A Persistent Web IDentifier (PWID) URN Namespace
draft-pwid-urn-specification-02
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| Author | Eld Maj-Britt Olmuetz Zierau | ||
| Last updated | 2018-06-09 | ||
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draft-pwid-urn-specification-02
Internet Engineering Task Force E. Zierau, Ed.
Internet-Draft Royal Danish Library
Intended status: Informational June 9, 2018
Expires: December 11, 2018
A Persistent Web IDentifier (PWID) URN Namespace
draft-pwid-urn-specification-02
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 in web
archives in a way that can make them potentially resolvable.
The PWID URN can assist in two ways: First, by providing potential
resolvable precise and persistent reference scheme for web archive
materials, which is not sufficiently covered by existing web
reference practices and new suggested referencing methods. Second,
to specify web elements in web collections (also known as web corpus)
even for collections where there are references to web elements in
several archives.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on December 11, 2018.
Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Namespace Registration Template . . . . . . . . . . . . . . . 4
3. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13
4. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.1. Normative References . . . . . . . . . . . . . . . . . . 13
4.2. Informative References . . . . . . . . . . . . . . . . . 14
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 15
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;
o can be used for technical solutions e.g. to make them resolvable
o can cover references to all sorts of materials in web archives
o can cover references to materials from all sort of web archives
The motivation for defining a PWID namespace is the growing challenge
of references to 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. This regards both referencing of
web resources from research papers and definition of web collection/
corpus. In detail 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
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constant change, persistency can only be obtained by referring to
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 new initiatives for web archive referencing, - most
of them are centralised solutions which offers harvest and
referencing, but these cannot be used for existing materials in
web archives. Other initiatives only cover open web archives,
which does not cover material in closed archives and where there
is a risk of imprecision if a resource in an alternative archive
is the result of resolving such a resource. The PWID URN is
needed in order to fill these gaps where other techniques are not
sufficient.
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 [ResawColl]).
The PWID is especially useful for web material where precision is in
focus and/or there are references to materials from closed 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]:
o Identification of web archive
o Identification of source:
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* 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 [RFC2119].
2. Namespace Registration Template
Namespace Identifier:
PWID
Version:
2
Date:
2018-06-09
Registrant:
Eld Maj-Britt Olmuetz Zierau
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 e.g. to make them
resolvable
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* can cover references to all sorts of materials in web archives
* can cover references to materials from all sort of web archives
The motivation for defining a PWID namespace is the growing
challenge of references to 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.
This regards both referencing of web resources from research
papers and definition of web collection/corpus. In detail the
challenges are:
* 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 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]).
* There are many new initiatives for web archive referencing, -
most of them are centralised solutions which offers harvest and
referencing, but these cannot be used for existing materials in
web archives. Other initiatives only cover open web archives,
which does not cover material in closed archives and where
there is a risk of imprecision if a resource in an alternative
archive is the result of resolving such a resource. The PWID
URN is needed in order to fill these gaps where other
techniques are not sufficient.
* 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 [ResawColl]).
The PWID is especially useful for web material where precision is
in focus and/or there are references to materials from closed web
archives requiring special grants in order to gain access. The
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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.
Strict unambiguous syntax is needed for the PWID reference 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, which strict syntax can make
possible. Examples of technical solutions that is enabled by
strict are:
* resolving of a references and automatic extraction of web
collection defined by PWID URNs [ResawRef] [ResawColl]
* Resolving of a PWID reference by resolving services. As a
start, there is work on a prototype that can work for the
Danish web archive data and open web archives with standard
patterns for the current technologies. There may come
different implementations for resolving which may rely on
different protocols and application
The purpose of the PWID is also to express a web archive reference
as simple as possible and at the same time meeting requirements
for sustainability, usability and scope. Therefore, 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]:
* Identification of web archive
* Identification of source:
+ Archived URI or identifier
+ Archival timestamp
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* 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.
Syntax:
The syntax of the PWID URN is specified below in Augmented Backus-
Naur Form (ABNF) [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"
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].
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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
* 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
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
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* 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:
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:
* the PWID URN conforms to the URI standard defined as in RFC
3986 [RFC3986] and the URN standard RFC 8141 [RFC8141]
* the 'archival-time' of the PWID URN conforms to the URI
standard defined as in RFC 3986 [RFC3986]W3C profile ISO 8601
[ISO8601] (also defined in RFC 3339 [RFC3339]) and to the WARC
standard ISO 28500 [ISO28500] using UTC dates only
* the 'archived-item' is a URI which 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
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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:
* 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/<time>/<uri>
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We can manually (or technically) deduce an actual (current 2017)
access https address:
https://web.archive.org/web/20160122112029/http://www.dr.dk
and regard the referred web page as the reference.
The same recipe can be used for other Wayback platforms - and
possibly also other web archive access tools platforms, as the
crucial information is date and URI, which are requested to be
looked up in a specified archive.
Note that this also includes access to archives that are only
accessible via a local proxy to a restricted environment. Here
the difference is that the archive information is used to identify
the local environment used (possibly on-site) and then construct
local http/https address based on knowledge from the local access
installation. In November there was created a prototype for PWIDs
to the Netarkivet, and there are plans to extend it.
Automatic access of a referenced web resource may work on the open
net for open web archive or in restricted environments for the
closed web archives. There may be a need for varied operation
depending on the available technology and applications, e.g.:
* Via locally installed browser plug-ins or applications forming
http/https URIs:
+ http/https URIs for standard web archive interfaces
At this stage there are initiatives on streamlined and
standardize APIs to web archives interfaces, - and in case
such APIs will be implemented generally, it may be used for
resolving of the PWID URNs. This could be on form (denoting
pwid parts in <> using syntax names):
https://<archive-id>/pwid?time=<archival-
time>&coverage=<coverage-spec>&item=<archived-item>
The example from previous section would then resolve by
https://archive.org/pwid?time=2016-01-22T11:20:29Z&covera
ge=page&item=http://www.dr.dk
+ http/https URIs for archive material for individual web
archives
Using the current open access http/https address pattern for
the individual web archives, which for the example is
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https://web.archive.org/web/20160122112029/
http://www.dr.dk
This would require a registry of the different patterns for
the individual web archives
* Via web research infrastructures
this is a future solution scenario as a web archive research
infrastructure do not yet exists. However, it is a likely
future scenario, as it is currently being proposed in the RESAW
community [RESAW]. The PWID URN resolving could in such cases
be a question of starting a special application, as for the
'mailto' scheme RFC 6068 [RFC6068].
Documentation:
None relevant
Additional Information:
The PWID was originally suggested as a URI based on research
between a computer science researcher with know of web archiving
and researchers from humanity subject (History and Literature).
This resulted in the paper "Persistent Web References - Best
Practices and New Suggestions" [IPRES] from the iPres 2016
conference. In this paper the PWID is referred to as WPID.
However, one of the feedbacks has been a concern that WPID was
interpreted as a PID related to a PID-system, e.g. as the DOI.
All though PID does not have a precise definition that makes it
wrong to call it a "WPID. The danger is that it is confused with
PID systems, which is not the intension. Consequently, this
suggestion names the PWID instead.
The comments on the drafted PWID URI ([DraftPwidUri]) has been
that is seems to be a URN rather than a URI. Which is the reason
why it is now suggested as a URN, although there is a danger that
users of the reference style can be confused by the the additional
"urn:" prefix.
At the RESAW 2017 conference there are two related papers: One on
referencing practices [ResawRef] and one on research data
management practices [ResawColl]. This practice is also planned
to be used for Danish web collections.
The interest for this new PWID has already been shown. There was
a lot of response at iPRES. Especially at the RESAW 2017
conference, web researchers from digital humanities have expressed
strong interest in the PWID, since it can fill a gap and make it
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possible for them to make all the references they need to make.
Therefore, 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 is also suggested in a textual form in a draft of the
revision of the ISO 690 reference standard.
Revision Information:
This is the second version of PWID as a URN where it has been made
more clear where the PWID URN makes a difference
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,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet:
Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
<https://www.rfc-editor.org/info/rfc3339>.
[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,
<https://www.rfc-editor.org/info/rfc3986>.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008,
<https://www.rfc-editor.org/info/rfc5234>.
[RFC8141] Saint-Andre, P. and J. Klensin, "Uniform Resource Names
(URNs)", RFC 8141, DOI 10.17487/RFC8141, April 2017,
<https://www.rfc-editor.org/info/rfc8141>.
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4.2. Informative References
[DOI] International DOI Foundation, "The DOI System", 2016,
<https://web.archive.org/web/20161020222635/
https:/www.doi.org/>.
urn:pwid:archive.org:2016-10-20T22:26:35:site:https://www.
doi.org/
[DraftPwidUri]
Zierau, E., "DRAFT: Scheme Specification for the pwid URI,
version 4", June 2018, <https://datatracker.ietf.org/doc/
draft-pwid-uri-specification/>.
[IPRES] Zierau, E., Nyvang, C., and T. Kromann, "Persistent Web
References - Best Practices and New Suggestions", October
2016, <http://www.ipres2016.ch/frontend/organizers/media/
iPRES2016/_PDF/
IPR16.Proceedings_4_Web_Broschuere_Link.pdf>.
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,
<https://www.iso.org/standard/68004.html>.
[ISO8601] International Organization for Standardization, "Data
elements and interchange formats -- Information
interchange -- Representation of dates and times", 2004,
<https://www.iso.org/standard/40874.html>.
[RESAW] The Resaw Community, "A Research infrastructure for the
Study of Archived Web materials", 2017,
<https://web.archive.org/web/20170529113150/
http://resaw.eu/>.
pwid:archive.org:2017-05-29T11:31:50Z:site:http://resaw.eu
/
[ResawColl]
Jurik, B. and E. Zierau, "Data Management of Web archive
Research Data", 2017,
<https://archivedweb.blogs.sas.ac.uk/files/2017/06/
RESAW2017-JurikZierau-
Data_management_of_web_archive_research_data.pdf>.
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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,
<https://archivedweb.blogs.sas.ac.uk/files/2017/06/
RESAW2017-NyvangKromannZierau-
Capturing_the_web_at_large.pdf>.
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,
<https://www.rfc-editor.org/info/rfc6068>.
[W3CDTF] W3C, "Date and Time Formats: note submitted to the W3C. 15
September 1997", 1997,
<http://www.w3.org/TR/NOTE-datetime>.
W3C profile of ISO 8601 urn:pwid:archive.org:2017-04-
03T03:37:42Z:page:http://www.w3.org/TR/NOTE-datetime
Author's Address
Eld Maj-Britt Olmuetz Zierau (editor)
Royal Danish Library
Soeren Kierkegaards Plads 1
Copenhagen 1219
Denmark
Phone: +45 9132 4690
Email: elzi@kb.dk
Zierau Expires December 11, 2018 [Page 15]