[Odrl-version2] Common Vocabulary - Constraints on Duties

[ri at odrl.net]

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