In an event-based architecture, distributed software components interact by generating and consuming events. The occurrence of an event in a component (called source) is asynchronously notified to any other component (called recipient) that has declared some interest in it. This paradigm holds the promise of supporting a flexible and effective interaction among highly reconfigurable distributed software components. We have developed an object-oriented infrastructure, called JEDI (Java Event-based Distributed Infrastructure), to support the development and operation of event-based systems. During the past year, JEDI has been used to implement the OPSS workflow management system. A WorkFlow Management System (WFMS) is an environment for developing and executing process-based applications. A process-based application is a software system that guides the execution of a coordinated set of activities involving both humans and computerized tools. Typical examples, are business services such as customer care or interoffice procedures. The presentation illustrates JEDI main features and how we have used it to implement the OPSS workflow management system. Moreover, it provides an initial evaluation of our experiences in using an event-based architectural style.