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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 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 with New Release Service and online dissertations without "Gemeinsame Normdatei" (GND) dnb-all
Restricted to subject class
dnb:sg020 (example of library and information science)
Restricted to bibliography series
dnb:reiheA (example)
Restricted to subject class
dnb:reiheA:sg720 (example of architecture)
online publications
Restricted to subject class
dnb-all:online:sg020 (example of library and information science)
online dissertationsdnb-all:online:dissertations
Restricted to subject class
dnb-all:online:dissertations:sg720 (example of architecture)
"Gemeinsame Normdatei" (GND)


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

Formate und Beispiel
XML variant of MARC 21
DNB Casual (oai_dc)
Selection of Dublin-Core elements
only for bibliographic data
Linked Data Service

Test access / Access requirements

You can use the OAI interface for free in a 1-week test phase (one series or GND).
To do so, please send a mail containing your contact details and a fixed IP address or IP-range, catalogue and desired format to the . Alternatively it is also possible to obtain access via an individual access code (access token). We will contact you as soon as possible to clarify any unresolved issues and to request any additional data which is required.
Following a successful test run you will be sent the agreement forms for accessing charged data on request.

Conditions and costs

During the test phase, use of the OAI interface is free of charge via the OAI interface.
Afterwards a charge may be levied, depending on the selected set and the required data format.
Authority data is supplied free of charge, so too is bibliographic data on online publications (Series O der Deutschen Nationalbibliografie) Also free of charge is the use of all data in RDFxml format and bibliographic data in DNB Casual (Selection of Dublin Core elements), see also the business model for use of data services of the German National Library. A fee is payable for all other formats when using bibliographic data from series A, B, C, H, M and T.
The records are provided, as available, with no guarantee to its being continuous, punctual, error-free or complete, or to its not infringing the rights of third parties (e.g. personal rights and copyright).

The following annual fees are charged (EUR) each bibliographic year (valid until 30 June 2015):

DNB Casual and RDFxml
Series APublishing trade publications 1,581.00free of charge
Series BPublications not from publishing trade 994.00free of charge
Series CMaps 114.00free of charge
Series HUniversity publications420.00free of charge
Series MPrinted music (probably available as of October 2015) 132.00free of charge
Series TSound recordings (probably available as of October 2015) 288.00free of charge
New Release ServicePublisher announcements regarding future and new publications to VLB510.00free of charge
GNDIntegrated Authority Filefree of chargefree of charge

For those requesting individual series, access via the OAI interface to subscribed series is free, i.e. is included in the subscription price.
For submitters of online publications, access to metadata they themselves have submitted is free of charge via the OAI interface. Here, the ID of the submitter needs to be added to the "dnb-all:online" set request: ":dyn:ido:<ID of submitter>". In this case the metadata format is freely selectable.
Special arrangements have been agreed for library networks and service centres. The commercial use of charged bibliographic data (except for CC0 conditions) is subject to separate agreements.


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=2012-04-23Parameter "from" defines the start of the query period
&until=2012-04-24Parameter "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: 22.5.2015

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