Re: [poe] Split LeftOperands into constraints and refinements

re @riannella 

re 1. What is  an alternative to indicate "this LeftOperand instance should be used with refinement Constraints" or "this LeftOperand instance should be used with refinement Constraints" (as default relationship) without defining a new feature triggering a new CR?
Could this be a free-text table acting as non-normative guideline with a LeftOperand in each row and columns for constraint Constraints and refinement Constraint and an "x" shows the preferred use? Should this be written down in a special Note document?

re 3.  The current formal definition in [2.5.4 of the IM](https://w3c.github.io/poe/model/#constraint-action) is:
_An Action MAY include the refinement property to indicate a Constraint/Logical Constraint that narrows the semantics of the Action operation directly. To meet this condition of narrower semantics for the Action, all of the Constraints/Logical Constraints referenced by the refinement property MUST be satisfied._
How to satisfy a constraint this is defined in [2.5.1 of the IM](https://w3c.github.io/poe/model/#constraint-class):
_A Constraint class is used for expressions which compare two operands (which are not Constraints) by one relational operator. If the comparison returns a match the Constraint is satisfied, otherwise it is not satisfied. The Constraint class formulates a comparison expression, such as, the number of usages (the leftOperand) must be smaller than (the operator) the number 10 (the rightOperand)._

Apply these definitions to our frequently used refinement of an action:
`<odrl:payAmount> <odrl:eq> "50 EUR" .`
odrl:payAmount is defined as "The amount of a financial payment. " therefore "is the amount of a financial payment equal to 50 EUR" needs to be compared, but how? Does the party having to exercise the payment check it accounts for available 50 EUR, or does it have to check if its accounting department is able to pay 50 EUR, or does a manager has to show thumbs up for paying 50 EUR to set the Constraint to Satisfied or Not-Satisfied?

My summary of that: the IM does not define something wrong but it leaves the evaluation of a refinement of an action open to random ways of comparing - this does not support interoperability. 
Is clarifying this in a Best Practice Note an option? I still think that @simonstey 's outline would be a good description.




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Received on Wednesday, 29 November 2017 08:39:22 UTC