Only transactional asynchronous listeners can use the Exactly Once notification feature in a clustered Integration Server environment. The Exactly Once notification feature ensures that notification data will not be duplicated even if a failure occurs during processing. This is achieved by assigning unique IDs for each publishable document. After a processing failure, Integration Server checks for duplicate records in storage and ignores any duplicate IDs.

For more information on setting up and using the Exactly Once notification feature with a transactional asynchronous listener in a clustered environment, see Using the Exactly Once Notification Feature in a Clustered Environment.