[Odrl-version2] Common Vocabulary - Constraints on Duties

[Francis Cave]

Hi Renato

I quite like your suggestion, but I think there may be a problem with it.

I think one needs to be able to distinguish between the following cases:

- You are permitted to make one copy of the asset, but must obtain consent
first.

- You are permitted to make any number of copies of the asset, but must
obtain consent first.

- You are permitted to make any number of copies of the asset, but must
obtain consent first IN EACH CASE.
	
According to your explanation below, a 'count eq 1' Constraint on the 'copy'
Action could imply either the first or third of these cases.
	
One could argue that this could be resolved by careful interpretation of the
'count' constraint when on the Permission Action only (the first case above)
or on the Duty Action only (the second case) or on both (the third case).

If that is the intention, should this be explained in the Vocabulary? Such
an interpretation is not self-evident.

I don't think these address the case where consent would need to be renewed
periodically, but that is possibly where Alapan's explanation becomes
relevant: the assignee's system would need to be informed separately of any
complex rules that control the circumstances in which it is necessary to
obtain consent.

I think I volunteered to come up with a more detailed description of how
each Constraint should be interpreted in different Action contexts, so maybe
I'm just giving myself more work...

Regards,

Francis




> -----Original Message-----
> From: ri at odrl.net [mailto:ri at odrl.net]
> Sent: 14 June 2011 04:25
> To: francis at franciscave.com; ODRL-Version2
> Subject: Re: [Odrl-version2] Common Vocabulary - Constraints on Duties
> 
> Francis - the general idea is that the Duty has to be performed (ie
> once) to get access to the Permission's action.
> 
> Once the Duty has been performed, then you can undertake the Action in
> the Permission.
> 
> So, for example, if the Duty is "pay" - you do this once, then you can
> "play" the video (ie what the Permission says).
> 
> If the Permission says you can play the video once (ie count constraint
> = 1), then this means you can play the video once.
> If you want to play it again, then you perform the Duty again (eg the
> payment).
> Hence, you have "per-play" model for payment.
> 
> Similarly, if you wanted an obtainConsent Duty on each "read" of my
> data record, then you can have the "read" action with count constraint
> = 1 (in the Permission).
> 
> As for the "when" to do a Duty, we introduced a new Event value in the
> last Vocab update.
> Please see the "event" entry in Section 2.3 of the Common Vocabulary.
> 
> I hope this makes it all clearer?
> 
> (PS I will add some more text to the Duty section)
> 
> Cheers
> 
> Renato Iannella
> ODRL Initiative
> http://odrl.net
>