Questions about ShEx

Hello,

I’ve been watching the evolution of the ShEx (http://www.w3.org/2013/ShEx/Primer.html) model with considerable interest.   I’m curious, however, how ShEx is envisioned to fit into the larger RDF ‘validation’ (publication of invariants + validation) use cases.  Questions:


  1.  This model is “… constrained scenario with a starting point in both the graph and the schema.”   — how does one determine such a starting point?  Whether one is validating the contents of a (potentially huge) triple store or a single set of triples, it seems like one first needs to evaluate some set of preconditions to determine what (or whether) the graph should be validated using the given shape expression.
  2.  Some of the use cases presented in the workshop involved two graphs — one containing the information to be added (or removed?) and a second the current state of an RDF dataset.  Evaluation of validity involved the combination of the two — whether, together, they met the requirements.  As an example, an instance issue report well reference an EmployeeShape in an existing triple store, or it may extend an existing UserShape to include the information needed to qualify it as a UserShape.  Is it envisioned that ShEx could be applied to two (or more) graphs concurrently?
  3.  Traditional state transforms involve a combination of invariants (things that are always true about a given RDF Dataset), preconditions (things that must be true before an RDF dataset can undergo a transformation from one state to another) and postconditions (things that are true once a given transformation takes place).   Is it envisioned that ShEx could be used for all three aspects?

Harold Solbrig