I have declared two types:

declare Motion
@role( event )
@expires( 5s )
@timestamp( eventTime )
eventTime : long
end

declare Recording
end

and following rules:

rule "StartRecording"
when
Motion()
not Recording()
then
insert(new Recording())
end

the problem is that when I put a lot of "Motions", sleep (so "Motions" become expired) and then do fireAllRules(), I got "StartRecording" executed multiple times (and not only once), event though "Recording" is inserted every time.

Another issue would be when instead of "StartRecording" rule I would have "StopRecording" rule:

rule "StopRecording"
when
$m : Motion()
$r : Recording()
then
System.err.println("Recording: " + $r);
retract($r);
end

then when there is a "Recording" fact inserted and multiple expired "Motions", the rule would be executed multiple times (when "Motions" expire) and $r would be null after the first "StopRecording" rule execution.