If a client needs to receive all the messages published on a topic, including the ones published while the subscriber is inactive, it uses a durable
IMessageConsumer. The JMS server retains a record of this durable subscription and insures that all messages from the topic's publishers are retained until they are acknowledged by this durable subscriber or they have expired.
Sessions with durable subscribers must always provide the same client identifier. In addition, each client must specify a name which uniquely identifies (within client identifier) each durable subscription it creates. Only one session at a time can have a
IMessageConsumer for a particular durable subscription. An inactive durable subscriber is one that exists but does not currently have a message consumer associated with it.
A client can change an existing durable subscription by creating a durable
IMessageConsumer with the same name and a new topic and/or message selector. Changing a durable subscriber is equivalent to unsubscribing (deleting) the old one and creating a new one.
ITopicto subscribe to
IMessageConsumer for the specified destination
Warning: Delete unused durable subscriptions using
ISession.Unsubscribe. Unused durable subscriptions continue to accumulate topic messages as new messages are produced to the topic, even when no consumer is attached to the durable subscription; this consumes resources on the JMS server and can eventually lead to resource issues such as quota exceptions, or even out-of-memory, because no consumer is ever removing messages from the durable subscription.
|MessageException||if the session fails to create a subscriber due to some internal error.|
|InvalidDestinationException||if an invalid topic is specified.|
|InvalidSelectorException||if the message selector is invalid.|