I would like to measure the time of cars with an unique Id with NEsper. My problem is, that there are several cars on a road. This road has predefined steps. I want to start to stop the time for every unique car that is in first step until this car receives the last step.
select ice.* from pattern[ice = IncomingCarEvent -> every timer:interval(1 sec) and not LastStepEvent]
The problem is, that I don't know how to separate the cars with a given Id. In this example, if one of the cars receives the last step the event does not fire anymore.
I'm not very clear on why you measure until the last step and the pattern says "not lastestep". Partitioning can be done by correlating the events in the patterns such as "a=A => B(id=a.id)". You can also partition using a context declaration which is in this link: http://esper.codehaus.org/esper-5.1.0/doc/reference/en-US/html_single/index.html#context_def_keyed Or you may find the match-recognize to be easier to use as it has more of a step-wise approach to expressing a match much like regular expressions.