[rules-users] How to catch two (or more) strictly sequential events

Dear all, I'm trying to develope a cep system using drools and java. On my system, I instantiated the drools engine in Stream mode and catch my events (called SimpleEvents and composed by (String id, Long timestamp, String data)) correctly. Now I'm trying to create a rule able to match simple pattern like A -> B or A -> B -> C Using the feature "after", I am able to know if eventB is preceded by a eventA .. but this rule match even the pattern: A -> .....(events of any kind different from B)... -> B Question: There's a way to know when (if) eventA is strictly followed by eventB ? Thanks in advance ;) --Antonello