The JMS API supports two delivery modes for messages to specify whether messages are lost if the JMS provider fails. These delivery modes are fields of the the DeleveryMode interface.
The PERSISTENT delivery mode, which is the default, instructs the JMS provider to take extra care to ensure that a message is not lost in transit in case of a JMS provider failure. A message sent with this delivery mode is logged to stable storage when it is sent.
The NON-PERSISTENT delivery mode does not require the JMS provider to store the message or otherwise guarantee that it is not lost if the provider fails.
After a producing client sends a message to the Java Message Service, the service preserves the message until it has been delivered using a standard strategy, or a non-standard TIBCO EMS strategy:
These strategies are called Delivery Modes in JMS.PERSISTENT.
failsafe The message is first written to the external store using unbuffered I/O, and after the write completes, the message is acknowledged to the producing client. This results in increased reliability in the case of a JMS failure, but at the cost of low throughput, since acknowledgements are delayed by the disk write.
Tibjms.RELIABLE_DELIVERY This non-standard strategy conpletely avoids acknowledgements,results in potentially increased throughput, but without the possibility of reporting service trouble to the producing client, via an acknowledgement.