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Library Cloud is a metadata service that provides open, programmatic access to the metadata available within the Harvard Library ecosystem. It normalizes metadata so that it can be found across silos, and enriches it with connections to information within the Library’s collection and beyond. and beyond. If a resource that should be part of Library Cloud is added or updated, the metadata should be in LibraryCloud the next day.
LibraryCloud offers item and collection APIs that provide search access to Harvard collections metadata:
- The item API searches over 20 million aggregated metadata records sourced from Harvard Library's main catalog (Alma), JSTOR Forum (for visual information components), and ArchivesSpace (for archival finding aid components). When digitized content is available, these metadata records are enriched with information from Harvard Library's digital repository (DRS).
- The collection API provides access to metadata about groupings or sets of these items created for administrative and discovery purposes by Harvard staff.
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The base URI for the collections API is httphttps://api.lib.harvard.edu/v2/collections. Use this API to:
- Retrieve a list of all existing collections (sets), with full set metadata including set name, abbreviation (setSpec), set identifier, size, and description:
https://api.lib.harvard.edu/v2/collections?limit=100 (include a limit parameter, otherwise this query returns the first 10 sets only). - Retrieve collection metadata for a single set, by set identifier:
https://api.lib.harvard.edu/v2/collections/57203//2/ (11/13/23 Note: currently unavailable, under investigation) - Retrieve a list of items in a specific set, by set identifier:
https://api.lib.harvard.edu/v2/collections/572032/items (returns a simple list of record identifiers for items in the set)
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- Retrieve items by collectionID:
https://api.lib.harvard.edu/v2/items?collectionId=572032 - Retrieve items by collectionTitle:
https://api.lib.harvard.edu/v2/items?collectionTitle=English Crime and Execution Broadsides - Retrieve items by setName:
https://api.lib.harvard.edu/v2/items?setName=English Crime and Execution Broadsides - Retrieve items by setSpec:
https://api.lib.harvard.edu/v2/items?setSpec=crimes
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You can combine limit with either the start or cursor parameters to paginate an entire result set. Do not combine start and cursor parameters in a single query.
| Parameter | Description |
|---|---|
| limit | The number of results to return. Omit limit and the default is 10 records. May be between 0 and 250. |
| start | The row number to start returning results from. If omitted, will default to 1. |
| cursor | Encoded pointer to a specific record in the search results set. On subsequent requests, the server returns results after the given pointer. |
Paginating with Start
Use the start parameter to set a numerical offset at which the next page will start and add the limit parameter to set the number of results per page. (Omit the limit parameter and the api will return 10 records per page by default.) For example, the following query will return results starting at item 100, with a page size of 50 (e.g., records 100 through 149):
https://api.lib.harvard.edu/v2/items?title=peanuts&start=100&limit=50
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This query returns results sorted in descending order by recordIdentifier of item:
https://api.lib.harvard.edu/v2/items?title=peanuts&sort.desc=recordIdentifier
| Parameter | Description |
|---|---|
| sort.asc OR sort | The field to use for sorting, in ascending order |
| sort.desc | The field to use for sorting, in descending order |
Facets
Facets are attributes of an item (name, genre, type of resource, language, date, etc.) that can be used to power a faceted search or browse option in a discovery system. The items API supports a facets parameter that will return a list of facet values present in the query results. Many item API fields are available for faceting – see the Field Reference "Can Facet" column for an indication of which fields can be faceted.
For example, this query will return items that contain "peanuts" in a title followed by a list of facet values (and counts) for the “name” and “resourceType” fields that are present in the query results:
https://api.lib.harvard.edu/v2/items.json?title=peanuts&facets=name,resourceType
| Parameter | Description |
|---|---|
| facets | A comma-separated list of facets to return |
| facet_size | The maximum number of facets to be returned for each faceted field. Default is 10. May be between 1 and 100. |
Response Format
By default, all responses are in MODS format. Dublin Core (DC) can be requested by adding .dc to the base URI
https://api.lib.harvard.edu/v2/items.dc?title=peanuts
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By default, all responses are returned as XML. Responses can be returned as JSON either by adding “.json” to the base URI, or by setting the “Accept” HTTP header in the request to “application/json”. When specifying both the response format and serialization, the format should be added first.
https://api.lib.harvard.edu/v2/items.json?title=peanuts
https://api.lib.harvard.edu/v2/items.dc.json?title=peanuts
API Request Rate Limit
The LibraryCloud API is limited to an average of 300 requests per 5 minutes; if, after 5 minutes, that limit is exceeded, the client will receive a 5 minute timeout before they can resume requests. Please limit your requests to no more once per second.
Cross-Domain Queries
The API sets the necessary CORS header to allow cross-domain requests in supported browsers. Cross-domain queries can also use JSONP by specifying a callback function name in a “callback” parameter.
https://api.lib.harvard.edu/v2/items.json?title=peanuts&callback=myfunction
| Parameter | Description |
|---|---|
| callback | Javascript function name. The response data will enclosed in a javascript function call with this name. |
API API Versioning
The version number of the API is specified in the base URL (e.g. “v2”). A version number is always required when accessing the API. The version number will be incremented whenever breaking (non backwards-compatible) changes are made to the API.
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This section describes the fields available for searching through the API. In some cases, fields available through the API aggregate multiple fields within the MODS records. When applicable, this is identified in the MODS field mapping column.
| Name | Exact Match Search | Alpha Sort | Can Facet | MODS Field Mapping | Examples/Notes |
|---|---|---|---|---|---|
abstractTOC | No | No | No | abstract | This query returns items with the keyword "justinian" in an abstract or table of contents field: https://api.lib.harvard.edu/v2/items?abstractTOC=Justinian |
classification | Yes | No | Yes | classification Physical organization code. Includes bibliographic-level classification but not holdings. See shelfLocator for holdings-level classification. | https://api.lib.harvard.edu/v2/items?classification=F1435.3 Case-sensitive exact match: |
collectionId | Yes | No | Yes | extension.sets.systemId Query by the set/collection ID assigned to items that have been grouped together for delivery via Harvard Digital Collections. | This query returns items associated with a specific set by its identifier: Case-sensitive exact match: |
collectionTitle |
future)
| future) | |||||
| dates.start | No | No | No | originInfo.dateIssued Use YYYY format to search. | This query returns all works by Molière published from 1990 forward: This query returns all works by Molière published from 1990 backward: This query returns all works by Molière published from 1990 to 2000: |
| dates.end | |||||
edition | Yes | No | Yes | originInfo.edition | https://api.lib.harvard.edu/v2/items?name=Molière&edition=7th. ed. Case-sensitive exact match: |
genre | Yes | No | Yes | genre | https://api.lib.harvard.edu/v2/items?q=fish+watercolor&genre=Drawings Case-sensitive exact match: |
identifier |
Yes | No | No | identifier (Identifier of an item in another system) | This query returns an item by |
its ISBN: |
isCollection |
Yes | No | Yes | typeOfResource (where collection="yes") Values are “true” or “false”. Indicates whether or not a record describes a collection of items. | https://api.lib.harvard.edu/v2/items?q=colonial+north+america&isCollection=true | |
isManuscript |
Yes | No | Yes | typeOfResource (where manuscript="yes") Values are “true” or “false”. Indicates whether or not a record describes manuscript or archival material. | https://api.lib.harvard.edu/v2/items?q=colonial+north+america&isManuscript=true | |
isOnline |
No | Yes† | Yes | "true" if location.url[@access = 'raw object'] exists, "false" otherwise Indicates whether or not an item is available in digital form; values are "true" or "false". See also inDRS. | https://api.lib.harvard.edu/v2/items?q=earhart amelia&isOnline=true †Will sort all @access=raw object items together in a result set. | |
issuance | Yes | No | Yes | originInfo.issuance | This query returns items with subject "astronomy" issued as a serial: https://api.lib.harvard.edu/v2/items?subject=astronomy&issuance=serial |
languageCode | Yes | No | Yes | language.languageTerm (where languageTerm type="code") Search is based on language ISO code. | This query returns items of Shakespeare in Chinese: https://api.lib.harvard.edu/v2/items?name=shakespeare&languageCode=chi |
languageText | Yes | No | Yes | language.languageTerm (where languageTerm type="text") Facet as "language" rather than "languageText". For exact match, use "language_exact". Search is based on language name text. | This query returns items by or about Laozi in Chinese: Case-sensitive exact match: |
name | Not available | No | Yes | name.namePart e.g. "Greenblatt, Stephen" | Will find term in any name field: |
originDate | Yes | No | Yes | originInfo.dateIssued | https://api.lib.harvard.edu/v2/items?name=asimov+isaac&originDate=1961 Case-sensitive exact match: |
originPlace | Yes | No | Yes | originInfo.place.placeTerm | https://api.lib.harvard.edu/v2/items?q=colonial+north+america&originPlace=Boston Case-sensitive exact match: |
physicalDescription |
No | No | physicalDescription.form | This query returns items in print form with "peanut" in the title: https://api.lib.harvard.edu/v2/items?title=peanut&physicalDescription=print | ||
physicalLocation |
No | No | Yes | location.physicalLocation Includes Harvard repository names but also non-Harvard locations, especially for artworks. | https://api.lib.harvard.edu/v2/items?physicalLocation=tozzer&subject=cylinder seals | |
publisher | Yes | No | Yes | originInfo.publisher | https://api.lib.harvard.edu/v2/items?q=shakespeare&publisher=Arden Case-sensitive exact match: |
recordIdentifier | Yes | No | No | recordInfo.recordIdentifier at the top level only priorrecordids.recordIdentifier e.g. recordIdentifier=sch00443c00117 (for finding aids), recordIdentifier=S26791_olvsurrogate827653 (for images), recordIdentifier=012956251 (for Aleph) Internal recordInfo.recordIdentifier elements in finding aid components and image records can be searched as keywords. | https://api.lib.harvard.edu/v2/items?recordIdentifier=990148733450203941 (for Alma) https://api.lib.harvard.edu/v2/items?recordIdentifier=014873345 (for Aleph) https://api.lib.harvard.edu/v2/items?recordIdentifier=sch00227c00197 (for finding aids) https://api.lib.harvard.edu/v2/items?recordIdentifier=W42143_urn-3:FHCL:1176307 (for images) Use a keyword query to retrieve items based on record ID in finding aid components and image records: |
repository |
| Yes | No | Yes | Search: location.physicalLocation (where @type="repository") Facet: extension.librarycloud.HarvardRepositories.HarvardRepository Includes Harvard repositories only. A search will query the long form repository name (e.g.Eda Kuhn Loeb Music Library); faceting will return the short form repository name (e.g. Loeb Music). | https://api.lib.harvard.edu/v2/items?q=peanuts&repository=Oakes Ames | |||||||
resourceType (4/11/19: not working correctly) | Yes | No | Yes | typeOfResource | https://api.lib.harvard.edu/v2/items?name=shakespeare&resourceType=three dimensional object | ||||||
role | Yes | No | Yes | name.namePart.role.roleTerm | https://api.lib.harvard.edu/v2/items?name=shakespeare&role=publisher | ||||||
| seriesTitle | Yes | No | Yes | In relatedItem[@type='series']: titleInfo.title facet as "relatedItem" rather than "seriesTitle" | https://api.lib.harvard.edu/v2/items?seriesTitle=Harvard-Yenching Institute Monograph Series | ||||||
| Yes | No | Yes | location.shelfLocator | https://api.lib.harvard.edu/v2/items?q=peanuts&shelfLocator=Film Mas Case-sensitive exact match: | ||||||
source | No | Yes | Yes | recordInfo.recordIdentifier source attribute Sources are currently MH:ALMA (from Alma), MH:VIA (image items from JSTOR forum), or MH:OASIS (finding aid components from ArchivesSpace). Attribute occurs only on top-level recordInfo.recordIdentifier elements | https://api.lib.harvard.edu/v2/items?q=earhart amelia&source=MH:ALMA | ||||||
subject | Yes | No | Yes | subject.topic | https://api.lib.harvard.edu/v2/items?subject=perseus Case-sensitive exact match: Note: An exact query can match on contents of a single field only. In LibraryCloud MODS, a subject heading and its subdivision(s) are split into separate fields, e.g. the subject heading "Older people -- Services for" appears in the LibCloud MODS record as these fields: <mods:topic>Older people</mods:topic> |
Yes | No | Yes | location.url.access (range = <preview, raw object>) facet as url.access.preview or url.access.raw_object Query for records containing a url field with a specific @access attribute. Values are: "preview"= indicates link to image thumbnail | This query returns items containing a url with the attribute access="preview" (i.e., an image thumbnail link is present): This query returns items containing a url with the attribute access="raw object" (i.e., a link to full digital content is present): | |
urn |
| No | No | No | location.url Queries an item by its NRS URN (the URN only e.g., " urn-3 |
:FHCL:1155043" minus the actionable URL components). | https://api.lib.harvard.edu/v2/items?urn=urn-3:FHCL:1155043 | ||||
| DRS Extensions | |||||
| drsFileId (valid if inDRS=true) | extension.HarvardDRS.drsFileId The database identifier in the DRS for a file. | This query will return a LibraryCloud item by the corresponding DRS file ID: https://api.lib.harvard.edu/v2/items? | |||
| drsFileId=481890727 | ||||||
| drsObjectId (valid if inDRS=true) | extension.HarvardDRS.drsObjectId The database identifier in the DRS for an object. | This query will return an item for the Harvard Book by corresponding DRS object ID: This query will return all items in Library Cloud that have a corresponding digital object in the DRS: | ||||
|
| Yes | No | Yes | extension.HarvardDRS.accessFlag (range = <P, R, N>) P (publicly accessible), R (restricted to Harvard), N (not available for delivery) See also: availableTo to query human-readable version of DRS accessFlags. | https://api.lib.harvard.edu/v2/items?genre=daguerreotype&accessFlag=P | ||
|
| Yes | No | Yes | extension.HarvardDRS.contentModel (range = <AUDIO, DOCUMENT, PDS DOCUMENT, PDS DOCUMENT LIST, STILL IMAGE, TEXT, VIDEO>) Use _exact query to find "DOCUMENT". See also: digitalFormat to query by human-readable value derived from the contentModel for an object in Harvard's Digital Repository Service (DRS). | https://api.lib.harvard.edu/v2/items?title=biodiversity&limit=100&contentModel=PDS DOCUMENT Use the case-sensitive exact match query to find "DOCUMENT": | |
| contentModelCode (valid if inDRS=true) | extension.HarvardDRS.contentModelCode An identifier that uniquely identifies a specific DRS content model. For example, CMID-5.0 identifies the Still Image content model. See the DRS Content Guide for content model names and identifiers. | This query will return all items in Library Cloud that have a corresponding digital object in DRS with content model CMID-5.0 (Still Image): https://api.lib.harvard.edu/v2/items?contentModelCode=CMID-5.0 | |||
fileDeliveryURL (valid if inDRS=true) |
| Yes | No | No | extension.HarvardDRS.fileDeliveryURL, eg. "http://nrs.harvard.edu/urn-3:FHCL.HOUGH:1090399" Query an item by its full delivery URL. | https://api.lib.harvard.edu/v2/items?title=annual+report&fileDeliveryURL=https://nrs.harvard.edu/urn-3:HMS.COUNT:22923642 | ||
| harvardMetadataLinks | ||||||
|
| Yes | No | Yes | extension.HarvardDRS.inDRS (range = <"true", "false">) Query for items in Harvard Library's digital repository service. See also isOnline. | https://api.lib.harvard.edu/v2/items?genre=daguerreotype&inDRS=true | |
| insertionDate | |||||
| lastModifiedDate | |||||
| maxImageDeliveryDimension (future) | Future | No | Future | extension.HarvardDRS.maxImageDeliveryDimension - e.g., "600". Value is in pixels. |
metsLabel (valid if inDRS=true) |
| Yes | No | No | extension.HarvardDRS.metsLabel eg. Any text string Query for items by keywords in the descriptive METS label - if defined in DRS metadata. | https://api.lib.harvard.edu/v2/items?metsLabel=seward Case-sensitive exact match: | |
modified.after (valid if inDRS=true) |
| Yes | No | No | extension.HarvardDRS.lastModifiedDate - eg. "2016-05-03 Query items by the "last modified" date of a linked digital object in DRS (in YYYY-MM-DD format). | This query returns items in DRS last modified after 2016-01-05: This query returns items in DRS last modified before a specific date: This query returns items in DRS last modified on 2016-01-05: https://api.lib.harvard.edu/v2/items?q=*&modified.after=2016-01-04&modified.before=2016-01-06 | |
| modified.before (valid if inDRS=true) |
| No | No |
This query returns items in DRS last modified prior to 2015-01-01: https://api.lib.harvard.edu/v2/items?q=*&modified.before=2015-01-01 | |||||
| ownerCode (valid if inDRS=true) | Yes | No | Yes | extension.HarvardDRS.ownerCode, eg. "FHCL.HOUGH" | https://api.lib.harvard.edu/v2/items?q=cookbook*&ownerCode=RAD.SCHL |
| ownerCodeDisplayName (valid if inDRS=true) | Yes | No | Yes | extension.HarvardDRS.ownerCodeDisplayName, eg. "Houghton Library" | https://api.lib.harvard.edu/v2/items?q=daguerreotype&ownerCodeDisplayName=Schlesinger |
| ownerSuppliedName (valid if inDRS=true) | extension.HarvardDRS.ownerSuppliedName The distinctive name for the digital item provided by the owning Harvard repository responsible for the content. This is the DRS object owner supplied name (OSN). | This query returns the LibraryCloud item for the Harvard Book by its object owner supplied name: https://api.lib.harvard.edu/v2/items?ownerSuppliedName=124783.xml | |||
| suppliedFilename (valid if inDRS=true) | extension.HarvardDRS.suppliedFilename | ||||
uriType (valid if inDRS=true) |
| Yes | No | Yes | extension.HarvardDRS.uriType (range = <FDS, IDS, PDS, PDS_LIST, SDS, SDS_VIDEO>) Query for items by type of delivery urn, which is a proxy for type of delivery service. Delivery service types: FDS (text documents), IDS (images), PDS (page-turned objects), PDS_LIST (list of page-turned objects), SDS (streaming audio), (SDS_VIDEO (streaming video) | https://api.lib.harvard.edu/v2/items?subject=jazz&uriType=SDS | ||
| viewText (valid if inDRS=true) | extension.HarvardDRS.viewText (range = <on, off>) Query items by status of the View Text setting of the object in DRS. View Text is an object-level field that controls the View Text menu option in the PDS user interface. | This query returns items owned by Houghton that have the View Text control set "off": https://api.lib.harvard.edu/v2/items?repository=houghton&viewText=off | ||||
| LibraryCloud Extensions | ||||||
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| Yes | No | Yes | extension.librarycloud.availableTo Human-readable values for access to digital content in Harvard's Digital Repository Service (DRS). Values are "Everyone" (corresponds to accessFlag=P) and "Harvard only" (corresponds to accessFlag=R). See also: availableTo to query by DRS accessFlag. | https://api.lib.harvard.edu/v2/items?q=colonialism&availableTo=Everyone | ||
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| No | Yes | extension.librarycloud.digitalFormats.digitalFormat Human readable values derived from the contentModel for an object in Harvard's Digital Repository Service (DRS). Values are audio, books and documents, images, and video. See also: contentModel to query by the DRS content model of an object in Harvard's Digital Repository Service (DRS). | https://api.lib.harvard.edu/v2/items?subject=poetry&digitalFormat=audio | ||
processed.after | Yes | No | No | extension.librarycloud.processingDate Use YYYY-MM-DD format to search. This processing date indicates the most recent re-ingest of a metadata record (an "item") into LibraryCloud from its source catalog. | This query returns items processed after the date specified: This query returns items processed before the date specified: This query returns items processed between the specified dates: |
processed.before | |||||
| Sets Extensions | |||||
| setName | |||||
| No | Yes | extension.sets.set.setName Human-readable names that identify a set of materials selected by, for example, a curator for administrative or discovery purposes or for harvesting via OAI-PMH. | https://api.lib.harvard.edu/v2/items?setName=chinese rare books | ||
| setSpec |
| No | Yes | extension.sets.set.setSpec Codes used to identify a set of materials selected by, for example, a curator for administrative or discovery purposes or for harvesting via OAI-PMH. | https://api.lib.harvard.edu/v2/items?setSpec=crb |
More Query Examples
#Search all of LibraryCloud for “peanuts” in the title:
https://api.lib.harvard.edu/v2/items?title=peanuts
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