Internet DRAFT - draft-pwid-uri-specification
draft-pwid-uri-specification
Internet Engineering Task Force E. Zierau, Ed.
Internet-Draft Royal Danish Library
Intended status: Informational June 9, 2018
Expires: December 11, 2018
Scheme Specification for the pwid URI
draft-pwid-uri-specification-04
Abstract
This document specifies a Uniform Resource Identifier (URI) for
Persistent Web IDentifiers to web material in web archives using the
'pwid' scheme name. 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 URI 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.
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 December 11, 2018.
Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved.
Zierau Expires December 11, 2018 [Page 1]
Internet-Draft Scheme Specification for the pwid URI June 2018
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 . . . . . . . . . . . . . . . . . . 4
2. Demonstrable, New, Long-Lived Utility . . . . . . . . . . . . 4
3. Syntactic Compatibility . . . . . . . . . . . . . . . . . . . 5
4. Well Defined . . . . . . . . . . . . . . . . . . . . . . . . 7
5. Definition of Operations . . . . . . . . . . . . . . . . . . 8
6. Context of Use . . . . . . . . . . . . . . . . . . . . . . . 9
7. Internationalization and Character Encoding . . . . . . . . . 10
8. Scheme Name Considerations . . . . . . . . . . . . . . . . . 10
9. Interoperability Considerations . . . . . . . . . . . . . . . 10
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
12. Clear Security and Privacy Considerations . . . . . . . . . . 11
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
13.1. Normative References . . . . . . . . . . . . . . . . . . 11
13.2. Informative References . . . . . . . . . . . . . . . . . 11
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction
The purpose of the PWID URI 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 URI scheme is the growing
challenge of references to web resources, which the PWID as a URI 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
Zierau Expires December 11, 2018 [Page 2]
Internet-Draft Scheme Specification for the pwid URI June 2018
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
constant change, persistency can only be obtained by referring to
archived snapshots of the web. The PWID URI 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 URI 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 URI 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]).
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.
Zierau Expires December 11, 2018 [Page 3]
Internet-Draft Scheme Specification for the pwid URI June 2018
For the sake of usability and sustainability, the definition of the
PWID URI scheme 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 URI scheme represents this information in an unambiguous
way, and thus enabling technical solutions to be defined based on
this scheme.
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. Demonstrable, New, Long-Lived Utility
The purpose of the PWID URI is to represent needed referencing
information (as listed in the introduction) in a scheme that can be
used for technical solutions. As described in [ResawColl] such
references can be represented in a textual way. However, 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 scheme 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 URI scheme has already been shown, a
paper about the invention of the PWID URI "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 URI so far indicates that this is a
recognized issue, and that the PWID URI can fill a gap.
Zierau Expires December 11, 2018 [Page 4]
Internet-Draft Scheme Specification for the pwid URI June 2018
The PWID URI could function as a URN [RFC8141], and will be as a
starting point (proposal has been be sent in December 2017 with
updates June 2018). The ambition is to make an easily understandable
and technology independent persistent identifier, where the prefixing
of "urn:" will be desturbing. Therefore it is also suggested as an
URI, as there in time will come a way where it can function as a URI
and also enjoy the same common syntactic, semantic, and shared
language benefits that the URI presentation confers.
It should be noted that for closed web archives, the PWID URI can be
used to resolve within a closed environment. Likewise, the PWID can
be resolved within coming web archive research infrastructure, which
is currently being proposed in the RESAW community [RESAW].
3. Syntactic Compatibility
The syntax of the PWID URI Scheme is specified below in Augmented
Backus-Naur Form (ABNF) [RFC5234] and it conforms to URI syntax
defined in [RFC3986]. The syntax definition of the PWID URI is:
pwid-uri = pwid-scheme ":" pwid-spec
pwid-scheme = "pwid"
pwid-spec = 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
o 'unreserved' is defined as in RFC 3986 [RFC3986]
o 'coverage-spec' values are not case sensitive (i.e. "PAGE" /
"PART" / "PaGe" / ... are valid values as well.)
o 'archival-time' is a UTC timestamp conforming to the W3C profile
ISO8601 ISO 8601 [ISO8601] (also defined in RFC 3339 [RFC3339]),
Zierau Expires December 11, 2018 [Page 5]
Internet-Draft Scheme Specification for the pwid URI June 2018
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 few exceptions for the 'datetime-
delim' and 'full-pwid-time', as well as using "." is used instead
of ":" in order not to collide with ":" used for delimitation of
URI parts. 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".
o '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:
o part
the single archived element, e.g. a pdf, a html text, an image
o page
the full context as a page, e.g. a html page with referred images
o subsite
the full context as a subsite within its domain, e.g. a document
represented in a web structure
o site
the full context as a site within its domain
o collection
a collection/corpora definition, e.g. defined as descibed in
[ResawColl]
o snapshot
a snapshot (image) representation of web material, e.g. a web page
o recording
a recording of a web browsing
Zierau Expires December 11, 2018 [Page 6]
Internet-Draft Scheme Specification for the pwid URI June 2018
o other
if something else
Note that the 'coverage-spec' is a parameter that could have been
specified as a query. However, since the 'pwid-uri' 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-uri' or the 'archived-item'.
4. Well Defined
The information in a PWID URI 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. One of the reasons for defining PWID as a
URI is to enable a general, technology agnostic, persistent
representation to be resolvable at any time.
The information needed is:
o Web archive identification
to find the archive holding the material
o Archived URI or identifier of item
as part of identifying the material
o Date and time associated with the archived URI/item
as part of precise identification of the material
o Coverage of what is referred
as part of clarification of what the referred material covers
(page, part etc.)
For example the PWID URI:
pwid:archive.org:2016-01-22T11.20.29Z:page:http://www.dr.dk
has the information:
o archive.org
currently known identifier in form of the Internet Archive domian
name for their open access web archive
o 2016-01-22T11.20.29Z
UTC date and time associated with the archived URI
o page
Zierau Expires December 11, 2018 [Page 7]
Internet-Draft Scheme Specification for the pwid URI June 2018
clarification that the reference cover the full web page with all
its inherited parts selected by the web archive
o 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>
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.
5. Definition of Operations
The PWID URI Scheme is another step in facilitating, supporting, and
standardizing the problem of persistent web references to resources
in web archives. There is not a specific definition of computational
operation yet. It is expected that there may be different
implementations in pace with needed use and available technology and
infrastructures.
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.:
o Via locally installed browser plug-ins or applications forming
http/https URIs:
Zierau Expires December 11, 2018 [Page 8]
Internet-Draft Scheme Specification for the pwid URI June 2018
* 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 URIs. 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&coverage=
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
https://web.archive.org/web/20160122112029/http://www.dr.dk
This would require a registry of the different patterns for the
individual web archives
o 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
URI resolving could in such cases be a question of starting a
special application, as for the 'mailto' scheme RFC 6068
[RFC6068].
Use of URIs for standard web archive interfaces is preferred as
dependency on registries and infrastructures may pose too many
limits.
6. Context of Use
The PWID URI scheme facilitates, supports and standardise a scheme
for specification of identification of web archive resources in a
general, global, sustainable, humanly readable, technology agnostic,
persistent and precise way. The standard is needed to address web
materials meeting precision and persistency issues on par precision
in with traditional references for analogue material.
The purpose with the PWID URI is to represent this information in a
scheme that can be used for technical solutions, for example for
Zierau Expires December 11, 2018 [Page 9]
Internet-Draft Scheme Specification for the pwid URI June 2018
resolving of a references and automatic extraction of web collection
defined by PWID URIs [ResawRef] [ResawColl]. As described above,
there may come different implementations for resolving which may rely
on different protocols and application.
7. Internationalization and Character Encoding
Internationalization and character encoding for PWID URIs are
relevant for the 'webarchive-id' and 'archived-item' syntactical
units of the scheme-specific-part of the PWID URI. The rest of the
main syntactical units ('archival-time' and 'coverage-spec') are only
constructed by a very limited set of characters, and do therefore
need internationalization and character encoding.
The 'webarchive-id' will not be case sensitive, but can allow for
percent encodings, although for simplicity reasons, it may turn out
that the coming establishment of an archiving registry will recommend
using letters that do not need encodings.
The 'archived-item' follows the rules of URIs in general (currently
for http and https URIs archived in web archives). The 'archived-
item' is only case sensitive to the extent that the web archive can
handle archived case sensitive URIs.
8. Scheme Name Considerations
The scheme name is "pwid" - short for Persistent Web Identifier.
Initially, the scheme name "wpid" was reserved. 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 scheme "pwid"
instead.
9. Interoperability Considerations
This is covered by comments on the date in the section of Syntactic
Compatibility, where the 'archival-time' conforms to the W3C profile
ISO8601, except for minor modification in order to make it fit into a
URI. Furthermore, the 'archived-item' conforms to the URI standard.
10. 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
Zierau Expires December 11, 2018 [Page 10]
Internet-Draft Scheme Specification for the pwid URI June 2018
web collection/copora definitions. Also thanks to all that have
contributed to this work with the research and reviewing this RFC.
11. IANA Considerations
The URI scheme name 'pwid' is reserved as a provisional URI as result
of request IANA #938449
12. Clear Security and Privacy Considerations
Security and privacy considerations are restricted to accessible web
resources in web archives. If resolvers to PWID URIs 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.
13. References
13.1. 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>.
13.2. Informative References
[DOI] International DOI Foundation, "The DOI System", 2016,
<https://web.archive.org/web/20161020222635/
https:/www.doi.org/>.
pwid:archive.org:2016-10-20T22.26.35:site:https://www.doi.
org/
Zierau Expires December 11, 2018 [Page 11]
Internet-Draft Scheme Specification for the pwid URI June 2018
[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>.
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
Zierau Expires December 11, 2018 [Page 12]
Internet-Draft Scheme Specification for the pwid URI June 2018
[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>.
[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>.
[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 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 13]
