W3C home > Mailing lists > Public > public-odrl-contrib@w3.org > April 2012

Policy as Asset and Relationship

From: Michael Steidl \(IPTC\) <mdirector@iptc.org>
Date: Fri, 27 Apr 2012 12:30:14 +0200
To: "'ODRL Community Group \(Contrib\)'" <public-odrl-contrib@w3.org>
Message-ID: <00a101cd2460$bba5d480$32f17d80$@iptc.org>
Dear ODRLers:


While going over examples on our new RightsML pages - e.g.
http://dev.iptc.org/RightsML-Newspaper-Licensing-Agency-NLA-case-study -  I
came across ambiguous specifications of Asset and Relation:


The Core Model spec defines:
The Asset entity is aimed at identifying the content that is the subject of
an ODRL policy, e.g. a media file or ebook.

. and:

The Relation entity is an association class and can be used to link to an
Asset from either Permission, Duty or Prohibition, indicating how the Asset
MAY be utilised in respect to the entity that links to it.


The Common  Vocabulary defined a set of two terms for the relation: 
- target: The Asset upon which the Action is performed
- output: The Asset which is created from the output of the Action


The XML Encoding spec has an example 4.6 Offer and Next Policy

(and I have to add: this Next Policy is a use case which is liked by a
couple of IPTC members ..)

At the point of expression around the Next Policy the syntax and the specs
do not align:


<o:duty uid="d2">

  <o:action name=" <http://w3.org/ns/odrl/vocab>

  <o:asset uid=" <http://example.com/policy:7777>
http://example.com/policy:7777" relation=" <http://w3.org/ns/odrl/vocab>



<o:policy . uid=" <http://example.com/policy:7777>


        <o:asset uid=" <http://example.com/wallpaper:2321>
http://example.com/wallpaper:2321" relation=" <http://w3.org/ns/odrl/vocab>

        <o:action name=" <http://w3.org/ns/odrl/vocab>




My comments: 

-          In the context of o:duty above the <asset> refers to an entity
which is definitely *not* "content" as specified in the Core Model. 

-          IPTC is not against this extension of the use of asset but then
the specs have to be explicitly extended too.

-          And what about @relationship: the definition of "target" is
ambiguous in this use case. What exactly is the asset upon which the action
NextPolicy" is performed: the "wallpaper:2321" or the "policy:7777".
The problem with such ambiguous definitions is that a user/implementer can
only infer from examples which of the possible options should be used - but
then examples become part of the specification.
Possible solution: add a third term to the @relation vocabulary like
"targetPolicy" and define if a reference asset is a policy it has to be

-          Only a minor consideration on @relation
- the specs say (Core Model and XML Encoding) that it is REQUIRED
- the specs say it has a default value of "target".
- hm, in which case would this default value apply as the attribute is
mandatory? Usually default values of an XML node apply if this node does not


Thanks for considering my comments.





Michael Steidl

Managing Director of the IPTC [mdirector@iptc.org]

International Press Telecommunications Council 
Web:  <http://www.iptc.org/> www.iptc.org - on Twitter
<http://www.twitter.com/IPTC> @IPTC

Business office address: 

20 Garrick Street, London WC2E 9BT, United Kingdom

Registered in England, company no 101096

Received on Friday, 27 April 2012 10:30:53 UTC

This archive was generated by hypermail 2.3.1 : Tuesday, 6 January 2015 19:41:22 UTC