Michael, Yes, it is surelly heavier to make database calls in the LHS of a rule when compared to handling objects in memory. Sometimes, though, it is not possible or not worth to load your objects from the database in advance and you need to go for loading as needed in LHS. Although, the best would be to use "from" CE, as it caches some results and allow Rahul to do more or less what he wants. Example: pretend you have Power and Temperature objects, you could do something like: rule "Device not working (condition id = 4)" when alertDefinition : AlertDefinition (conditionID== 4, eid : entityID) Power( value < 1000 ) from dao.getPower( eid ) Temperature( deviceTemp > 50, ambTemp > 40 ) from dao.getTemperature(eid) then log("Triggered Device not working alert for "+ eid); end Hope it helps, Edson Anstis, Michael (M.) wrote: >It seems inefficient to make calls to a database from a rule LHS as (I'm >guessing [Edson?]) that the Rete network can't be built\optimised around >an evaluated predicate (trying to use the correct language, but possibly >failing badly). Would the AlertCondition not already have these >properties populated? Making the rule simpler too: > >Rule "Device not working (condition id = 4)" > when > $ac : AlertCondition (conditionId ==4, $eid : entityID, >$p : power, $at : ambTemperature) > then > log("Triggered Device not working alert for " + $eid + >", power=" + $p + ", ambient temperature=" + $at); >end > >-----Original Message----- >From: rules-users-bounces(a)lists.jboss.org >[mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Rahul Phadnis >Sent: 22 February 2007 21:12 >To: rules-users(a)lists.jboss.org >Subject: [rules-users] Rule definition help > >I am very new to JBoss rules and I am trying to use it >for evaluating alert conditions. > >I am asserting the AlertDefinition object as a fact >into the working memory. > >The rules file would define a variety of alert >condition rules. >for example > >rule "Device not working (condition id = 4)" > # the if part > when > alertDefinition : AlertDefinition (conditionID >== 4, > eid : entityID) > # here i would like to get the last power >reading from device > # with id == eid > eval (dao.getPower(eid).doubleValue() < 1000) > # then get temperature from the device > eval ((dao.getTemperature(eid) != null && >dao.getTemperature(eid) > 50) > || (dao.getAmbTemperature(eid) != null && >dao.getAmbTemperature(eid) > 40) > ) > > then > # what do we do if the rule evaluates to true > log("Triggered Device not working alert for " >+ eid); >end > > >Here are my questions: > >1. Am using the evals correctly? Can I possibly split >this into multiple rules to make it work better? > >2. Can assign dao.getTemperature(eid) to a field. The >getTemperature call is expensive and doing it twice is >not right. > >Any pointer would be appreciated. > >-Rahul > >_______________________________________________ >rules-users mailing list &gt;rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users > >_______________________________________________ >rules-users mailing list &gt;rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users > > > -- Edson Tirelli Software Engineer - JBoss Rules Core Developer Office: +55 11 3124-6000 Mobile: +55 11 9218-4151 JBoss, a division of Red Hat @ www.jboss.com _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users