In this paper we present DERMI, a decentralized wide-area event-based object middleware built on top of a peer-to-peer substrate. Its main building block is the underlying publish/subscribe event notification system provided by the peer-to-peer layer. By using this methodology, innovative benefits like distributed interception, high performance synchronous/asynchronous one-to-one/one-to-many notifications and decentralized object location services are provided. Moreover, new programming abstractions (anycall and manycall) are introduced, which allow the programmer to make calls to groups of objects without taking care of which of them responds until a determinate condition is met. We believe that such middleware is a solid building block for future wide-area distributed component infrastructures.