Internet DRAFT - draft-pwid-urn-specification
draft-pwid-urn-specification
Internet Engineering Task Force E. Zierau, Ed.
Internet-Draft Royal Danish Library
Intended status: Informational September 5, 2019
Expires: March 8, 2020
A Persistent Web IDentifier (PWID) URN Namespace
draft-pwid-urn-specification-09
Abstract
This document specifies a Uniform Resource Name (URN) for Persistent
Web IDentifiers for web material in web archives using the 'pwid'
namespace identifier.
The main purpose of the standard is to support specification of
references that are not covered by other reference techniques: to
support references to material in web archives with restricted
access. Furthermore, it supports persistent technology agnostic
references to web archives in general, in a form that can work as an
algorithmic basis for finding web archive resources in general. An
additional important benefit is that the standard can be used for
specifying web collections, which can then form a persistent
computational basis for the extract of the archived collection parts.
The PWID URN is designed to meet requirements for proper referencing
needed by researchers. Therefore, it is designed as general, global,
sustainable, humanly readable, technology agnostic, persistent and
precise web references for web materials in web archives.
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
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on March 8, 2020.
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Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 5
2. Namespace Registration Template . . . . . . . . . . . . . . . 5
3. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19
4. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.1. Normative References . . . . . . . . . . . . . . . . . . 19
4.2. Informative References . . . . . . . . . . . . . . . . . 20
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 22
1. Introduction
The PWID URN is a supplement to existing reference standards, where
the PWID URN will support references to web archives, including areas
that are not supported today: support of references to material in
web archives with restricted access. Furthermore, the PWID URN
enables technology agnostic references to web archives in general,
which can be needed, for instance for references to dynamic web
material with frequent updates (e.g. a news site) or a specific
version of a web material (e.g. specific version of the DOI
handbook).
The PWID URN is in a form which can work as an algorithmic basis for
finding the resource. This also enables computation of archived web
parts to a collection from one or more web archives, if the
collection parts are specified by PWID URNs.
Furthermore, the PWID URN includes information about the resource
which makes it possible to find alternative resources, in cases where
the original precise resource has become unavailable.
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The PWID URN is designed to be a persistent reference that is
general, global and technology agnostic in order to enhance its
chances of being sustainable. Furthermore, it is designed to be
humanly readable and with an ability to specify precision about what
the referenced web archive resource covers. This design enables a
PWID URN to:
o be used in technical solutions, e.g. to make them resolvable
o cover references to materials from all sorts of web archives
The motivation for defining a PWID namespace is the growing
challenges of references to archived web resources, and the PWID as a
URN can assist in overcoming a lot of these challenges. The standard
is needed to address web materials meeting precision and persistency
issues on par with precision in 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 collections/corpora. In detail the challenges are:
o Persistent Identifier systems (like DOI [DOI]) will only cover
registered resources. In general, citation guidelines do not
cover general and persistent referencing techniques for web
resources that are not registered. However, an increasing number
of references point to resources that only exist on the web, e.g.
blogs that turn out to have a historical impact. In order to
obtain persistency for a reference, the target needs to be stable.
For non-registered web resources, the common rule is that the
resource will change, since the live-web is constantly changing.
Persistency can only be obtained by referring to something stable,
i.e. an archived version of the resource from the web. The PWID
URN is therefore focused on referencing archived web material in a
technology agnostic way (research documented in [IPRES2016] and
[ResawRef]).
o References to materials, which only exist in web archives (i.e. no
longer on the live web) are not well supported, especially not for
materials that only exists in archives with restricted access.
There are many new initiatives for web archive referencing, - most
of which are centralized solutions offering harvesting and
referencing, but these cannot be used for materials that only
exist in web archives. The PWID URN can be used for all web
archives, including web archives with restricted access.
o One of the referencing initiatives for open web archives uses URLs
which depend on the current setup of the web archive's access
platform. These URLs are usually technology and placement
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dependent, and therefore such a reference style is not suited for
references that are important to retrace for a long period. The
PWID URN can be used for such reference purposes, since it is
technology agnostic.
o Another referencing initiative, for open web archives, is omitting
specification of the web archive where the resource was found.
This strategy is used in order to open the possibility of using
alternatives from other archives. However, this also adds a risk
of imprecision since different archives tend to have different
versions even when harvesting at the same time. Therefore, such a
reference style is not suited for references where it is important
that the reference is precisely the verified reference. The PWID
URN can provide an exact reference for where the reference was
validated. Additionally, the PWID contains the needed information
in order to search for alternative resource, if needed.
o For web collections/corpora (possibly across different web
archives), recent research have found that various legal and
sustainability issues has led to a need of a collection definition
of references to their web parts. Furthermore, there is a need
for a similar persistent referencing for all parts for calculation
and sustainability reasons. So far, there has been no stable
standard for definition of such collection parts. The PWID URN
can be used for such definitions in order to fulfil these
requirements (research documented in [ResawColl]).
The PWID URN is especially useful for web material where precision is
in focus and/or there are references to materials from web archives
requiring special permissions in order to gain access. The precision
regards two aspects. Firstly, pointing out the archive where the
resource was found and validated against its purpose (other archived
versions in other web archives may differ both regarding completeness
and contents even within short time periods). Secondly, specifying
whether the referred resource is a web page or a part in form of one
file.
The possibility of specifying the part/file precision enables the
PWID URN to be used in specification of contents of a web collection.
Definitions of web collections are often needed for extraction of
data used in production of research results, e.g. for future
evaluations. Current practices are not persistent as they often use
some CDX version, which vary for different implementations.
Strict syntax is needed for the PWID URN, in order to ensure that it
can act as a reference which can used for computational purposes.
This is especially relevant for automatic extraction of parts from
web collection definitions. Furthermore, today's readers of research
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papers are expecting to be able to access a referenced resource by
clicking an actionable URI, therefore a similar possibility will be
expected for references to available archived web material, and this
is possible with a strict syntax. A prototype for resolving URN
PWIDs has been developed for the Danish web archive data and open web
archives with standard patterns for the current technologies.
Implementations for resolution of PWID URNs for other web archives
may be developed.
The purpose of the PWID URN is also to express a web archive
reference as simple as possible and at the same time meet the
requirements for sustainability, usability and scope. Therefore, the
PWID URN is focused on having only the minimum required information
to make a precise identification of a resource in an arbitrary web
archive. Recent research have shown that this can be obtained by the
following information [ResawRef]:
o Identification of web archive
o Identification of source:
* Archived URI or identifier
* Archival timestamp
o Intended precision (page, part/file)
The PWID URN represents this information in a human readable way as
well as a well-defined way that enables technical solutions to
interpret the 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:
1
Date:
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2019-09-06
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 PWID URN is a supplement to existing reference standards,
where the PWID URN will support references to web archives,
including areas that are not supported today: support of
references to material in web archives with restricted access.
Furthermore, the PWID URN enables technology agnostic references
to web archives in general, which can be needed, for instance for
references to dynamic web material with frequent updates (e.g. a
news site) or a specific version of a web material (e.g. specific
version of the DOI handbook).
The PWID URN is in a form which can work as an algorithmic basis
for finding the resource. This also enables computation of
archived web parts to a collection from one or more web archives,
if the collection parts are specified by PWID URNs.
Furthermore, the PWID URN includes information about the resource
which makes it possible to find alternative resources, in cases
where the original precise resource has become unavailable.
The PWID URN is designed to be a persistent reference that is
general, global and technology agnostic in order to enhance its
chances of being sustainable. Furthermore, it is designed to be
humanly readable and with an ability to specify precision about
what the referenced web archive resource covers. This design
enables a PWID URN to:
* be used in technical solutions, e.g. to make them resolvable
* cover references to materials from all sorts of web archives
The motivation for defining a PWID namespace is the growing
challenges of references to archived web resources, and the PWID
as a URN can assist in overcoming a lot of these challenges. The
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standard is needed to address web materials meeting precision and
persistency issues on par with precision in 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 collections/corpora.
In detail the challenges are:
* Persistent Identifier systems (like DOI [DOI]) will only cover
registered resources. In general, citation guidelines do not
cover general and persistent referencing techniques for web
resources that are not registered. However, an increasing
number of references point to resources that only exist on the
web, e.g. blogs that turn out to have a historical impact. In
order to obtain persistency for a reference, the target needs
to be stable. For non-registered web resources, the common
rule is that the resource will change, since the live-web is
constantly changing. Persistency can only be obtained by
referring to something stable, i.e. an archived version of the
resource from the web. The PWID URN is therefore focused on
referencing archived web material in a technology agnostic way
(research documented in [IPRES2016] and [ResawRef]).
* References to materials, which only exist in web archives (i.e.
no longer on the live web) are not well supported, especially
not for materials that only exists in archives with restricted
access. There are many new initiatives for web archive
referencing, - most of which are centralized solutions offering
harvesting and referencing, but these cannot be used for
materials that only exist in web archives. The PWID URN can be
used for all web archives, including web archives with
restricted access.
* One of the referencing initiatives for open web archives uses
URLs which depend on the current setup of the web archive's
access platform. These URLs are usually technology and
placement dependent, and therefore such a reference style is
not suited for references that are important to retrace for a
long period. The PWID URN can be used for such reference
purposes, since it is technology agnostic.
* Another referencing initiative, for open web archives, is
omitting specification of the web archive where the resource
was found. This strategy is used in order to open the
possibility of using alternatives from other archives.
However, this also adds a risk of imprecision since different
archives tend to have different versions even when harvesting
at the same time. Therefore, such a reference style is not
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suited for references where it is important that the reference
is precisely the verified reference. The PWID URN can provide
an exact reference for where the reference was validated.
Additionally, the PWID contains the needed information in order
to search for alternative resource, if needed.
* For web collections/corpora (possibly across different web
archives), recent research have found that various legal and
sustainability issues has led to a need of a collection
definition of references to their web parts. Furthermore,
there is a need for a similar persistent referencing for all
parts for calculation and sustainability reasons. So far,
there has been no stable standard for definition of such
collection parts. The PWID URN can be used for such
definitions in order to fulfil these requirements (research
documented in [ResawColl]).
The PWID URN is especially useful for web material where precision
is in focus and/or there are references to materials from web
archives requiring special permissions in order to gain access.
The precision regards two aspects. Firstly, pointing out the
archive where the resource was found and validated against its
purpose (other archived versions in other web archives may differ
both regarding completeness and contents even within short time
periods) Secondly, specifying whether the referred resource is a
web page or a part in form of one file.
The possibility of specifying the part/file precision enables the
PWID URN to be used in specification of contents of a web
collection. Definitions of web collections are often needed for
extraction of data used in production of research results, e.g.
for future evaluations. Current practices are not persistent as
they often use some CDX version, which vary for different
implementations.
Strict syntax is needed for the PWID URN, in order to ensure that
it can act as a reference which can used for computational
purposes. This is especially relevant for automatic extraction of
parts from web collection definitions. Furthermore, today's
readers of research papers are expecting to be able to access a
referenced resource by clicking an actionable URI, therefore a
similar possibility will be expected for references to available
archived web material, and this is possible with a strict syntax.
A prototype for resolving URN PWIDs has been developed for the
Danish web archive data and open web archives with standard
patterns for the current technologies. Implementations for
resolution of PWID URNs for other web archives may be developed.
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The purpose of the PWID URN is also to express a web archive
reference as simple as possible and at the same time meet the
requirements for sustainability, usability and scope. Therefore,
the PWID URN is focused on having only the minimum required
information to make a precise identification of a resource in an
arbitrary web archive. Recent research have shown that this can
be obtained by the following information [ResawRef]:
* Identification of web archive
* Identification of source:
+ Archived URI or identifier
+ Archival timestamp
* Intended precision (page, part/file)
The PWID URN represents this information in a human readable way
as well as a well-defined way that enables technical solutions to
interpret the URN.
Syntax:
The syntax of the PWID URN is specified below in Augmented Backus-
Naur Form (ABNF) [RFC5234] and conforms to URN syntax defined in
[RFC8141]. The syntax definition of the PWID URN is:
pwid-urn = "urn:" pwid-NID ":" pwid-NSS
pwid-NID = "pwid"
pwid-NSS = archive-domain ":" archival-time ":" precision-spec
":" archived-uri
archival-time = utc-date ["T" utc-time] "Z"
utc-date = utc-year "-" utc-month "-" utc-day
utc-year = 4DIGIT
utc-month = 2DIGIT ; 01-12
utc-day = 2DIGIT ; 01-28, 01-29, 01-30, 01-31 based on
; month/year in UTC time
utc-time = utc-hour ":" utc-minute [":" utc-second [secfrac]]
utc-hour = 2DIGIT ; 00-23
utc-minute = 2DIGIT ; 00-59
utc-second = 2DIGIT ; 00-58, 00-59, 00-60 based on leap second
; rules
secfrac = "." 1*9DIGIT
precision-spec = "part" / "page"
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where
* All parts of the pwid-NSS are case insensitive, except for
cases where the archived-uri represents a URI with case
sensitive parts. According to [RFC8141] (section 3.1) this
means that the PWID URNs in general are case insensitive,
except from cases where it includes a case sensitive archived
URI.
* 'archive-domain' is defined as in (section 3.5) [RFC1034].
The 'archive-domain' must identify the web archive by the
domain for the archive leading to descriptions of how to access
(or apply for access) materials in the archive. (Discussion of
this way to identify the web archive is described in the
"Assignment" section and discussed in the "Additional
information" section).
* 'archival-time' is a UTC timestamp which conforms to the W3C
profile of [ISO8601] [W3CDTF] and a subset of date-time
specified in [RFC3339] (except from allowing partial time
specification).
The 'archival-time' may be specified at any of the levels of
granularity, as long as it reflects exactly the granularity of
the timestamp recorded in the archive (which is in accordance
with the WARC standard [ISO28500]).
* 'DIGIT' is defined as in [RFC5234].
* 'archived-uri' is defined as 'URI' in [RFC3986] but where
occurrences of "[", "]", "?", "#" and "%" are %-encoded in
order not to clash with URN reserved characters [RFC8141] as
well as having unambiguous use of "%".
The 'archived-uri' must be the URI for the archived source.
The precision specification is expressing the intended precision
of the reference, which is needed for specification of
* precise coverage of the reference
e.g. to an html file, since the precise meaning of what the
reference covers can be very varied (the html file itself? the
web page it renders to?) or precise web parts of a collection
specification.
* degree of how precise the reference is with respect to what can
be viewed in the future
The html file itself will be the same. However for web pages,
there are interpretation involved, which mean the result of
rendering them in the web archive can change over time. This
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may happen in case the web archive's algorithm for calculation
of which archived web parts to use for the web page. It may
also happen if the web page refers to parts which are added to
the web archive later, and therefore will give another
expression than the originally referenced expression.
The following valid precision-spec values are exists:
* 'page'
Meaning that an application like Wayback calculates a resulting
web page based on calculated referenced web parts (display
templates, images etc.). For example, an html page displaying
an image will need both the html and the referred image.
* 'part'
Meaning the single archived file/web part harvested as from the
specified URI. For references to web pages with html code
(i.e. pages where there is an option to "View page source"),
this will mean the actual file with the html code. It is
relevant to refer to web pages this way, in case it is part of
a collection specification or in case it is the html that is of
interest (e.g. java scripts or hidden links that are not
visible when rendering the web page).
For all other types of files, the URI will be for single files
to be interpreted a file.
Assignment:
The PWID URNs do not have to be assigned by an authority, as they
are based on the information created at the time of archiving. In
other words: a PWID URN is created independently, but following an
algorithm which ensures that the referred item can be found if it
is still available. A prerequisite for assignment of a PWID is
that the web archive can be identified (with a domain describing
the web archive) and that it has registered metadata about the
archived URI and the time of archiving (also discussed in section
"Additional Information").
A PWID URN is created by finding the relevant information of the
syntax parts of the PWID:
"urn:pwid:" archive-domain ":" archival-time ":" precision-spec
":" archived-uri
The PWID URN for an archived item at hand can be constructed by
exchanging the unspecified PWID parts with relevant information,
as explained in the following:
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* archive-domain (identification of web archive):
This must be the domain of the web archive as identification of
the web archive (e.g. archive.org for Internet Archive's open
web archive and netarkivet.dk for the Danish web archive with
restricted access). Use of the web archive domain as an
identification of a web archive is chosen, since most web
archives have a web archive domain page that leads to a
description of how to access the web archive, e.g. by online
access or by applying for access grants. Furthermore, it is
more precise than e.g. the name of the archive, since there
may be more than one installation of web archives at the same
organization, e.g. archive.org and archive-it.org are both
covered by Internet Archive.
A more precise and persistent identification would require a
formal registry of web archives, but such a registry does not
yet exist.
* archival-time (archival timestamp):
The archival time for the archived item must be specified with
as much granularity as possible in order to make sure it
uniquely identifies the resource at hand. The archival time
may be displayed along with the archived item, but there are
different implementations. It is important to be aware of
whether a more precise timestamp can be found, and whether the
correct timestamp is used. In many Wayback implementations,
the precise timestamp can be found as part of the URI used for
viewing the archived item. For example, the archive http URI
https://web.archive.org/web/20160122100823/https://www.dr.dk
for an archived resource viewable via the Internet Archive's
Wayback installation, the number 20160122100823 represents the
archival time 2016-01-22T10:08:23Z. In other installations,
the most precise timestamp may be found in the URI from a
search result leading to the resource (which usually redirects
on basis of a call to the underlying archive index).
Especially for web pages with frames, there may be cases where
the actual time is not displayed with the source, since only
the times for the contents of the frames are displayed.
* precision-spec (part or page):
The precision specification specifies how the referred item
should be regarded. A typical PWID URN reference in a paper
would be 'page', where a tool will be needed to render the web
page. Alternatively, the precision-spec can be 'part', which
is the most precise reference since it reference a specific
file where no additional calculations are needed (e.g. as part
of a collection, a specific html file with hidden links or to
indicate that a single image is referenced). In order to see
whether a viewed browser page is a computed web page or a
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single file, browsers have a function "View page source" which
is not activated if for single files).
* archived-uri (archived URI):
The URI that was harvested by the web archive for the
referenced resource.
A much easier way to construct PWID URNs is to use tools that
construct them. Currently, there is also a prototype for a SOLR-
Wayback tool (Source at https://github.com/netarchivesuite/
solrwayback) [PWIDprovider], which can assist in finding the most
precise reference to an archived web page. This Wayback version
can provide all PWID URNs belonging to a shown page where the page
PWID URN is provided at the top of the PWID URN list with 'part'
precision, i.e. the page PWID URN can be taken replacing the
'part' with 'page' or all provided PWID URNs can be taken and e.g.
used in a collection definition.
Security and Privacy:
Security and privacy considerations are restricted to accessible
web resources in web archives. Resolvers to PWID URNs will
usually only be possible using the web archives' access tools,
where security and privacy are covered by these tools. In such
cases, security and privacy will be as covered by these tools.
It should be noted that an archived web page or part could be just
as dangerous as a "live" page or part; for instance, it could
include insecure scripts, malware, trackers, etc. Furthermore, an
archived page can in fact be more dangerous, because it could
include outdated scripts with known vulnerabilities that can never
be patched because the script is archived for all time in a
vulnerable state.
Interoperability:
This is covered by comments in the Syntax description:
* the PWID URN conforms to the URI standard defined as in
[RFC3986] and the URN standard [RFC8141]
* the 'archival-time' of the PWID URN conforms to the UTC
timestamp as described in the W3C profile of ISO 8601 [ISO8601]
[W3CDTF] and is in accordance with the WARC standard ISO 28500
[ISO28500].
* for 'archived-uri', this URI conforms to the URI standard
defined as in [RFC3986], with %-encodings of "[", "]", "#", "?"
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and "%" in order to conform to the URN standard [RFC8141] as
well as having unambiguous use of "%"
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. Resolution of a PWID
URN is the primary motivation of making a formal URN definition,
instead of just textual representation of the needed parts of a
PWID.
Resolution is done based on the PWID parts. This can be done
manually by using information from the PWID parts to lookup the
web archive and use the web archives tools to search for the
resource. It can also be done automatically by using the
information from the PWID parts to construct an URI to locate the
archived resource the internet (for online web archives) or a
local restricted network (for web archives with access
restrictions). The relevant information from the PWID parts are:
* Web archive domain for web archive holding referred resource
The domain name for the web archive. For the manual solution,
this domain is used to find a description of how to access the
web archive's materials. For example, "archive.org" is the
domain name leading to the Internet Archive's interface to
their online web collection, and "netarkivet.dk" is the domain
name leading to the website for the Danish web archive with
information about how to apply for access permission to the web
collections. For an automatic solution, the domain will be
used to identify how to calculate the pattern for the URI for
the resource.
* Archived URI of archived resource
For the manual solution this domain, the archived URI for the
resource must be used in search for the resource. For the
automatic solution, this is used as a parameter for
construction of the URI for the resource.
* Date and time associated with the archived item
The archival date and time must be used in manual search for
the resource or as parameter to automatic construction of the
URI for the resource.
* Precision of what is referred
The precision contributes to the guidance of how to view the
referred item. If the precision is 'page', the resource must
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be browsed using the web archive browsing tool, which computes
all parts needed for browsing of the page. If the precision is
'part', the "View page source" browser function can be used for
pages to get the referred resource. If the resource is a
single file (this option is not activated, since the full
resource is already shown). The part precision can also be
indicator for tools (e.g. a collection extraction tool) that
they can fetch the contents by fetching the file pointed to.
In the following, the different resolution techniques are
explained (manual as well as via a service) using the following
PWID URN as an example:
urn:pwid:archive.org:2016-01-22T10:08:23Z:page:https://www.dr.dk
In this example the information from the URN PWID parts are:
* "archive.org"
Currently known identifier in form of the Internet Archive
domain name for their open access web archive.
* "2016-01-22T10:08:23Z"
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
* "https://www.dr.dk"
archived URI of the referenced resource
A manual resolution technique would be to go through the following
steps using the specified web archive's search interface (which
will work for both open web archives and web archives with
restricted access onsite):
* Browse the web archive domain "archive.org"
In this case, the domain leads directly into a page where you
can search for archived URIs (in other cases there may be need
for additional clicks to get to search interface or
descriptions of how to apply for access).
* Enter the archived URI "https://www.dr.dk" in the search field
and make a search, which will result in an overview of the
different times that the resource was archived.
* Use the archival time "2016-01-22T10:08:23Z" to select the
correct resource
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The "page" information is used in verification that the right
precision level is reached. In case the precision-spec had been
'part', it would require an extra step selecting "View page
source" on the resulting page.
It is also noteworthy that the information in the PWID can help in
finding an alternative resource, in case the original referred
resource is no longer available. The archived URI can be searched
in other web archives, where the date and time can help to find
the best match, e.g. via Memento [MEMENTO] (for some open web
archives) or via possible coming web archive infrastructures.
Alternative resolution (automatically or manually) of this URN
PWID can be deduced based on the current (2019) knowledge of
Internet Archive's open Wayback access web interface, which has
the pattern:
https://web.archive.org/web/<time>/<uri>
Using this pattern (where only digits from the timestamp is
included), it is possible to deduce the online https URI:
https://web.archive.org/web/20160122100823/https://www.dr.dk
The same recipe can be used for other Wayback platforms for open
web archives. For web archives with restricted access, there may
be similar recipes, but it may also require special applications
to extract the local URI for the resource (e.g. for Netarkivet, it
is constructed using an API which uses the local CDX to generate
the correct local URI for the resource).
A resolving service is currently available in form of code for a
prototype which run at the Royal Danish Library [PWIDresolver] and
is planned to be more widely available. This service currently
covers both the Danish web archive (with the proper rights) and
open web archives with access services based on a pattern
including archive, archival time and archived URI. In other
words, for open web archives it covers conversion of PWID URNs
for: archive.org, archive-it.org, arquivo.pt, bibalex.org,
nationalarchives.gov.uk, stanford.edu and vefsafn.is. For the
Danish web archive with restricted access, the prototype works
locally accessing the CDX of the library, and providing access via
a local proxy to a restricted environment. The source code for
this prototype is available from
https://github.com/netarchivesuite/NAS-research/releases/
tag/0.0.6.
Documentation:
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None relevant
Additional Information:
Background:
The PWID was originally suggested as a URI, based on research
between a computer science researcher with knowledge of web
archiving and researchers from humanity subjects (History and
Literature). This resulted in the paper "Persistent Web
References - Best Practices and New Suggestions" [IPRES2016] from
the iPres 2016 conference. In this paper, the PWID is referred to
as WPID. However, feedback was received displaying a concern that
WPID was interpreted as a PID related to a PID-system, e.g. as the
DOI. Although the definition of a PID does not contradict the
name "WPID", there would still be a danger of confusing it with
PID-systems, which is not the intension. Consequently, this
suggestion names the PWID instead.
Comments on the drafted PWID URI ([DraftPwidUri]) have suggested
that it should be a URN rather than a URI, which is why the PWID
URN is defined here.
There has been expressed interest for the PWID at several
occasions, where it has been presented (iPRES 2016 [IPRES2016]
paper, RESAW 2017 [ResawRef][ResawColl] papers, iPRES 2018
[IPRES2018] best poster, iDCC 2019 [IDCC2019] poster. Especially,
web researchers from digital humanities have expressed a strong
interest in the PWID, since it will fill a gap and make it
possible for the researchers to make the necessary references.
Limitations to when a PWID URN can be created:
It can be argued that the PWID URN should not have any
restrictions to which material it can be applied. However, in
order to make a standardized general way to identify material,
there need to be assumptions on a set of information that can be
used for identification.
The limits made are can also be argued to be essential for
material that are to be referenced on a long time basis, to have
information about which archive, when it was archived and what was
archived. (See also discussion of web archive identification
below).
Discussion of the web archive identification:
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Using the domain for a web archive as an identifier of the web
archive is not ideal, but it is workable. There are a number of
examples where the domain may not work in the future:
The web archive no longer exist
The web archive have been merged into another web archive
The web archive have change the domain they use
In the first case, the precise material has been lost, which would
be a similar situation if the web archive had been identified in
any other way. It is however recommendable for any user of
references to evaluate the possible sustainability of a web
archive before using the reference, e.g. by evaluating the
probability of continues funding for the web archive. In any
case, the PWID contain information about archived URI and archival
time, which enables a possibility to search for an alternative
(possibly less precise) reference in other web archives, e.g. by
using Memento.
In the second and the third case, identification of the resource
will require that the new domain is found. The likelihood of
finding such information is rather high for well-established web
archives, by using one of two ways. One way is to search for the
domain change information online (if transition is described for
the web archive at the new domain for the web archive). Another
way would be to search other web archives for the last harvests of
the archive domain with information about forthcoming transition
(many web archives harvests each other's domain home page, e.g.
all the web archives mentioned in this document can be found in
both archive.org and arquivo.pt).
It would of course be ideal to have a registry that has exactly
one identifier for a web archive, with different domains/patterns
for online material for different periods if there have been
changes.
Possible extensions to be investigated:
This first version of the PWID only contains a basic definition,
which means that it does not include all of the possible
extensions which have been suggested at different conferences.
The reason is that these suggestions are not mature enough to be
included at this stage. The extensions suggested so far have
been:
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* Having web archives identified by registered identifiers.
There will be work on looking at an update to the PWID URN, if
there can be found a workable solution e.g. by making such a
registry by IANA.
* Having the possibility to use PWID for other web material than
archived URIs, e.g. snapshots and collections
* Various possibilities for specifying the identified material,
e.g. snapshot
* Discussion of how to extend use of PWID URNs via plugins in
browsers, standardized way to ask web archives for resource
specified as a PWID URN and access via future web research
infrastructure
Revision Information:
This is the first version of PWID as a URN.
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 who
contributed with supplementary research concerning requirements for
web collection/corpora definitions. Also thanks to everybody who has
contributed to this work with the research parts and with reviewing
of this RFC.
4. References
4.1. Normative References
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<https://www.rfc-editor.org/info/rfc1034>.
[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>.
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[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>.
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:page: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/>.
[IDCC2019]
Zierau, E., "Web References Meeting Requirements for
Proper Referencing Principles"", February 2019,
<http://www.dcc.ac.uk/sites/default/files/documents/IDCC19
/222_Web%20References%20Meeting%20Requirements%20for%20Pro
per%20Referencing%20Principles.pdf>.
Poster at 14th International Digital Curation Conference
(iDCC) 2019
[IPRES2016]
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
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[IPRES2018]
Zierau, E., "Precise and Persistent Web Archive References
- Status, context and expected progress of the PWID",
September 2018, <https://osf.io/u5w3q/>.
In: proceedings of the 15th International Conference on
Preservation of Digital Objects (iPres) 2018, DOI:
10.17605/OSF.IO/U5W3Q
[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>.
[MEMENTO] Memento Development Group, "About the Memento Project",
January 2015, <http://mementoweb.org/about/>.
urn:pwid:archive.org:2018-11-
01T15:26:28Z:page:http://mementoweb.org/about/
[PWIDprovider]
Royal Danish Library (Netarkivet), "SolrWayback 3.1",
2018, <https://github.com/netarchivesuite/solrwayback>.
urn:pwid:archive.org:2018-06-
11T02:00:05Z:page:https://github.com/netarchivesuite/
solrwayback
[PWIDresolver]
Royal Danish Library (Netarkivet), "NAS-research version
0.0.6", 2018, <https://github.com/netarchivesuite/NAS-
research/releases/tag/0.0.6>.
urn:pwid:archive.org:2018-07-
16T06:53:51Z:page:https://github.com/netarchivesuite/NAS-
research/releases/tag/0.0.6
[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
[W3CDTF] W3C, "Date and Time Formats: note submitted to the W3C. 15
September 1997", 1997,
<http://www.w3.org/TR/NOTE-datetime>.
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 March 8, 2020 [Page 22]
