[Odrl-version2] Common Vocabulary - Constraints on Duties

[Francis Cave]

Hi Alapan

In cases where the ODRL expression is being interpreted on an end-user
reading device, you are probably right, but where do the precedence rules
come from? Don't these rules have to be built on the basis of the usage
terms provided by the rights holder? The ACAP Profile is concerned with
communicating usage rules within a supply chain, i.e. from rights holder to
intermediary, who will be distributing the content on to end-users. We are
not much concerned with communicating direct with end-users.

Regards,

Francis



> -----Original Message-----
> From: Alapan [mailto:alapan at gmail.com]
> Sent: 13 June 2011 07:56
> To: francis at franciscave.com; ODRL-Version2
> Subject: Re: [Odrl-version2] Common Vocabulary - Constraints on Duties
> 
> Hi Francis,
> 
> You raise some interesting points. But, surely this will be handled as
> per the DRM controller specification's precedence rules (as opposed to
> ODRL precedence rules)?
> 
> Regards,
> Alapan
> 
> On Sunday, 12 June 2011, Francis Cave <francis at franciscave.com> wrote:
> > New text in the latest Draft Specification of the ODRL V2.0 Core
> Model states: “A Duty entity does not, by itself, specify any
> conditions on when the Duty Action must or should be performed, such as
> to pay before viewing the movie. Such conditions should be expressed
> through Constraint entities.” Let us suppose that the Duty Action must
> be performed before the Permission Action may be performed. This can be
> expressed by a “dateTime” Constraint.  Setting aside the issue of how
> to express a Constraint where the time of the Permission Action is not
> known (the ACAP Profile achieves this by using a category identifier,
> or a variable if you prefer), there is also the question of how many
> times the Duty must be performed. The obvious answer is “once”. This
> can be expressed using a “count” Constraint with operator “eq” and
> right operand “1”. But what does this mean? Does it mean one time only,
> or one time for every time that the Permission Action is to be
> performed, once a year, once every time the Action is to be performed
> in a new place,
? One answer is that it depends upon the Duty. Maybe
> one might argue that if the Duty is “obtainConsent”, one might assume
> that this only needs to be performed one time only, while a Duty to
> “pay” (as in pay-per-view) might have to be performed afresh for the
> Permission to apply. However, I think that a more flexible approach
> would be to define a new Constraint called something like
> “countDenominator”, which would take values such as “only”,
> “perAction”, “perRecipient”, “perYear”. An alternative would be to have
> an expression as the rightOperand value of the “count” Constraint, that
> incorporates both numerator and denominator, but this seems to me to be
> inappropriate, when the goal is not to wrap up important rights
> expression semantics in some unspecified syntax. Given the statement in
> the Core Model specification that I quote above, I don’t think that
> this is an issue that should be left to be resolved in different ways
> by different Profiles. However, I would accept that only a limited
> range of options are likely to be widely applicable and therefore
> suitable for inclusion in the Common Vocabulary. Francis Cave
> 
> --
> Blog: http://idiots-mind.blogspot.com/
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