Queue managers manage queues and provide programming interface access to the queues. The queues are not directly visible to an application and all interactions with the queues take place through queue managers. Each queue manager can have queues that it manages and owns. These queues are known as local queues. WebSphere MQ Everyplace also allows applications to access messages on queues that belong to another queue manager. These queues are known as remote queues. The same sets of operations are available on both local and remote queues, with the exception of defining message listeners (see Message listeners).
The messages on the queues are held in the queue's persistent store (see Storing messages). The backing store used by a queue can be changed using an WebSphere MQ Everyplace administration message. Changing the backing store is not allowed while the queue is active or contains messages. If the backing store used by the queue allows the messages to be recovered in the event of a system failure, then this allows WebSphere MQ Everyplace to assure the delivery of messages.