Mediator topology contains a single event queue and a mediator that arranges for the events in the queue to be directed to their respective processors. The events are then passed through a filter or a preprocessor of events from an event channel.

The event queue can be implemented in the form of a simple message queue or an interface that passes messages in a large distributed system. The second form of implementation also requires the involvement of complex messaging protocols, such as Rabbit MQ, and Kafka.