IETF URNbis WG J. Hakala
Internet-Draft The National Library of Finland
Obsoletes: 3188 (if approved) A. Hoenes, Ed.
Intended status: Standards Track TR-Sys
Expires: April 28, 2012 October 26, 2011
Using National Bibliography Numbers as Uniform Resource Names
draft-ietf-urnbis-rfc3188bis-nbn-urn-01
Abstract
National Bibliography Numbers, NBNs, are widely used by the national
libraries and other organizations in order to identify various
resources such as digitized monographs and monographs pre-dating the
emergence of the ISBN system. Generally, NBNs may be applied to all
kinds of resources that do not have an established (standard)
identifier system of their own.
A URN (Uniform Resource Names) namespace for NBNs was established in
2001, and since then, tens of millions of unique URN:NBNs have been
assigned. The namespace registration was performed in RFC 3188 and
applied to the NBNs in use at that point. No URN:NBN resolution
services existed at the time when that RFC was written. Since then,
national libraries in several countries including Finland, Germany,
Italy, and the Netherlands have established these services.
This document replaces RFC 3188 and defines how NBNs can be supported
within the updated URN framework. A revised namespace registration
(version 4) is included.
Discussion
Comments are welcome and should be directed to the urn@ietf.org
mailing list or the authors.
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 http://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
Hakala & Hoenes Expires April 28, 2012 [Page 1]
Internet-Draft NBN URN Namespace October 2011
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 April 28, 2012.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://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.
This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
Hakala & Hoenes Expires April 28, 2012 [Page 2]
Internet-Draft NBN URN Namespace October 2011
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Conventions used in this document . . . . . . . . . . . . . . 5
3. Fundamental Namespace and Community Considerations for NBN . . 6
3.1. The URN:NBN Namespace . . . . . . . . . . . . . . . . . . 6
3.2. Community Considerations for NBNs . . . . . . . . . . . . 6
4. National Bibliography Numbers (NBNs) . . . . . . . . . . . . . 8
4.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.2. Encoding Considerations and Lexical Equivalence . . . . . 9
4.3. Resolution and Persistence of NBN-based URNs . . . . . . . 11
4.4. Additional Considerations . . . . . . . . . . . . . . . . 13
4.5. URN Namespace ID Registration for the National
Bibliography Number (NBN) . . . . . . . . . . . . . . . . 13
5. Security Considerations . . . . . . . . . . . . . . . . . . . 18
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 18
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
8.1. Normative References . . . . . . . . . . . . . . . . . . . 18
8.2. Informative References . . . . . . . . . . . . . . . . . . 19
Appendix A. Draft Change Log . . . . . . . . . . . . . . . . . . 20
A.1. draft-hakala-rfc3188bis-nbn-urn-00 to
draft-ietf-urnbis-*-00 . . . . . . . . . . . . . . . . . . 20
A.2. draft-ietf-urnbis-rfc3188bis-nbn-urn-00 to -01 . . . . . . 20
Hakala & Hoenes Expires April 28, 2012 [Page 3]
Internet-Draft NBN URN Namespace October 2011
1. Introduction
One of the basic permanent URI schemes (cf. RFC 3986 [RFC3986],
[IANA-URI]) is 'URN' (Uniform Resource Name) as originally defined in
RFC 2141 [RFC2141] and now being formally specified in RFC 2141bis
[I-D.ietf-urnbis-rfc2141bis-urn]. Any identifier, when used within
the URN system, needs to have a namespace of its own. As of October
2011, IANA had registered 44 formal URN namespaces (see [IANA-URN]),
one of which belongs to NBN, National Bibliography Number, as
specified 2001 in RFC 3188 [RFC3188].
URN:NBNs are in production use in several European countries
including (in alphabetical order) Austria, Finland, Germany, Italy,
the Netherlands, Norway, Sweden, and Switzerland; several other
countries in Europe and elsewhere are considering usage of them. The
URN:NBN namespace is managed by the national libraries. URN:NBNs
have been applied to diverse content including Web archives,
digitized materials, research data, and doctoral dissertations.
As a part of the initial development of the URN system back in the
late 1990s, the IETF URN working group agreed that it was important
to demonstrate that the URN syntax can accommodate existing
identifier systems.
The bibibliographic community (including, e.g., publishers and
libraries) is dependent on the use of identifiers. Bibliographic
identifiers function as persistent names for books, serials, articles
etc. that exist in print and, increasingly, in various electronic
formats. There are also standard identifiers for works -- immaterial
entities which only become "real" via manifestations such as printed
or electronic books.
RFC 2288 [RFC2288] investigated the feasibility of using three
identifiers (ISBN, ISSN and SICI, see below) as URNs, with positive
results; however, it did not register corresponding URN namespaces.
This was in part due to the still evolving process to formalize
criteria for namespace definition documents and registration,
consolidated later in the IETF into RFC 3406 [RFC3406]. That RFC, in
turn, is now being updated as well into RFC 3406bis
[I-D.ietf-urnbis-rfc3406bis-urn-ns-reg].
URN Namespaces have subsequently been registered for NBN (National
Bibliography Number), ISBN (International Standard Book Number), and
ISSN (International Serial Standard Number) in RFCs 3188 [RFC3188],
3187 [RFC3187], and 3044 [RFC3044], respectively. The ISBN namespace
registration is being revised so that it will cover both ISBN-10 and
ISBN-13; [I-D.ietf-urnbis-rfc3187bis-isbn-urn]. The current ISSN
registration still does not cover ISSN-L, defined in the new version
Hakala & Hoenes Expires April 28, 2012 [Page 4]
Internet-Draft NBN URN Namespace October 2011
of ISSN; there is work in progress in the URNbis WG to update the
existing namespace registration, RFC 3044 [RFC3044].
NBN differs from the other bibliographic identifier systems listed
above because it is not a single identifier system with standard-
specified syntax. There is not and there will never be a standard
describing all the NBN systems in use, although each NBN implementer
MUST keep track on how the identifier is used. The term "National
Bibliography Number" encompasses unique and persistent local
identifier systems that the national libraries and their partner
organizations use in addition to the more formally (and
internationally) established identifiers.
Historically, NBNs were only applied in the national bibliographies
to identify the resources catalogued into it. Prior to the emergence
of bibliographic standard identifiers, every publication got an NBN;
after, e.g., the ISBN system was established, NBNs were given only to
those books that did not have an ISBN -- whether due to human error
or because they did not qualify.
During the last 10 years, the NBN scope has been extended to cover a
vast range of digital resources available via the Internet. Only a
small subset of these resources are catalogued in the national
bibliographies or other bibliographical databases. Digitized books
are an example of this group; the ISBN manual does not allow ISBN
assigment to them, even if the original printed book had had an ISBN.
Objects harvested into Web archives are an example of resources that
will not be catalogued but which may nevertheless receive an NBN.
For now, NBNs have been used to identify manifestations of resources.
However, they may be used to identify (immaterial) works as well, if
the local NBN assignment practices allow that. In such a case, URN
resolution SHOULD supply, for instance, descriptive metadata of the
work itself, and/or links to the manifestations of the work.
Simple guidelines for using NBNs as URNs and the original namespace
registration were published in RFC 3188 [RFC3188]. The RFC at hand
replaces RFC 3188; sections discussing the methods in which URN:NBNs
should be resolved have been updated and the text is compliant with
the stipulations of RFC 3406bis
[I-D.ietf-urnbis-rfc3406bis-urn-ns-reg], the successor of RFC 3406
[RFC3406], which previously had replaced RFC 2611 [RFC2611] (the
latter was applied in the initial registration).
2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
Hakala & Hoenes Expires April 28, 2012 [Page 5]
Internet-Draft NBN URN Namespace October 2011
document are to be interpreted as described in RFC 2119 [RFC2119].
NBN refers to any National Bibliography Number identifier system used
by the national libraries and other institutions using the system
with the national library's permission.
3. Fundamental Namespace and Community Considerations for NBN
3.1. The URN:NBN Namespace
NBNs are widely used to identify hand-held or digital objects covered
by legal requirements on national libraries and similar institutions
to preserve the cultural heritage of their constituents. All objects
in deposit collections will be preserved for long term. While the
methods for digital preservation may vary, the favourite one is
migration. As a rule, the old versions are not removed, in order to
alleviate the effects of failed migrations. This means that
eventually there will be multiple manifestations of every digital
object. Each manifestation MUST have its own NBN. All
manifestations of an object SHOULD be interlinked, for example via
providing links in the descriptive metadata.
NBNs SHOULD only be used for objects when the standard identifiers
such as ISBN are not applicable. However, they MAY be used for
component parts (fragments) even when the identified resources as a
whole qualify for standard identifiers. For instance, even if an
e-book has an ISBN, a chapter or image within the book MAY receive an
NBN if it is available separately.
Standard identifier systems (such as ISBN and ISSN) have a limited
scope; they are applicable only to certain kinds of objects. The
role of the NBN is to fill in the gaps; collectively, the standard
bibliographic identifiers and NBNs cover -- at least in theory -- all
resources the national libraries and their partners need to preserve
for long term.
Section 4 below, and there in particular Section 4.1, presents a more
detailed overview of the structure of the NBN namespace, related
institutions, and the identifier assignment principles used.
3.2. Community Considerations for NBNs
National libraries are the key organizations providing persistent URN
resolution services for objects identified with NBNs, independent of
their form. National libraries MAY allow other organizations such as
university libraries or governmental organizations to assign NBNs to
the resources they preserve for long term. In such case, the
national library MUST co-ordinate the use of NBNs at the national
Hakala & Hoenes Expires April 28, 2012 [Page 6]
Internet-Draft NBN URN Namespace October 2011
level. The national library MAY also provide URN resolution services
and other technical services to other NBN users. These other
organizations MUST either establish their own resolution services or
use the technical infrastructure provided by the national library.
Bibliographic objects often have a logical structure. For instance,
books can be divided into component parts such as articles, chapters,
short stories / novellas, images, and so on. Depending on, e.g., the
technical infrastructure, it may be possible to access these
component parts directly, necessitating identification. NBNs MAY be
assigned to these component parts, depending the local NBN assignment
policy.
The NBN namespace does not specify a generic, intrinsic syntax for
fragment identification, since all candidate characters such as colon
or full stop MAY already be in other use. In practice, there are at
least three different ways in which component parts can be identified
and used within the NBN namespace.
The simplest approach is to assign a separate NBN for each component
part. In these cases, the resolution process SHOULD link the URN:NBN
to a URI belonging to an object such as a text file containing a
chapter of a book.
Second, a local fragment syntax MAY be used, independently of the
requirements of RFC 3986. Fragment identifiers will only be
recognized as such in the application responding to the request. It
MUST be able to process the URN:NBN correctly; the result MUST be the
identified logical component of the entire resource, or a surrogate
such as descriptive metadata about the component.
Finally, if the stipulations of the URI standard (RFC 3986
[RFC3986]), the URI Syntax (RFC 2141bis
[I-D.ietf-urnbis-rfc2141bis-urn]), and those of the Internet media
type as specified in RFC 2046 [RFC2046] are met, URI fragments MAY be
applied in the NBN string. In such cases the resolution process
SHALL retrieve the entire document, and the fragment selection is
then applied to it. This will take the user to, e.g., the beginning
of a relevant journal article within an XML file containing the
entire issue.
The objects identified by NBNs do not need to be available in the
Internet. If so, the URN:NBN resolver SHOULD supply descriptive
metadata about the resource, possibly including information about
where its physical manifestations are stored in the owning
institutions' holdings. A resolver MAY also deliver a digital
surrogate, if one exists, or information about other versions of the
object.
Hakala & Hoenes Expires April 28, 2012 [Page 7]
Internet-Draft NBN URN Namespace October 2011
If an NBN identifies a work, descriptive metadata SHOULD be supplied.
These metadata records MAY include links to the physical
manifestations of the work. Metadata records describing these
manifestations MAY include links to each other and to the work level
metadata record.
Section 4 below, and in particular Section 4.3 therein, presents a
detailed overview of the application of the URN:NBN namespace as well
as the principles of, and systems used for, the resolution of NBN-
based URNs.
4. National Bibliography Numbers (NBNs)
4.1. Overview
National Bibliography Number (NBN) is a generic name referring to a
group of identifier systems administered by the national libraries
and institutions authorized by them. The NBN assignment is typically
performed by the organization hosting the resource. These
organizations (national libraries and institutions in liaison with
them) are usually committed to preserving their deposit collections
for a long time -- at least decades, and possibly centuries.
Resources belonging to these collections SHOULD receive NBNs only if
no standard identifier is applicable.
Each national library uses its own NBNs independently of other
national libraries; there is no global authority that controls NBN
usage. For this reason, NBNs as such are unique only on the national
level. When used as URNs, NBN strings MUST be augmented with a
controlled prefix such as the ISO 3166-1 alpha-2 two-letter country
code. These prefixes guarantee uniqueness of the NBN-based URNs at
the global scale [Iso3166MA].
NBNs have traditionally been assigned to objects that do not have (or
cannot have) a formal (standard) identifier, but are catalogued to
the national bibliography. Examples of this include books that
predate the introduction of the ISBN standard in the 1970s, modern
books that for some reason have not received an ISBN, and all
digitized books.
In principle, NBNs enable identification of any kind of resource and
their component parts, such as periodical articles and still images
within them, or short stories and poems published in book form or in
the Web. The national libraries often specify national assignment
policies; such policy may limit the NBN usage to resources stored
permanently in the national library's legal deposit collection.
However, the scope of the NBN assignment can be significantly
broader; for instance, NBNs are already used to identify research
Hakala & Hoenes Expires April 28, 2012 [Page 8]
Internet-Draft NBN URN Namespace October 2011
datasets (which are not part of legal deposit in any country yet).
Some national libraries (e.g., Finland, Norway, Sweden) have
established Web-based URN generators, which enable authors and
publishers to retrieve NBN-based URNs. There are also applications,
used for instance in digitization processes, that assign NBNs
automatically to resources or even their component parts such as
still images published in monographs or serials.
Within the limits set by the URI Generic Syntax (RFC 3986 [RFC3986])
and the URN Syntax (RFC 2141bis [I-D.ietf-urnbis-rfc2141bis-urn]),
each national library using URN:NBNs SHOULD specify the scope of the
system. Such scope document SHOULD clarify the local policy
concerning fragment identification and the local fragment syntax used
(if any). The policy MAY specify the maximum length of the NSS and
other relevant syntactical features in order to simplify NSS parsing.
4.2. Encoding Considerations and Lexical Equivalence
Expressing NBNs as URIs is usually straightforward, as traditionally
only ASCII characters have been used in NBN strings. If necessary,
NBNs must be translated into canonical form as specified in
RFC 2141bis [I-D.ietf-urnbis-rfc2141bis-urn].
[[ Editorial Note: The text below is scheduled for revision in the
next draft version in order to better align it with the ABNF in
Section 4.5. ]]
When an NBN is used as a URN, the namespace-specific string (NSS)
MUST consist of three parts:
o a prefix, consisting of either a two-letter ISO 3166-1 country
code or another registered string,
o a delimiting character that is either hyphen (-) or colon (:), and
o the NBN string.
The prefix, consisting of either the ISO 3166-1 country code or other
registered prefix string, is case-insensitive. The NBN string MAY be
case sensitive, depending on the NBN syntax applied locally. Future
NBN implementations SHOULD make the NBN string case insensitive as
well.
Different delimiting characters are not semantically equivalent.
Use of colon as the delimiting character is allowed if and only if a
country code-based NBN namespace is split further into smaller sub-
Hakala & Hoenes Expires April 28, 2012 [Page 9]
Internet-Draft NBN URN Namespace October 2011
namespaces. These sub-divisions are part of the prefix. A colon
MUST NOT be used for any other purpose, or in the another registered
string.
A hyphen MUST be used for separating the prefix and the NBN string,
or the part of the NBN string that is assigned to the identified
object by a sub-division authority. A registered prefix string MUST
NOT contain any hyphens, since they would make parsing of URN:NBNs
impossible. The first hyphen SHALL indicate the end of the prefix.
"indicates" ?? Since the NBN string itself can contain hyphens,
parsing cannot be based on the last hyphen being the delimiting
character.
If there are several national libraries in one country, these
libraries MUST agree on how to divide the national namespace between
themselves using this method before the URN:NBN assignment begins in
any of these libraries.
A national library MAY also assign to trusted organization(s) such as
a university or a government institution its own NBN sub-namespace.
The sub-namespace MAY be further divided by the partner organization
(or by the national library on request of the partner).
Sub-namespace identifier strings are case-insensitive. They MUST NOT
contain any hyphens.
Non-ISO 3166-1 alpha-2 prefixes, if used, MUST be registered on the
global level. The U.S. Library of Congress maintains the central
register of assigned non-ISO 3166-1 prefix strings together with the
name and contact information of the registrant. Each prefix MUST
have one and only one user organization, which is responsible for
maintaining the delegated sub-namespace according to the general
rules set out in this document.
Since the setup of that registry, and up to the time of this
writing, no such prefixes have been registered, and it is expected
that demand will remain low. Therefore, no more complicated rules
(for instance for a hierarchical structure of such prefixes), are
specified here. For this unlikely case of unexpected future
needs, a revision of this document would be needed to accommodate
that.
[[ Note: If the NBN community does not see a need to maintain this
-- so far unused -- option for prefixes not based on ISO 3166-1,
it could be dropped without breaking backwards compatibility.
Another option to consider would be migrating the registry to IANA
if that would be preferred by the Library of Congress. ]]
Hakala & Hoenes Expires April 28, 2012 [Page 10]
Internet-Draft NBN URN Namespace October 2011
Sub-namespace codes beneath a country-code-based namespace MUST be
registered on the national level by the national library that
assigned the code. The national register of these codes SHOULD be
made available online.
All two-letter prefixes are reserved for existing and possible future
ISO country codes (or for private use) [Iso3166MA] and MUST NOT be
used as non-ISO country-code prefixes.
Models (indicated linebreak inserted for readability):
URN:NBN:<ISO 3166 alpha-2 country code>-<assigned NBN string>
URN:NBN:<ISO 3166 alpha-2 country code>:<sub-namespace code>-\
<assigned NBN string>
URN:NBN:<non-ISO 3166 prefix>-<assigned NBN string>
Examples (using actually assigned NBNs):
URN:NBN:fi-fe201003181510
urn:nbn:ch:bel-9039
urn:nbn:se:uu:diva-3475
urn:nbn:hu-3006
From the libraries' point of view, one of the key benefits of using
URNs and other persistent identifiers is that there is only one
location -- the resolution service -- where the linking infomation
(URL) has to be maintained. If bibliographic records in libraries'
on-line public access catalogues (OPACs) contain URLs, then each
record must be modified whenever the URL changes. This could mean
hundreds of changes for a popular resource. With URNs, only the URN
- URL linking in the mapping table of the resolution servicem needs
to be kept up-to-date. All links in the bibliographic records point
to the resolution service where the URN is translated to one or more
valid URL(s).
4.3. Resolution and Persistence of NBN-based URNs
Eventually, URN:NBNs will be resolved with the help of a resolver
discovery service (RDS). No such system has been installed yet in
the Internet infrastructure. Therefore, URN:NBNs MAY be embedded in
HTTP URIs in order to make them actionable in the present Internet.
In these HTTP URIs, the authority part must point to the appropriate
URN resolution service. In Finland, the address of the national URN
Hakala & Hoenes Expires April 28, 2012 [Page 11]
Internet-Draft NBN URN Namespace October 2011
resolver is <http://urn.fi>. Thus the HTTP URI for the Finnish URN
in the example above is <http://urn.fi/URN:NBN:fi-fe201003181510>.
This public persistent identifier will not change. In contrast,
since the resource has already moved once from one DSpace system to
another, its DSpace-internal Handle has changed (to
https://helda.helsinki.fi/handle/10138/18199). Since Handles are in
this case only internal identifiers, they do not need to persist, and
users are asked to rely on the URN-based HTTP URI when they make
persistent links to the document.
The country code-based prefix part of the URN namespace-specific
string will provide a hint needed to find the correct national
resolution service for URN:NBNs from the resolver discovery service
when it is established.
There are three inter-related aspects of persistence that need to be
discussed: persistence of the objects itself, persistence of the
identifier and persistence of the URN resolvers.
NBNs have traditionally been assigned to printed resources, which
tend to be persistent. Many books published in the 15th century are
still perfectly readable. In contrast, digital resources require
frequent migrations to guarantee accessibility. Although it is
impossible to estimate how often migrations are needed, hardware and
software upgrades take place frequently, and even a life time of
10-20 years can be considered as long.
Migration is often a lossy process, so different manifestations of an
object may have different look and feel, and possibly even
intellectual content. Because of this, each manifestation must have
a different identifier. Any intellectual work will eventually be
represented by a set of manifestations in which each successive
version is likely to be more and more distant from the original
object. It is not possible to know which one of these versions will
fit the needs of a user best; therefore it is necessary to interlink
URNs belonging to the different manifestations of an object (possibly
via a work level metadata record) so as to make the users aware of
all the existing manifestations of the object and to enable them to
retrieve the one that matches their interests best.
Thus, even if manifestations of digital objects are not and will not
be persistent per se, persistent identifiers such as URN:NBNs SHOULD
support construction of an information architecture thath enables
persistent access to the identified intellectual content, although
the look and feel of their manifestations will inevitably change over
time.
Persistence of URN resolvers themselves is mainly an organizational
Hakala & Hoenes Expires April 28, 2012 [Page 12]
Internet-Draft NBN URN Namespace October 2011
issue, related to the persistence of organizations maintaining them.
As URN:NBN resolution services will be supplied (primarily) by the
national libraries to enable access to their (legal) deposit
collections, these services SHOULD be persistent.
4.4. Additional Considerations
None.
4.5. URN Namespace ID Registration for the National Bibliography Number
(NBN)
This registration describes how National Bibliography Numbers (NBNs)
can be supported within the URN framework.
[[ RFC Editor: please replace "XXXX" in all instances of "RFC XXXX"
below by the RFC number assigned to this document. ]]
Namespace ID: NBN
This Namespace ID was formally assigned to the National
Bibliography Number in October 2001 when the namespace was
registered officially. Utilization of URN:NBNs started in demo
systems in 1998; since then, tens of millions of URN:NBNs have
been assigned. The number of users of the namespace has grown in
two ways: new national libraries have started using NBNs, and some
national libraries using the system have formed new liaisons.
Registration Information:
Version: 4
Date: 2011-10-25
Declared registrant of the namespace:
Name: Mr. Juha Hakala
Affiliation: Senior Adviser, The National Library of Finland
Email: juha.hakala@helsinki.fi
Postal: P.O.Box 15, 00014 Helsinki University, Finland
Web URL: http://www.nationallibrary.fi/
The National Library of Finland registered the namespace on behalf
of the Conference of the European National Librarians (CENL) and
Conference of Directors of National Libraries (CDNL), which have
both made a commitment in 1998 to foster the use of URNs. The NBN
namespace is available for free for the national libraries and the
organizations co-operating with them. The national libraries may
allow these organizations to use the namespace for free or for a
Hakala & Hoenes Expires April 28, 2012 [Page 13]
Internet-Draft NBN URN Namespace October 2011
fee; such fees, if collected, may be based on, e.g., the
maintenance costs of the system.
Declaration of syntactic structure of NSS part:
The namespace-specific string (NSS) will consist of three parts:
a prefix, consisting of either an ISO 3166-1 alpha-2 country
code and optional sub-namespace code(s) separated by colon(s)
or other registered string (which must not contain the
delimiting characters colon (:) and hyphen (-)),
a hyphen (-) as the delimiting character, and
an NBN string assigned by the national library or sub-delegated
authority.
Formal declaration of the NSS, using ABNF [RFC5234]:
nbn_nss = prefix "-" nbn_string
prefix = cc_prefix / reg_prefix
; these prefixes are case-insensitive
cc_prefix = iso_cc *( ":" subspc )
iso_cc = 2ALPHA
; country code as assigned by ISO 3166, part 1 --
; identifies the national library
; to which the branch is delegated
subspc = 1*(ALPHA / DIGIT)
; as assigned by the respective national library
reg_prefix = 3*(ALPHA / DIGIT)
; as assigned by the Library of Congress --
; identifies a trusted third party
; to which the branch is delegated
nbn_string = <specific per prefix>
; MUST adhere to RFC 3986 <path-rootless> syntax;
; parsers must regard nbn_strings as case-sensitive
Colon MAY be used as a delimiting character only within the
prefix, between ISO 3166-1 country code and sub-namespace code(s),
which split the national namespace into smaller parts.
Dividing non-ISO 3166-based namespaces further with sub-namespace
Hakala & Hoenes Expires April 28, 2012 [Page 14]
Internet-Draft NBN URN Namespace October 2011
codes MUST NOT be done.
Whereas all prefixes are regarded as case-insensitive, NBN-strings
MAY be case-sensitive at the preference of the assigning
authority; parsers therefore MUST treat these as case-sensitive;
any case mapping needed to introduce case-insensitivity MUST be
implemented in the responsible resolution system.
Hyphen MUST be used as the delimiting character between the prefix
and the NBN string. Within the NBN string, hyphen MAY be used for
separating different sections of the identifier from one another.
Non-ISO prefixes used instead of the ISO country code MUST be
registered. A global registry, maintained by the Library of
Congress, has beeen created and made available via the Web.
Contact information: <mailto:nbn.register@loc.gov.us>.
All two-letter codes are reserved by the ISO 3166 Maintenance
Agency for either existing and possible future ISO country codes
(or for private use) and MUST NOT be used as non-ISO prefixes.
Sub-namespace codes MUST be registered on the national level by
the national library that assigned the code. The list of such
codes SHOULD be available via the Web.
See chapter 4.2 for examples.
Relevant ancillary documentation:
National Bibliography Number (NBN) is a generic name referring to
a group of identifier systems used by the national libraries and
other organizations for identification of deposited publications
and other objects (and their component parts) that lack a
'canonical' identifier. NBN can also be used to identify works.
Each national library uses its own NBN system independently of
other national libraries; there is neither a general standard
defining the NBN syntax nor a global authority to control the use
of these identifier systems.
Each national library decides locally its NBN assignment policy.
These identifiers have traditionally been assigned to documents
that cannot have a standard identifier, but are nevertheless
catalogued to the national bibliography. Due to the extension of
the scope of the (legal) deposit actitivies to Internet resources,
NBN assignment has been extended to, e.g., harvested Web pages.
The syntax of NBNs is specified by each national library
independently. Historically, NBNs used in national bibliographies
Hakala & Hoenes Expires April 28, 2012 [Page 15]
Internet-Draft NBN URN Namespace October 2011
contained only characters that belong to the US-ASCII character
set. Following the expansion of NBN scope and semi- and fully
automated NBN assignment processes, some NBNs may contain
characters that must be translated into canonical form according
to the specifications in RFC 2141bis
[I-D.ietf-urnbis-rfc2141bis-urn].
Conformance with URN syntax:
[[ Editorial Note: Need to discuss new specification requirements
from the RFC 2141bis draft! ]]
Rules for lexical equivalence of NSS part:
Prefix, consisting of either ISO 3166-1 country code and its
(optional) sub-divisions, or other registered string, is case-
insensitive. NBN string MAY be case-sensitive; the recommendation
is that new NBN implementations should be case-insensitive.
Requirements expressed in RFC 2141bis
[I-D.ietf-urnbis-rfc2141bis-urn] must be taken into account as
well.
Formally, two URN:NBNs are lexically equivalent if they are octet-
by-octet equal after the following (conceptional) preprocessing:
1. normalize the case of the leading "urn:" token;
2. normalize the case of the prefix (country code and its optional
sub-divisions or other registered string);
3. normalize the case of any percent-encoding;
4. ignore <query> parameters (if included).
Note: The case used in the normalization steps is a local matter;
implementations can normalize to lower or upper case as they see
fit, they only need to do it consistently.
Identifier uniqueness and persistence considerations:
NBN strings assigned by two national libraries may be identical.
In order to guarantee global uniqueness of NBN-based URNs,
therefore a controlled prefix is present in the namespace specific
string. These NBNs, once given to the resource, MUST be
persistent. Persistence of the resources themselves will be
guaranteed by the national libraries as a part of their legal
deposit activities.
An NBN, once it has been assigned, MUST never be re-used for
another resource.
Users of the NBN namespace MAY utilise different policies for
Hakala & Hoenes Expires April 28, 2012 [Page 16]
Internet-Draft NBN URN Namespace October 2011
guaranteeing uniqueness of NBNs. The identifiers can be assigned
sequentially by programs (URN generators) in order to avoid human
mistakes. It is also possible to use printable representations of
checksums such as SHA-1 [RFC6234] or MD5 [RFC1321] as NBN, as long
as the registration process prevents collisions (irrespective of
the minuscule probability for these to occur).
Process of identifier assignment:
Assignment of NBN-based URNs MUST be controlled on national level
by the national library / national libraries. Although the basic
principles are the same, there MAY be differences in scope. The
common denominator, however, is that the identified resources
themselves are persistent.
National libraries have applied different strategies in assigning
NBN-based URNs, and different approaches have varying levels of
control with respect to the persistence of the documents. Manual
URN assignment by the library personnel provides the best possible
control, especially if this is done only when the document is
catalogued into the national bibliography. In most libraries the
scope of URN:NBN is much broader than this. From a control point
of view, the most liberal approach is a URN generator that builds
URNs for anonymous users, with no guarantee that the resource
identified will be preserved or accessible. Every national
library must decide the degree of freedom it allows to the URN:NBN
assignment. Usage rules may of course vary within one country,
from one sub-namespace to the next. As of yet there are no
international guidelines for NBN use beyond what has been
stipulated above, but more stringent rules may be developed in the
future.
Process for identifier resolution:
See Section 4.3 of RFC XXXX.
Validation mechanism:
None specified on the global level (beyond a routine check of
those characters that require special encoding when employed in
URIs). NBNs may have a well specified and rich syntax (including,
e.g., fixed length and checksum). In such case, it is possible to
validate the correctness of the NBN programmatically.
Scope:
NBN are applied to resources held in the collections of national
libraries and their partner organizations. NBNs may also be used
Hakala & Hoenes Expires April 28, 2012 [Page 17]
Internet-Draft NBN URN Namespace October 2011
to identify works that these resources manifest.
5. Security Considerations
This document proposes means of encoding NBNs within the URN
framework. A URN resolution service for NBN-based URNs is depicted,
but only at a generic level; thus, questions of secure or
authenticated resolution mechanisms and authentication of users are
out of scope of this document. It does not deal with means of
validating the integrity or authenticating the source or provenance
of URNs that contain NBNs. Issues regarding intellectual property
rights associated with objects identified by the NBNs are also beyond
the scope of this document, as are questions about rights to the
databases that might be used to construct resolution services.
6. IANA Considerations
IANA is asked to update the existing registration of the Formal URN
Namespace 'NBN' using the template given above in Section 4.5.
7. Acknowledgements
Revision of RFC 3188 started during the project PersID
(<http://www.persid.org>). Later the revision was included in the
charter of the URNbis working group in the Applications Area. The
author wishes to thank his colleagues in the PersID project and the
URNbis participants for their support.
Tommi Jauhiainen has provided feedback on an early version of this
draft.
Your name could go here ...
8. References
8.1. Normative References
[I-D.ietf-urnbis-rfc2141bis-urn]
Hoenes, A., "Uniform Resource Name (URN) Syntax",
draft-ietf-urnbis-rfc2141bis-urn-00 (work in progress),
November 2010.
[I-D.ietf-urnbis-rfc3406bis-urn-ns-reg]
Hoenes, A., "Uniform Resource Name (URN) Namespace
Definition Mechanisms",
draft-ietf-urnbis-rfc3406bis-urn-ns-reg-00 (work in
progress), December 2010.
Hakala & Hoenes Expires April 28, 2012 [Page 18]
Internet-Draft NBN URN Namespace October 2011
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
8.2. Informative References
[I-D.ietf-urnbis-rfc3187bis-isbn-urn]
Huttunen, M., Hakala, J., and A. Hoenes, "Using
International Standard Book Numbers as Uniform Resource
Names", draft-ietf-urnbis-rfc3187bis-isbn-urn-01 (work in
progress), October 2011.
[IANA-URI]
IANA, "URI Schemes Registry",
<http://www.iana.org/assignments/uri-schemes/>.
[IANA-URN]
IANA, "URN Namespace Registry",
<http://www.iana.org/assignments/urn-namespaces/>.
[Iso3166MA]
ISO, "ISO Maintenance agency for ISO 3166 country codes",
<http://www.iso.org/iso/country_codes.htm>.
[RFC1321] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
April 1992.
[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", RFC 2046,
November 1996.
[RFC2141] Moats, R., "URN Syntax", RFC 2141, May 1997.
[RFC2288] Lynch, C., Preston, C., and R. Jr, "Using Existing
Bibliographic Identifiers as Uniform Resource Names",
RFC 2288, February 1998.
[RFC2611] Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom,
"URN Namespace Definition Mechanisms", BCP 33, RFC 2611,
June 1999.
[RFC3044] Rozenfeld, S., "Using The ISSN (International Serial
Standard Number) as URN (Uniform Resource Names) within an
ISSN-URN Namespace", RFC 3044, January 2001.
[RFC3187] Hakala, J. and H. Walravens, "Using International Standard
Hakala & Hoenes Expires April 28, 2012 [Page 19]
Internet-Draft NBN URN Namespace October 2011
Book Numbers as Uniform Resource Names", RFC 3187,
October 2001.
[RFC3188] Hakala, J., "Using National Bibliography Numbers as
Uniform Resource Names", RFC 3188, October 2001.
[RFC3406] Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom,
"Uniform Resource Names (URN) Namespace Definition
Mechanisms", BCP 66, RFC 3406, October 2002.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, January 2005.
[RFC6234] Eastlake, D. and T. Hansen, "US Secure Hash Algorithms
(SHA and SHA-based HMAC and HKDF)", RFC 6234, May 2011.
Appendix A. Draft Change Log
[[ RFC-Editor: Whole section to be deleted before RFC publication. ]]
A.1. draft-hakala-rfc3188bis-nbn-urn-00 to draft-ietf-urnbis-*-00
- formal updates for a WG draft; no more "Updates: 2288";
- introduced references to other URNbis WG documents;
- changes based on review by Tommi Jauhiainen;
- Sect. 3 restructured into namespace and community considerations;
- old Sect. 7 incorporated in new Sect. 3.1;
- Security Considerations: old Section 4.5 merged into Section 5;
- added guidelines for when two manifestations of the same work
should get different URN:NBNs;
- clarified role of ISO 3166/MA for ISO 3166-1 country codes;
- clarified role of non-ISO prefix registry maintaind by the LoC;
- resolved inconsistency in lexical equivalence rules: as already
specified for ISO alpha-2 country-codes, and in accordance with
established practice, the whole NBN prefix is now declared case-
insensitive;
- registration template adapted to rfc3406bis [-00];
- numerous editorial fixes and enhancements.
A.2. draft-ietf-urnbis-rfc3188bis-nbn-urn-00 to -01
- Numerous changes to accommodate the outcome of the discussions on
the urn list;
- three different ways of identifying fragments specified;
- removed some redundant/irrelevant paragraphs/subsections;
- the "one manifestation, one URN" principle strenghtened;
Hakala & Hoenes Expires April 28, 2012 [Page 20]
Internet-Draft NBN URN Namespace October 2011
- introduced the idea of interlinking manifestations;
- extended the scope of the NBN explicitly to works;
- added reference to S4.2 in namespace registration;
- numerous editorial fixes and enhancements.
Authors' Addresses
Juha Hakala
The National Library of Finland
P.O. Box 15
Helsinki, Helsinki University FIN-00014
Finland
Email: juha.hakala@helsinki.fi
Alfred Hoenes (editor)
TR-Sys
Gerlinger Str. 12
Ditzingen D-71254
Germany
Email: ah@TR-Sys.de
Hakala & Hoenes Expires April 28, 2012 [Page 21]
