Evaluation of digital libraries assesses their effectiveness, quality and overall impact. In this paper we present a novel, multi-level logging framework that will provide complete coverage of the different aspects of DL usage for user-system interactions. Based on this framework, we can analyse for various DL stakeholders the logging data according to their specific interests. In addition, analysis tools and a freely accessible log data repository will yield synergies and sustainability in DL evaluation and encourage a community for DL evaluation by providing for discussion on a common ground.