Re: notNext() and next(negation) not yielding same output in Flink CEP

[Yassine MARZOUGUI]

Hi Dawid,

Thanks a lot for the explanation, it's all clear now.

Best,
Yassine

2017-07-23 13:11 GMT+02:00 Dawid Wysakowicz :

> 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 
> 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
>
>

Re: notNext() and next(negation) not yielding same output in Flink CEP

[Dawid Wysakowicz]

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  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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