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Posted to user@flink.apache.org by Shailesh Jain <sh...@stellapps.com> on 2017/12/19 16:27:54 UTC

Triggers in Flink CEP

Hi,

Similar to the way it is exposed in Windows operator, is it possible to use
Triggers inside the Pattern Operator to fire partially matched patterns
(when certain events are very late and we want some level of controlled
early evaluation)?

I assume that Windows are used internally to implement the CEP library, so
wanted to know how much of a work will it be to extend the library to
expose this functionality.

Thanks,
Shailesh

Re: Triggers in Flink CEP

Posted by Shailesh Jain <sh...@stellapps.com>.

Thanks, Kostas.

On Tue, Dec 19, 2017 at 10:13 PM, Kostas Kloudas <
k.kloudas@data-artisans.com> wrote:

> Hi Shailesh,
>
> The pattern operator does not use Flink’s windowing mechanism internally.
> Conceptually you may think that there are windows in both, and this is
> true, but there
> are significant differences that prevent using Flink windowing for CEP.
>
> The above implies also that using triggers for early firing is not
> supported and is far from
> trivial to implement.
>
> Thanks,
> Kostas
>
> > On Dec 19, 2017, at 5:27 PM, Shailesh Jain <sh...@stellapps.com>
> wrote:
> >
> > Hi,
> >
> > Similar to the way it is exposed in Windows operator, is it possible to
> use Triggers inside the Pattern Operator to fire partially matched patterns
> (when certain events are very late and we want some level of controlled
> early evaluation)?
> >
> > I assume that Windows are used internally to implement the CEP library,
> so wanted to know how much of a work will it be to extend the library to
> expose this functionality.
> >
> > Thanks,
> > Shailesh
>
>

Re: Triggers in Flink CEP

Posted by Kostas Kloudas <k....@data-artisans.com>.

Hi Shailesh,

The pattern operator does not use Flink’s windowing mechanism internally.
Conceptually you may think that there are windows in both, and this is true, but there 
are significant differences that prevent using Flink windowing for CEP.

The above implies also that using triggers for early firing is not supported and is far from 
trivial to implement.

Thanks,
Kostas

> On Dec 19, 2017, at 5:27 PM, Shailesh Jain <sh...@stellapps.com> wrote:
> 
> Hi,
> 
> Similar to the way it is exposed in Windows operator, is it possible to use Triggers inside the Pattern Operator to fire partially matched patterns (when certain events are very late and we want some level of controlled early evaluation)?
> 
> I assume that Windows are used internally to implement the CEP library, so wanted to know how much of a work will it be to extend the library to expose this functionality.
> 
> Thanks,
> Shailesh