[rules-dev] Fine Grained Property Change Listeners (Slot Specific)

[Michael Anstis]

Property specific?

sent on the move

On 13 Jan 2012 22:31, "Mark Proctor" <mproctor at codehaus.org> wrote:

> Mario just got a first cut working for fine grained property change
> listeners. Previously when you call update() it will trigger revaluation
> of all Patterns of the matching object type in the knowledeg base.
>
> As some have found this can be a problem, forcing you to split up your
> objects into smaller 1 to 1 objects, to avoid unwanted evaluation of
> objects - i.e. recursion or excessive evaluation problems.
>
> The new approach now means the pattern's will only react to fields
> constrained or bound inside of the pattern. This will help with
> performance and recursion and avoid artificial object splitting.  We
> previously discussed this here:
> http://blog.athico.com/2010/07/slot-specific-and-refraction.html
> You can see the unit test here:
>
> https://github.com/droolsjbpm/drools/blob/ca55c78429cbc0f14167c604c413cdc3faaf6988/drools-compiler/src/test/java/org/drools/integrationtests/MiscTest.java
>
> The implementation is bit mask based, so very efficient. When the engine
> executes a modify statement it uses a bit mask of fields being changed,
> the pattern will only respond if it has an overlapping bit mask. This
> does not work for update(), and is one of the reason why we promote
> modify() as it encapsulates the field changes within the statement. You
> can follow Mario's chain of work on this at his github activity feed:
> https://github.com/mariofusco.atom
>
> The adventerous amoung you can pick this up from hudson, or from maven,
> and start playing now. My hope is that this will make drools much easier
> to use:
>
> https://hudson.jboss.org/hudson/job/drools/lastSuccessfulBuild/artifact/drools-distribution/target/
>
> Btw we are after a name. Drools is not a frame based system, so "slot
> specific" doesn't seem appropropriate. Property Specific seems a bit of
> a mouth full. I'm quite liking High Fidelity Change Listeners :) any
> other suggestions?
>
> slot-specific is the name used by Jess for this feature,
> http://www.jessrules.com/docs/71/constructs.html. It's also the standard
> way that Clips COOL works, which is the Clips OO module. Although that's
> partly a side effect of the triple representation of properties used in
> COOL, and the modifications are triple based. I don't know what
> mechanism Jess is using to enable this.
>
> Mark
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