Apache Eagle (called Eagle in the following) platform supports CEP engine as first class policy engine, i.e. Eagle platform runs CEP engine on top of Apache Storm and make rules be hot deployed.
Specifically Eagle platform uses WSO2 Siddhi CEP library, source code is here.
With embedded CEP engine, Eagle platform provides comprehensive alerting rules as follows. Also please go to Siddhi site for language reference.
Filter Rule
Window based Rule