The simplest topology is a bus consisting of a single server. Use this configuration if there is not a great volume of message throughput and scalability is not essential.
In a single-server bus, there is one messaging engine. All destinations, such as queues and topic spaces, are assigned to this single messaging engine.
The decision as to whether a single messaging engine is adequate is affected by such factors as the number of client connections, message throughput rates, and the size of messages.