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From Dawid Wysakowicz <wysakowicz.da...@gmail.com>
Subject Re: notNext() and next(negation) not yielding same output in Flink CEP
Date Sun, 23 Jul 2017 11:11:15 GMT
Hi Yassine,

First of all notNext(A) is not equal to next(not A). notNext should be considered as a “stopCondition”
which tells if an event matching the A condition occurs the current partial match is discarded.
The next(not A) on the other hand accepts every event that do not match the A condition.

So let’s analyze a sequence of events like “b c a1 a2 a3 d”. For the first version with
next(not A) the output will be “c a1 a2 a3 d” which is what you expect, I think. In the
other version with notNext(A) a partial match “c a1” will be discarded after “a2”
as the notNext says that after the A’s there should be no A.

I hope this helps understanding how notNext works.

Regards,
Dawid

> On 22 Jul 2017, at 20:32, Yassine MARZOUGUI <y.marzougui@mindlytix.com> wrote:
> 
> Hi all,
> 
> I would like to match the maximal consecutive sequences of events of type A in a stream.
> I'm using the following :
> Pattern.begin("start").where(event is not A)
> .next("middle").where(event is A).oneOrMore().consecutive()
> .next("not").where(event is not A)
> I This give the output I want. However if I use notNext("not").where(event is A) instead
of next("not").where(event is not A), the middle patterns contain only sequences of single
elements of type A.
> My understaning is that notNext() in this case is equivalent to next(negation), so why
is the output different?
> 
> Thank you in advance.
> 
> Best,
> Yassine


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