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OAI-PMH (https://www.openarchives.org/OAI/openarchivesprotocol.html) provides an application-independent interoperability framework based on metadata harvesting.

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Metadata is provided in the MODS schema (http://www.loc.gov/standards/mods/) as extended in the Harvard LibraryCloud Schema (URL)with some LibraryCloud extensions) and Dublin Core. 

Base URI

The service's base address is: https://api.lib.harvard.edu/oai

ListSets

This query to the OAI data provider lists The ListSets verb will return a list of all harvestable OAI sets defined as LibraryCloud Collectionscollections.  

https://api.lib.harvard.edu/oai/?verb=ListSets

ListRecords

ListRecords requests the OAI data provider to The ListRecords verb will return full metadata records for a given LibraryCloud Collectioncollection. Results can be returns 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=CNAREVIEWscores

ListIdentifiers

ListIdentifiers requests the OAI data provider to The ListIdentifiers verb will return the identifiers of records for in a given LibraryCloud Collectioncollection.

https://api.lib.harvard.edu/oai/?verb=ListIdentifiers&metadataPrefix=mods&set=CNAREVIEWscores 

Identify

xxxThe Identify verb will return information about Harvard's LibraryCloud repository. 

https://api.lib.harvard.edu/oai/?verb=Identify

GetRecord

The GetRecord

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xxxverb will return 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

The ListMetadataFormats verb will return 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:vc.harvard.edu:scarlet.000796856

ListMetadataFormats

xxx/?verb=ListMetadataFormats
https://api.lib.harvard.edu/oai/?verb=ListMetadataFormats&identifier=990007968560203941

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 a ListRecords request in the Scarlet collection -- https://api.lib.harvard.edu/oai/?verb=ListRecords&metadataPrefix=mods&set=scarlet -- this is how to use the resumption token to retrieve additional data beyond the first 10 items:

1. Make the initial ListRecords request: https://api.lib.harvard.edu/oai/?verb=ListRecords&metadataPrefix=mods&set=scarlet. 
   
   
2. 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.
   
   
3. Remove the “metadataPrefix=x&set=y” parameters from the original request url and replace with the resumptionToken as an argument, like this: 
   
   https://api.lib.harvard.edu/oai/

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1. ?verb=ListRecords&resumptionToken=10:0001-01-01:9999-12-31:scarlet:mods
   
   
2. Re-issue the request to get the next set of 10 items.