Re: ODRL Evaluator Rules

> On 31 May 2017, at 01:58, Phil Archer <phila@w3.org> wrote:
> 
> Proposed Initial statement:
> 
> If the WG agrees with this then for any operation, the OE has a minimum of two input parameters:
> - the IRI of the specific Asset;
> - the IRI of the Policy.

I assumed that we need to look at Constraints only for OE.
That is, if all Constraints are “evaluated” and the responses (from the “black box”) is “true” then you can say the Rule is in “effect”.


> The simplest output would be a binary in effect|not in effect. Do we want to go further and say that the OE should return what the rule is? i.e. taking the first three examples from the IM, support an output like:
> 
> Example 1. You are permitted to play http://example.com/asset:9898.movie
> Example 2. http://example.com/party:org:abc gives you permission to play http://example.com/asset:9898.movie
> Example 3.  http://example.com/party:org:abc gives http://example.com/party:person:billie permission to play http://example.com/asset:9898.movie <http://example.com/asset:9898.movie>

These examples would only require Validation (not Evaluation) as there are no constraints to check?

(Also: we need to ensure that Validation includes the Policy Type, so for Example 2, this is an “offer for the permission” not the actual granted permission - which is what Example 3 does.)


> 2.2.1 Relation
> ==============
> 
> So you might say, OK, so the OE only accepts Assets that meet any Asset constraints, but then you'd need your supporting software to be able to read the ODRL to find out what the constraints on the Asset were. That seems brittle to me.

There seems to be two approaches to Evaluate Constraints on Asset and Party collections:

If you look at Example 18:
1 - I have asset X - Is it part of the “set of 50” in the media-catalogue? Yes, then I can print it.
or
2 - Tell me the actual assets in the set-of-50 that I can print from the media-catalogue

If you look at Example 19:
1 - I am user X - am I a “over 17 year old friend”? Yes, then let me display the asset.
or
2 - tell me the identity of the friends over 17 years old

Option 2) is the more “atomic” approach - it gets all the uids and, in effect, you could create a new Rule per uid.

Option 1) is more query-based, and assumes you have the source uid you want to Evaluate against the Asset/Party constraint.

Support both approaches?


Renato