FCF relies on Oracle Notification Service to propagate database events between the connection pool and the Oracle RAC database. At run time, the connection pool must be able to setup an Oracle Notification Service environment. Oracle Notification Service (ons.jar) is included as part of the Oracle Client software. Oracle Notification Service can be configured using either remote configuration or client-side Oracle Notification Service daemon configuration. Remote Oracle Notification Service subscription offers the following advantages:
Support for an All Java mid-tier software
An Oracle Notification Service daemon is not necessary on the client system, so you do not have to manage this process
Simple configuration by way of a DataSource property