Abstract: A new content-based routing (CBR) approach called ROSE (routing on subscription-forwarding and events-flood) is proposed for large scale publish/subscribe systems. In a ring space, ROSE routes subscriptions and events along distinct partitions which intersect at at least one node. An analytical model of ROSE is derived, and simulation validates the effectiveness of the presented model. The experimental results show that ROSE improves routing efficiency in a large-scale publish/subscribe system and provides a new method for traffic tuning during deployment.