13.1.2 Endpoint URL Data Sources

External RDF data sources are defined using an endpoint URL. In general, each RDF store has a generic URL that accepts SPARQL queries and SPARQL updates. Depending on the RDF store service, it may also provide some capabilities request to retrieve available datasets.

Table 13-1 External Data source Parameters

Parameters	Description
name	A generic name of the data source.
type	The type of the data source. For external data sources, the type must be ‘ENDPOINT’.
description	A generic description of the data source.
properties	Specific mapping parameters with values for data source properties: base URL: the base URL to issue SPARQL queries to RDF store. This is the default URL. query URL (optional): the URL to execute SPARQL queries. If defined, it will overwrite the base URL value. update URL (optional): the URL to execute SPARQL updates. If defined, it will overwrite the base URL value. capabilities (optional): Some RDF stores (like Apache Jena Fuseki) may provide a capabilities URL that returns the datasets available in service. A JSON response is expected in this case. get URL: the get capabilities URL. datasets parameter: defines the JSON parameter that contains the RDF datasets information. dataset parameter name: defines the JSON parameter that contains the RDF dataset name.

The following example shows the JSON representation of a Dbpedia external data source :

{
  "name": "dbpedia",
  "type": "ENDPOINT",
  "description": "Dbpedia RDF data - Dbpedia.org",
  "properties": {
      "baseUrl": "http://dbpedia.org/sparql",
      "provider": "Dbpedia"
   }
}

The following example shows the JSON representation of a Apache Jena Fuseki external data source. The ${DATASET} is a parameter that is replaced at run time with the Fuseki dataset name:

{
    "name": "Fuseki",
    "type": "ENDPOINT",
    "description": "Jena Fuseki server",
    "properties": {
      "queryUrl": "http://localhost:8080/fuseki/${DATASET}/query",
      "baseUrl": "http://localhost:8080/fuseki",
      "capabilities": {
        "getUrl": "http://localhost:8080/fuseki/$/server",
        "datasetsParam": "datasets",
        "datasetNameParam": "ds.name"
      },
      "provider": "Apache",
      "updateUrl": "http://localhost:8080/fuseki/${DATASET}/update"
    }
}