Overview
OAI-PMH (https://www.openarchives.org/OAI/openarchivesprotocol.html) provides an application-independent interoperability framework based on metadata harvesting.
The LibraryCloud OAI-PMH Data Provider provides access to metadata about pre-defined sets of items in the Harvard Library collections. OAI "sets" are pre-defined and named as "collections" in the LibraryCloud collection database.
Metadata is provided in the MODS schema (http://www.loc.gov/standards/mods/) as extended in the Harvard LibraryCloud Schema (URL)
Base URI
https://api.lib.harvard.edu/oai
ListSets
The ListSets verb will return a list of harvestable OAI sets defined as LibraryCloud Collections. At this time, the LibraryCloud ListSets verb does not support a resumptionToken, so the response will always include the first 10 collections only.
https://api.lib.harvard.edu/oai/?verb=ListSets
ListRecords
ListRecords requests that the OAI data provider return full metadata records for a given LibraryCloud collection. Results can be returned as MODS or DC.
https://api.lib.harvard.edu/oai/?verb=ListRecords&metadataPrefix=mods&set=scores
https://api.lib.harvard.edu/oai/?verb=ListRecords&metadataPrefix=oai_dc&set=scores
ListIdentifiers
ListIdentifiers requests that the OAI data provider return the identifiers of records in a given LibraryCloud collection.
https://api.lib.harvard.edu/oai/?verb=ListIdentifiers&metadataPrefix=mods&set=scores
Identify
This verb is used to retrieve information about Harvard's LibraryCloud repository.
https://api.lib.harvard.edu/oai/?verb=Identify
GetRecord
Use GetRecord to retrieve an individual metadata record from the LibraryCloud repository. Required arguments specify the identifier of the item to be requested and the format of the metadata that should be included in the record.
https://api.lib.harvard.edu/oai/?verb=GetRecord&metadataPrefix=mods&identifier=000796856 (using Aleph ID)
https://api.lib.harvard.edu/oai/?verb=GetRecord&metadataPrefix=oai_dc&identifier=990007968560203941 (using Alma ID)
ListMetadataFormats
Use ListMetadataFormats to retrieve the metadata formats available from the LibraryCloud repository. An optional argument restricts the request to the formats available for a specific item.
https://api.lib.harvard.edu/oai/?verb=ListMetadataFormats (works)
https://api.lib.harvard.edu/oai/?verb=ListMetadataFormats&identifier=990007968560203941 (why doesn't this work?)
Resumption tokens
The OAI requests for ListSets, ListRecords, and ListIdentifiers retrieve 10 results at a time, so the repeated use of a resumptionToken in the request URL is needed to retrieve the full amount of data.
For this ListRecords request in the Scarlet collection: https://api.lib.harvard.edu/oai/?verb=ListRecords&metadataPrefix=mods&set=scarlet, here is how to use the resumption token to retrieve additional data beyond the first 10 items:
- Make the initial ListRecords request: https://api.lib.harvard.edu/oai/?verb=ListRecords&metadataPrefix=mods&set=scarlet.
- Copy the resumptionToken value from the bottom of the list of 10 results, for example:
<resumptionToken completeListSize="445">10:0001-01-01:9999-12-31:scarlet:mods</resumptionToken>
The first part of the token value indicates the number at which the next list will start – "10" in the example above. - Remove the “metadataPrefix=x&set=y” parameters from the original request url and replace with the resumptionToken as a argument, like this:
https://api.lib.harvard.edu/oai/?verb=ListRecords&resumptionToken=10:0001-01-01:9999-12-31:scarlet:mods - Re-issue the request to get the next set of 10 items.