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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