The concept of a middleware was introduced to facilitate communication between entities in a heterogeneous distributed computing environment. The main task of an event-based middleware is to disseminate data to all interested parties in a largescale distributed system. Hence, an event model is needed to describe how data, and interest in that data, is expressed in the system i.e. event publication and event subscription respectively. In our system, we represent an event as an object and the event model is illustrated using a sample application.