In this paper we introduce the Data Licenses Clearance Center, which provides a library of machine readable standard licenses and allows users to compose arbitrary licenses. In addition, the system supports the clearance of rights issues by providing users with information about the equivalence, similarity and compatibility of licenses. A beta version of the system is available at https://www.dalicc.net/.
DALICC stands for Data Licenses Clearance Center. It is a software framework
that supports legal experts, innovation managers and application developers in
the legally secure reutilization of third party digital assets such as data sets,
software or content. The DALICC framework enables the automated clearance
of rights, thus helping to detect licensing conflicts and significantly reducing the
costs of rights clearance in the creation of derivative works. This is necessary
insofar as modern IT applications increasingly retrieve, store and process data
assets from a variety of sources. This can raise questions about the compatibility
of licenses and the application‘s compliance with existing law. In order to
provide commercial products and services on top of third party data assets, license
clearance is necessary to assure legal compatibility[
The DALICC framework consists of three main functional components, namely: license library, license search, and license composer, as shown in Figure 1. These are backed by storage for licenses and an automatic reasoning engine.
The license library is a repository that contains machine-readable and humanreadable representations of the licenses, the former as ODRL policies , and the latter as plain text. These are laid out in a UI as shown in Figure 3.
In the case of license search, the user defines a set of permissions or prohibitions (cf. Figure 2) which are then matched against existing licenses via a JavaScript triggered SPARQL query and processed by a reasoning mechanism which returns the licenses that are consistent with the given input.
Data Sources R e a s o n e r
The license composer (cf. Figure 4) allows to create customized licenses from a set of questions which are mapped to ODRL, ccREL and DALICC vocabularies. The composer allows for the declaration of necessary provenance information about an asset (e.g., purl:title for the work’s title and cc:deprecatedOn for the expiration date of the license) and gives the possibility to download an RDF representation and a human-readable version of the created license.
Technology-wise, the DALICC system combines the following components: a Virtuoso6 triplestore, a Drupal7 based web application, the PoolParty Semantic Suite8, and a Clingo Answer Set Programming (ASP) reasoner that checks license consistency and allows to detect conflicts between licenses.
In order to represent license concepts in a structured machine-readable format we chose the ODRL policy expression language, which includes a flexible and interoperable information model9 and an extendable vocabulary10.
The ODRL information model is particularly suitable for modeling licenses in the form of policies that express permissions, prohibitions and duties related to the usage of assets.
ODRL also defines a vocabulary of general terms (e.g., odrl:modify , odrl:reproduce, odrl:distribute) and can be further extended with terms from other vocabularies such as CC REL (e.g., cc:CommercialUse, cc:DerivativeWorks)11 or, like in our case, with a custom one.
To finally model legally valid licenses we extended the expressivity of ODRL with a DALICC vocabulary providing additional legal terms such as dalicc: worldwide as a jurisdictional property, dalicc:perpetual as a validity type, dalicc:chargeLicenseFee as permission and prohibition actions, and dalicc: modificationNotice as a duty action.
Additionally, DALICC utilises a dependency graph encoding the expert
knowledge about the implicit and explicit semantic dependencies between
actions. Following the work of Steyskal and Polleres [
Figure 5 depicts the central role of odrl:Action in integrating the licenses, dependency graph and the composer and search functionalities. 3
To reason over licenses we use Answer Set Programming (ASP)[
Policies are derived from the RDF graphs of the licenses. Herein, a rule that permits or prohibits the execution of an action on certain assets does not only affect other rules that govern the execution of the same action on the same asset(s) but also those permitting or prohibiting related actions on the same asset(s). In this sense, clingo is an alternative to extensive materialization, which in this case is essential for search, and also enables listing sets of compatible
odrl:Action dalicc:excludesPermission dalicc:excludesDuty dalicc:excludesProhibition dalicc:needsPermission dalicc:needsDuty dalicc:needsProhibition dalicc:question dalicc:Questionnaire Questionnaire statements. This is necessary for effective computation of conflicts between licences, in particular for identifying the conflicting and non-conflicting parts of a license. 4
Licensing and rights clearance are complex topics that require a high level of problem awareness and legal expertise. The potential for future work directions are as follows: (i) enabling organizations to create their own applications and workflows using DALICC APIs; (ii) the visualization of data workflows taking into account the license provenance information; (iii) utilizing already existing capabilities of the reasoning component for conflict resolution; (iv) the provision of license management schemes that tackle consistence and trustability issues at the document and workflow level by leveraging transparent infrastructures such as blockchains.
Acknowledgments. Funded by the Austrian Federal Ministry of Transport, Innovation and Technology (BMVIT) DALICC project https://www.dalicc.net.