Thanks Till. The only way I can change the behavior would be to post filter the result then.
Anwar. On Tue, Apr 5, 2016 at 11:41 AM, Till Rohrmann <trohrm...@apache.org> wrote: > Hi Anwar, > > yes, once we have published the introductory blog post about the CEP > library, we will also publish a more in-depth description of the approach > we have implemented. To spoil it a little bit: We have mainly followed the > paper “Efficient Pattern Matching over Event Streams” for the > implementation. > > Concerning your questions: > > 1.) followedBy means that there can be an arbitrary sequence of events > between two matching events, as long as they occur in the specified time > interval. Thus, TemperatureEvent(40) will match together with > TemperaturEvent(50), TemperaturEvent(70), TemperaturEvent(65) and > TemperaturEvent(60). > > 2.) The same applies here for the next operator. It says that the second > matching event has to follow directly after the previous matched event. > However, a matching event can be part of multiple matching sequences. Thus, > you will get TemperaturEvent(70), TemperaturEvent(65) and > TemperaturEvent(65), TemperaturEvent(60) as two distinct matching sequences. > > To make a long story short, there is currently no option to change the > sequence semantics so that events are only part of one matching sequence. > At the moment, events can participate in multiple matching sequences. I > hope that answers your question Anwar. > > Cheers, > Till > > > On Mon, Apr 4, 2016 at 11:18 AM, Anwar Rizal <anriza...@gmail.com> wrote: > >> Hi All, >> >> >> I saw Till's blog preparation. It will be a very helpful blog. I hope >> that some other blogs that explain how it works will come soon :-) >> >> I have a question on followedBy pattern matching semantic. >> >> >> From the documentation >> https://ci.apache.org/projects/flink/flink-docs-master/apis/streaming/libs/cep.html >> , >> >> <citaton> >> >> Non-strict contiguity means that other events are allowed to occur >> in-between two matching events. A non-strict contiguity pattern state can >> be created via the followedBy method. >> >> Pattern<Event, ?> nonStrictNext = start.followedBy("middle"); >> >> >> </citation> >> >> I try to use Till's examples in the blog, to understand the semantic of >> followedBy >> >> -- >> First question. >> Say, I have sequence of temperatures in a time window that corresponds to >> the within clause (say in 20 minutes). >> >> TemperatureEvent(40) , OtherEvent(...), TemperatureEvent(30), >> TemperatureEvent(50), OtherEvent(...), TemperatureEvent(70), >> TemperatureEvent(65), TemperatureEvent(60) >> >> say I want to match two TemperatureEvents whose temperatures > 35. >> >> What will be the matches in this case ? >> >> >> - Will TemperatureEvent(40) , TemperatureEvent(50), match ? (because >> we have TemperatureEvent(30) at time 3 that does not match. >> - Will TemperatureEvent(40) , TemperatureEvent(70) match ? (because >> the pair matches also the specification of pattern , the difference is we >> have TemperatureEvent(50) which happened before TempertureEvent(70) ). >> Similar question for TemperatureEvent(40) - TemperatureEvent(65) and >> TemperatureEvent(50)-TemperatureEvent(65) etc. pairs. >> >> >> >> -- >> Second question. >> For next (and also for followedBy) , I have also questions regarding >> example above: >> Will TemperatureEvent(70), TemperatureEvent(65) and TemperatureEvent(65), >> TemperatureEvent(60) be returned , or the second pair is no longer returned >> because TemperatureEvent(65) has been used in the first pair ? >> >> >> >> Is there a way to define the different sequence semantics for the two >> questions I asked above ? >> >> >> Thanks, >> Anwar. >> >> >> >> >> >> >> >> > >
