OAI - overview
Short URL: http://www.dnb.de/EN/oai
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.
- Standard of the OAI interface
- OAI-PMH Protocol
- OAI harvester
- OAI functions
- German National Library catalogues (sets) accessible via OAI
- Access requirements
- Practical examples
Standard of the OAI interface
Protocol: OAI-PMH Version 2.0
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.
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
The OAI-PMH protocol includes six basic functions which are appended to the baseURL (e.g. "http://services.dnb.de/oai/repository") using "?verb=":
Identify: Display general information about OAI repository, e.g.
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 selection||Value for "set" parameter|
|Deutsche Nationalbibliografie without "Gemeinsame Normdatei" (GND)||dnb|
|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)||probably available as of October 2015|
|Deutsche Nationalbibliografie, Series O (Online Publications)||probably available as of October 2015|
|Deutsche Nationalbibliografie, Series T (Recorded Music)||probably available as of October 2015|
|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)|
|Deutsche Nationalbibliografie with New Release Service and online dissertations without "Gemeinsame Normdatei" (GND)||dnb-all|
|New Release Service (publishers' reports)||dnb-all:reiheN|
|Restricted to subject class||dnb-all:online:sg020 (example of library and information science)|
|Restricted to subject class||dnb-all:online:dissertations:sg720 (example of architecture)|
|"Gemeinsame Normdatei" (GND)||authorities|
The following formats are offered in Changes to UTF-8 character set (PDF, 25KB, Not barrier-free file.):
|MARC 21-XML |
|XML variant of MARC 21||http://www.loc.gov/standards/marcxml/schema/MARC21slim.xsd|
|DNB Casual (oai_dc) |
|Selection of Dublin-Core elements|
only for bibliographic data
|Linked Data Service||http://www.w3.org/2000/07/rdf.xsd|
For free access to the OAI interface send an e-mail to the Interface Service 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.
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).
|Interface Service||Monday - Friday from 9.00 a.m. to 3.00 p.m.|
|Nicole von der Hude||Tel.: +49-69-1525-1632|
|Heike Eichenauer||Tel.: +49-69-1525-1074|
Syntax of an OAI request
|Request to OAI server of the German National Library|
|?verb=ListIdentifiers||Command to server|
|&from=2012-04-23||Parameter "from" defines the start of the query period|
|&until=2012-04-24||Parameter "until" defines the end of the query period|
|&metadataPrefix=MARC21-xml||Format desired for OAI reply|
|&set=authorities||Defines 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: 24.7.2015