[rules-users] Correlation of events

Hi, I am working on a system where I need to correlate few error conditions happening in the network infrastructure. I have gone through the documentation for Jboss rules engine (Drools) and I am planning to use it for the correlation purpose. Can anyone let me know a way in which I can get an object from workingmemory in the "then" part of the rule? For e.g., I need the following rule "new error" when $error : Error (state == NEW_ERROR) then (search workingmemory if this error was already registered) if (found) { $errFromWorkingMemory.setLastTimestamp(currentTimestamp) retract($error); } End Thanks, Ashfaq