A connection can have a client identifier. This identifier is used to associate a JMS client’s connection to a message service, with state information maintained by the message service for that client. The JMS provider must ensure that a client identifier is unique, and applies to only one connection at a time. Currently, client identifiers are used to maintain state for durable subscribers. In defining a client identifier, you can use a special variable substitution syntax that allows multiple connections to be created from a single ConnectionFactory object using different user name parameters to generate unique client identifiers. These connections can be used by multiple durable subscribers without naming conflicts or lack of security.
Message Queue allows client identifiers to be set in one of two ways:
Programmatically: You use the setClientID method of the Connection object. If you use this method, you must set the client id before you use the connection. Once the connection is used, the client identifier cannot be set or reset.
Administratively: The administrator specifies the client ID when creating the connection factory administrative object. See Client Identifier in Sun Java System Message Queue 4.3 Administration Guide.