Hi Elias,
You can do it with 1.3 and IterativeConditions. Method
ctx.getEventsForPattern("foo") returns only those events that were matched
in "foo" pattern in that particular branch.
I mean that for a sequence like (type =1, value_b = X); (type=1,
value_b=Y); (type=2, value_b=X) both events of type = 1 create a seperate
pattern branch and the event with type = 2 will be checked for a match
twice for both of those branches.
Regards,
Dawid
2017-04-26 7:48 GMT+02:00 Elias Levy <fearsome.lucid...@gmail.com>:
> There doesn't appear to be a way to join events across conditions using
> the CEP library.
>
> Consider events of the form (type, value_a, value_b) on a stream keyed by
> the value_a field.
>
> Under 1.2 you can create a pattern that for a given value_a, as specified
> by the stream key, there is a match if an event of type 1 is followed by an
> event of type 2 (e.g. begin("foo").where(_.type==1).
> followedBy("bar").where(_.type==2). But this will return a match
> regardless of whether value_b in the first event matches value_b in the
> second event.
>
> 1.3 snapshot introduces iterative conditions, but this is insufficient.
> In 1.3 you can do:
>
> begin("foo").where(_.type==1).followedBy("bar").where(
> (v, ctx) => {
> v.type == 2 &&
> ctx.getEventsForPattern("foo").asScala.exists(prev => prev.value_b
> == v.value_b)
> })
>
> This will accept the current event if any if any previously had a value_b
> that matches the current event. But the matches will include all previous
> events, even those that did not match the current event at value_b, instead
> of only matching the previous event where value_b equals the current event.
>
> Is there a way to only output the match there previous event matches the
> current event value_b (e.g. foo == (type=1, value_a=K, value_b=X) and bar
> == (type=2, value_a=K, value_b=X)?
>
>
>
