I have an application that needs to do things periodically.
I created a Java object containing the current time. It is updated
every minute by a separate thread. When I need an action to be executed
repeatedly, say every 5 minutes, I record the time the action has been
executed last. The rule computes the time difference between the last
execution and the current time and tests that the difference is >= 5
minutes.
I don't know how your application works, but maybe you could implement a
generic timer that the users can refer to?
Note that every time you update the timer, JESS will review its agenda,
so it might not be a reasonable to update the timer every second. I
don't know how much times that takes.
Mrinal Khanvilkar wrote:
Thank you Ernest..but in my application i am just allowing the user to
enter rules and facts into the engine. I cannot provide him the
functionality of adding deffunction(since it would be inconsistant
with the application) .
My question is , whether the engine process rules even if there are no
facts being inserted into the engine which may fire the rules.
If yes, then we can write predicates in such a way that they will be
true after some time and the rule fires without any facts being inserted.
but if no, then i will have to add and retract facts on a periodic basis.
Any suggestions?
Regards,
Mrinal
On 5/29/07, *Ernest Friedman-Hill * <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
On May 29, 2007, at 12:48 PM, Mrinal Khanvilkar wrote:
> Hi,
>
> Is there a way to generate a rule and firing it periodically?
> for e.g.
>
There's a discussion of something like this in the FAQ, under "How do
I make Jess run forever?":
http://herzberg.ca.sandia.gov/jess/FAQ.shtml#Q9
But I think what I'd recommend is to use the "implement" function to
create a Runnable that calls a deffunction, and then use the Runnable
with a java.util.Timer to have it called periodically.
> (defrule rule1
>
> fire after every time t
>
> =>
>
> someactions)
>
> the predicates in this case is only going to be the time interval
> for which the rule is being fired.
>
> thanks,
> Mrinal
---------------------------------------------------------
Ernest Friedman-Hill
Advanced Software Research Phone: (925) 294-2154
Sandia National Labs FAX: (925) 294-2234
PO Box 969, MS 9012 [EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>
Livermore, CA 94550 http://www.jessrules.com
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