Open Data - Bibliotheksverbund Bayern

B3Kat - Open Data

The joint union catalogue of the Bavarian Library Network (Bibliotheksverbund Bayern - BVB) and the Cooperative Library Network Berlin-Brandenburg (KOBV) contains more than 27 million bibliographic records from university libraries, academic libraries and many other libraries of Bavaria, Berlin and Brandenburg.
The data is published under the Creative Commons License CC0 in MARCXML data format in compliance with the conventions made for Germany.

Regionally defined MARC21 fields, specifically assigned fields:

001	B3Kat-ID (example: BV018229257)
049	Holdings information (ISIL), see the List of B3Kat libraries
940 ind. 1 = 1	Regional and local codes (MAB 078)
	Subfield f	selection code language area
	Subfield n	selection code interlibrary bibliographies and projects
	Subfield q	library-specific selection codes
940 ind. 1 = 2	Subfield r	ISIL of revising library (in the context of VD18, MAB 088 subfield r)
941	Subfields b,h,j,m,t,r,s	Structured Source Citation / Host Item Entry (component parts)
942 ind. 1 = 1, ind. 2 = 1	Synthesized Classification Number Components
	Subfield c	Base number (topical)
	Subfield f	Digits added from classification number in external table (chronological)
	Subfield g	Digits added from classification number in external table (geographical)
	Subfield e	Edition number
999	OAI identifier of the record (example: oai:aleph.bib-bvb.de:BVB01-011000001)

Download and OAI-Repository

The catalog (as of November 1st, 2023) is provided as a download in 35 packages:

You can harvest new data and data modifications since November 1st, 2023, 00:00 UTC+01:00 from our OAI repository. The request

http://bvbr.bib-bvb.de:8991/aleph-cgi/oai/oai_opendata.pl?verb=ListRecords&metadataPrefix=marc21&from=2023-10-31T23:00:00Z

would return all records that have been added or updated since the creation of the latest full export. Please note that we strongly recommend to split the request with from and until parameters into shorter timestamp area sections to recall the data consecutively.

Harvesting individual records

Individual records can be retrieved from the OAI repository by using the verb GetRecord. To specify the desired record you can chose either the OAI-identifier or the B3Kat-ID as the value of the accompanying parameter identifier.

http://bvbr.bib-bvb.de:8991/aleph-cgi/oai/oai_opendata.pl?verb=GetRecord&metadataPrefix=marc21&identifier=oai:aleph.bib-bvb.de:BVB01-011000001

http://bvbr.bib-bvb.de:8991/aleph-cgi/oai/oai_opendata.pl?verb=GetRecord&metadataPrefix=marc21&identifier=BV018229257

Please note that the syntax of the second option expands the OAI-PMH standard to provide you more comfort. A consistent synchronization with B3Kat (in particular keeping track of deletions) can only be accomplished by using the OAI-identifier instead of the B3Kat-ID!

Set-specific harvesting

In addition to the options described above, you can use an appropriate set parameter to restrict harvesting to data records with specific contents in MARC fields 024, 049, 084, 912 or 940.

For example you may want to request

http://bvbr.bib-bvb.de:8991/aleph-cgi/oai/oai_opendata.pl?verb=ListRecords&metadataPrefix=marc21&from=2016-06-20&until=2016-06-30&set=VD18 for all VD18-relevant records that were added or changed between June 20th, 2016 and June 30th, 2016;
http://bvbr.bib-bvb.de:8991/aleph-cgi/oai/oai_opendata.pl?verb=ListRecords&metadataPrefix=marc21&from=2016-01-01&set=DE-12 for all records that have been added or changed since January 1st, 2016 and contain a holding symbol of the Bavarian State Library;
http://bvbr.bib-bvb.de:8991/aleph-cgi/oai/oai_opendata.pl?verb=ListRecords&metadataPrefix=marc21&from=2017-09-13T09:55:57Z&set=by for all records that have been added or changed since September 13th, 2017, 09:55:57 UTC and contain a "by" within MARC 024, 049, 084 or 940.

A record is considered to be a member of a set X if:

Field 024, first indicator "8", subfield a starts with X (e.g. set "VD18").
Field 049, subfield a is equal to X ("Holding of library X"). Exception: holding symbols of administrative courts.
X is "kobv" and field 049, subfield a is a holding symbol of any KOBV library ("Holdings of KOBV libraries").
Field 084 subfield 2 is "fid" or "ssgn" and subfield a is equal to X ("Sondersammelgebiets-/Fachinformationsdienst-numbers"). Note: SSG numbers contain commas "," which are not allowed in set names. Therefore commas in SSG numbers may be substituted by dots "." so to harvest records with SSG number "9,2" a set "9.2" has to be specified.
X is "digit" and field 912, subfield a is "digit" ("DigiTool").
Any subfield of field 940, first indicator "1" starts with X.

Please note that this use of the "set" parameter for a type of free text search in certain data fields goes beyond the OAI-PMH standard functionally, but is also subject to the restrictions described in the following section.

Restrictions for set-specific harvesting

The (potentially infinitely large) list of all "sets" available in this way can not be requested using the OAI verb ListSets.
Result sets exceeding 30 records are delivered in portions (with a resumption token at the end of each portion, which can be used to request the next one if necessary). If you specify a "set" parameter with your query, the repository ignores it internally in the frist instance. Only when it comes to delivery the more general result set is split up into portions and records that do not qualify for the specified set are discarded. Therefore, apart from the resumtion token, delivered portions may well be empty - even repeatedly. This, however, is not in compliance with the OAI-PMH standard (according to the OAI-PMH XML schema definition OAI-PMH.xsd both a ListIdentifiers response and a ListRecords response must contain at least one <header/> or at least one <record/> element) and could thus confuse some of the ready-made OAI harvesters out there.
You can try to work around this problem by shortening the timestamp range queried per request, because this procedure tends to yield result sets small enough so they never get split up into portions at all. Doing so increases the likelyhood for but cannot guarantee getting 100 % valid OAI-PMH-XML.
In case you are dependent on 100% valid OAI-PMH-XML the only option remaining at the moment is to harvest without any "set" parameter and to filter out the records relevant to you on the client side yourself.

Please keep these restrictions in mind when using set specific harvesting!

Questions or feedback?

If you have any questions or would like to provide feedback on B3Kat Open Data please don't hesitate to contact open.data@bib-bvb.de.

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