Peer-to-peer needs new middleware technologies and counterparts to the widely established CORBA, EJB, COM+, and messaging systems products. Specially designed middleware would release the advantages of peer-to-peer networks to a broad spectrum of applications. Network-specific advantages like scalability, fault tolerance, and resource availability could easily be utilized without any concerns about their underlying infrastructure and resources. We address this need with our P2P Messaging System, which focuses on high-performance group communication based on a publish/subscribe model. The P2P Messaging System considers the heterogeneous and dynamic character of peer-to-peer networks by an augmented topology and its supporting features. The P2P Messaging System was evaluated by experimental benchmark tests, and the results provide evidence of its efficiency and scalability.