A guaranteed processing application incorporates both guaranteed processing and persistence. Depending on your application needs, you might want to enable just one of these features in Sybase CEP Engine.
Guaranteed processing without Persistence: If you enable guaranteed processing for the Sybase CEP Engine components of your application without enabling persistence, the application will perform exactly once processing as long as the software components are running. This scenario recovers from failures such as a lost network connection, but not from failures that involve restarting any of the software components. Because the overhead of enabling persistence can have a significant negative impact on performance, you may decide that this option is acceptable for your needs. This variation is called semi-reliable delivery.
Persistence without guaranteed processing: If you enable persistence for the Sybase CEP Engine components of your application without enabling guaranteed processing, the application will still perform best-effort processing, but if Sybase CEP Server restarts, it will continue processing from the saved state rather than starting fresh. This reduces, but does not eliminate, the possibility of discarded messages.