Thanks David, I will look at your references 👍🏻

> On 19 Mar 2020, at 09:51, David Anderson <da...@ververica.com 
> <mailto:da...@ververica.com>> wrote:
> 
> Humberto,
> 
> Although Flink CEP lacks notFollowedBy at the end of a Pattern, there is a 
> way to implement this by exploiting the timeout feature. 
> 
> The Flink training includes an exercise [1] where the objective is to 
> identify taxi rides with a START event that is not followed by an END event 
> within two hours. You'll find a solution to this exercise that uses CEP in 
> [2].
> 
> [1] https://training.ververica.com/exercises/longRides.html 
> <https://training.ververica.com/exercises/longRides.html>
> [2] 
> https://github.com/ververica/flink-training-exercises/blob/master/src/main/java/com/ververica/flinktraining/solutions/datastream_java/cep/LongRidesCEPSolution.java
>  
> <https://github.com/ververica/flink-training-exercises/blob/master/src/main/java/com/ververica/flinktraining/solutions/datastream_java/cep/LongRidesCEPSolution.java>
> 
> Best,
> David
> 
> 
> 
> On Thu, Mar 19, 2020 at 4:41 AM Zhijiang <wangzhijiang...@aliyun.com 
> <mailto:wangzhijiang...@aliyun.com>> wrote:
> Hi Humberto,
> 
> I guess Fuji is familiar with Flink CEP and he can answer your proposed 
> question. I already cc him.
> 
> Best,
> Zhijiang
> 
> ------------------------------------------------------------------
> From:Humberto Rodriguez Avila <rhumber...@outlook.com 
> <mailto:rhumber...@outlook.com>>
> Send Time:2020 Mar. 18 (Wed.) 17:31
> To:user <user@flink.apache.org <mailto:user@flink.apache.org>>
> Subject:FlinkCEP - Detect absence of a certain event
> 
> In the documentation of FlinkCEP, I found that I can enforce that a 
> particular event doesn't occur between two other events using notFollowedBy 
> or notNext.
> 
> However, I was wondering If I could detect the absence of a certain event 
> after a time X. For example, if an event A is not followed by another event A 
> within 10 seconds, fire an alert or do something.
> 
> Could be possible to define a FlinkCEP pattern to capture that situation?
> 
> Thanks in advance, Humberto
> 
> 

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