PWID URN is to represent this information in a way that can be used for technical solutions, for example for resolving of a references and automatic extraction of web collection defined by Zierau Expires June 10, 2018 [Page 4] Internet-DraftA Persistent Web IDentifier (PWID) URN NamespDecember 2017 PWID URNs [ResawRef] [ResawColl]. There may come different implementations for resolving which may rely on different protocols and application. As a start there is work on a prototype that can work for the Danish Netarkiv data and open web archives with standard patterns for the current technologies. Further work will be done to make this more internationally integrated. The ambition is to make the PWID URN namespace definition a constituent part of a standard being developed in the IETF or some other recognized standards body. The textual version of the PWID (see additional information) is already in draft of the revision of the ISO 690 reference standard. Syntax: The syntax of the PWID URN is specified below in Augmented Backus- Naur Form (ABNF) RFC 5234 [RFC5234] and it conforms to URN syntax defined in RFC 8141 [RFC8141]. The syntax definition of the PWID URN is: pwid-urn = = "urn" ":" pwid-NID ":" pwid-NSS pwid-NID = "pwid" pwid-NSS = archive-id ":" archival-time ":" coverage-spec ":" archived-item archive-id = +( unreserved ) archival-time = full-date datetime-delim full-pwid-time datetime-delim = "T" full-pwid-time = time-hour [":"] time-minute [":"] time-second "Z" coverage-spec = "part" / "page" / "subsite" / "site" / "collection" / "recording" / "snapshot" / "other" Zierau Expires June 10, 2018 [Page 5] Internet-DraftA Persistent Web IDentifier (PWID) URN NamespDecember 2017 archived-item = URI / archived-item-id archived-item-id = +( unreserved ) where * 'unreserved' is defined as in RFC 3986 [RFC3986] * 'coverage-spec' values are not case sensitive (i.e. "PAGE" / "PART" / "PaGe" / ... are valid values as well.) * 'archival-time' is a UTC timestamp conforming to the W3C profile ISO8601 ISO 8601 [ISO8601] (also defined in RFC 3339 [RFC3339]), with a few exception. It has to be a UTC timestamp in order to conform with web archiving practices, which always uses UTC in order to avoid confusions. The 'full-date' is defined as in RFC 3339 [RFC3339]. The 'archival-time' must represent the time specified in the archive, and can therefore be specified at any of the levels of granularity as described in [W3CDTF] and in accordance with teh WARC standard ISO 28500 [ISO28500]. In line with RFC 3339 [RFC3339] the "T" may alternatively be lower case "t". 'time-hour', 'time-minute' and 'time-second' are defined as in RFC 3339 [RFC3339]. In line with RFC 3339 [RFC3339] the "Z" may alternatively be lower case "z". * 'URI' is defined as in RFC 3986 [RFC3986] The 'coverage-spec' defines the type of archived item, serving as a precision to what is referred: * part the single archived element, e.g. a pdf, a html text, an image * page the full context as a page, e.g. a html page with referred images * subsite the full context as a subsite within its domain, e.g. a document represented in a web structure * site the full context as a site within its domain Zierau Expires June 10, 2018 [Page 6] Internet-DraftA Persistent Web IDentifier (PWID) URN NamespDecember 2017 * collection a collection/corpora definition, e.g. defined as descibed in [ResawColl] * snapshot a snapshot (image) representation of web material, e.g. a web page * recording a recording of a web browsing * other if something else Note that the 'coverage-spec' is a parameter that could have been specified as a query. However, since the 'pwid-urn' can include an URI as 'archived-item', it would introduce ambiguities if the 'coverage-spec' was specified as a query, since it would not be clear whether the query belonged to the 'pwid-urn' or the 'archived-item'. Assignment: There are no authorities for assigning PWID URNs to resources, as the rule is the it is the given by the syntax that the name is assigned according to the * Identification of web archive * Identification of source: + Archived URI or identifier + Archival timestamp * Intended coverage (page, part, subsite etc.) Therefore, the PWID URNs are created independently, but following an algorithm that itself guarantees uniqueness. The name will always be unique, as the only way to define a clash would be that a web archive cease to exist, and by time another web archive gets the same name space and have resources with the same name and same archiving timestamp, but with different contents. This is a highly unlikely scenario. Security and Privacy: Zierau Expires June 10, 2018 [Page 7] Internet-DraftA Persistent Web IDentifier (PWID) URN NamespDecember 2017 Security and privacy considerations are restricted to accessible web resources in web archives. If resolvers to PWID URNs are created, there should be made an analysis of whether they can be restricted to the former mentioned registry of web archives. Security and privacy will then be a question of security and privacy considerations related to the web archive resources. Interoperability: This is covered by comments in the Syntax description, where the 'archival-time' conforms to the W3C profile ISO 8601 [ISO8601] (also defined in RFC 3339 [RFC3339]) and use of date conforms to the WARC standard ISO 28500 [ISO28500] using UTC dates only. Furthermore, the when the 'archived-item' is a URI, this conforms to the URI standard defined as in RFC 3986 [RFC3986]. Resolution: The information in a PWID URN can be used for locating a web archive resource, for any kind of web archive. It includes the minimum information for web archive materials, which enables resolvability, manually or by a resolver. The plan is to develop a resolving service, but this is only in a prototype form at the moment. Resolution of a PWID URN is the primary motivation of making a formal URN definition, instead of just textual representation of the for needed parts of a PWID: * Web archive identification to find the archive holding the material * Archived URI or identifier of item as part of identifying the material * Date and time associated with the archived URI/item as part of precise identification of the material * Coverage of what is referred as part of clarification of what the referred material covers (page, part etc.) in the following the different resolution techniques are explained (manual as well as via a service) An example of a PWID URN is: urn:pwid:archive.org:2016-01-22T11:20:29Z:page:http://www.dr.dk has the information: Zierau Expires June 10, 2018 [Page 8] Internet-DraftA Persistent Web IDentifier (PWID) URN NamespDecember 2017 * archive.org currently known identifier in form of the Internet Archive domian name for their open access web archive * 2016-01-22T11:20:29Z UTC date and time associated with the archived URI * page clarification that the reference cover the full web page with all its inherited parts selected by the web archive * http://www.dr.dk archived URI of item With knowledge of the current (2017) Internet Archive open access web interface having the form: https://web.archive.org/web/