[rules-users] Attribute activations vs object activations

[Mark Proctor]

firstly I wouldn't recommend you use the dynamic update stuff its not 
very efficient. its no less efficient than jess, but the principle 
itslef is bad. The reason is because each field change results in a 
notification to the engine, where as you really want to notify the 
engine after a batch of changes to the instance.

The feature I believe you are after is called slot-specific, so that 
only fields which are constrained on pick up the notifications if those 
fields have changed. This is not currently supported - sorry. Will 
probably be in our next major release in Q1.

Mark

Joshua Undesser wrote:
> I am sorry if this has already been answered, I tried a few different 
> search
> combinations within this user forum and didn't find an answer.
>
> I am pretty new to Drools, but am no stranger to JESS and CLIPS.   We are
> currently looking at moving over our product implementations from JESS to
> DROOLS.   In looking at what it will take to do the conversion, and 
> working
> with a few sample systems, i've noticed that DROOLS doesn't seem to 
> support
> attribute activations, only object activations.    What I mean by this is
> say that I have two rules.....
>
> rule "Rule 1"
> when
>        $o : ObjectType (type == OBJECTTYPE.STATIC )
> then
>        System.out.println("ObjectType is Static");
> end
>
> rule "Rule 2"
> when
>        $o : ObjectType (active == false)
> then
>        System.out.println("ObjectType not active");
> end
>
>
> (My sample system is utilizing the default Drools 4.0 shadow fact 
> support so
> as an ObjectType object is created I am calling memory.insert(obj, 
> true) for
> dynamic updates.)
>
> If on external property change event occurs on an ObjectType:active
> attribute, both rules fire.  Which to me signifies that if any 
> attribute on
> the ObjectType object happens, all rules that contain ObjectType on 
> the LHS
> of the rule will be re-evaluated (not re-fired, but re-evaluated).  Now I
> realize these rules are simple and that I could code the rules in a 
> way to
> avoid them being fired, but non the less, they would still need to be
> evaluated to the point where the engine realizes it should run.   
> Instead,
> performance-wise, wouldn't it be more beneficial to only re-evaluate the
> rules that contain the attribute that changed that you are interested 
> in?   I.E.  In the above scenario, only RULE 2 would fire because rule 
> 1 doesn't
> contain the attribute that changed.  
> The early versions of JESS did not support attribute activations (aka per
> slot activations), which was a major stumbling block.   However ever 
> since
> JESS 5.0, if I remember right, they've been included.  
> So I guess my question is, does DROOLS support attribute activations 
> and I
> am just blind?    If Drools does not support this, is it scheduled to be
> supported in the future?   
> Thank you in advance!
>
> Joshua
>
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