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Setting up an RDF server

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John Bradley edited this page Jul 18, 2022 · 1 revision

GRASP as it comes is all very well if you want to build queries against the DPRR or PoMS RDF servers. What must you do if you want to build queries for an RDF server other than these two?

GRASP uses the concept of an "RDF Server" to provide information that allows SPARQL queries to be built for an RDF dataset by holding information about an RDF Server's OWL Ontology and information about URLs that give access to the RDF data itself through SPARQL queries. Thus, althoiugh GRASP comes with two RDF Servers set up (for the PoMS and DPRR datasets) by creating a new "RDF Server" you can add your own as well.

To do this, first open GRASP's RDF Servers View. This is done by clicking on the 2nd button from the left in the button bar (near the top of GRASP's window). If it is clicked the RDF Servers View will open and appear on top of the Classes View. If you have not yet created any server entries yourself, it will show the DPRR and PoMS RDF servers only. They can be double clicked on to allow you to modify them if you wish, and entries can be deleted by selecting one and pushing the delete button (although deletion cannot be undone here, so use this option with care).

However, if you wish to create an entirely new entry, click with the other mouse button to open the contextual menu. The only choice there will be "Add new RDF Server". Choose this and you will see:

Figure image019.png

The fields provided here are:

  • RDF Server Name: the name to be used to display this server entry within GRASP.

  • SPARQL Server URI (data):* *A fragment of a URI that GRASP is to use when requesting RDF data through a SPARQL query. GRASP uses the mechanisms provided by the W3C for this in its Sparql 1.1 Protocol (https://www.w3.org/TR/sparql11-protocol/). GRASP will append the "query" parameter to the given URL.

  • SPARQL Server URI (data): A fragment of a URI that GRASP is to use when submitting a SPARQL query that is to generate results for a browser. This might be the same URI as the one used for data requests.

  • OWL Ontology URI: A pointer to the OWL Ontology that describes this dataset. GRASP makes significant use of the class definition and hierarchy data, as well as the domain and range information for properties. It supports both http(s) and file protocols, so the Ontology can be provided either remotely or locally.

Once the new server is set up, it will turn up among the choices for RDF servers that can be chosen once one starts a new SPARQL query.

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