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diff --git a/doc/rfc/rfc3188.txt b/doc/rfc/rfc3188.txt new file mode 100644 index 0000000..f389102 --- /dev/null +++ b/doc/rfc/rfc3188.txt @@ -0,0 +1,731 @@ + + + + + + +Network Working Group J. Hakala +Request for Comments: 3188 Helsinki University Library +Category: Informational October 2001 + + + Using National Bibliography Numbers as + Uniform Resource Names + +Status of this Memo + + This memo provides information for the Internet community. It does + not specify an Internet standard of any kind. Distribution of this + memo is unlimited. + +Copyright Notice + + Copyright (C) The Internet Society (2001). All Rights Reserved. + +Abstract + + This document discusses how national bibliography numbers (persistent + and unique identifiers assigned by the national libraries) can be + supported within the URN (Uniform Resource Names) framework and the + syntax for URNs defined in RFC 2141. Much of the discussion is based + on the ideas expressed in RFC 2288. + +1. Introduction + + As part of the validation process for the development of URNs the + IETF working group agreed that it is important to demonstrate that + the current URN syntax proposal can accommodate existing identifiers + from well established namespaces. One such infrastructure for + assigning and managing names comes from the bibliographic community. + Bibliographic identifiers function as names for objects that exist + both in print and, increasingly, in electronic formats. RFC 2288 + [Lynch] investigated the feasibility of using three identifiers + (ISBN, ISSN and SICI) as URNs. + + This document will analyse the usage of national bibliography numbers + (NBNs) as URNs. The need to extend analysis to new identifier + systems was briefly discussed in RFC 2288 as well, with the following + summary: "The issues involved in supporting those additional + identifiers are anticipated to be broadly similar to those involved + in supporting ISBNs, ISSNs, and SICIs". + + + + + + + +Hakala Informational [Page 1] + +RFC 3188 Using National Bibliography Numbers as URNs October 2001 + + + A registration request for acquiring a Namespace Identifier (NID) + "NBN" for national bibliography numbers has been written by the + National Library of Finland on the request of the Conference of + Directors of National Libraries (CDNL) and the Conference of the + European National Librarians (CENL). Chapter 5 contains a URN + namespace registration request modeled according to the template in + RFC 2611. + + The document at hand is part of a global co-operation of the national + libraries to foster identification of electronic documents in general + and utilisation of URNs in particular. Some national libraries, + including the national libraries of Finland, Norway and Sweden, are + already assigning NBN-based URNs for electronic resources. + + We have used the URN Namespace Identifier "NBN" for the national + bibliographic numbers in examples below. + +2. Identification vs. Resolution + + As a rule the national bibliography numbers identify finite, + manageably-sized objects, but these objects may still be large enough + that resolution to a hierarchical system is appropriate. + + The materials identified by a national bibliography number may exist + only in printed or other physical form, not electronically. The best + that a resolver will be able to offer in this case is bibliographic + data from a national bibliography database, including information + about where the physical resource is stored in a national library's + holdings. + + The URN Framework provides resolution services that may be used to + describe any differences between the resource identified by a URN and + the resource that would be returned as a result of resolving that + URN. However, NBNs will be used for instance to identify resources + in digital Web archives created by harvester robot applications. In + this case, NBN will identify exactly the resource the user expects to + see. + +3. National bibliography numbers + +3.1 Overview + + National Bibliography Number (NBN) is a generic name referring to a + group of identifier systems utilised by the national libraries and + only by them for identification of deposited publications which lack + an identifier, or to descriptive metadata (cataloging) that describes + the resources. In many countries legal (or voluntary) deposit is + being extended to electronic publications. + + + +Hakala Informational [Page 2] + +RFC 3188 Using National Bibliography Numbers as URNs October 2001 + + + Each national library uses its own NBN strings independently of other + national libraries; there is no global authority which controls them. + For this reason NBNs are unique only on national level. When used as + URNs, NBN strings must be augmented with a controlled prefix such as + country code. These prefixes guarantee uniqueness of the NBN-based + URNs on the global scale. + + NBNs have traditionally been given to documents that do not have a + publisher-assigned identifier, but are cataloged to the national + bibliography. NBNs can be seen as a fall-back mechanism: if no + other, better established identifier such as ISBN can be given, an + NBN is assigned. In principle, NBN usage enables identification of + any Internet document. Local policies may limit the NBN usage to a + much smaller subset of documents. + + Some national libraries (e.g., Finland, Norway, Sweden) have + established Web-based URN generators, which enable authors and + publishers to fetch NBN-based URNs for their network documents. At + least national libraries of Sweden and Finland are harvesting and + archiving domestic Web documents (and a number of other libraries + plan to start this activity), and long-time preservation of these + materials requires persistent and unique identification. NBNs can be + and are in fact already used as internal identifiers in these Web + archives. + + Both syntax and scope of NBNs can be decided by each national library + independently. Typically, an NBN consist of one or more letters + and/or digits. This simple syntax makes NBNs infinitely extensible + and very suitable for e.g., naming of the Web documents. For + instance the application used by the national library of Finland for + Web harvesting creates NBNs which are based on the MD5 checksum of + the archived resource. + +3.2 F-code + + F-code is the NBN used by the National Library of Finland. + + F-codes have been used since early 20th century to identify catalogue + cards and later MARC records in the national bibliography. In 1998 + the national library decided to enable the Finnish authors and + publishers to assign F-codes to their Internet documents, if these + documents do not qualify for other identifiers such as ISBN. F- + codes, embedded into URNs, can be fetched from the URN generator + (http://www.lib.helsinki.fi/cgi-bin/urn.pl) developed in co-operation + between the national library of Finland and the Lund University + library, NETLAB unit. Attached to the generator there is a user + guide (http://www.lib.helsinki.fi/meta/URN-opas.html; only in + Finnish), which tells the users how to use URNs. + + + +Hakala Informational [Page 3] + +RFC 3188 Using National Bibliography Numbers as URNs October 2001 + + + F-codes are also used within the Web harvesting and archiving + software (http://www.csc.fi/sovellus/nedlib/), which has been built + for the Networked European Deposit Library (NEDLIB) project (see + http://www.kb.nl/nedlib). NEDLIB harvester calculates MD5 checksum + for each archived resource, and then builds an NBN-based URN from the + checksum. The URN serves then as a unique identifier to the archived + resource. Traditional identifiers can not be used for this purpose, + since there may for instance be several variants of a book which + (quite rightly so) all have the same ISBN. Moreover, identifiers + embedded into a document do not necessarily belong to the document + itself; thus the Web archiving application can not trust the + identifiers embedded into the body of the document. + + The F-code built by the URN generator consist of: + + Prefix (for example fe) + Year (YYYY; for example 1999) + Number (for example 1055) + + The generator also adds namespace identifier "NBN" and ISO 3166 + country code. Thus a URN based on F-code would in this case be for + instance urn:nbn:fi-fe19991055. + + URNs created by the Web archiving application have similar overall + structure, except that prefix (which may be defined by the operator) + is fea and year is not used. An example: urn:nbn:fi-fea- + 5c5875e6e49ae649cad63e5ee4f6c346. + + F-codes never need any special encoding when used as URNs, since they + consist of alphanumeric codes only (0-9, a-z). This is often the + case for other national libraries' NBN systems as well. + +3.3 Encoding Considerations and Lexical Equivalence + + Embedding NBNs within the URN framework usually presents no + particular encoding problems, since all of the characters that can + appear in commonly used NBN systems can be expressed in special + encoding, as described in RFC 2141 [MOATS]. + + When an NBN is used as a URN, the namespace specific string will + consist of three parts: prefix, consisting of either a two-letter ISO + 3166 country code or other registered string, delimiting character + which is either hyphen (-) or colon (:), and NBN string assigned by + the national library. Delimiting characters are not lexically + equivalent. + + Hyphen is always used for separating the prefix and the NBN string. + + + + +Hakala Informational [Page 4] + +RFC 3188 Using National Bibliography Numbers as URNs October 2001 + + + Colon is used as the delimiting character if and only if a country + code-based NBN namespace is split further in smaller sub-namespaces. + If there are several national libraries in one country, these + libraries can split their national namespace into smaller parts using + this method. + + A national library may also assign a trusted organisation(s) its own + sub-namespace. For instance, the national library of Finland has + given Statistics Finland (http://www.stat.fi/index_en.html) a sub- + namespace "st" (e.g., urn:nbn:fi:st:). The Finnish Council of State + (http://www.vn.fi/vn/english/index.htm) will use sub-namespace "vn" + (e.g., urn:nbn:fi:vn). + + Non-ISO 3166-prefixes, if used, must be registered on the global + level. The Library of Congress will maintain the central register of + reserved codes. This register will be available to the national + libraries and other users in the Web. + + Sub-namespace codes beneath a country-code-based namespace need to be + registered on the national level by the national library which + assigned the code. The national register must be available in the + Web and should also be linked to the global register maintained by + the Library of Congress. + + Two-letter codes may not be used as non-ISO prefixes, since all such + codes are reserved for existing and possible future ISO country + codes. If there are several national libraries in one country who use + the same prefix - for instance, a country code -, they need to agree + on how to split the namespace between them. + + Models: + URN:NBN:<ISO 3166 country code>-<assigned NBN string> + URN:NBN:<ISO 3166 country code>:<sub-namespace code>-<assigned NBN + string> + URN:NBN:<non-ISO 3166 prefix>-<assigned NBN string> + + Examples: + URN:NBN:fi-fe19981001 (A "real" URN assigned by the National Library + of Finland). + +3.4 Resolution of NBN-based URNs + + The (usually) country code-based prefix part of the URN namespace + specific string will provide a guide to where to find a resolution + service, and the NBN register will identify the assigning agency. + Once the NBN-based URN resolution is in global usage, the number of + prefixes will slowly approach and may eventually exceed the number of + national libraries. + + + +Hakala Informational [Page 5] + +RFC 3188 Using National Bibliography Numbers as URNs October 2001 + + + If NBN assignment for a given country is limited to the national + bibliography database, then all NBN-based URNs for that country will + be resolved there. In one model these databases contain detailed + resource descriptions including URLs, which will point both to the + copy of the document in the Internet and to the copy in the national + library's (legal) deposit collection. Due to the limitations in the + usage of legal deposit documents it is possible that the deposited + electronic materials can not be delivered in electronic form outside + the premises of the national library. + + If it is possible for the authors and publishers to retrieve NBNs to + Web documents and there is no obligation to deposit thus identified + documents to the national library, URN resolution service is not + possible without a national Web index and archive, maintained by the + national library or other organisation(s). A Web index/archive will + also resolve machine-generated URNs to the archived Web documents. + +3.5 Additional considerations + + Guidelines adopted by each national library define when different + versions of a work should be assigned the same or differing NBNs. + These rules apply only if identifier assignment is done manually. If + identifiers are allocated programmatically, the only criteria that + can be used is that two documents which are identical on the bit + level (have the same MD5 checksum) are deemed identical and should + receive the same NBN. The likelihood of this happening to dissimilar + documents is about 2^64, according to the RFC 1321. + + The rules governing the usage of NBNs are less strict than those + specifying the usage of ISBN or other, better established + identifiers. Since the NBNs have up to now been given only by the + personnel (cataloguers) working in the national libraries, the + identifier assignment has in practice been well co-ordinated. + + A NBN-based URN will resolve to single instance of the work if + identifier assignment has been automatic. Given the nature of NBNs + it is also likely that different versions of the same work will + receive different NBNs even if the identifier is given manually. + +4. Security Considerations + + This document proposes means of encoding several existing + bibliographic identifiers within the URN framework. This document + does not discuss resolution except at a very generic level; thus + questions of secure or authenticated resolution mechanisms are out of + scope. It does not address means of validating the integrity or + authenticating the source or provenance of URNs that contain + bibliographic identifiers. Issues regarding intellectual property + + + +Hakala Informational [Page 6] + +RFC 3188 Using National Bibliography Numbers as URNs October 2001 + + + rights associated with objects identified by the various + bibliographic identifiers are also beyond the scope of this document, + as are questions about rights to the databases that might be used to + construct resolvers. + +5. Namespace registration + + URN Namespace ID Registration for the National Bibliography Number + (NBN) + + Namespace ID: + + NBN + + This Namespace ID has been in production use in demonstrator systems + since summer 1998; thousands of URNs from this namespace have already + been delivered in Finland, Sweden and Norway. + + Registration Information: + + Version: 3 + Date: 2001-01-30 + The first registration of the NID "NBN" was done via the URN WG in + 1998. The second, slightly edited registration request was done in + 1999. + + Declared registrant of the namespace: + + Name: Juha Hakala + E-mail: juha.hakala@helsinki.fi + Affiliation: Helsinki University Library - The National Library of + Finland, Conference of European National Librarians (CENL) and + Conference of Directors of National Libraries (CDNL) + Address: P.O.Box 26, 00014 Helsinki University, Finland + + Both CENL and CDNL made decisions to foster the usage of URNs during + 1998. The latter organisation has set up a working group for this + purpose. One item in the common work plan is utilisation of national + bibliography numbers as URNs for identification of grey literature + published in the Internet. The NBN namespace will be available for + free for all national libraries in the world. + + Declaration of syntactic structure: + + + + + + + + +Hakala Informational [Page 7] + +RFC 3188 Using National Bibliography Numbers as URNs October 2001 + + + The namespace specific string will consist of three parts: + + prefix, consisting of either a two-letter ISO 3166 country code or + other registered string and sub-namespace codes, + + delimiting characters (colon (:), or hyphen (-), and + + NBN string assigned by the national library. + + Colon is used as a delimiting character only within the prefix, + between ISO 3166 country code and sub-namespace code, which splits + the national namespace into smaller parts. This technique can be + used when there are several national libraries, which all need their + own namespaces, or when the national library allows trusted partners + to set up their own sub-namespaces within the national NBN namespace. + + Dividing non-ISO 3166-based namespaces further with sub-namespace + codes is not allowed. + + Hyphen is used as a delimiting character between the prefix and the + NBN string. Within the NBN string, hyphen can be used for separating + different sections of the code 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, will be created and made available via the Web. Contact + information: nbn.register@loc.gov.us. + + All two-letter codes are reserved for existing and possible future + ISO country codes and may not be used as non-ISO prefixes. + + Sub-namespace codes must be registered on the national level by the + national library which assigned the code. The register must be + available via the Web, and it should be accessible via the global + registry set up by the Library of Congress. + + Models: + + URN:NBN:<ISO 3166 country code>-<assigned NBN string> + URN:NBN:<ISO 3166 country code:sub-namespace code>-<assigned NBN + string> + URN:NBN:<non-ISO 3166 prefix>-<assigned NBN string> + + Example: + + A country code-based URN: URN:NBN:fi-fe19981001 (A URN assigned by + the National Library of Finland). + + + + +Hakala Informational [Page 8] + +RFC 3188 Using National Bibliography Numbers as URNs October 2001 + + + Relevant ancillary documentation: + + National Bibliography Number (NBN) is a generic name referring to a + group of identifier systems used by the national libraries for + identification of deposited publications which lack an identifier, or + to descriptive metadata (cataloguing) that describes the resources. + Each national library uses its own NBN system independently of other + national libraries; there is no global authority which controls + syntax of these identifier systems. + + Each national library can decide freely which resources will receive + NBNs. These identifiers have traditionally been assigned to + documents that do not have a publisher-assigned identifier, but are + nevertheless catalogued to the national bibliography. Typically + identification of grey publications have largely been dependent on + NBNs. + + Some national libraries (Finland, Norway, Sweden) have established + Web-based URN generators, which enable authors and publishers to + fetch NBN-based URNs for their network documents. + + Both syntax and scope of NBNs is decided by each national library + independently. Typically, a NBN consist of one or more letters and a + number. + + Identifier uniqueness considerations: + + NBN strings assigned by two national libraries may be identical. For + this reason usage of a controlled prefix in the namespace specific + string is obligatory in order to guarantee global uniqueness of NBN- + based URNs. + + In the national level, libraries utilise different policies for + guaranteeing uniqueness. A national library may automate the + delivery of NBN-based URNs. In this case, the NBNs are assigned + sequentially by a program (URN generator). + + Identifier persistence considerations: + + Persistence of the NBNs as identifiers is guaranteed by the + persistence of national libraries and information systems, such as + national bibliographies, maintained by them. NBNs have been used for + several centuries for printed materials. NBN-based identification of + electronic documents is a recent practice, but it is likely to + continue for a very long time. + + + + + + +Hakala Informational [Page 9] + +RFC 3188 Using National Bibliography Numbers as URNs October 2001 + + + Process of identifier assignment: + + Assignment of NBN-based URNs is always controlled on national level + by the national library / national libraries. The Conference of + Directors of National Librarians (CDNL) has established in 1999 a + task force, which will co-ordinate the URN usage in all national + libraries. + + National libraries may choose different strategies in assigning NBN- + based URNs. One option is assignment by the library personnel only. + This is done when the document is catalogued into the national + bibliography. Thus in this case the national bibliography database + will serve as the URN resolution service. + + A national library may also set up a URN generator (generators), and + allow publishers and authors to retrieve NBN-based URNs from there. + In this case there is no guarantee that the identified resource will + ever be catalogued into the national bibliography, and URN resolution + is dependent on Web index/archive. + + Process for identifier resolution: + + URNs based on NBNs will be primarily resolved via the national + bibliography databases. In one model these databases contain + detailed resource descriptions including URLs, which will point both + to the copy of the document in the Internet and to the copy in the + national library's (legal) deposit collection. Due to the + limitations in the usage of legal deposit documents it is possible + that the deposited materials can not be delivered outside the + premises of the national library. + + For those documents not catalogued into the national bibliography + database URN resolution may take place via national or international + Web indexes and/or archives. Nordic national libraries have + established in autumn 2000 a joint initiative called Nordic Web + Archive (NWA), which aims at creating a national Web archive into all + Nordic countries. Indexes to these archive systems will be able to + act as URN resolution services of any document which a) is or has + been available via the Web, and b) had an URN embedded into it. + + Country code and additional sub-namespace information will provide a + guide to where to find appropriate resolution services. For + instance, if the country code is "fi", the primary resolution service + is the national bibliography database. Secondary resolution service + is the Web archive. + + + + + + +Hakala Informational [Page 10] + +RFC 3188 Using National Bibliography Numbers as URNs October 2001 + + + Generally, there will be one or more resolution services specified + for each country, depending on the assignment policy and services of + the national library. If NBN assignment is limited to the national + bibliography database, then all NBN-based URNs for that country will + be resolved there. If the authors and publishers have been allowed + to retrieve NBNs to their Web resources, URN resolution services + require a national Web archive. If other organisations have been + allowed to assign NBNs, they may also set up their own URN resolution + services. + + Rules for Lexical Equivalence: + + None in the global level. Any national library may provide its own + rules, on the basis of its NBN syntax. + + Conformance with URN Syntax: + + All NBNs we know of are ASCII strings consisting of letters (a-z) and + numbers (0-9). If NBN contains characters that are reserved in the + URN syntax, this data must be presented in hex encoded form as + defined in RFC 2141. A national library may limit the full scope of + its NBN strings in URN usage in such a way that there are no reserved + characters in the URN namespace specific strings. + + Validation mechanism: + + None specified on the global level. A national library may use NBNs, + which contain a checksum and can therefore be validated, but this is + for the time being not a common practice. + + Scope: + + Global. + +6. References + + [Daigle] Daigle, L., van Gulik, D., Iannella, R. and P. Faltstrom, + "URN Namespace Definition Mechanisms", RFC 2611, June 1999. + + [Lynch] Lynch, C., Preston, C. and R. Daniel, "Using Existing + Bibliographic Identifiers as Uniform Resource Names", RFC + 2288, February 1998. + + [Moats] Moats, R., "URN Syntax", RFC 2141, May 1997. + + + + + + + +Hakala Informational [Page 11] + +RFC 3188 Using National Bibliography Numbers as URNs October 2001 + + +7. Author's Address + + Juha Hakala + Helsinki University Library - The National Library of Finland + P.O. Box 26 + FIN-00014 Helsinki University + FINLAND + + EMail: juha.hakala@helsinki.fi + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +Hakala Informational [Page 12] + +RFC 3188 Using National Bibliography Numbers as URNs October 2001 + + +8. Full Copyright Statement + + Copyright (C) The Internet Society (2001). All Rights Reserved. + + This document and translations of it may be copied and furnished to + others, and derivative works that comment on or otherwise explain it + or assist in its implementation may be prepared, copied, published + and distributed, in whole or in part, without restriction of any + kind, provided that the above copyright notice and this paragraph are + included on all such copies and derivative works. However, this + document itself may not be modified in any way, such as by removing + the copyright notice or references to the Internet Society or other + Internet organizations, except as needed for the purpose of + developing Internet standards in which case the procedures for + copyrights defined in the Internet Standards process must be + followed, or as required to translate it into languages other than + English. + + The limited permissions granted above are perpetual and will not be + revoked by the Internet Society or its successors or assigns. + + This document and the information contained herein is provided on an + "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING + TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING + BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION + HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF + MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. + +Acknowledgement + + Funding for the RFC Editor function is currently provided by the + Internet Society. + + + + + + + + + + + + + + + + + + + +Hakala Informational [Page 13] + |