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RDF Constraints

·210 words·1 min

SST Core is not a general purpose RDF toolkit
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SST Core is highly optimised in various ways for speed and efficiency. To achieve this goal certain restrictions are introduced, with the result that SST Core is not a general purpose RDF toolkit. In practise this means, every RDF file generated with SST-Core is valid according to the W3C standards, but not every RDF file can be imported into SST Core.

In detail the RDF restrictions are:

  • every Datasets is identified by an URI (URN or URL) without any fragment
  • every NamedGraph is identified by an URI (URN or URL) without any fragment
  • even the default graph of a Dataset is a NamedGraph in SST, and this default NamedGraph has the same URI as the Dataset (for which it is the default one)
  • IBNodes are owned and located in exactly one NamedGraph with the same base URI plus a fragment; only the owning NamedGraph can contain triples with the owned IBNodes as subject
  • in addition to the above each NamedGraph has an implicitly IBNode that has the same URI as the NamedGraph with no fragment; this is used to make statements about the NamedGraph
  • blank node can be referenced as object only within the same NamedGraph where they are defined