RDF Named Graph
Specific requirements that the Prov-WG has on RDF named graphs
RDF WG Dataset Proposal
RDF WG Provenance Use Case
1. Ability to collectively refer to a set of provenance assertions - to make additional assertions regarding date, author, and related provenance information
- This is a requirement of the account construct, which also identifies a scope within which some properties must hold (e.g. at most one process execution generating an entity). [Luc]
2. Ability to retrieve the provenance of a RDF resource (requires finer level of granularity at the level of Subject, Predicate and Object - which is not supported by RDF named graph construct)
3. Ability to compare two graphs and determine if they are equal. This is useful if we want to compare provenance.
- Jena API has method for both graph compare (isIsomorphicWith) implementing the "method described in RDF document" and graph merge (implemented in our work on provenance query operators)[Satya]
4. Ability to group of triples down to a single triple such that we can describe that groupings provenance.
5. [GK] Possible need to use named graphs to record contextualization of provenance assertions - depends on discussions about provenance - see http://lists.w3.org/Archives/Public/public-prov-wg/2011Sep/0000.html. See in particular the paragraph starting "I then think our discussion becomes one of how the contextualization of an assertion is captured..." about the middle of the email.
6. An entity contains a fixed list of attribute-value pairs. There must be a mechanism by which it is possible to identify which attribute-value pairs have been asserted. Named graphs may be used for this. [Luc]
- Is this different from grouping a set of assertions? [Satya]
7. Would be nice to have a mechanism to sign a provenance graph. Is this a requirement for named graphs? [Luc]
- We can make assertions about a named graph - author, signature, "validator" etc. [Satya]