[rules-users] Writing a pattern in which each event constraint depends on the previous event

[Wolfgang Laun]

2011/1/31 Greg Barton <greg_barton at yahoo.com>
>
> Yes, the accumulate function itself should maintain the sort internally.

Which, in this case, means that the timestamp can't be in the
FactHandle, i.e., it must be a field of the class representing the
fact and set by code when the fact is inserted (or received in the
system).

I don't really know (from the first mail in this thread) what the rule
should detect, i.e., due to which condition it should fire. But to
detect a monotonically decreasing sequence over a window of a givent
length it is sufficient to check for the absence of any increase from
one event to a later event. Therefore, a simple "not" pattern should
do. Another pattern would have to ascertain that there are at least 2
elements.

$a : StockTick( $p: price ) over window:time(20s)
exists StockTick( this after $a) over window:time(20s)
not StockTick( this after $a, price >= $p ) over window:time(20s)

-W


>
> @OlliSee : See the thread titled "How to write a rule that fires when it matches against specific facts in working memory."
> --- On Sun, 1/30/11, Wolfgang Laun <wolfgang.laun at gmail.com> wrote:
>
> From: Wolfgang Laun <wolfgang.laun at gmail.com>
> Subject: Re: [rules-users] Writing a pattern in which each event constraint depends on the previous event
> To: "Rules Users List" <rules-users at lists.jboss.org>
> Date: Sunday, January 30, 2011, 10:25 AM
>
>
>
> On 30 January 2011 12:55, OlliSee <o.roess at seeburger.de> wrote:
>
> @Wolfgang: I guess you are referring to the list I use. Of course I expect
> them to be ordered by timestamp.
>
>
> You sure do, but the question is whether you get them in this order during processing by accumulate. There is no documentation that accumulate passes through a set of selected facts in the order they were inserted. It could just as well be the (random) order of some hash key, or reverse, or whatever.
>
> -W
>
>
>
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