In this paper we present a wide area distributed system using a content-based publish/subscribe communication middleware which can deterministically detect and report failures with respect to timely message delivery and message omission. Our approach does not require external clock synchronization nor does it impose any constraints on the publish/subscribe middleware. We show that our system performs better and is safer than when using NTP for external clock synchronization. We provide a proof of concept implementation and present results of experiments carried out in the PlanetLab environment.