A Universal Messaging Realm is the name given to a single Universal Messaging server. Universal Messaging realms can support multiple network interfaces, each one supporting different Universal Messaging protocols.

A Universal Messaging Realm can contain many Channels, Message Queues or Peer to Peer services.

Universal Messaging provides the ability to create clusters of realms that share resources (see Messaging Paradigms supported) within the namespace. Cluster objects can be created, deleted and accessed programmatically or through the Universal Messaging Administration Tool.

Objects created within a cluster can be accessed from any of the realms within the cluster and Universal Messaging ensures that the state of each object is maintained by all realms within a cluster. The clustering technology used within Universal Messaging ensures an unsurpassed level of reliability, resilience, scalability.

Realms can also be added to one another within the namespace. This allows the creation of a federated namespace (see Federation Of Servers) where realms may be in different physical location, but accessible through one physical namespace.