Uniform Resource Name (URN) Management for online dissertations at the German National Library

One strategy pursued by the German National Library is to ensure long-term availability of archived network publications. This includes application of conversion, emulation and migration techniques as well as efficient identification and addressing mechanisms. Please find additional information on the archive server of the German National Library. The application of URNs for unequivocal identification and permanent addressing of digital objects is an essential component in this context.

In the framework of the CARMEN-AP4 project (1999-2002), a distributed URN management was established, oriented towards co-operation with library associations and university libraries. Since September 2001, Persistent Identifiers of the URN specification for evaluated digital contents, namely online dissertations, have been administered and resolved at the German National Library.

Structure of Uniform Resource Names (URN)

URNs, managed at the German National Library, can be deduce from the international namespace "NBN"(National Bibliography Number). The namespace "NBN" is an initiative of national libraries and emerged from CDNL and CENL activities. The concept intends distributed administration with assignment, administration, and resolving of URNs to individual national libraries according to their collection policy. Thus, the German National Library is responsible for managing URNs with the namespace "nbn:de".

In Mai 2001, an expert meeting with representatives of library associations, held to prepare the introduction of an unequivocal URN numeric structure in Germany, resulted, among other things, in recommendations for a formal string structure. Hence, a URN is created as follows:

urn:nbn:de:[designations of library association]:[official notation of university libraries ]-[production number][P]



[library association] is a designation of the respective library association, [official notation of university libraries] stands for the numerical library notation of the university library, and [production number] has to be an unequivocal (production-)number. [P] defines the check digit for validating the URN string.

Administration and workflow

The administration scheme is based on decentralised URN assignment and central URN registration, resolving, and archiving of online documents at the German National Library. A URN is recorded as part of the bibliographic description and points as link in OPAC via the intermediate resolving service of the German National Library to the URL and thus, directly to the document. The following scheme illustrates the URN workflow.

URN assignment

Assigning URN sub-namespaces e.g. "urn:nbn:de:gbv:089" are carried out centrally by the German National Library. Within these sub-namespaces URNs can be individually assigned in line with current requirements, though these must comply with the guidelines for structuring a URN.

URN reporting

General requirements

Technical transfer interfaces

There are several technical transfer interfaces in order to register URNs. URNs assigned for online thesis and dissertations can be registered at the German National Library as follows:

Further information concerning the tranfer requirements and technical transfer interfaces are available under the menu item "URN Implementation".

URN integration in information systems

After transferring the online dissertation together with document related metadata, the catalogue entry is generated. The URN is registered in field 2050 of the catalogue (PICA/ILTIS), delivered according to MAB (field: 552 $b) (MAB-Documentation), and appears in the printed bibliographic information services of the German National Library (Series A,H of Deutsche Nationalbibliografie / German national bibliography).

0500 Oa
0599 01-10-16 : a
0600 rh
1100 2001
1101 Dguu
1500 /1eng
2050 urn:nbn:de:gbv:089-3321752945
3010 !123256836!
4000 Nitric oxide in the olfactory epithelium [[Elektronische Ressource]] / von Oliver Schmachtenberg
4083 =A $
4085 =s ca. 2,0 MB =u http://edok01.tib.uni-hannover.de/edoks/e01dh01/332175294.pdf
4204 Hannover, Univ., Diss., 2001
4700 fi
4701 ep/Kai
5050 33;32
7001 09-10-01 : x
7800 076937046
7900 10-10-01 08:13:15.695

The URN is indicated to the user in online catalogue (Web-OPAC), Z39.50 gateway, and as link, pointing to the URL presentation of the URN. At present, both URN and the URL of the archive server of the German National Library are indicated in OPAC in order to prevent indication of inconsistent links and to use the advantages of URNs.

Searching URNs

Online catalogue (Web-OPAC) offers selective search for URNs through search category "Standard number".

The German National Library services

Link check procedure

A daily URL check ensures that only valid URLs are issued in the resolving process. If desired a hash key is checked in order to guarantee the consistency of the according documents. The user is automatically referred to the archive URL of the German National Library if URLs are identified unavailable.

URL error messages may occur temporarily through e.g. faulty network connections or unstable servers. However, when URLs are available again, this is indicated in the resolving process. The procedure runs completely automatically. At present, individual agreement is applied to label URLs once permanently inactive e.g. due to server modifications.

Updated information is available in the category Statistics.

Transfer requirements and conditions for the URN administration

Further information is available under the menu item "Implementation (URN)".

Retrospective URN registration for Online thesis and dissertations

A specific characteristic in context of the URN management for Online theses and dissertations is the retrospective URN registration for those objects which already have been archived at the German National Library.
For simplified collective recording of URNs assigned in retrospect, the German National Library, upon request, provides a file containing all those data sets in fixed format which are not yet assigned URNs. These URNs must be added to the data records and then returned to the German National Library. Acknowledgement is given immediately upon registration of data records. To minimise work for storing retrospectively assigned URNs in the bibliographic information system at the German National Library, the updating takes place every 6 months.

Resolving of URNs

The URN (NBN) resolver is able to perform the following requests:

The EPICUR project developed a Plugin for the Mozilla browser (version 1.5 onwards), which Netscape 7.1 and Firefox 0.8 provided a direct resolution of URNs with the "NBN" namespace.