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OAI - overview

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OAI (Open Archives Initiative) is an initiative aimed at defining an open interface for the exchange of metadata. Communication in such an interface takes place between the German National Library as the data provider and a service provider requesting the data. The data is collected automatically by an "OAI harvester". The protocol used for the communication is called OAI-PMH (OAI-Protocol for Metadata Harvesting). OAI permits continuous synchronisation of large amounts of data; this is based on the import of data from an up-to-date basic stock (dump) to a separate database.
Following login and authorisation, the German National Library allows its data to be searched using an HTTP or HTTPS interface and the OAI-PMH protocol.

Frequently Asked Questions (FAQ) / Troubleshooting

Standard of the OAI interface

Protocol: OAI-PMH Version 2.0

OAI-PMH Protocol

The OAI-PMH protocol is web-based. The OAI harvester works with simple requests using HTTP-GET or -POST and receives an HTTP response back from the data provider. Embedded in an XML structure, this response contains the requested metadata. An advantage is that an OAI repository can be searched even with a web browser.

OAI harvester

In order to use OAI to compare the data between the German National Library and a service provider, the service provider must have implemented an OAI harvester (e. g. OAI-PMH Harvester Manager) The OAI harvester calls itself repeatedly in a continuous loop. It executes a "ListRecords command" limited to the dataset (catalogue) defined for the service provider. In addition, the „ListRecords-command“ is given the time of the last call in the form of a Time stamp.This ensures that

  • no change is missed
  • changes are shown with minimum delay in the service provider's database
  • no data which is irrelevant for the service provider is transported

OAI functions

The OAI-PMH protocol includes six basic functions which are appended to the baseURL (e.g. "") using "?verb=":

  • Identify: Display general information about OAI repository, e.g.

    • repositoryName
    • baseURL
    • protocolVersion

  • ListSets: Information about all data sets (catalogues) available in OAI repository

  • ListMetadataFormats: List of all data formats available in OAI repository

  • GetRecord: Call of individual data records using the ID. The identification number of the data record concerned must be known for this (MARC 21: 035 $a with prefix DE-101 respectively DE-599)


    • identifier: Identification number of required data record
    • metadataPrefix: Name of the data format in which the data record is to be issued. The selection of values can be requested using the ListMetadataFormats command (see above).

  • ListRecords: Harvest data records by entering the time period (from / until) and/or data sets. This is the core command of OAI. It permits selective harvesting, i.e. the harvester can restrict the request to data records which

    • originate from a particular catalogue and
    • were created or changed in a particular period

    The time is given in UTC.


    • from / until: Points which define the time period for the selective harvesting. Depending on the OAI repository these can be either defined to the day (YYYY-MM-DD) or to the second (YYYY-MM-DDThh:mm:ssZ)
    • set: The catalogue from which the data records originate
    • metadataPrefix: see above
    • resumptionToken: Permits the return of part responses. The OAI harvester is sent a token which he can use for a new request to obtain the next responses from the OAI repository. The token sends back details of the date of expiry, the size of the total list and counter (optional).

German National Library catalogues (sets) accessible via OAI

Catalogue selectionValue for "set" parameter
Deutsche Nationalbibliografie without "Gemeinsame Normdatei" (GND)
Deutsche Nationalbibliografie, Series A (Monographs and periodicals from the publishers' booktrade)dnb:reiheA
Deutsche Nationalbibliografie, Series B (Monographs and periodicals from outside the publishers' booktrade)dnb:reiheB
Deutsche Nationalbibliografie, Series C (Maps)dnb:reiheC
Deutsche Nationalbibliografie, Series H (University Publications)dnb:reiheH
Deutsche Nationalbibliografie, Series M (Printed Music)dnb:reiheM
Deutsche Nationalbibliografie, Series T (Recorded Music)dnb:reiheT
Deutsche Nationalbibliografie, Series O (Online Publications)dnb:reiheO
Deutsche Nationalbibliografie, restricted to subject class
dnb:sg020 (example of library and information science)
Deutsche Nationalbibliografie, Series A, restricted to subject class
dnb:reiheA:sg720 (example of architecture)
Catalogue Deutsche Nationalbibliothek with New Release Service and online dissertations without "Gemeinsame Normdatei" (GND)dnb-all
New Release Service (publishers' reports)dnb-all:reiheN
Online Publications (without limitation on Series O)
Restricted to subject class
dnb-all:online:sg020 (example of library and information science)
Online Dissertations dnb-all:online:dissertations
Restricted to subject class
dnb-all:online:dissertations:sg720 (example of architecture)
German Music Archive (DMA, incl. the collection of historical sound recordings)dnb-all:dma
"Gemeinsame Normdatei" (GND)


The following formats are offered in Changes to UTF-8 character set (PDF, 25KB, Not barrier-free file.):

Formate und Beispiel
MARC 21-XMLXML variant of MARC 21
DNB Casual (oai_dc)Selection of Dublin-Core elements
only for bibliographic data
RDFxml Linked Data Service
Limited to bibliographic records for which an RDFxml version is available.
The harvesting of redirects in RDFxml will be available mid 2016.

Access requirements

For free access to the OAI interface send an e-mail to the including your contact details, the required OAI set (e.g. bibliographic and/or authority data), the data format and, if applicable, details of the fixed IP address or IP address range. Alternatively it is also possible to obtain access using an individual access code (access token). You will receive a message from us as soon as access is activated for you.

Terms of use and purchase

From 1 July 2015 all bibliographic data of the German National Library and the authority data of the Integrated Authority File (GND) will be provided free of charge and can be freely re-used under "Creative Commons Zero" (CC0 1.0) terms.
The metadata and online interfaces are provided with no guarantee of their being continuous, punctual, error-free or complete, or of their not infringing the rights of third parties (e.g. personal rights and copyright).


Monday - Friday from 9.00 a.m. to 3.00 p.m.
Nicole von der HudeTel.: +49-69-1525-1632
Heike EichenauerTel.: +49-69-1525-1074

Practical examples

Syntax of an OAI request

Syntax of an OAI request with example and explanation
Request to OAI server of the German National Library
?verb=ListIdentifiersCommand to server
&from=2015-04-23Parameter "from" defines the start of the query period
&until=2015-04-24Parameter "until" defines the end of the query period
&metadataPrefix=MARC21-xmlFormat desired for OAI reply
&set=authoritiesDefines the catalogue or set

Syntax of an OAI request with a specific ID number

Syntax of an OAI request for online dissertations from the "Social sciences, sociology, anthropology" subject class within a specific time period

Last update: 26.10.2015

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