SemDRMS is an implementation of a Digital Rights Management (DRM) System based on Semantic Web technologies. It is based on the ontologies presented in the Ontological Infrastructure section. These ontologies provide the formal semantics for the copyright domain and the main rights expression languages, MPEG-21 REL and ODRL.It is important to note the the use of semantic technologies makes the management system capable of dealing with content from a wider perspective that a mere management of access restrictions. The system is capable of managing content in the context of the copyright model provided by the Copyright Ontology, which contitutes its core component, and consequently should be seen as a Copyright Management System.
Table of Contents
These are the ontologies used by the Semantic DRM System. The base ontology is the one providing the semantics for the copyright domain, the Copyright Ontology. It is based on the work carried out in the PhD thesis "A Semantic Web Approach to Digital Rights Management".
This base ontology is complemented with ontologies for the main rights expression languages, MPEG-21 REL and ODRL. They are generated automatically from the XML Schemas that define this languages using the XML Semantics Reuse Methodology and the ReDeFer XSD2OWL tool. These ontologies provide the hook points for integrating MPEG-21 REL and ODRL expressions into the SemDRMS ontological framework. More details in the Interoperability with RELs section.
There is also an ontology for the MPEG-21 RDD, which has been generated using and ad-hoc method that translates the MPEG-21 RDD ontology language to OWL.
This ontology is the basic building block of the SemDRMS ontological infrastructure. It provides the fundamental primitives for the copyright domain, which can be used to model rights statements, agreements, offers, etc. Altogether, it allows modelling the whole copyright value chain. There are more details in the Copyright Ontology web page.
MPEG-21 REL is composed of the XML schemas for the Core, Standard Extensions and Multimedia Extensions, all of them are mapped to OWL ontologies. Moreover, the previous XML schemas import the schemas for XML Digital Signature and XML Encryption, which are also mapped to OWL ontologies:
Once they are mapped to ontologies, it is possible to make a drawing for the combined REL Ontologies: GIF
Drawings for the combined ODRL Ontologies:
As it has been said, the XSD2OWL mappings has been aplied to generate OWL ontologies for the XML Schemas that define the MPEG-21 and ODRL RELs. From this point, it is also possible to map XML instances, i.e. rights expressions like offers or licenses. This is performed by the ReDeFer XML2RDF tool, which transforms the XML tree into a RDF graph and enrichs it semantically. This enrichment is performed by connecting the RDF resources to the concept definitions in the OWL ontologies corresponding to the involved XML Schemas.
The following sections show examples of such mappings for MPEG-21 REL and ODRL.
The XML2RDF mapping has been applied to the following examples:
The same XML2RDF mapping can be applied to ODRL instances. For instance, it has been applied to some rights scenarios included in the ODRL 1.1 Specification:
The implementation of the DRMS is based on the OWL-DL version of the Copyright Ontology. Therefore, it is based on Description Logic (DL) tools.
Licenses and modelled as OWL Classes and copyrighted content inteded uses are modelled as instances. Then, in order to check if a usage (instance) is authorised by a set of licenses (classes) a DL reasoner is used to classify the instance in the available classes. If the instance is classified into a class that models an agreement, the Agree class as specified in the Copyright Ontology, the usage is authorised.
The implementation is actually work in progress. Pellet is being used in order to implement DL classification as it deals with nominals (e.g. used to define classes of authorised users) and custom datatype (e.g. used to define authorisation time spans).
The main problem of this OWL-DL implementation is that of the Open World Assumption (OWA) of Description Logics. The OWL-DL primitives that lead to OWA problems are the for all restriction (∀R.C) and the maximum cardinality restriction (≤ n R).
In order to avoid the open world when we want to model a restriction of a license slot to just values from a class, the idea is to negate the restriction and move the negation to the metalevel. The negation is modelled at the metalevel introducing the Disagree class, which is the opposite to the Agree class.
Therefore, the "for all" restriction on the theme of an Agree, i.e. Agree theme ∀R.C, is converted into a "for some" restriction on the theme of a Disagree, i.e. Disagree theme ∃R.¬C. On the other hand, the "maximum cardinality" restriction on the theme of an Agree, i.e. Agree theme (≤ n R), is converted into a "minimum cardinality" restriction on the theme of a Disagree, i.e. Disagree theme (≥ n+1 R).
"DRM, from research to implementation" track, Smart University 2007
September 19-20, Sophia Antipolis, France
Title: "Enabling interoperable and rights-aware DRM using the SemanticWeb"
2012-2014 MediaMixer (EU FP7-318101)
Community and Networking for the Remixing of Online Media
2009-2011 OMediaDis Spanish Government (TIN2008-06228)
Open Plataform for Multichannel Content Distribution Management, http://omediadis.udl.cat
NOTE: This site links to the draft versions of the papers. For final versions, please, contact the corresponding publisher.
A Semantic Web Approach to
García, R.; Gil, R.
8th International Workshop for Technical, Economic and Legal Aspects of Business Models for Virtual Goods, Virtual Goods'10,
30 September - 1 October 2010, Namur, Belgium
Namur University Press, pp. 61-76, 2010
García, R.; Gil, R.Information Systems, Vol. 35, No. 4, pp. 483-495. Elsevier, 2010
ISSN 0306-4379 / DOI: 10.1016/j.is.2008.12.001
García, R.;Gimeno, J.M.
Position paper, W3C Workshop on the Future of Social Networking, 15-16 January 2009, Barcelona
García, R.; Gil, R.
In Breuker, J.; Casanovas, P.; Klein, M.; Francesconi, E. (Eds.) Law, Ontologies and the Semantic Web
Frontiers in Artificial Intelligence and Applications, Vol. 188, pp. 145-162. IOS Press, 2009
García, R.; Pariente, T.
1st World Summit on the Knowledge Society, WSKS'08
Lecture Notes in Artificial Intelligence, Vol. 5288, pp. 253-262. Springer, 2008
García, R.; Gil, R.
Special issue on "Contract Architectures and Languages".
International Journal of Electronic Commerce, in press. M.E. Sharpe, 2007
Springer, M.; García. R.
5th International Workshop for Technical, Economic and Legal Aspects of Business Models for Virtual Goods, Virtual Goods'07
Nova Science Publishers, 2007. In press
García, R.; Gil, R. and Delgado, J.
Journal of Artificial Intelligence and Law, Vol. 15, No. 2, pp. 137-154. Springer-Verlag, 2007
García, R.; Tummarello, G.
2nd International Semantic Web Policy Workshop, SWPW'06
International Semantic Web Conference, Athens, USA, 2006
CEUR Workshop Proceedings, Vol. 207, pp. 102-109, 2006
García, R.; Gil, R.
IFIP WG 2.12 & WG 12.4 International Workshop on Web Semantics, SWWS'06
Lecture Notes in Computer Science, Vol. 4278, pp. 1745-1754. Springer-Verlag, 2006
García, R. and Delgado, J.
18th Annual Conference on Legal Knowledge and Information Systems, JURIX 2005
Frontiers in Artificial Intelligence and Applications, Vol. 134, IOS Press, 2005
Tous, R.; García, R.; Rodríguez, E. and Delgado, J.
E-Commerce and Web Technologies: 6th International Conference, EC-Web 2005
Lecture Notes in Computer Science, Vol. 3590, pp 1 - 10. Springer-Verlag, 2005
García, R.; Gil, R.; Gallego, I. and Delgado, J.
Open Digital Rights Language Workshop, ODRL 2005
Gil, R.; García, R. and Delgado, J.
Legal Ontologies and Artificial Intelligence Techniques, LOAIT 2005
IAAIL Workshop Series, pp. 135-148. Wolf Legal Publishers, 2005
García, R., Gil, R. and Delgado, J.
OTM Confederated International Conferences, CoopIS, DOA, and ODBASE 2004
Lecture Notes in Computer Science, Vol. 3291, pp 689 - 704. Springer-Verlag, 2004