I also was interested in this support for rules by the DB, but I was disappointed to read the news of its discontinuation and suggestion to purchase another product :
Obsolescence Notice: Rules Manager and Expression Filter Features of Oracle Database [ID 1244535.1]
"The Rules Manager and Expression Filter features of Oracle Database is are being removed in the next major release of Oracle Database. Support will only be available for the life of Oracle Database Release11g Release 2.
Customers should not begin new projects with Rules Manager or Expression Filter. Any current user of Rules Manager should consider migrating to Oracle Business Rules, a component of Oracle Fusion Middleware. "