With the advent of the Internet, access to database servers from autonomous clients will become more and more popular. In this paper, we propose a monitoring service that could be offered by such database servers, and present algorithms for its implementation. In contrast to published view maintenance algorithms, we do not assume that the server has access to the original materialization when computing differential view changes to be notified. We also do not assume any database capabilities on the client side and therefore compute precisely the required differentials rather than just an approximation, as is done by cache coherence techniques in homogeneous clientserver databases. The method has been implemented in ConceptBase, a meta data management system supporting an Internet-based client-server architecture, and tried out in some cooperative design applications.