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SPARQL

SPARQL support is activated and configured through the public repository which is maintained in parallel to the main repository. SPARQL queries can be made either against the whole repository or a single context. The public repository contains only publicly accessible metadata.

Configuration

The supported configuration settings are:

entrystore.repository.public=on|off (default: off)
entrystore.repository.public.type=memory|native
entrystore.repository.public.path=file:///srv/../../public
entrystore.repository.public.indexes=cspo,spoc,posc
entrystore.repository.public.rebuild-on-startup=on|off (default: off)
entrystore.repository.public.sparql.max-execution-time=<seconds> (default: 10)

The type is either memory or native. The memory setting allows for faster SPARQL queries but requires an adequate amount of memory. As the memory store does not persist, a rebuild of the public repository takes place automatically upon start or restart of the EntryStore repository.

A rebuild on startup is performed under the following circumstances:

  • when explicitly turned on
  • when the public repository is used for the first time (in the case of the native store)
  • on every startup when the configured store type is "memory"

Usage

Queries can be made through either GET or POST requests. There are endpoints for every single context and a global endpoint.

Note: Named Graph information is lost when querying against a specific context.

Context endpoint

http://{base}/{context-id}/sparql

Global endpoint

http://{base}/sparql

Parameters for GET requests

  • query: the SPARQL query. Mandatory parameter which has to be URL encoded.
  • format: the format of the result. Possible values: application/json, text/csv or application/xml. Optional parameter, default is binary output.
  • callback: if the JSON result should be wrapped inside a JavaScript-method (i.e. JSONP), then the callback parameter can be used to specify the name of the method.

Parameters for POST requests

The parameters should be sent in the body of the POST request.

  • query: the SPARQL query.
  • output: the format of the result. Possible values: json, csv or xml. Optional parameter, default is binary output.