Recently, analysts and vendors have been promoting Event Driven architecture as the "Next Big Thing". Simple event-driven processing has been in common use for at least 10 years with technology such as message-oriented middleware and, in the past few years, message-driven Enterprise JavaBeans. However, the "Next Big Thing" they are referring to is the architecture that supports processing complex business events to address business real time needs. This architecture could have the potential for changing many traditional business models. For example, a Car Rental Business could implement, a "just in time" process to allocate cars for only those passengers that have actually landed in the airport. This is achieved by receiving and processing a landing event populated with relevant information of passengers from the airlines. The same event could be used by other businesses that have interest in being notified by the arrival of the passengers (e.g., hotels and restaurants in which those passengers made reservations).