[rules-users] Is there any way to find out last two events with some common properties

[Tan Hui Onn]

Below is my idea.
The rule check that there is
1) no event  between E1 and E2 and
2) no event after E2
which induce that E1 and E2 are the last 2 event. I think it should work but
I didn't test it.

rule "Props"
    when
        $E1 : MyEvent(prop1 == "MyProp") from entry-point MyStream
        $E2 : MyEvent(prop1 == "MyProp", this after $E1) from entry-point
MyStream
        // no event in between $E1 and $E2
        not (MyEvent(prop1 == "MyProp", this after $E1, this before $E2)
from entry-point MyStream)
        // no event after $E2 ($E2 is the last)
        not (MyEvent(prop1 == "MyProp", this after $E2) from entry-point
MyStream)
    then
        //Do something
end



Best regards.

On Sun, Jan 16, 2011 at 1:26 AM, umesh kumar sain <
umesh.sain at alcatel-lucent.com> wrote:

>
>  Is there any way to find out last two events with some common properties.
> In
> my app I'd defined a pojo as drools event whose expiry time is say 5 mins.
> Now I want to access the properties of last two events.
>
> say something like this
>
> rule "Props"
> when
> $E1 : MyEvent(prop1 = "MyProp") from entry-point MyStream
> $E2 : MyEvent(prop1 = "MyProp", this != $E1) from entry-point MyStream
> then
> Do something
> end
>
> In the above rule my concern is that since the expiry time is 5 minutes and
> I can receive any no of events during this period. How can I be sure that
> the above two events $E1 and $E2 are the latest one i.e. last two events
> received. I also thought of using sliding window but I don't know when they
> are going to be received say 1s, 1m, or 5m.
>
> kindly suggest
>
> --
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