Setting a Client Identifier

To keep track of durable subscriptions, Message Queue uses a unique client identifier that associates a client’s connection with state information maintained by the message service on behalf of the client. By definition, a client identifier is unique, and applies to only one connection at a time.

The messaging service uses a client identifier in combination with a durable subscription name to uniquely identify each durable subscription. If a durable subscriber is inactive at the time that messages are delivered to a topic destination, the broker retains messages for that subscriber and delivers them when the subscriber once again becomes active.