[Odrl-version2] Still not sure about constraints on duties

[Renato Iannella]

On 9 Jun 2006, at 00:14, Vicky Weissman wrote:
> If I understood your response correctly, then the following two  
> statements are equivalent.
>
> Party=Alice
> Perm=Download
> Asset=F
> Duty=d
> Duty.Constraint=c
>
> Party=Alice
> Perm=Download
> Asset=F
> Duty=d
> Constraint=c
>
> Is this right?  If so, why allow duties to have constraints at all?
The Constraint in the second example has to be associated with a  
Permission, Duty, or Prohibition.
(This is the  V2.0 Model semantics.) Hence, you can't just have a  
Constraint by itself - does that clear up things?

>
> Again, if I understood correctly, then
>
> Party=Alice
> Perm=Download
> Asset=F
> Duty=Pay[amt=5]
> Duty.Constraint=Date[before30June06]
>
> says that Alice may download F if she has paid 5 and the current  
> date is before June 30, 2006.  So the encoding does not match the  
> example I gave; namely, Alice may download F (now) if she pays 5  
> dollars at the end of the month.  Examples of similar policies in  
> real life include credit card policies (you can buy what you want  
> but are obligated; that is, have a duty, to pay a certain  
> percentage of your balance at the end of the month) and traditional  
> library policies (you can check out a book but are obligated to  
> return it within 2 weeks).
You can do what you want by adding the following to your example:

Duty.Relax=True

This would fit into the model of "buy now, pay later" - even to the  
point of not paying by the due date and incurring interest
or worse, a library fine ;-0

>
> ---------------
> Finally, is it true that duties can only require some party to make  
> a payment, or could a duty require other types of actions such as  
> attribution being given?  (Note: if a duty can only discuss a  
> payment, then duties are less expressive than requirements as  
> defined in v1.0, although maybe requirements in v1.0 can be  
> captured by constraints in v2.0.)
Duties can relate to *any* action, not just payments.

Cheers...  Renato Iannella
National ICT Australia (NICTA)



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