A bus that consists of multiple servers provides advantages of scalability, the ability to handle more client connections and greater message throughput. A multiple-server bus allows an application running on one server to send messages to applications running on another server.
You can configure a bus to have multiple server bus members, each of which runs one messaging engine. All the servers in the bus must belong to the same cell.
All of the messaging engines in the bus are implicitly connected, and applications can connect to any messaging engine in the bus. Knowledge of the resources assigned to each messaging engine in a bus is shared between all the messaging engines in the bus.
There is no requirement for all the messaging engines in the bus to be running at the same time; if one of the messaging engines is stopped, the rest of the messaging engines continue to operate. However resources owned by a messaging engine, specifically destinations assigned to that messaging engine, are unavailable if the engine is stopped.