Agents enacting business processes in large open environments need to adaptively accommodate exceptions. Work on multiagent approaches can flexibly model business processes. This paper proposes an event-driven architecture that enriches such models with events resulting in a more robust and proactive system. Specifically, we place this architecture in a business process framework based on protocols and policies, where agents' behaviors are specified via rules. The contributions of this paper include (1) an event-driven architecture, (2) a specification language that combines event logic with rules and (3) a methodology to incorporate events into a process (such as for fine-grained monitoring), (4) a way to manage subscriptions to simple events efficiently. This approach is applied on a well-known business scenario.