The API to the Digitale Collectie ErfGeo Enrich service consists of an OAI-PMH endpoint as well as a
(In addition to these an SRU endpoint exists at
/sru, but that is currently not specified other than by example by including the specific request as part of the JSON response to a
/search interface takes at least a
query parameter that follows the Contextual Query Language (CQL). It returns a JSON response containing search result items that are described in JSON-LD.
A simple query takes the form
Queries can refer to specific fields, e.g.:
dc:title=nachtwacht AND dc:creator=rembrandt
A bounding box can be specified as part of the query by specifying ranges for the fields
dcterms:spatial.geo:lat>50.2 AND dcterms:spatial.geo:long>3.6 AND dcterms:spatial.geo:lat<53.1 AND dcterms:spatial.geo:long<7.1.
However, for convenience (and url readability) the bounding box can also be specified by using the (virtual) fields
minGeoLat=50.2 AND minGeoLong=3.6 AND maxGeoLat=53.1 AND maxGeoLong=7.1.
A year range can be specified by way of the
dc:date.year field in which normalized year values from
dcterms:created fields are indexed. E.g.
dc:date.year>1720 AND dc:date.year<1722.
Records can be queried by the size of the referred images by way of the
schema:height fields. E.g.
Having obtained a record id in response to an earlier search request, that specific record can be requested by referring to the
id field. E.g.
/search?query=id exact "NIOD_BBWO2:niod:3379966"/
Currently the following fields are distinguished in the search index:
Facets can be requested with the
facets parameter, with separate facet fields separated by a , character (
%2C url encoded).
More than the default number of 10 facets can be requested by adding a colon and a number (250 max.) to specified facet fields.
Currently, the following fields are available as facets:
By default a maximum of 10 records is returned. More records can be requested, up to a maximum of 30 per request, by providing a
maximumRecords parameter. More search results can be requested by specifying an offset by means of the
startRecord parameter. E.g.
random parameter was added for the purpose of content discovery. So, by passing
random=true the results in the query reponse are taken randomly (thus ignoring relevance scores) from a larger set of matching results. E.g.
Note: for performance reasons a limit applies to the number of matching results that are considered (i.e. instead of the most relevant 10 results, the most relevant 1000 results will make up the population of which a sample of 10 is taken).
The OAI-PMH interface(s) implements the Open Archives Initiative Protocol for Metadata Harvesting.