Publish/subscribe systems offer a loosely coupled communication paradigm in distributed information systems. However, supporting expression of semantic events, expression of logical and temporal patterns of composite events, and how to manage and route composite events and subscriptions still need further research. In this paper, we present the design and implementation of JTang composite and semantic publish/subscribe system over structured P2P networks, and highlight its novel features, including semantic broker network, composite event and subscription language and distributed composite subscription management. The experiments based on the Peersim simulator over the Pastry overlays show that the ontology routing table helps decrease the average number of hops and the use of composite subscriptions significantly reduces the load on the network.