Re: Tweet

Hi !

Explaining a problem in a single tweet is not an easy challenge… ;-)

I’m studying ODRL and I have some questions about it.

To simplify (a little bit) my questions, lets take :
- [HTML] : http://www.w3.org/ns/odrl/2/ODRL21 <http://www.w3.org/ns/odrl/2/ODRL21>
- [TTL] : ODRL21.ttl <http://www.w3.org/ns/odrl/2/ODRL21.ttl>
- [Voc] : https://www.w3.org/community/odrl/vocab/2.1/ <https://www.w3.org/community/odrl/vocab/2.1/>
- [Core] : https://www.w3.org/community/odrl/model/2.1/ <https://www.w3.org/community/odrl/model/2.1/>

1. My tweeter question

First, my question posted by tweeter. Imagine you have a database of standard licenses (like RDFLicense http://rdflicense.appspot.com <http://rdflicense.appspot.com/>). Then, Alice (http://www.example.org/Alice/alice.foaf <http://www.example.org/Alice/alice.foaf>) wants to give her document http://www.example.org/Alice/book.pdf <http://www.example.org/Alice/book.pdf> to Bob (http://www.example.org/Bob/bob.foaf <http://www.example.org/Bob/bob.foaf>). But Alice also wants to use a license derived from a standard one (for example http://purl.org/NET/rdflicense/ARTISTIC2.0 <http://purl.org/NET/rdflicense/ARTISTIC2.0>). She doesn’t want to copy the license code because of maintaining a copy can be dangerous considering possible modifications. So, she wants to create a license (http://www.example.org/Alice/artistic2-alice <http://www.example.org/Alice/artistic2-alice>) which inherits from http://purl.org/NET/rdflicense/ARTISTIC2.0 <http://purl.org/NET/rdflicense/ARTISTIC2.0> . In ODRL, such license is written like :

@prefix rdf:     <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs:    <http://www.w3.org/2000/01/rdf-schema#> .
@prefix odrl:    <http://www.w3.org/ns/odrl/2/> .

<http://www.example.org/Alice/artistic2-alice>
      a       odrl:Policy ;
 odrl:inheritFrom <http://purl.org/NET/rdflicense/ARTISTIC2.0>  .

My question is : how to declare the Alice’s document as target, Alice as assigner et Bob as assignee ?
For the first part, it can be (like [HTML] shows in the first example) :
<http://www.example.org/Alice/book.pdf <http://www.example.org/Alice/book.pdf>> dat:license <http://www.example.org/Alice/artistic2-alice> .

But, for the two others, I don’t know how to do.

2. Inheritance

About inheritance, I have another question. I don’t understand the specification of the « inheritFrom » property. In [HTML], an example of inheritance is presented. But, it seems to me that some triples are inherited (permission, action…) but not some others (like assignee). In fact, the comment says : « Since the child policy also inherits from the parent policy, then the party http://example.com/class:IT01 can also print the parent’s target asset. ». But <…IT01> is only declared as assignee of <…report:2333>. This question is linked to the preceding one. If policy:9999 have not more permission to declare, how to link  <…IT01> with <….report:2321> ?

3. Conflict

I don’t understand the « conflict » attribute. In [HTML], an example presents it in only one license. So it seems to resolve a conflict into a given license. In this example, it says, if there is a permission and a prohibition which concerns the same action, so the permission « wins ».

But in [Core], the text is « The conflict attribute is used to resolve conflicts arising from the merging of policies ». So, to merge policies, it is necessary to have at least 2 policies… In this context, if the fist one declares « odrl:conflict odrl:perm » and the other one declares « odrl:conflict odrl:prohibit », there is a conflict on « conflict » attributes! The document doesn’t explain the algorithm.

4. Action.

With the property « odrl:action » all examples of [HTML] are with only one Action. Can we put more than one Action ? I think it’s possible consulting [TTL] and examples of RDFLicense.

5. DateTime vs. Duration

In [HTML], example « Privacy Policy », the property « odrl:dateTime » has the value « P30D » with the type xsd:dateTime. It’s wrong. « P30D » is a xsd:duration. So  « odrl:dateTime » can’t be a xsd:duration regarding [HTML,TTL] (xsd:date ou xsd:dateTime). One can find the same problem presenting this property in [Voc] (it can not be a period).

« meteredTime » and « timeCount »  are defined as refs:Literal [TTL,HTML]… not xsd:duration ?

In [Voc], the property « timeInterval » is presented as a period but [TTL] gives the type « rdfs:Literal ». xsd:duration is better ?

6. Vocabulary

in [Voc], the actions are presented by categories (Action for permission or Prohibition, toward third-parties only, Duty, uses, etc.). It would be better to propose this taxonomy also in the ontology [TTL] ?

7. Deprecated terms.

Some terms « deprecated » in [Voc] are « stable » in [TTL] like writeTo or appendTo. Others are deprecated in [TTL] but not presented deprecated in [Voc] like « export », « copy », device », etc.

8. Profile

In [Core] and in [HTML], section « Profile », a « ODRL Profile » is refereeing but I didn’t find any description of it.

9. About the « duty » property

In [HTML,TTL], the « duty » property is defined with the domain « Permission ». But figure 2.1 in [Core] show that this property can be associated with an Asset. Examples in [HTML] present it in a Policy. So, the domain must be : owl:unionOf ( :Permission :Policy ) ?

10. Permission in a Policy

in [Core], figure 2.1, a policy may contains zero, one ore more Permissions but, in the text, you say « at least ore » .

11. Relation and role

Il would be interesting that « relation »  and « role »  can link en Policy, not only a Rule. It make be possible to declare the same assignee or the same target for all rules of a Policy.

Sorry for my english.

E. Desmontils
—
Directeur adjoint du département Informatique, Faculté des sciences et techniques
Membre de l’équipe GDD du LINA (CNRS, UMR  6241)
http://www.univ-nantes.fr/desmontils-e <http://www.univ-nantes.fr/desmontils-e>
Adoptez l'éco-attitude. N'imprimez ce mail que si cela est vraiment nécessaire


> Le 12 mai 2016 à 12:56, Renato Iannella <renato.iannella@monegraph.com> a écrit :
> 
> Hi Emmanuel, I got your tweet..
> 
> "@odrl Need of help. How can I add an assignee (or assigner or target) to an existing #odrl license, e.g. add foaf:Tom to rdflicense:ccBy.”
> 
> But was not sure what you meant by it…Can you explain a little more?
> 
> 
> Renato Iannella, Monegraph
> Co-Chair, W3C Permissions & Obligations Expression (POE) Working Group
>