Hi
As Sinhaa said, you can use the SNMP traps to trigger workflows using WFA RESTful Api.
BTW what version of OCUM are you using ? If its 5.x you can even call a script in the context of an alarm which is tied to an event.
This script in turn can call the WFA workflow using RestFul Api.
BTW could you explain more on what kind of trigger are you looking for ?
Regards
adai