Re: [poe] 3.7 Action

Re @riannella: such a description could be written down but that means
 a receiver of such a policy has to read the spec document from A to Z
 to learn by one of its sections how to deal with that as in fact this
 design does not comply with RDF rules. 
My approach for my alternative design was: stick to the RDF rules, 
make it easy to understand at first sight - @vroddon thanks for you 
comment supporting this assumption.

Another issue came up today: how to parse a constraint in RDF? For 
retrieving information about a resource it is common to check the 
defined properties of a class. Example: a FOAF Person has a firstName 
and a surname and some "knows" relationships to other persons, the 
assumption that these properties exist as predicates of RDF triples is
 based on the definition of this class - 
http://xmlns.com/foaf/spec/#term_Person

For an ODRL constraint a left and a right operand and an operator are 
REQUIRED properties = they MUST be there. A parser will easily find 
the operator, but how to find the operands? A leftOperand doesn't have
 to be defined by ODRL, any "Name of Constraint" defined by any party 
could be used there. So how should the poor parser find out that a 
predicate like iptc:usagePeriod is the left operand - what makes this 
predicate special to know/assume/guess/hope that this is the left 
operand? Defining that a constraint must consist of only three 
assertions - one about the type, one for the operator, one for the 
left and right operand - doesn't work in practice as the Constraint 
class also defines optional properties.


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Received on Tuesday, 13 December 2016 15:50:26 UTC