The crazy 'qualified' idea:-)

Guys,

I promised on the call that I would jot down the the line of thought I had based on the Prov ontology 'qualified' approach[1]. Here it is...

If my understanding is correct, the way a constraint is used in the current (RDF version of) the ODRL model is something like:

:aRule odrl:constraint :aConstraint .
:aRule a odrl:Rule .
:aConstraint a odrl:Constraint .

If we use the approach used by the Prov vocabulary[1], we would have an _additional_ property, called odrl:qualifiedConstraint. It usage would be something like:

:aRule odrl:qualifiedConstraint [
	a odrl:QualifiedConstraint ;
	odrl:theConstraint :aConstraint .
	# any other properties one wants to attach here.
] .

It is like putting a more complex object instead of a simple predicate. Of course, I can also give it a URL:

:myOwnQualifiedConstraint
	a odrl:QualifiedConstraint ;
	odrl:theConstraint :aConstraint .

and use

:aRule odrl:qualifiedConstraint :myOwnQualifiedConstraint .

(ie, the "real" constraint is hidden)

If I use 'anotherConstraint' to express some time limit, then I may be able to do something like:

:aRule odrl:qualifiedConstraint :myOwnQualifiedConstraint .
:myOwnQualifiedConstraint odrl:constraint :anotherConstraint .

Or, let us say I have three constraints, and I want to express that I need the OR of those:

:myOwnQualifiedConstraint1 a odrl:qualifiedConstraint .
:myOwnQualifiedConstraint2 a odrl:qualifiedConstraint .
:myOwnQualifiedConstraint3 a odrl:qualifiedConstraint .
:aRule odrl:constraint [
	a odrl:OrCombination, odrl:Constraint ;
	odrl:onConstraints (:myOwnQualifiedConstraint1 :myOwnQualifiedConstraint2 :myOwnQualifiedConstraint3)
] .

I am not sure it all works but may worth some thoughts.

Note that this structure is _on top_ of the existing one. In other words, if a user does not want to use these complex solutions, then he/she can safely forget about them.

Ivan

[1] http://www.w3.org/TR/2013/REC-prov-o-20130430/

----
Ivan Herman, W3C
Digital Publishing Technical Lead
Home: http://www.w3.org/People/Ivan/
mobile: +31-641044153
ORCID ID: http://orcid.org/0000-0003-0782-2704