Internet Engineering Task Force E. Zierau, Ed.
Internet-Draft Royal Danish Library
Intended status: Informational July 16, 2018
Expires: January 17, 2019

A Persistent Web IDentifier (PWID) URN Namespace


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 exact referencing method which includes support for references to archives with restricted access, for exact references to existing web material, and for exact specification of elements in a web corpus (possibly spanning over several web archives). The PWID URN therefore offers a scheme to make references that are not currently supported.

The PWID is designed for researchers and therefore it is designed as general, global, sustainable, humanly readable, technology agnostic, persistent and precise web references for web materials in web archives, and in a way that can make them potentially resolvable.

Status of This Memo

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This Internet-Draft will expire on January 17, 2019.

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Table of Contents

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;

The motivation for defining a PWID namespace is the growing challenge of references to archived web resources, which the PWID as a URN can assist in overcoming. The standard is needed to address web materials meeting precision and persistency issues on par precision in with traditional references for analogue material. Furthermore, it is needed in order to address web archive resources that are not freely available online. The PWID URN covers both referencing of web resources from research papers and definition of web collection/corpus. In detail the challenges are:

The PWID is especially useful for web material where precision is in focus and/or there are references to materials from web archives requiring special grants in order to gain access. The precision regards both regards precise reference where there can be no doubt about that you have the correct web material as well as precision about what is actually referred by the reference (e.g. is it the page or the whole website)

Furthermore the PWID is very useful in specification of contents of 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.

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]:

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 [RFC2119].

2. Namespace Registration Template

Namespace Identifier:





        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"
        archived-item = URI / archived-item-id
        archived-item-id = +( unreserved )



Security and Privacy:




Additional Information:

Revision Information:

3. Acknowledgements

A special thanks to Caroline Nyvang and Thomas Kromann who have contributed to the research identifying the minimum information required in a persistent web reference, and to Bolette Jurik contributed with supplementary research concerning requirements for web collection/copora definitions. Also thanks to all that have contributed to this work with the research and reviewing this RFC.

4. References

4.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997.
[RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet: Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002.
[RFC3986] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, DOI 10.17487/RFC3986, January 2005.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, DOI 10.17487/RFC5234, January 2008.
[RFC8141] Saint-Andre, P. and J. Klensin, "Uniform Resource Names (URNs)", RFC 8141, DOI 10.17487/RFC8141, April 2017.

4.2. Informative References

[DOI] International DOI Foundation, "The DOI System", 2016.

[DraftPwidUri] Zierau, E., "DRAFT: Scheme Specification for the pwid URI, version 4", June 2018.
[IPRES] Zierau, E., Nyvang, C. and T. Kromann, "Persistent Web References - Best Practices and New Suggestions", October 2016.

In: proceedings of the 13th International Conference on Preservation of Digital Objects (iPres) 2016, pp. 237-246

[ISO28500] International Organization for Standardization, "Information and documentation -- WARC file format", 2017.
[ISO8601] International Organization for Standardization, "Data elements and interchange formats -- Information interchange -- Representation of dates and times", 2004.
[PWIDprovider] Royal Danish Library (Netarkivet), "SolrWayback 3.1", 2018.

[PWIDresolver] Royal Danish Library (Netarkivet), "Date and Time Formats: note submitted to the W3C. 15 September 1997", 2018.

[RESAW] The Resaw Community, "A Research infrastructure for the Study of Archived Web materials", 2017.

[ResawColl] Jurik, B. and E. Zierau, "Data Management of Web archive Research Data", 2017.

In: proceedings of the RESAW 2017 Conference, DOI: 10.14296/resaw.0002

[ResawRef] Nyvang, C., Kromann, T. and E. Zierau, "Capturing the Web at Large - a Critique of Current Web Referencing Practices", 2017.

In: proceedings of the RESAW 2017 Conference, DOI: 10.14296/resaw.0004

[RFC6068] Duerst, M., Masinter, L. and J. Zawinski, "The 'mailto' URI Scheme", RFC 6068, DOI 10.17487/RFC6068, October 2010.
[W3CDTF] W3C, "Date and Time Formats: note submitted to the W3C. 15 September 1997", 1997.

W3C profile of ISO 8601

Author's Address

Eld Maj-Britt Olmuetz Zierau (editor) Royal Danish Library Soeren Kierkegaards Plads 1 Copenhagen, 1219 Denmark Phone: +45 9132 4690 EMail: