[rules-users] Question about timing rules

[Alexander Claus]

It is perhaps not the optimal solution for your case, but you could use for 
example the duration keyword to enable a cyclic behaviour: Simply add a 
dummy object of a certain class into the working memory and do a 
pseudo-modification in the rhs of the rule to this object. This ensures that 
the rule will be reactivated:

rule "A cyclic rule"
    duration 1000
    when
        o : DummyObject()
    then
        System.out.println("fire");
        modify (o) {};
end

So you could model cyclic behaviour with a predefined cycle time. 
Unfortunately you could not change the duration parameter at runtime.
Hope I could inspire you...

Alexander Claus


----- Original Message ----- 
From: "Bagwell, Allen F" <afbagwe at sandia.gov>
To: "Rules Users List" <rules-users at lists.jboss.org>
Sent: Thursday, June 05, 2008 7:14 PM
Subject: RE: [rules-users] Question about timing rules


>
> I've already followed something similar to Corneil's suggestion just by 
> poking around on my own. What I've found is that the timers have to be set 
> up to be checked first, then that caused focus to change to evaluate rules 
> affected by those timers going off.
>
> That's at least one way of doing it. I was wondering if others had used 
> different methods.
>
> In our old rule engine software, optional keywords could be used to set up 
> what was essentially an interval timer under the hood on a per rule basis. 
> Like this:
>
> RULE: "example rule"
> TIME_INTERVAL: 60; // (seconds)
> WHEN
>        ....
> THEN
>        ....
>
> So rule activation based on the WHEN criteria only happened at a 
> consistent interval of 60 seconds.
>
> It was convenient, very easy to work with, and didn't require creating 
> additional objects that had to referenced in the LHSs of rule writing. So 
> with Drools we're experimenting with analagous ways of achieving the same 
> thing.
>
> Allen
>
> -----Original Message-----
> From: rules-users-bounces at lists.jboss.org 
> [mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Scott Reed
> Sent: Thursday, June 05, 2008 10:35 AM
> To: Rules Users List
> Subject: Re: [rules-users] Question about timing rules
>
> To parameterize each rule's frequency, you can add an object with a 
> frequency property for each rule or group of rules with the same frequency 
> and check the frequency in the LHS against Corniels proposed timer object. 
> You can then modify the frequency property of these objects and signal the 
> rule engine that the change was made and the new frequency will be be used 
> to trigger the rules.
>
> I am not sure you need to fireAllRules periodically. I think you can just 
> update the timer object that Corneil proposes and signal the update to the 
> rule engine and it will reevaluate the rules automatically.
>
> Corneil du Plessis wrote:
>> It should not be an issue to have an object inserted representing the
>> current time and have rules checking against the object
>>
>> ----------------------------------------------------------------------
>> --
>> *From:* rules-users-bounces at lists.jboss.org
>> [mailto:rules-users-bounces at lists.jboss.org] *On Behalf Of *Bagwell,
>> Allen F
>> *Sent:* 05 June 2008 17:34
>> *To:* Rules Users List
>> *Subject:* [rules-users] Question about timing rules
>>
>>
>> Another noob question:
>>
>> Is there a generally understood way of implementing the concept of a
>> time interval rule?
>>
>> That is, lets say I have a Drools-enabled client which is constantly
>> receiving information from outside resources. Most of this data (and
>> the consequences of its changes) is time sensitive, so I'm calling the
>> fireAllRules() method in a loop every minute.
>>
>> And now, let's say I have a rule that in addition to being driven by
>> incoming data changes has to be linked to a repeating clock interval
>> or synched with wall time such that the rule only activates and fires
>> if the data meets certain parameters AND it's been exactly 1 hour
>> since the last check or that it will fire at the top of every wall
>> time hour (1 PM, 2PM, 3 PM, etc.).
>>
>> Furthermore, timing may change. A successful rule activation and
>> firing might do something like "now change this timing so that for the
>> next 24 hours, this rule must be examined every 30 minutes instead of
>> every hour".
>>
>> My initial reading of the Drools documetation I came across the
>> Duration, and Date-* keywords. Their descriptions didn't seem to fit
>> the bill.
>>
>> I ask this because our old rules engine software that has been retired
>> to obsolescence allowed this kind of thing to be easily set up. Coming
>> at it in the Drools world seems a lot more challenging.
>>
>> Thoughts? Examples?
>>
>> -Allen
>>
>>
>>
>>
>> ----------------------------------------------------------------------
>> --
>>
>> _______________________________________________
>> rules-users mailing list
>> rules-users at lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/rules-users
>>
>
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