[Odrl-version2] RE: ODRL-Version2 Digest, Vol 6, Issue 3

[Vicky Weissman]

Hi all,

I categorized my feedback using the section headings in the draft.  The
comments fall roughly into 3 categories: a number without a `*' indicates a
question, a place where I'm double-checking my understanding, or a minor
comment; a number with a single `*' is a fairly minor remark; and a number
with `**' is more interesting.

Best,
Vicky

2.1 Rights Class Model
----------------------
1) I'm assuming that the Context in a Rights entity can be extended according
to the needs of the particular application.  Is this right?

2*) If the Context includes a `space' for textual comments and remarks, why
do you need another space for the human readable formulation of the rights
expression?  

3**)  It seems to me that there are two types of Rights entity, an agreement
and a request.  A statement is a partial agreement, an offer is a type of
statement where only the assignee(s) is missing; a ticket is an agreement
where the assignee(s) is the ticket holder; and a Next Rights is an agreement
where the assignee(s) is given permission to assign rights to others.  If
this is correct, then wouldn't it be simpler and clearer to remove all but
the agreement and request entities and to say that partial agreements can be
created to suit an application's needs (e.g. an agreement without an assignee
could be used as an offer for a perspective customer).  I think this approach
would also address Steve Rowat's second point in his email from May 21.
   
4) I don't understand the Request entity.  Could you send me a few examples?
I'm particularly curious about Request entities in which the asset in the
request is different from the asset in the permission/prohibitions, the
permission/prohibition has constraints, there is more than one Assignee, and
the Assigner is known.

2.2 Asset Model
---------------
1) The document calls an asset the `Target' of a permission/prohibition.  In
XaCML, the word means something else.  So you might want to use a different
word to avoid confusion (though I don't think this is a big deal).   

2*) The document says `If a parent Asset with child Parts is referenced as
the Target of a rights expression, then all of the Parts are considered also
to be the Target of the same rights expression'.  I don't understand why you
would want to build this into the language.  In particular, suppose that an
agreement gives Alice the right to copy a speech that has 5 parts.  Why
should it necessarily follow that Alice may copy only one of the parts,
possibly taking it out of context?

3) Suppose that Alice is allowed to download asset A; asset B inherits from
A; and asset C inherits from B.  I think it follows that Alice may download
asset C.  Also, if Alice transfers the right to download A to Bob, then I
think Bob can access assets B and C.  Is this right?

2.4.1 Action Model
------------------
1) It seems odd that an `Action' (singular) contains a set of Action Names
(plural).  

2*) Could an Action describe a set of actions, instead of naming them.  For
example, could an `Action' be every action that has the property of leaving
the asset unchanged (this could include actions such as `downloading' and
`copying', but not `changing' or `appending')?

3) In ODRL version 1.1, the set of actions was closed under AND, OR, and
Exclusive-OR.  Is that no longer true?

4) Suppose that an agreement includes a permission whose Action is {`copy',
`download'} and the exclusive Boolean flag is set.  Can another agreement
include a permission whose Action is {`copy'}?  What if the assigners are
different?    What if the assets are different?  I think I'm missing the
intuition behind the flag.

2.4.2 Constraint Model
----------------------
1) Can a constraint capture the fact that an assignee has a certain property
(e.g., is a student, has no outstanding fines)?  Can a constraint capture
that an assignee does not have a certain property (e.g., is not a felon or is
not on the do-not-sell-to list)?  Can a constraint capture math terms with
negation (e.g., number of copies is not greater than one)?    

2.4 Duty Model
--------------
1) In practice, what's the difference between a Duty in which the Relax flag
is true and no duty at all?  

2) Could an agreement include a duty that requires an action to be done at a
particular time, but not before the permission is exercised?  For example,
could an agreement allow me to watch as many movies as I want, provided that
I pay a bill at the end of the month?  If so, should duties come with
consequences for noncompliance? 

Misc
----
1) Are you assuming that each asset a has a single owner o and, for any
agreement that includes a, the assigner is o?

2) Suppose that a user wants to do a particular action (e.g., Alice wants to
download a file f).  Given a set of agreements, how do we determine whether
she has permission to do the desired act?