The two main topologies of event-driven architectures are broker-based and mediator-based. Those topologies differ in how the events flow through the system.
The mediator topology is best used when processing an event that requires multiple tasks or steps that can be performed independently. All events produced initially land in the mediator's event queue. The mediator knows what needs to be done in order to handle the event, but instead of performing the logic itself, dispatches the event to appropriate event processors through each processor's event channel.
If this reminds you of how business processes flow, then you've got good intuition. You can implement this topology in Business Process Management (BPM) or Business Process Execution Language (BPEL). However, you can also implement it using technologies such as Apache Camel, Mule ESB, and others:
A broker, on the other hand, is a lightweight...
