A Formally Grounded ODRL Evaluator: Implementation and Comparison

2026-07-17

AI Summary

This work addresses the lack of formal semantics in the ODRL standard, which leads to inconsistent policy interpretations and undermines system interoperability and evaluation reliability. Building upon existing semantic models, we formally define the problems of static and streaming policy evaluation in access control and monitoring scenarios and design efficient algorithms to solve them. We present the first evaluator that supports all ODRL rule types and incorporates transparent, formal semantics, thereby filling a critical gap left by the standard’s underspecified semantics. Experimental results demonstrate that our system scales well with respect to both policy complexity and data volume. Furthermore, comparative analysis reveals significant differences among existing evaluators in terms of functionality and evaluation paradigms.

Abstract

The ODRL policy language is emerging as the de-facto standard for policy modelling data access and usage preferences, AI governance policies and data workflows in European dataspaces. The current standard has no mathematical formal semantics to describe how a system should implement policy evaluation. This has resulted in a variety of systems and tools that implement their own interpretation of the language, which limits interoperability and cannot guarantee consistent results. Based on an existing semantic model of ODRL, we formalise the problems of ODRL evaluation for the access control and monitoring scenarios, in both static and streaming settings, and we provide a novel, efficient algorithm and implementation. We present the first ODRL Evaluator with transparent formal semantics and supporting all rule types. We experimentally measure its performance, analysing different scalability dimensions related to policy complexity and size of the data on which a policy is evaluated. We compare our system with the state-of-the-art by providing a comparative review of existing ODRL evaluators, which highlights the differences in supported ODRL features and evaluation modes.

Problem

• ODRL
• policy evaluation
• formal semantics
• interoperability
• access control

Innovation

• ODRL evaluator
• formal semantics
• policy evaluation
• access control
• streaming data