Gartner defines an event broker as a technology that enables the publish-subscribe communication pattern between event producers and event consumers. An event broker can be delivered as hardware, as software or as a service. Event producers (also known as publishers or sources) publish events to a topic. Event consumers (also known as subscribers or sinks) subscribe to topics to see all related events. This means that event producers are typically unaware of, and decoupled from, event consumers. The role of the event broker is to mediate communications between event producers and event consumers