Preconditions for Saving Messages and Graceful Shutdown

Preconditions for saving messages and graceful shutdown are as follows:

It is only applicable in case of messages already in the messaging server queue for workflow execution. Such messages are not lost and when the messaging server is available again, the application automatically connects to the messaging server and processes the messages.
If the messaging server becomes unavailable before a message is sent to the queue, message recovery and graceful shutdown is not possible, and the message is lost. In such cases, you can follow the process to recover failed messages. For more information, refer to the TIBCO MDM System Administrator's Guide.
If the messaging server becomes unavailable after a message is delivered to the queue but before receiving the message acknowledgement, the message remains in the messaging server. After the messaging server is available again, the message is redelivered. Inspite of this, some activities may show an error in the process log.
If workflow execution is in process and tries to send a message to the messaging server, and if the messaging server is unavailable at that time, the retry logic applies, failing which, graceful shutdown takes place.
Non-repeatable activities (in workflow execution) are not recovered even thought the message is redelivered.